This FAQ was kindly provided by Ray Williams and Chris Lloyd, GTiR FAQ gods in their own lunchtimes.
Visit their sites on the links page.
Q
I want to fit small number plates to my car - what's the score?
================================================================
From
the EVO list ... by David Johnson ...
"The
laws relating to figure size and spacing are as follows:
Group
1: For a single line-Characters 89mm(3 1/2") high.
64mm(2
1/2") wide-"1" width-16mm(5/8")
Spacing:
Either end of the registration-25mm(1")
Top
and Bottom----------------13mm(1/2")
Between
letters-----------------13mm(1/2")
Between
the groups of figures--38mm(1 1/2")
For
two lines: Same rules but space between upper and lower line-19mm(3/4").
Group
2 : For a single line- Characters 79mm(3 1/8") high
57mm(2
1/4") wide-"1" width-14mm(9/16")
Spacing:
Either end, Top and Bottom--11mm(7/16")
Between
letters----------------11mm(7/16")
Between
the groups-----------33mm(1 5/16")
For
two lines: Same rules but space between upper and lower line-19mm(3/4").
A
major minefield then-don't forget that there is a fine of up to £1000 and the possibility
of having your registration withdrawn-especially relevant if, like me, you've
got a personalized reg. Mind you, from the figures above I think we are all
crossing the line. A five figure reg even including a "1" needs a
plate 13 5/16" long ( I think!!)-pedantry maybe but some police live for
that.
Q
Wheels & tyres - what size will fit?
======================================
Generally
7" x 16 but if you want to roll the arches (the arch shape "L"
becomes a squashed "J" but you'll probably muck up the paint. I hear
it's possible to persuade the lip of the arch into the right shape with a wooden
baseball bat! I won't be trying this) then you might go to 7.5" x 17.
However, I also hear that when stretching the limits it's possible to get
fouling against the damper. Caleb has 17's on his, the SE-R net list shows 17's
too. One is shod with 215x35 profiles: this example also has
"Nulothane" bushes so it's possible that the owner has no sense of
feeling in his/her body - or it's a circuit car.
Tyres
are a moot point: generally, tyres that are good in the wet are not as good in
the dry (e.g., more wear) and tyres that are good in the dry are usually
hopeless in the wet. No tyre is "the best" at everything. There may be
an excellent compromise tyre, but is it too expensive for your budget? Also, in
the UK, it is rare for the air temperature to rise over 30c. On the two days a
year when that happens in the UK (like 1998) a certain tyre may give the best
'bite' and 'feel'. It's more likely to snow than that. If you do track days, get
a pair of spare rims, check the weather forecast (hahaha-UK only) and kit them
up with suitably grippy low-profiles. More debate on this one I feel certain!
Q
I want clear side repeaters?
Demon
Tweeks part no : ABCN-300, description : Side repeaters SUNNY/PRIMERA clear pair
(even says sunny GTI-R on the back)
Q
What should I do if I drown-out or have to cross a flood/ford?
================================================================
From
Craig Rogers - On the clutch housing, there is a rubber plug, after driving
through water that is over the height of the housing (not very deep if your car
is lowered), then you are supposed to remove this plug to drain [everything]
off, then put the plug back in. This is from the Nissan handbook that comes with
the car! - Craig
Q
How much boost can I run safely?
==================================
The
more, the less. That is - it depends what you want to do with the car. If you're
out to post the fastest time on a drag strip and can afford a rebuild
afterwards, then I've seen figures of 450 BHP from a well over boosted car. That
owner has gone through a couple of gearboxes, too. Standard boost is 9psi (give
or take 1psi) and if the usual engineering tolerances are built in, then up to
10% extra might be acceptable for everyday use, hence varying 'standard' boost
quotes up to e.g., "about 10.6psi". If you run anywhere near 300bhp
you'll probably fry the standard clutch. You pays your money and you takes your
chances.
Q
Oil - what's the best and what's to avoid?
============================================
Aside
from the obvious (use branded before it's too late, and change it as frequently
as you can afford) there is a debate raging on every car club site about what to
use for turbo's. If the oil you want to use meets the specification in the
handbook, you should feel confident that it will perform. If you're buying an
oil on a mate's advice - can he/she prove that the oil won't damage your motor?
If in doubt - ask your local Nissan dealer. I have used 0W-40 and 10W-50 with no
problems, both are fully synthetic.
Q
How low will it go?
=====================
-35mm
(1 1/2in) is probably as far as you'd want to go for everyday use: but check
first that your car hasn't already been lowered! After that - it depends on
whether you want to use all four (five) seats at the same time.
Chris
Lloyd adds ... UK spec Eibach lowering springs drop the back by about 30-35mm,
but the front is down a good 60-65mm but when you've got your mates in though it
sits fine.
James
Kazim says it's possible to go more than -100mm!
Q
What are the best geometry settings?
======================================
Horses
for courses - go radical and buy tyres twice as frequently as you should. That
is, too much camber (positive or negative ) will give uneven wear. So will too
much toe-in/out. But if it's for the track - you'd want the settings that give
the best performance and to heck with tyre wear.
Thanks
for the following from Chris Glassock <fritzsgtir@hotmail.com>
From
Nissan in China for a N14 / 4WD / SR20DET
----------------------------------------------
Where
d = degrees
Front
-----
Toe-in
(mm) 2 +/- 1
Camber
(degrees) -0 d 05' +/- 45'
Caster
(degrees) 1 d 15' +/- 45'
Kingpin
inclination (degrees) 13 d 15' +/- 45'
Rear
----
Toe-in
(mm) 1 +/- 2
Camber
(degrees) -0 d 10' +/- 45'
From
a Wheel Alignment Machine's Handbook in Sweden
---------------------------------------------------
For
a 1991 - 1993 Sunny / Pulsar GTi-R N14
Where
d = degrees
Front
-----
Min Max
Left
Toe 0 d 03' 0 d 09'
Right
Toe 0 d 03' 0 d 09'
Total
Toe 0 d 06' 0 d 18'
Set
Back ******* ******
Left
Camber -0 d 39' 0 d 50'
Right
Camber -0 d 39' 0 d 50'
Camber
Diff. ******* 0 d 30'
Left
Caster 0 d 30' 2 d 00'
Right
Caster 0 d 30' 2 d 00'
Caster
Diff. ******* 0 d 30'
Rear
----
Min
Max
Left
Toe -0 d 03' 0 d 08'
Right
Toe -0 d 03' 0 d 08'
Total
Toe -0 d 06' 0 d 16'
Thrust
Line ******* *******
Left
Camber -0 d 55' 0 d 34'
Right
Camber -0 d 55' 0 d 34'
Q
How do I keep my wheels looking like new?
===========================================
Oh
no! My wheels got dirty. Sorry, but for me there's more to life than worrying
about minor scrapes and smudges. If they're originals and they're bad you can
get them re-manufactured at almost any wheel/tyre outlet (they'll forward it to
one or two specialist wheel restorers): the current price is about GBP35-45 (GBP
= Great Britain, Pounds). I've seen some that have been done like this and it
seemed to me that a lot of meat was taken off, making the rims more susceptible
to further damage. Note that some tyres have a built-in 'shoulder' to help
prevent damage.
If
you must use a toothbrush to clean them, here's what works for me (every 2-3
years, I really hate this work). Wait until they're cold. Clean them out of the
hot sunlight - it just makes life easier. Wash with a wax-free shampoo: not a
washing up detergent - that will seize your callipers. Don't dry. Rinse and
agitate with a nylon bristle brush. Dry. Remove tar with a proper removing
fluid. Use Wonder Wheels or a similar product, as directed. Wash again. Dry. Wax
- no, seriously! But don't spray the wax, drop some onto a rag and rub
vigorously. Buff the polish off and that's about the best you can do. (Colour
Magic is good e.g., black for dark-pained wheels, because it has a slight de-oxidising
effect. That is, it takes a layer of paint/lacquer off ... not enough to make
any difference to the paint but a big difference to the finish). I would never
use power tools to do any of the above.
Maybe
toothpaste works, I've never tried it but I hear it will make your wheels smell
better that your average polish.
Q
Should I keep using the climate control in the winter?
========================================================
Yes.
It keeps the pump seals lubricated.
Q
Can I run leaded petrol?
==========================
One
has to ask why, but yes you can so long as the catalyst and lambda sensor have
been removed. If you live in the UK, removing a catalyst is illegal. This may be
true in your country, too. A lambda sensor will rapidly fail if leaded fuels is
used. A failed sensor will cause erroneous (possibly catastrophic) fuelling in
your engine. Still want to do it?
Q
What's a Lambdar(?) sensor, then?
===================================
The
Lambdar or O2 sensor measures the amount of unburned oxygen in the exhaust. From
this the ECU can fine tune the fuel mixture. This helps to improve efficiency
and is absolutely critical for the operation of the catalytic converter. Peak
operation of the cat is only possible at an air fuel ratio of 14.7:1 referred to
as "Lambda". An air fuel ratio of Lambdar is great for low emissions
and fuel consumption, but bad for high boost and engine speed. Consequently the
ECU ignores the lambda sensor at high boost and RPM. Therefore they cannot be
depended on for fixing fuel system problems.
Then
there's the following thesis by a Subaru owner which includes comparisons of
engine management systems ... "First off having carried out a great deal of
comparative work using the standard ecu and the Link ecu I would say that the
standard ecu works under close loop lambda control until the throttle is moved
significantly and then the ecu goes open loop and follows a pre-set map. On my
car it provides for an air/fuel ratio of approx 12.6:1 which coincides with max
performance.
Under
cruise or idle the air/fuel ratio is maintained at approx 13.6:1 by the closed
loop system. Davids comments about the principle of operation are therefore
supported by the checks I've done. For ideal economy the afr ought to be 14.7:1
(stoichmetric point).
The
lambda sensor being a galvanic oxygen concentration cell containing solid state
electrolyte becomes conductive for oxygen at approx 350 deg C.
Basically
it reacts to the state of the exhaust gas and, without boring everyone with the
tech detail, produces a variable voltage dependant on the amount of oxygen
present. (It needs NO external power to do this) Rich mixture will produce
voltages of circa 800-1000 mv and lean mixtures will produce circa 100 mv. The
transition from lean to rich is in the 450-500 mv range. The sensor operates
best in the temp range of 350 - 800 deg C. If 850 deg is exceeded then the life
of the sensor starts to be seriously shortened.. Most sensors are heated so that
they can be used after a few seconds. (that's why there are three wires exiting
them) The Bosch engine management system rocks the ecu about the ideal
(transition) point to achieve ideal emissions and best economy, the Subaru does
the same but does not "seem" to use the ideal point hence (I believe)
the richer running and poor consumption.
As
a definition Lambda equals the "actual inducted air mass" divided by
the "theoretical air requirement" and is an indicator for the
"excess-air factor" The stoichmetric air to fuel ratio is the mass
ratio of 14.7 kg of air to 1 kg of fuel "theoretically" necessary to
complete combustion.
So
output can obviously vary from sensor to sensor but exhaust gas temperature can
have just as great an effect on the readings, so can poor electrical contacts,
so can the ecu tolerances, fuel grade, contamination, too rich a mixture map etc
etc. The fuel consumption of an individual car is far more likely to be related
to its mapping and component tolerance than a variation in sensors. I know of an
instance where a sensor was seen to be malfunctioning (inconsistent output) and
was changed without giving any improvement in consumption. Also don't forget
that each time you move the accelerator whether on boost or off the ecu provides
extra enrichment to the engine so driving along with no boost and moving the
pedal frequently will result in increased consumption. Engine revs are obviously
a significant factor. Lead will kill a normal sensor, it destroys the platinum
coating, some sensors are more resistant to contamination than others ie Nissan
and some Bosch ones. For interest I ran a 270 bhp Vauxhall Turbo and used to
regularly achieve mid 30's in enthusiastic use. With care I could get high 30's.
Since
alterations to the afr must not be abrupt there is a time constant built into
the ecu which ensures that the adjustments are made progressively ... imagine
what would happen if mixture was adjusted instantaneously ... the car would jerk
around and become very uncomfortable not to mention the extra strain placed on
transmission etc.
So
swapping sensors may bring a change but, if it was me I would not be betting on
it.
BTW
they are also very fragile and can be expensive to replace dependant on
type." Phew!
Q
What's a turbo timer and must I use one?
==========================================
Last
point first: no. You can go without a turbo timer but after a period of on-boost
running, wait for at least a minute before switching the engine off or else the
turbo will be damaged by oil overheating in the bearings/shaft. You can guess
from this it's the purpose of a turbo timer to automatically prevent the engine
from being turned off and avoid consequent damage to the turbo. Note that it is
illegal to leave a car unattended with the engine running, even if it's locked,
in the UK.
Here's
what one user says using an automatic unit ...
"I
have a Blitz TT and it automatically works out the "OFF" time as to
the pressure that the turbo has been using . i.e. at 70MPH and an instant power
off this will require 4 min's. At 90MPH and an instant power off will require
5mins but if hitting traffic and then a town and then a power off this will
require any time from 10sec to ????? The average for most trips i.e.
town/fast/parking is 1.30mins. The most dangerous time for the turbo is fast
motorway then stopping at a service station.....loads of boost , loads of
heat...thus cooked oil on the turbo."
Q
What's the best alarm system?
===============================
How
about a very big, angry dog wearing a bullet-proof vest? It'd make me think
twice! Seriously, there's a golden rule about theft of any kind. Thieves, if
they want it, they'll get it. The better systems give you a chance of getting it
back at some later date e.g., Tracker (for details, see later FAQ q & A).
The better the (non-canine) system, the more it will cost. Currently, the
Disklock is popular in the UK. It fits over, and completely covers, the steering
wheel. My insurance demands a Thatcham (Association of British Insurers)
Category 1 Alarm plus Immobiliser. That, to me, is the bare minimum I'd
contemplate. With a rare (and getting rarer) model like the GTi-R all spares are
hard to get, legally. And like any work of art they have a relatively high price
on the street. Shame, but that's just the way it is. There's a popular story
about a high-performance car that the owner parked in his converted garage - in
pit lowered by a four-poster lift, all locked up. He'd had the work done because
he was fed up with it being nicked all the time. One morning he went out his
front door to see the car parked outside his house. With the keys on the
driver's seat. The tealeaves did it just to prove that it could be done.
Thatcham
approved alarms are listed at http://www.thatcham.org/preview/html/seclist.htm
Q
Can I replace the standard catalyst with a high-performance one?
==================================================================
There
have been no reported problems with doing this.
Q
what's an extended warranty and must I have one?
==================================================
Last
point first, again: no. But if you don't get a warranty and the starter motor
goes you could be facing a bill up to four times the cost of the annual warranty
premium. That's what an extended warranty does - it covers you against certain
unforeseen expenses. So, it's another form of insurance. Warranties generally
exclude items that are subject to "wear and tear" - like exhaust,
brake pads and clutch. There are usually limits on claims, too. For example my
policy covers me for up to GBP1,000 per claim and no more than GBP3,000 in
total. Check the list of excluded items before you buy the cover and judge for
yourself whether it's worth it. There are a number of national and international
organisations providing extended warranties. A warranty of this type usually
requires that the insurer arranges an inspection: it's to cover shed's being
covered then huge claims being made.
Q
What does the intercooler do? Can I get rid of it?
====================================================
When
air is compressed heat is generated. The air compressed by a turbocharger can
easily reach 250F or more. At that extreme, the air density is down, and so is
power. For best engine efficiency and optimal power, the ideal air temperatures
is at or below 160F.
Some
intercoolers cool down the air from 250F to 160F, but suffer a large pressure
drop in doing so. This can cost 20-25% in power. On the other hand, some
intercoolers do a good job of retaining pressure but at the expense of cooling.
What's
needed is a super-efficient intercooler that maintains boost pressure and
slashes charge temperature. Free-flowing intercoolers help the turbocharger,
especially at high RPM. Done right, intercoolers also reduce engine-threatening
detonation.
There's
often not enough room to fit an intercooler of sufficient size: some employ what
they call an "inner-fin" design.
Another
rule of thumb - the more boost you run, the hotter the compressed air.
An
old rule of thumb used to be 1bhp per degree C. A recent quote said "The
expected figures should be 1bhp per 3-5 degrees C that you can lower the intake
temperature by".
So,
don't throw the intercooler away, unless you want less power and are trying to
destroy the engine.
Q
How can I get a Workshop Manual
=================================
Order
part numbers Part # SM1E-1N4BG0 (Vol 1) and SM1E-2N4BG0 (Vol 2)
In
Australia get workshop manuals from Bookworks in Sydney. This mob is the
supplier for all Nissan manuals.
Contact:
Bret Shadwell
56
Bonds Road, Punchbowl NSW 2196 Australia
Ph:
61 2 9740 6766
Fx:
61 2 9740 6591
Vol
1 - Aud$395
Vol
2 - Aud$295 (just mortgage the house)
There
is also a supplementary book which just covers airbags, air conditioning, seat
belts for an extra Aud$90.
Huge
thanks to Carolyn Peterson for that info.
Q
Are standard brakes adequate? If not, what can I do to improve them?
======================================================================
It
depends on what you define as adequate. What do you want to use your car for? Is
it a full-out circuit car or a cruismobile? That's the deciding factor. How
often will maximum braking be required? If the answer is "only in
emergencies" then the standard brakes are probably "adequate".
More than that and the question is more difficult to answer. Why? Well a bit of
theory won't go amiss, first, in helping you to decide what to do.
Few
cars can exceed 0.8g deceleration. The limit is the tyres breaking grip
(locking). Full braking from 120kph on a GTi-R generates enough energy to bring
2 litres of water to the boil from ambient temperature. This heat has to be
eliminated. Nearly all the energy lost during braking is turned into heat in the
disk. The pads heat up, of course but it is also their job to insulate the
caliper from heat. A small amount of noise is unavoidable.
Size
matters! If the disc becomes too thin, wear will increase exponentially, because
heat cannot be eliminated into and from the mass of the disk during braking. The
disk overheats and stresses form in all components. As an example, the surface
temperature of a worn, 4mm thick disk increases by almost 3 times that of a new
10mm thick disk. At a depth of 2mm below the surface the temperature can bu up
to 800oC. The minimum thickness of a disk is indelibly marked on the outside
edge. Final surprise: the disk melts during braking. Not much - but just a few
microns under the surface, the temperature exceeds the melting point of cast
iron.
So
how can the brakes be improved? Well, under maximum braking the load is
transferred to the front axle, so the front brakes are the most critical.
If
you want to retain standard running gear the only options available are improved
pad material and braking fluid.
There
are four major components of a braking system;-
a)
disc
b)
pads (or more specifically, the pad material)
c)
caliper, piston(s) and seals
d)
brake fluid
If
you want to use the car on the track, you'll probably need to change everything,
including your budget.
i)
bigger diameter discs inside bigger wheels
ii)
cross-drilled and grooved disks (ventilated, of course)
iii)
competition pads that only work after they have need brought up to temperature
(dangerous for road use)
iv)
competition brake fluid that resists boiling better than standard fluid
v)
lighter, open, multi-pot calipers in aluminium to get rid of heat and keep it
away from the brake fluid
vi)
full stainless steel braided hoses
Failures
can be characterised in any of these components, however, catastrophic events
due to high-energy use will generally only occur in either the disk or the
fluid. Brake fade due to vapour lock in the fluid is usually progressive, so
that just leaves the disks.
Failure
commonly arises from;-
1)
poor fitting (over-torque/dirt on the braking surface/mis-alignment/no
running-in/caliper movement)
2)
incorrect theory (disk is too small/thin/poor design/non-homogenous/wrong
mix/under-specified)
3)
wrong or poor pad material (vitrified disk/excessive pad wear/scoring)
4)
excessive wear/cracks (not checked before use)
There
are many other elements embodied in the brake system: the pad material can
comprise up to 20 separate components. Most surprising (to me, anyway) are the
inclusion of marble and graphite! The discs contain 93-94% grey cast iron.
Carbon, silicon and manganese make up nearly all the rest but there are 9 other
elements which are mainly impurities of manufacture and are impossible to
eliminate.
Conclusion:
generally, bad brakes are ones that are just plain being asked to do more than
was intended in the original design or are not properly checked/fitted. A 1974
1.5 Golf weighing 780kg uses the same disk as a 1030kg MKIII - because they got
it right for normal, everyday use.
For
the really brake-addicted, add water cooling. Fog water into the back side of
the rotors with a separate windshield washer motor. This pump can run
continuously on the track. With these simple modifications you can vastly
increase your stock brake's performance without spending huge money.
Q
Is the standard clutch ok. How can I tell (answers from Dean Brown)
=====================================================================
Clutches
are rated by how many kg's they can handle. A standard road car will be able to
handle 400kg. Most NA 4 cylinder cars have 400kg clutches. A hypo 4wd car will
have a stronger clutch because there is more weight to push around in the
drivetrain. The Nissan Pulsar GTi-R has a standard 600kg clutch, this will and
does feel heavier than a standard road car. Nismo make upgrades to 880kg and a
special 960kg (almost a 1 tonne clutch).
Also
when upgrading clutches try and get a carbon kevlar clutch as these will last 3
times as long as the standard unit. I am upgrading and will be getting a real
mix and match job done. 1 side will be copper for total grip, and the other side
will be kevlar for a bit of slip. One other thing to note is that kevlar grips
better the hotter it gets.
Would
you buy a secondhand car 'blind'?
Do
all the usual checks first - Japanese log book/service record. And don't be
fobbed-off, good ones have a full Japanese service history to back up the odo.
Clocking is rife, so buyer beware!
Here's
what one NZ list member has to say ...
Some
guy went over to Japan because of these rumours and went to an auction and
watched and noted the cars the NZers bought, he got the original reg forms from
the authorities over there and brought them back. He found the people that
brought the cars and they did a TV show on it. One guy had a 90 Subaru Legacy RS
that had 65000km on the clock and in Japan it had 155000km on the clock.
Why
do they do it? Because clocked cars are cheaper and about all that is available
over here. Some places guarantee the odo reading and they have stopped winding
them back, but it hasn't affected the price. Yep buyer beware, most people don't
believe the odo reading anymore so that is OK, you just have to get the car
checked for everything.
The
upside of this is that if the car is three years old (or 5, 7 etc) in Japan the
owner has to get the car totally checked and every nut and bolt is replaced to
meet their rules for a Warrant of Fitness ("shaken", see below). So If
you get a car that has been through this situation you should be fine.
Japanese
cars are sold with "shaken" which is commonly referred to as motor
vehicle registration, but is actually a series of taxes, tests and compulsory
insurance that you must have to drive your vehicle on the road. It consists of a
Safety Inspection, Compulsory Insurance, Weight Tax and Vehicle tax. It's like
an amalgamation of UK MOT (but taken to a much greater extreme) and insurance.
The "shaken" that comes with a new car is valid for three years, but
must be renewed at expiration at an average cost of US$1,500. The Japanese
enforce this rule with strict penalties. The "shaken" is renewable on
a bi-annual basis for the duration of ownership of the vehicle. Consequently,
most vehicles available on the used market are 3,5,7 and 9 years old as they are
usually traded in or sold by the user when the "shaken" expires.
Purchasing vehicles with 6 months or more valid "shaken" increases the
value of the vehicle domestically and generally is more expensive than units
with no "shaken" left.
Q
what are all the suspension bits? What do they do? Must I fit a strut brace?
==============================================================================
Rather
than try to answer all this, I've ducked out - look at http://www.geocities.com/MotorCity/2195/suspension_bible.html
for all your answers.
Q
But the GTi-R uses a system called ATTESA! (bless you) - what's that, then?
=============================================================================
Here
are a few mails received on the subject ...
Thanks
to Dean Browne for the following;-
ATTESA
- Advanced Total Traction Engineering System for All-terrain
Yep,
thats what ATTESA stands for and thats what it does, except it is not so
advanced. One thing to note about the ATTESA system in the GTi-R is that it is
not electronically controlled. The R33 and R34 Nissan Skyline GTR have the
Electronically controlled version of this but that system has the actual name of
ATTESA-ETS. The R32 and ["luxury"] GTi-R Nissans have a mechanical
system based on so called clutches
GTi-R
Rear Diff and front diff: It may not be called an LSD by most people but in fact
it's design and function are very similar. The basic function of the limited
slip diff is to distribute power to the wheel with the most traction. The GTi-R
ATTESA set up is built to do this. The rear and front diffs have clutches in
them (well almost), these look like a CDROM disc with the last 1-2cm of the
CDROM bent out on an angle. These clutches work in a surprisingly easy way. When
the person driving the car puts the foot to the floor so to speak there are a
several events that happen.
1,
The power to driveshaft increases.
2,
The spider gears push the side gears away from the diff towards the wheels.
3,
This increased load(push) causes the clutches to straighten and lock.
4,
The lock increases the power to that wheel. (remember this happens to both sides
of the car).
What
happens when a wheel loses traction, The clutch on that side of the diff will
lose its lock and therefore power will be forced onto the other wheel. simple??
The
centre diff on the GTi-R:
There
are 2 type systems used on GTi-Rs, If you own a rally version you should be able
to see the centre diff underneath your car. If you own a road version the centre
diff is actually incorporated inside the gearbox housing. The reasons for this
are obvious as the rally cars may have needed to have the centre diff changed
during a rally and the easiest way to do this is to have the centre diff on the
outside of the gearbox. These 2 systems function in the exact same way though.
I
have heard stories about the centre diffs in the GTi-R about whether they are a
fluid/gel based unit or just another locking unit with clutches. I don't know
which one it is yet but they both do the same thing it will sense (not really,
it's mechanical) the loss of traction and distribute power in the other
direction.
That
is as simple as I can make it and about as much as I know at the moment. When I
get more information I will pass it on. There is nothing really advanced about
this system and most other 4wd vehicles have a very similar system. As for the
50:50 torque split, it well known that this split is best used on gravel or wet
roads.
Hope
this enlightens some and helps others. Any feedback or other ideas about this
system will be appreciated. Dean
Anthony
Dix adds ...
The
rally cars (Group A/WRC car not the homologation version) have an active centre
diff (hydraulic clutch), just like a R32 GT-R. I assume they also had electronic
control using g-sensors and wheel speed inputs. ATTESA is totally rear wheel
drive until wheel spin is detected, then the centre clutch is engaged to feed
torque to the front. ATTESA E-TS is the same but can also electronically control
torque split between the rear wheels.
Joe
Peterson says (and I believe him!) ...
The
ATTESA 4WD system is not a true all time 4WD. The rear diff has a viscous
coupling permitting both wheels to drive under power, if one looses drive it is
then transferred to the opposite wheel locking the rear drive shafts as one, the
front is a conventional spider gear diff with no viscous coupling inside thus
power is lost when one front wheel loses traction, the front viscous coupling
sits between the transfer case and drive shaft to the rear diff, which would
allow a certain amount of slip to the rear diff. Drive from the gearbox is
always available to the rear wheels through the transfer case. If 4WD was to be
maintained all the time ie. 4 wheels truly under power you would not suffer from
oversteer as GTiR 's do because the car would be pushed and pulled through a
corner not just pushed. If you look at the homologated GTiR its a totally
different ball game, as it is a true all time 4WD dependant on what diff and
transfer case combination you choose. It had additional electronic torque split
and controlled slip diff with an automatic rear torque releasing system. In race
or rally cars all time 4WD is feasible as with wheel spin or lifting off one or
more wheels during hard cornering you dont suffer from diff bind as you would in
a road car. Hope this helps without getting to technical, (all this is out of
the w/shop manual & the original FIA GTiR Homologation Grp A Forms)
Finally
(for now) from Anthony Dix ...
I
have been in contact with Protech Developments in Melbourne re the GTiR 4WD
system.
The
Nissan WRC car based on the GTiR had an active centre diff under computer
control. This car is far from the 'Rally' version available to the public. (i.e.
your car.)
The
two versions available to the public (luxury and rally) had the same 4WD system:
-
viscous limited slip diff at rear
-
viscous coupling at the centre (passive)
-
open front diff
Q
I've heard about intercooler watersprays - what does it do?
=============================================================
The
aim of the exercise is NOT to wet the intercooler.
By
spraying an atomised mist of water into the stream of air entering the scoop,
this air is "air-conditioned" by your evaporative air-conditioner, and
is thus cooled to below ambient air temperature, effectively creating a
wind-chill. An Australian turbo owner (non-GTi-R) has done tests with heat
probes and found that a good waterspray (not a firehose!), plus airscoop
splitter, will reduce the outlet temperature from a Subaru intercooler by 10% or
8 degrees celcius. This is horspower for (almost) nothing, and is also a really
"cool" trick. A useful addition is a small LED which lights up when
the pump (switched on by boost) is pumping.
Q
Have I got a problem with my turbo?
=====================================
My
reference for this piece is Car Mechanics magazine. I've limited it to a
description of how turbo's work and Faults/Diagnosis.
How
does it work - this is fairly basic stuff, so skip if you already know. The
turbo has two distinct (and in terms of gasses, separate) sides, inlet and
exhaust. The turbo is driven by the hot exhaust gasses being passed over a
turbine before exiting the turbo housing to the exhaust system. The shaft that
the turbine is attached to also drives the inlet side, the impeller. The
impeller sucks fresh, FILTERED air in, compresses it and forces it through the
intercooler. The path over the impeller raises the fresh air to about 98C above
ambient: the intercooler tries to reduce this back to an acceptable level (not
very successfully on the GTi-R because the air/air rad sits on top of the hot
engine - bad design!). The turbine/impeller shaft has a hard life and the only
relief it gets from spinning at up to 200,000 rpm with one hot end and another
not-so-hot end is via the cooling oil bath forced through an oilway in the
centre housing between the turbine and the impeller - in at the top and out at
the bottom. Without anything to control it, the turbine would spin up
excessively. This would soon destroy the turbo - and the engine - so a bypass is
incorporated into the exhaust side to vent away excess gas to the exhaust before
it can drive the turbine to excess.
What
can go wrong - turbo's are'nt in the rocket science league: there's not much to
go wrong. But when it does it will be either a gradual loss of efficiency or a
catastrophic failure. Here's a list of common faults;-
A1)
Oil starvation: not just "no oil", but possibly also "the wrong
oil" (see this topic elsewhere in the FAQ). "No oil" can be
caused by blockage in the inlet OR the exit oil feeds, or in the oilways in the
central housing. "The wrong oil" could be poor quality/wrong SAE (see
this topic elsewhere in the FAQ) or contamination i.e., not changed frequently
enough, read "normal service intervals".
A2)
Damage to the impeller caused objects introduced by unfiltered air. This will
rapidly exacerbate the problem because the impeller will break-up and
self-destruct.
A3)
excessive build-up on the impeller or turbine blades. The turbine/impeller unit
is dynamically balanced during manufacture to very fine tolerances. Anything
that attaches itself to one or the other will un-balance the unit and create (or
accelerate) wear.
A4)
I want to repeat the bit about oil contamination, here. The turbine/impeller
shaft runs on phosphor-bronze bearings. Yes: solid metal. You can get
replacement roller bearing turbo's and yes, they are expensive. Anyway, whatever
the bearing, you get a bit of junk in there and ... instant bearing wear. You
don't get a second chance.
A5)
deliberately excessive overboost - the turbo is designed to run at the
manufacturers' settings on the wastegate actuator. If this is exceeded by any
huge amount - you'll have fun for a while, but it will cost in the long run.
What will eventually happen is that the turbine will "lose" bits off
the fins which in turn will hit other fins and so on. I've seen pictures of this
effect where 50% of the turbine blades are just not there any more. Better to
fit a different turbo more suited to the boost you want to run.
A6)
fragments of worn engine! Yep it can happen. So, if the engine is in that bad a
state that it's donating itself out the exhaust, these bits will hit the turbine
and break it up.
A7)
faulty actuator - sticking closed can cause excessive overboost (see above).
Q
How can I tell if my turbo is broken?
=======================================
Lack
of power, strange noises, excessive oil consumption, oil leaks and blue exhaust
smoke. If that all sounds like the symptoms of any other engine problem - you're
right. So, check the rest of the engine first. Get the cylinders
pressure-checked, make sure plugs and electrics are good etc etc.
If
the shaft is worn, oil will find it's way past the seals and exit either into
the inlet or the exhaust compressor: result - heavy oul consumption and blue
exhaust smoke.
If
the oil exit from the center housing is blocked you'll get the same result.
If
you're not sure - there are specialists who can give you an inspection and
report.
Q
How long will a turbo last?
=============================
Properly
serviced - and that just means oil/filter changes regular intervals with the
right grade/quality oil and a _proprietary_ filter (don't save pennies here it's
not worth it and the Nisssan unit is cheap anyway) - expect between 75,000 and
150,000 miles out of the turbo depending on how it's used.
Q
What's the best upholstery cleaner?
====================================
This
one could save you some money ... there is no "best". A recent survey
in the UK declared no outright winner. And, that _all_ the products tested made
the fabric come up the _same_. Even after long-term trials. Buy the best value
for money and the easiest one to use.
Q
What's "matching", then?
==========================
No,
it's not a dating agency - but the principle is similar. It's a technique used
in blueprinting any engine.
Imagine
two pipes of exactly the same diameter. Both have flanges welded on to one end
(the other two ends are irrelevant for this example).
They
are made by different companies.
Each
company works to the manufacturer's recommended tolerances.
And,
there's "give" in the (four) mounting holes.
Result
- the pipes won't form a continuous uninterrupted flow inside.
Solutions;-
1)
make a jig to line both pipes uo 100% - and use it every time the pipes need to
be reconnected. And make a new one every time you have to replace one of the two
pipes. And the jig must be able to be used "in situ". Not very
practical?
2)
weld two or three "pegs" into one flange and drill the same number of
holes (interference fit only) in the other flange. The trick is to mate the pegs
and holes (my wife who is "helping" with my spelling can't stop
laughing at this stuff!) so that the id of both pipes gives 100% flow. I did
this with a Ford xflow twin 40's inlet manifold and it worked a treat. I did it
by measuring (id-to-hole centre on one side, id-to-peg centre on the other).
Nothing's ever 100% but 99.9785% is ok for me.
A
by-product of pegging is that it's a piece of cake to get a 100% fit every time,
without fail. No matter how much of a hurry you're in nor how cack-handed you
are - like me.
This
whole idea is not for the casual, one-off fit, mind. It will take ages to do it
"perfectly" - especially for us amateurs. It's more suited to the
repeated removal/refit or them as wants a "perfection" once ever. Just
like that dating agency!
Q
What's a knock sensor then?
=============================
The
knock sensor is basically a piezoelectric microphone. The ECU uses a knock
sensor chip to provide a bandpass filter tuned to the knock frequency (unique to
each different engine design). It then full-wave rectifies and integrates the
signal to provide a level indicating knock. Typically two channels are used -
one as a reference not tuned to the knock frequency which is subtracted off the
knock signal to eliminate the (huge amount of) background noise. To further
eliminate noise, the ECU uses the camshaft position sensor to only
"listen" and the point when knock is likely to happen. All in all it's
quite involved to get a reliable electronic indication. (You may see the
"pings" on a digital oscilloscope though.) A stethoscope and a long
rubber tube was the best solution.
Harris
Semiconductor make suitable chips, full details on:
http://www.semi.harris.com/auto/engine.htm#KNOCK
Their
chips need a microprocessor interface to program the knock frequency.
I've
also seen teh "old fashioned" method - take any long screwdriver, put
the sharp end onto any part of the engine you're interested in and put the blunt
end on (_not_ in!) your ear.
Q
Can I add liquid power (additives)?
=====================================
Toluene
- see http://mail.odsnet.com/TRIFacts/36.html and decide for yourself!
Methyl
Benzene (aka toluene). If you take Premium unleaded as having an octane rating
of 96, then a 10% mixture of Methyl Benzene will raise it to 98, 20% to 100 and
30% to 102. They [Shell] do not recommend a mixture of more than 30% due to
volatility constraints.
Q
What happens if I break down - how do I get it towed?
=======================================================
Thanks
to Carolyn for this ...
NISSAN
recommends that the 4-wheel drive vehicle be towed with all wheels off the
ground as follows:
1.
Using a flat-bed truck.
2.
Using a combination of a tow truck and a dolly.
Towing
with four wheels on ground, observe the following restricted towing speeds and
distances.
Speed:
Below 50 km/h (30 MPH)
Distance:
Less than 65 km (40 miles)
Never
tow a 4-wheel drive model with front or rear wheels raised and rear or front
wheels on the ground as this may cause serious and expensive damage to the
transaxle. If it is necessary to tow the vehicle with the front or rear wheels
raised, always use a towing dolly under the rear or front wheels.
Q
What's a dump valve and what does it do? What are the different types of DV?
==============================================================================
When
the boost is increased on a modified turbo car, the standard dump valve usually
cannot cope with the extra air it has to release when the throttle is shut. This
can lead to permanent damage to the turbo as the air is forced back through the
inlet blades.
The
following three related topics are utter steals from another Turbo site - no
apologies ... it's common knowledge as long as you subscribe to every
potentially related list!
"The
purpose of a dump valve is to allow the turbo impeller to carry on spinning,
when the throttle is lifted. If one was not fitted, the impeller would stall
against the pressure that would build up, when the throttle butterfly closed,
blocking the passage of intake air. Without a dump valve, the turbo would have
to spool up from near standing, after every lift or gear change and the lag
would make the car very difficult to drive."
"If
any dump valve is working properly, it will be fully closed when the car is on
boost and there will not be any performance advantage from changing it."
"When
the throttle is lifted, the vacuum in the inlet manifold pulls opens the dump
valve diaphragm and the valve should open quickly and offer the minimum
resistance to venting intake pressure. "Vent to atmosphere" dump
valves (the noisy ones) offer slightly less resistance than re-circulating ones
(as fitted to Scoobies), but will allow air to enter the intake manifold through
the valve when driving off boost... giving false air mass sensor readings. This
is because the amount of air passing the air mass sensor is not the total amount
of air that the engine is breathing in."
"In
a re-circulating system, the dump valve still allows air in, through it, when
off boost. But that air has passed the air mass sensor."
"As
for sequential dump valves... hmmm. The best dump valves are the ones that go
fully open to fully closed as quickly as possible."
"Even
with vaccuum in the manifold there is positive pressure in the intercooler side
of the throttle body. At a brisk cruise off boost you could get up to 0.4 bar
pressure. (and you could have up to 0.4 bar of vaccuum, so 0.8 bar differential)
If the dump valve opens at approx 0.4 bar the differential will definately keep
it open if the
spring
is too weak. If you want an externally venting dump valve then the Bailey
Motorsport EVO one is the way to go. It has a double piston in it. The bottom
one stays shut and allows the top one to open under the conditions I've
described. The two open together when you come off hard boost so doing their
job. It ensures there is no air leakage from the system except under proper dump
conditions. Spent nearly 6 months trying different types on my Cav turbo. When
this one became available ... worked first time with no probs."
Q
I'm just a bit unsure about what happens in part throttle, on-boost situations
where the turbo is blowing more air than is being allowed past the throttle. Is
it possible for the dump valve to open here? Might it explain the 'blowing over
a bottle top' noise I get in these part throttle situations (but never under
full boost)? Or is my standard valve faulty?
==========================================================================================
In
these situations, the inlet manifold will register positive boost and the valve
will be shut. At a steady throttle, at say 70mph, the car is off boost. Move
your foot down an inch and the car will go on boost.
The
valve has a spring and the pressure of this spring will determine at what
negative pressure the valve will open.
Q
And I don't fully understand why a 'vent to atmosphere' dump valve should leak
air back into the inlet manifold. Surely that is more down to poor design than a
fundamental problem with this type of valve?
============================================================================================
The
"plug" will be held open by the negative inlet manifold pressure and
air can pass both ways. I have heard of VTA dump valves that have a non return
system, but the more complicated you make a dump valve, the less
reliable/efficient it will be.
Q
is there a cunning way to link the ECU to a pager to permit/restrict access to
the vehicle?
====================================================================================
"It
seems to me to be a really good and inexpensive idea to provide decent security.
I suspect that in the long term the problem might be that the cunning thief will
already have bypassed the ECU etc. to get the car started. In that case it might
be important that your pager system was totally unconnected to and remote from
the ECU. Something simple like it controlling a relay in the power supply to the
fuel pump might be the way to go."
"Some
time back there was an Escort Cosworth taken in Belfast despite hi-tech
protection. The thief brought his own "ECU" type device with him and
replaced the one already in the car. He then got in and drove off. There were
also cases of people owning desirable cars finding that their cars were broken
into in order to steal the ECU and it was thought that this was to produce
"hacked" units which could then be used to steal cars of the same
model."
"In
such a situation if [the thief] was able to get some distance before you shut
down the fuel pump then he would assume, hopefully, that his ECU had a fault/bad
connection etc. and might abandon the car."
"In
Belfast this system, like Tracker, is little use unless you could activate it
very quickly as the police do nothing about car crime. There are over 9000 cars
stolen every year in Belfast and almost all are found
burnt
out/wrecked in one very small area of the city. Due to politics (i.e. it would
be termed harassment) the police can't go into this area to halt the problem and
so they just ignore all car crime. If you didn't
activate
the system within a very few minutes of the car being taken then you would
probably find it burnt out in the same area as all the rest."
End
of steals!
Q
My HKS SQV makes a high-pitched "chirping noise" - how can I get rid
of it?
=============================================================================
The
squeaky noise is normal for a standard SQV. If you want to lose the high pitch
noise HKS do a replacement vane for the unit. It makes a huge improvement over
the Japanese sound of the original. The replacement vane is widely available for
about 12 gbp. The vane allows the valve to dump pressure without any whistle,
which sounds great when used with a cone filter (super powerflow etc...).
Q
What do I look for when buying a car?
=======================================
Received
and posted on to us by Craig from a guy in the states ...
"Things
to look for on GTi-Rs when purchasing, I will assume it is a fresh Japanese
import to the UK. First check for the basics, smoke out of the exhaust, oil
colour, water colour in radiator. If it is smoking don't buy
it,
if the colours are off see if it will be fully serviced. Check the hoses under
the intercooler for cracks, they dry in the heat and will crack after about 3-5
years, makes them very weak. While the intercooler is off check for oil on
either side of the endtanks, If there is oil in the intercooler this can cause
the car to smoke and is most likely caused by a lack of oil changes or a
broken/blocked oil separator. Start car and listen to idle if is rough O2 sensor
could be gone, also check the dump pipe on the turbo to see if it is
moving/shaking against the turbo, this is caused be some loose nuts and is easy
to fix.
When
driving the car don't test the radio :-), listen for clunking/thudding noise
when driving straight/around corners these noises will be the wheel bearings, if
the car has 16-17inch mags the wheel bearings will not last as
long
as they should. these are easy to fix if you have the tools otherwise it takes
about a day to do all four and will cost about 50 pounds for each one excluding
labour.
Check
boost level, if it goes off the gauge it will have some sort of computer/chip
upgrade of boost controller. These computers and chips are ok as long as you can
get 98 octane gas which is what they use in Japan. Using a chip/computer/boost
controller on low octane gas can cause collapsed pistons, bearing wear, smoke,
and dead engine in the long run. See if it will be easy to reprogram the
computer or buy a reprogrammable one.
Check
the glove box for holes and the dash for sticky residue, this can indicate the
placement of other controllers that would suggest the car has been running a
[lot] of boost and like most young guys in Japan the car may have been raced. A
roll cage is also a good indication of this :-)
Again
in the car, listen for whines from the drivetrain, if there is any whines from
the rear of the car the rear diff is stuffed. If the whine is from the front of
the car it can be the gearbox or the front diff. If the whine is all around the
car it could be both diffs and gearbox or the centre viscous LSD. any of these
will cost a packet to replace. Try over 1000 pounds for any new diff. When in
first gear there is most likely to be whine, I haven't worked out if this is
from straight cuts gears or if my bearings are [worn-out]. Any other whines in
different gears will most likely be the gearbox bearings or diffs.
Check
all the electric windows if it is the road version these seem to break easy and
will be held up by wood in the door. Check the chassis number it should be
something like RNN14-xxxxxxx. I can't remember if it is 7xs or
6xs.
The rally versions will not be numbered or will have no rear wiper, [cheap]
vinyl seats, manual windows, and mirrors. These are very limited but normally
sell for the same price as the road version."
Q
I've heard that the MAF sensor may give problems - what is the fix?
=====================================================================
Another
one from Craig ...
MAF
Sensor grounding
First,
you'll need a digital voltmeter and a small flat blade screwdriver.
The
MAF sensor is located just past the air intake. You'll need to pull back the
rubber cover to expose three wires. On mine, the outer two were orange, the
middle one is white. The middle pin is where we need to get a voltage reading
from (with the engine idling). Take the positive lead of the voltmeter and make
contact with the middle wire. The negative lead should be pressed to one of the
ground connectors on the engine block, near the firewall, right behind the fuel
injectors. You might have to look hard to see them, just look for a bolt with
several black wires running to it. Took me a while to spot it myself, several
vacuum hoses in the way...
The
voltage read should be less than 9mv (.009v), if it is above this value, the
sensor needs to be regrounded. To do this, a wire needs to be run from the
middle pin to the ground lug. You'll need to remove the connector from the MAF
to get a good angle on it. On either side of the connector is a small opening
for a small flat blade screwdriver. There is a wire that runs around the
connector to hold it in place, you need to pry this wire outwards, then move the
connector back a bit. Do one side, then the other, and it should pop right off.
I'd never seen this type of fastener before, once you have it off you'll see
what I mean.
You'll
want to solder a new wire to the middle pin, make sure you get a good
connection. Then, run the other end to the ground lug. If you want to do the job
right, you'll want to get a connector from Radio Shack or other electronics
store that has a ring that you can crimp the wire to. I don't remember the size
of the bolt, so I'm no help there. I just looped my wire around the bolt twice
and put it back on. I may go back and fix it up nice some other time.
Once
the sensor is regrounded, the voltage should drop significantly. Mine was at
around 11mv, after the fix it went down to less than 2mv.
Q
What's this pinking/detonation stuff and have I got it?
=========================================================
Pinking
is where the ignition is too far advanced..the burning in the combustion chamber
happens too early and actually tries to push the piston back down before it's
reached the top.
Detonation
is where the temperatures inside the combustion chamber are so high that the
fuel/air pre-ignites before receiving a spark. Same effect as pinking i.e.
burning occurs too soon.
98RON
"resists" detonation better than 95RON.
This
is why cars running high boost need methods of lowering the temp inside the
chambers - Water Injection is one method.
Nitrous
injection also has very good cooling properties.
And
I believe the grade of spark plug is important..one that runs too hot will
likely pre-ignite the mixture ?
Q
What's a Tracker, do I need it and what'll it cost?
=====================================================
24hr
tracker, they fit the car with motion sensors, so if the vehicle is moved an
alarm sounds at the tracker head quarters, they ring you immediately and
activate the tracker. The car has to move forward or backwards, not like the
interior sensor of an alarm.
Cost:
£778 fitted no yearly subs or £434 with a yearly sub of £95.
Example
- £130 saving on insurance.
It's
a bit pricey but ... it's cheaper than a new car?
Q
I want to upgrade but I'm confused - what do I do first?
==========================================================
Here's
my 8-step upgrade path ... it's just a suggestion. You can do as much/little as
your budget allows but step number one ...
A1)
Plan it.
A1.1)
Decide what you want to do and cost it - then double the cost, 'coz that'll be
more comfy for you if it costs less! Include Insurance increase too, to stay
legal.
A1.2)
When deciding what you want, for each part you're replacing ask yourself two
things
A1.2.1)
Will I be replacing it again in six/12 months? Selling new bits secondhand
hardly used can be heartbreaking - you rarely get what it's really worth.
A1.2.2)
Is it the best I can afford? You gets what you pays for - but be sure that what
you're getting is _really_ worth it by shopping around
A1.3)
Be realistic with your plan. Aside from "can you really afford it"
(you always will if you _really want to achieve the goal), by starting with a
bits list plan, budget and timetable you won't be frustrated because you always
seem to be waiting forever for the next thing to arrive. Speak to suppliers, one
I contacted recently was working off an 8 to 10 week order book.
A1.4)
When you plan what it is that you want, take into account insurance premiums
being hiked. Ask them _in writing_ first. Do it _before_ you start.
A1.5)
Get the info. Ask everyone, don't be put off and disbelieve everything unless it
can be proven (within reason).
A1.6)
Get hold of the experts. Find out who they are. Get their commitment. if it's a
"couple of pints" job then be prepared to be disappointed.
A1.7)
Insurance again - if you're getting anything done for you make sure the fitter
has got a recognised qualification. You might be asked, so it's worth checking
out.
A1.8)
When you're budgeting, include labour charges.
A1.9)
Finally, be honest with yourself: will the end product really be what you want.
Will it be "fit for your purpose" or will it be an expensive folly?
A2)
Brakes and tyres (& wheels)
To
quote a recent mag - what do you want more brakes for? They only slow you down!
Yep.
That's
the whole point. You _will_ slow and you _will_ be able to brake later (deeper
into the corner). Follow this, saving 0.5 sec because of _relatively_ cheap,
better braking system would cost a huge amount to increase BHP by an equivalent
margin.
If
you're not upgrading to bigger disks then tyres are first on your list of
upgrades.
If
you are fitting bigger disks, first comes the wheel size. Max practical is
7.5x17 (with a little fouling if combined with lowered springs). Then come
tyres. Then the brakes.
Don't
go more than 4-pot as the standard brake master cylinder can't cope: re-work
that and six-pots are back on your shopping list.
Don't
forget to upgrade the brake fluid and the flexible brake pipes.
Do
a proper brake ducting job: get fresh air directed onto the disks/calipers.
NB
Full-house brake pads don't work very well if they're cold. You might fail the
MOT(UK)! And you _will_ scare yourself in an emergency if they're not hot
enough.
A3)
Ok, it stops, but it wallows, understeers - and I want to lower it too!
For
the best - get a fully adjustable (rate & height) set of shocks. Uprate the
springs but balance the increased spring rate with comfort (back to the
"fit for purpose" tactic). Anything else will be a compromise and you
might end up getting the whole lot re-done to another compromise setting that -
if you'd planned - might have cost the same amount as the fully adjustable kit.
Don't forget to add _properly_ spec'd anti-roll bars. Get these wrong and you
could finish up with a wurlitzer instead of a roller skate. Max race spec
demands Nulothene bushes, too. The extra stress on standard rubber bushes will
put the alignment out and you will (that's WILL) eat tyres much quicker than
normal.
For
a full "road" suspension setup, see dEcKs article on the shared file
area of the Onelist site.
A4)
Increase your oil capacity. This is beneficial no matter what else you do to the
engine.
The
two stages are, in order;-
A4.1)
Fit an oil cooler/thermostat. It should add about 2 litres to your total
capacity - that's nearly 60% over standard.
A4.2)
Money no object? Add a baffled sump. Prices are astronomical given the low-tech
result but if you're going racing or plan regular track days it's a serious
piece of kit.
A4.3)
Next is a surge pump: it squirts extra oil around when required and (I think)
sucks it back when the panic's over. Sounds a bit iffy?
A4.4)
Instead of the baffled sump and the surge pump, get it dry-sumped. It'll
probably cost less in the long run.
A5)
If you're upgrading in stages, maybe because you can't get the whole kit
straight away, go for the exhaust next and get a mild steel system from the
turbo back. That way, you'll get a relatively cheap increase in performance. If
you're not planning any more major engine work, get a stainless job done
instead. When you can afford it, after any big engine upgrade, replace the mild
steel system with one more tuned for the final result. you might want to do the
manifold to the turbo if things are really serious.
A6)
Things will be getting hot at this point. So a front-mounted intercooler will be
a good idea. It's complex and you will probably want to remove the air
conditioning kit anyway (Northern Hemisphere climates or race/rally spec).
Notice the original fit. Rubber hose is kept to a minimum. Don't "do the
python" with metres of silicon hose: keep the rubber to an absolute
minimum. Top quality kits use aluminium pipe.
A7)
A simple next step - let it breathe. Steps are;-
A7.1)
Fit a flat race filter in the existing airbox instead of the standard one - but
check that it won't fold up under max boost
A7.2)
Replace the existing airbox with a cone-type
A7.3)
Re-do the whole thing with a fresh air system plumbed in from a well-protected
front-facing duct or better yet mount the air cleaner outside the engine bay
A8)
If you're planning the job, you'll get to this point and say - but I haven't
made it go any faster yet. Wrong: you should get anything up to 265BHP without
touching the engine, boost or ECU. So, which will it be? Frankly, engine
components that affect power should not be changed independently. Why - well,
here's a simple rule. Too much of any one thing is bad for you.
(Hear
about the vegetarian that ended up only eating carrots? Dead. And orange.) Go
for balance. This is where mega-bucks start. Too much boost and the engine
/turbo will lunch. Over-chip and it could be the most expensive couple of
hundred you'll ever spend. So, that leaves the engine. Eh? Yep, the engine.
Japanese engines are world renowned for quality.
Under
stress-free conditions, that is. I recently heard of one carefully looked-after
standard Japanese engine that lunched itself after a full running-in and TLC.
Oowner took it for it's first track day. Ok, there was a fault. But that's my
point. Getting the engine reworked _properly_ should enable race conditions
without nightmares.
Before
you start doing anything with the engine, decide what size you want it. 1998cc?
Fine.
But
you can go to 2.2 litres with a stroker kit. If that's what you want, do it now.
Not later. Now. But it'll cost the thick end of £3,500. Just for the (new)
parts.
Staying
with 2 litres: well any significant increase in boost will mean an uprated
clutch and one or all of the following ... forged pistons (included in the 2.2
stroker kit), water injection, special low-compression head gasket, modified
turbo ... think ceramic ball bearing at the top end of the scale,
cockpit-adjustable bleed valve (aka adjustable boost valve).
A9)
To complete (?) the shopping list add quick shift, six-speed straight-cut
close-ratio gearbox, LSD's (mechanical diff locks), throw all the weight out and
replace the standard seats with Kevlar jobbie(s). Going racing? There are
regulations to cover, but in general, fireproofing, a roll cage and fully
plumbed-in fire extinguisher are necessary for anything above night events (UK).
I've
run out of ideas at this point - what's missing?
Q
I've seen a water/air intercooler setup recently - what's the idea?
=====================================================================
In
summary ...
Selecting
an Intercooling System
--------------------------------
Both
air/air and water/air systems have their own benefits and disadvantages. Air/air
systems are generally lighter than water/air, especially when the mass of the
water (1kg a litre!) is taken into account. An air/air system is less complex
and if something does go wrong (the intercooler develops a leak for example),
the engine behaviour will normally change noticeably. This is not the case with
water/air, where if a water hose springs a leak or the pump ceases to work it
will not be immediately obvious. However, an air/air intercooler uses much
longer ducting and it can be very difficult to package a bulky air/air core at
the front of the car - and get the ducts to it! Finally, an air/air intercooler
is normally cheaper than a water/air system.
A
water/air intercooler is very suitable where the engine bay is tight. Getting a
couple of flexible water hoses to a front radiator is easy and the heat
exchanger core can be made quite compact. A water/air system is very suitable
for a road car, with the thermal mass of the water meaning that temperature
spikes are absorbed with ease. However, note that if driven hard and then
parked, the water within the system will normally become quite warm through
underbonnet heat soak. This results in high intake air temperatures after the
car is re-started as the hot water takes some time to cool down.
Type
of Intercooling
--------------------
Air/Air
eg Nissan 200SX
-------
Advantages;-
Efficient
Cheap
Cores
are readily available/fabricated
Disadvantages;-
Longer
induction air path or bad core siting
Packaging
of large intercoolers difficult without major structural engine bay rework
Large
pipes to and from intercooler are required
Water/Air
eg Subaru Liberty RS
---------
Advantages;-
Short
induction air path
Easy
to package
Excellent
for short power bursts (ie typical road use)
Disadvantages;-
Heavier
More
complex
More
expensive
Heat
exchangers may be hard to source
Water/air
intercooling is used less frequently than the air/air approach. However, it has
several benefits, especially in cramped engine bays. A water/air intercooler
uses a compact heat exchanger located under the bonnet and normally placed
in-line with the compressor-to-throttle body path. The heat is transferred to
water which is then pumped through a dedicated front-mounted radiator cooled by
the airflow generated by the car's movement. A water/air intercooler system
consists of these major parts: the heat exchanger, radiator, pump, control
system, and plumbing.
A
water/air intercooler has some distinct cooling advantages on road cars. Water
has a much higher specific heat value than air. The 'specific heat value' figure
shows how much energy a substance can absorb for each degree temp it rises by. A
substance good at absorbing energy has a high specific heat value, while one
that gets hot quickly has a low specific heat. Something with a high specific
heat value can obviously absorb (and then later get rid of) lots of energy -
good for cooling down the air.
Air
has a specific heat value of 1.01 (at a constant pressure), while the figure for
water is 4.18. In other words, for each increase in temp by one degree, the same
mass of water can absorb some four times more energy than air. Or, there can be
vastly less flow of water than air to get the same job done. Incidentally, note
that pure water is best - its specific heat value is actually degraded by 6 per
cent when 23 per cent anti-freeze is added! Other commonly-available fluids
don't even come close to water's specific heat value.
The
high specific heat value of water has a real advantage in its heat sinking
affect. An air/water heat exchanger designed so that it has a reasonable volume
of water within it can absorb a great deal of heat during a boost spike. Even
before the water pump has a chance to transfer in cool water, the heat exchanger
has absorbed considerable heat from the intake airstream. It's this
characteristic that makes a water/air intercooling system as efficient in normal
urban driving with the pump stopped as it is with it running! To explain, the
water in the heat exchanger absorbs the heat from the boosted air, feeding it
back into the airstream once the car is off boost and the intake air is cooler.
I am not suggesting that you don't worry about fitting a water pump, but it is a
reminder that in normal driving the intercooler works in a quite different way
to how it needs to perform during sustained full throttle. However, the downside
of this is once the water in the system has got hot (for example, after you've
been driving and then parked for a while), it takes some time for the water to
cool down once you again drive off.
The
Heat Exchanger
------------------
Off
the shelf water/air heat exchangers are much rarer than air/air types. Water/air
intercooling has been used in cars produced by Lotus, Subaru and Toyota. A few
aftermarket manufacturers also produce them. If you want to make your own, the
easiest way to go about it is to jacket an air/air core. Pick an air/air
intercooler that uses a fairly compact core that still flows well. If it uses
cast alloy end tanks (as opposed to pressed sheet aluminium) then so much the
better. (Plastic end tank types need not apply!) The core is then enclosed in
3mm aluminium sheet, TIG welded into place. Water attachment points can be made
by welding alloy blocks to the sheet metal, with these blocks then drilled and
tapped to take barbed hose fittings. Pressure-test the water jacket to make sure
that it actually does seal, and make sure that the water flow from one hose
fitting to the other can't bypass the core. Small baffles can be used to ensure
that the water does fully circulate before exiting.
Another
type of water/air heat exchanger can be made using a copper tube stack. These
small heat exchangers are normally used to cool boat engine oil, exchanging the
heat with engine coolant or river or seawater. While the complete unit uses a
cast iron enclosure and so is too heavy and large for car applications, the core
piece itself can be enclosed to make a very efficient heat exchanger. Comprising
a whole series of small-bore copper tubes joining two endplates, the core is
cylindrical in shape and relatively easy to package. The induction air flows
through the tubes while a water-tight sheet metal jacket can be soldered around
the cylinder. The resulting heat exchanger is a little like a steam engine
boiler, with induction air instead of fire passing down the boiler tubes! The
one here is shown installed on a car undergoing fuel pump testing.
As
with air/air designs, the more efficient that you can make the heat exchanger,
the better is the potential system performance. If you plan to use an
off-the-shelf heat exchanger that has specifications available for it, you will
be interested to know that the 150kW turbo Subaru Liberty (Legacy) RS uses a
factory-fitted water/air exchanger that has a 4kW capacity. This heat exchanger
also works quite effectively when power is increased to about 210kW. Remember in
your design considerations that you want a reasonable store of water in the
actual heat exchanger (2 or 3 litres at least) to help absorb the temperature
spikes.
Radiator
and Pump
-----------------
The
front-mounted radiator for the water/air intercooler should be completely
separate to the engine cooling radiator. Some turbo trucks use the engine
coolant to cool the water/air intercooler, but their efficiency is much reduced
by taking this approach. Suitable radiators that can be used include large oil
coolers, car air conditioning condenser cores, and scrap domestic air
conditioning condensers. If you use a car airconditioning condenser there is
likely to be available a small dedicated electric fan that attaches to the core
easily. This fan can be triggered to aid cooling when the vehicle is stationary.
The radiator should at least match (and preferably) exceed the cooling capacity
of the heat exchanger, but again finding proper specifications is often
difficult. The Subaru Liberty (Legacy) RS with the 4kW heat exchanger uses quite
a small radiator, only 45 x 35 x 3cm.
An
electric pump is the simplest way of circulating the water, with the type of
pump chosen influenced by how the pump is to be operated. Some factory systems
have the pump running at low speed continuously, switching to high speed at
certain combinations of throttle position and engine airflow. If you follow a
similar approach, the pump that is chosen must be capable of continuous
operation. Another approach is to trigger the pump only when on boost, or to
trigger a timing circuit that keeps the pump running for another (say) 30
seconds after the engine is off-boost. The latter type of operation will mean
that the pump operating time is drastically reduced over continuous running.
Twelve
volt water pumps fall into two basic types - impeller and diaphragm. An impeller
pump is of the low pressure, high flow type. In operation it is quiet with low
vibration levels. A diaphragm pump can develop much higher pressures but
generally with lower flows. A diaphragm pump is noisy and must be rubber-mounted
in a car.
Suitable
impeller type pumps are used in boats as bilge pumps and for deck washing. They
are relatively cheap and have very high flows - 30 litres a minute is common.
However, they are not designed for continuous operation and generally don't have
service kits available for the repair of any worn out parts. Diaphragm pumps are
used to spray agricultural chemicals and to supply the pressurised water for use
in boat and caravan showers and sinks. They are available in very durable
designs suitable for continuous running and have repair kits available. Flows of
up to 20 litres a minute are common and they develop enough pressure (45 psi) to
push the water through the front mounted radiator and heat exchanger without any
problems.
The
factory water/air intercooler system in the Subaru Liberty RS uses an
impeller-type pump rated at 15 litres a minute (all flow figures are open-flow).
It is automatically switched from low to high speed as required. This is an
ideal pump because it was designed by Subaru to circulate the water in a
water/air intercooling system! However, it is a very expensive to buy new, but
if one can be sourced secondhand it is ideal.
A
cheap and simple impeller pump is the Whale GP99 electric pump. It is so small
that the in-line pump can be supported by the hoses that connect to it. It flows
11 litres a minute and has 12mm hose fittings. It is 136 x 36mm in size and is
suitable for discontinuous operation. This pump is available from marine and
caravan suppliers.
The
Flojet 4100-143 4000 is a diaphragm pump suitable for water/air intercooler use.
The US-manufactured pump uses a permanent magnet brush-type fan-cooled motor
with ball-bearings and is fully rebuildable. The pumping head uses four
diaphragms which are flexed by a wobble plate attached to the motor's shaft. The
19 litre/minute pump uses ¾ inch fittings and is 230mm long and 86mm in
diameter. It is available from companies supplying agricultural spray equipment.
The
Flojet pump needs to be mounted either vertically with the pump head at the
bottom, or horizontally with the vent slots in the head facing downwards. This
is to stop any fluid draining into the motor if there are any sealing problems
in the pump head. At its peak pressure of 280 kPa (40 psi), the pump can draw up
to 14 amps; however, in intercooler operation the pressure is vastly less and so
the pump draws only about 5.5 amps at 12 volts. The pump is noisy (as all
diaphragm pumps are) but mounting it on a rubber gearbox crossmember mount
effectively quietens it. Note that these pumps are much louder when mounted to
the car's bodywork than they are when sitting on the bench!
Control
Systems
---------------
The
simplest is to switch the pump on and off with a boost pressure switch. This
means that whenever there is positive manifold pressure, the pump circulates the
water from the heat exchanger through the radiator and back to the heat
exchanger. If boost is used frequently and for only short periods, this approach
works well. However, it is better if a timer circuit is used so that the pump
continues to operate for a short period after boost is finished.
A
pressure switch is an adjustable Hobbs unit. This switch is relatively
expensive. A cheaper unit is easily found. Spa bath suppliers stock a
pressure-operated switch that is ideal for forced aspirated car use. The
pressure switch is designed to work as part of the air-actuated switching system
which is used in a spa bath so that bathers don't have to directly operate high
voltage switches. The switch triggers at around 1 psi and costs about half that
of a traditional automotive pressure switch. If a switching pressure above 1 psi
is required, simply tee a variable bleed into the pressure line leading to the
switch. Adjusting the amount of bleed will change the switch-on point.
Another
approach to triggering pump operation is to use a throttle switch. A micro
switch (available cheaply from electronics stores) can be used to turn on the
pump whenever a throttle position over (say) half is reached. A cam can be cut
from aluminium sheet and attached to the end of the throttle shaft. If shaped
with care, it will turn on the switch gently and then keep it switched on at
throttle positions greater than the switch-on opening throttle angle.
If
a two-speed pump operation is required, the pump can be fed current through a
dropping resistor to provide the slow speed. When full speed is required, the
dropping resistor can be bypassed. Suitable dropping resistors are the ballast
resistors used in older ignition systems or the resistor pack used in series
with some injectors. The value of the resistor that is used will depend on the
pump current and its other operating characteristics. In all cases, the resistor
will need to dissipate quite a lot of power and so will need to be of the high
wattage, ceramic type. The resistor will get very hot and can be placed on a
transistor-type heat sink mounted within the airstream, perhaps behind the
grille. When experimenting with resistors and a pump, you should know that
placing the multiple resistors in parallel will increase pump speed while wiring
the resistors in series will slow the pump.
Another
approach is to use a temperature switch, so that the pump doesn't run when the
intake air is not actually hot. This situation can occur on boost if the intake
air temperature is very low because the day is cold. Overly cold intake air can
cause atomisation problems, although this is not normally a problem in a high
performance car being driven hard! However, running the pump when the intake air
is perhaps only 5? is pointless and it can be avoided by placing a normally-open
temperature switch in series with the boost pressure or throttle position
switches. If the switch closes at temperatures above (say) 30 degrees, the pump
will operate only when it actually needs to. A range of low cost temperature
switches is available from RS Components (stores world-wide). Note that in all
pump control systems a relay should be used to operate the pump.
The
Water Plumbing
------------------
The
most obvious place for the pump to be within the system is immediately after the
radiator, so that it is then subjected only to relatively cool water
temperatures. However, this can't always be done because some designs of pump
are reluctant to suck through the restriction posed by the radiator. Depending
on the design of the radiator, its flow restriction may be substantial. During
the assembly of the system it is therefore wise to set it all up on the bench.
Check water flows with the pump running (at different speeds, if this is the
approach to be taken) and with the pump in different positions within the
system. The pump position that yields the greatest water flow should be the one
adopted - even if that places the pump immediately after the heat exchanger. In
practice, the temperature of the water exiting the heat exchanger will not be
extremely high if the water volume circulating through the system is adequate.
A
header tank should be positioned at the highest point of the system. This should
incorporate a filler cap and can actually be part of the heat exchanger if
required. Note that a water/air system can be pressurised if required by the use
of a radiator-type sealing cap. Be careful that the system design allows air to
be bled from any spots where it will become trapped. Air in the system degrades
performance and can cause pump problems. A filter placed in front of the pump is
a good idea and very cheap water filters can be found in the garden irrigation
section of hardware stores. These filters use a fine plastic mesh design and can
be easily placed in-line.
Q
Header Tank? Whats that?
==========================
Surge
Tanks (Also known as expansion tanks, fill cans, header tanks)
Using
a surge tank as part of a race car cooling system is a very good decision. Any
proper race car cooling system will incorporate a surge tank. If used properly
it is the very best way of filling your system, trapping air, and taking the cap
out of the vulnerable areas where pressure surges can lift the cap off of the
seat momentarily.
On
the return side of your cooling system, pressure can surge as high as 45-50 psi.
This is due to abrupt changes in water pump speed (RPM related) and
characteristics of the heat cycle and circulation in your system. When the
radiator cap is on the return side or anywhere on the radiator, it is
susceptible to this condition. A surge tank isolates the cap from these areas.
The
other advantage to a surge tank is, when mounted properly (high as possible and
highest point in cooling system,) it serves as an air trap and means for
expansion. By running a -10 AN line to the water pump and a -6 line from the
highest point of the radiator to the top of the surge tank, this will draw air
to the tank and trap it. By keeping a given air space in the tank, it allows for
temperature expansion.
To
totally optimize your cooling system, use a swirl pot In the return water line
along with the surge tank. This will insure that all the air is purged from your
system.
A
sight glass can be fitted and is usually an optional extra.
Q
Cryogenics - that's for John Travolta innit?
=====================================
Everything
you always wanted to know about cryogenic tempering of race parts can be found
on http://www.onecryo.com/motorsp.htm