Modifications

[SeanDezart]

Hi y'all,

I like to hear from any and all who've modded their Z31 with particular reference to engine upgrades.
Hope to hear from you soon.

 

[Black Bug]

I'm about to mod one, for weight purposes, by removing the engine, gearbox, drivetrain, wheels, brakes, suspension, erm, in fact anything that I can get off it. I'm sure performance won't be compromised in anyway though

Cheers,
Rob

 

[Mr.F]

Z31 NA mods are limited: induction kit (e.g. K & N), exhaust header manifolds, free flow exhaust and possibly an adjustable fuel pressure regulator. Decent ignition leads, e.g. 8mm silicone or better. Anything else will entail a degree of ingenuity and engineering skill.....

Suspension: lowering springs, uprated shocks (limited availability) and thicker anti-roll bars. Some urethane bushes now available. Best wheels and tyres you can afford.

Brakes: R32 Skyline front discs and calipers fit (I have a local customer who has done this) and, therefore, I would assume R33 Brembo fronts could also be used but I don't know of anyone who has gone that far.

 

[grolls]

mr f.wouldn't an adjustable fuel pressure regulator be a tad " hit and miss" im assuming your trying to get more fuel in for the same injector cycle duration?

if im right you are thinking this it might be worth speaking to super chips in milton keynes, a great bunch of guys, they made me a chip for my last race bike, the massive performance company yoshimura could only increase my fuel/air ratio by 20% they managed 30%. they also have a 4 wheel drive dyno!!!!!!!!

just thought it might help

 

[SeanDezart]

Aah Mike,

"R32 Skyline front discs and calipers fit ......... and, therefore, I would assume R33 Brembo fronts could also be used"

you just have to keep increasing my future shopping trolley list don't you !
Now, if a LSD could be simply bolted in.....

And I was of course referring to the turbo model !

 

[SeanDezart]

Anyone fitted an intercooler and was it worthwhile ?

 

[JEZ 280ZX]

Hi,
Have a look at Z31.com, they have an upgrade quide for the turbo cars....z31.com turbo faq
and a general
Modifications page.(The US cars are starting from a lower hp output of 200/205hp compared to 228 of the UK cars).
I think you would only need an intercooler once you've upgraded all the other components and are running a high boost setup.
Cheerz,
JEZ

 

[JEZ 280ZX]

Hi,
Also have a look at this thread....577hp!
Cheerz,
JEZ

 

[JEZ 280ZX]

Hi,
This site looks interesting too!......Boostvalve.com, they sell a kit for the Z31 Turbo
Cheerz,
JEZ

 

[neil300zx]

Hi

Have you thought about putting a boost controller on yours Jez

 

[JEZ 280ZX]

Hi,
I've thought about it, but there hasn't been a kit readily available to do the job!...I wouldn't mind turning up the boost a little bit now, just to keep ahead of those pesky turbo diesels on the roads!
Cheerz,
JEZ

 

[SeanDezart]

Mike's already given me lots of info, explaining why etc on add-ons - it seems all available and I am hoping to exchange views with someone who's already running with a higher boost !

I'll definitely check out the Z31 site - thanks !

Any advantage in changing the rear diff from a turbo 3.5 to a non-turbo 3.7 - would ultimately accelerate quicker and induce the turbo sooner, no ?

 

[JEZ 280ZX]

Hi,
When I first got my z31T I asked similar questions, but got very little in the way of answers, as there doesn't seem to be anyone tuning their Z31's in the UK.
Have a look on www.Z31.com or www.300zxclub.com as over in the US there's plenty running higher boost levels!
Cheerz,
JEZ

 

[SeanDezart]

Anyone ?

"Any advantage in changing the rear diff from a turbo 3.5 to a non-turbo 3.7 - would ultimately accelerate quicker and induce the turbo sooner, no ?"

And I don't get it, I just read a 1987 UK write up for the Z31 Turbo and it clearly lists a limited slip diff. as standard !!!

Has it or not ?

 

[Mr.F]

3.7 will accelerate quicker than a 3.5 but will have an effect on speed in gears and cruising speed in fifth. Numerically higher ratio = less speed at any given rpm in any gear compared to numerically lower ratio, but faster rate of acceleration. However, tyre rolling diameter has an effect on final gearing also. I rediscovered a handy little Performance Calculator programme lurking on an old dusty corner of my old computer...does all this sort of work for you at the touch of a button (or 2), so if you have tyre dimensions and proposed ratios we can work them out. Please - I hope I didn't just open a floodgate of work there!

U.K. cars do not have LSDs - surely you don't believe everything you read in print? You'll start believing me next .

 

[neil300zx]

Hi Mike
Yes you probably did open the flood gate as there are several questions i want to ask you but i thought i would wait until i had my bits but on second thoughts id better ask before i buy. btw im hoping to get a 1984 turbo 300zx complete so any bits i need i should have, Here goes.
1. can i fit the turbo from a 1984 300zx onto my 1986 non turbo or will i have to swap whole engines, will i need to change the ecu
2. im also going to do a auto to manual swap, any pointers?
3.i want to leave the auto diff in and fit the turbo manual box, im also using 245/45/17 wheels/tyres, what difference in top speed, acceleration , speedo etc.

hope i've explained myself enough

Thanking you in advance

 

[Mr.F]

There are so many differences between turbo and NA that it is better to start with a turbo car. You will need to transfer engine, gearbox, EGI loom and ECU. There may still be problems with the autobox electrics, although the series 1 is simpler than the series 2. You will need to patch between the auto box sub-loom and the manual box sub-loom. Turbo has an electronic speedo which might be difficult to implement. However, you will need to change some dashboard instruments anyway, so why not go the whole hog? I don't know how different the dashboard loom is, so you may well end up replacing that also.

For a 25.68" tyre height and assuming 5600rpm as a reasonable gear shift point, the final drive will have the following effect on MPH:

Gear 3.7 3.5

1 35 36
2 57 59
3 85 89
4 117 122
5 149 156

Ratios used from T5 turbo box.

Acceleration from the 3.7 will be improved over the 3.545 turbo diff. but speeds in each gear will be less for an equivalent rpm.

Standard turbo rear tyre height is 24.86" (225-50 16) - a 40 profile might be closer on a 245 section? Top speed in 5th at 5600rpm would then be 144 with the 3.7 and 150 with the 3.5 (close to the published road tests of the time!)

 

[JEZ 280ZX]

Originally posted by SeanDezart

And I don't get it, I just read a 1987 UK write up for the Z31 Turbo and it clearly lists a limited slip diff. as standard !!!

Has it or not ?

Hi,
....... The Autocar 1987 road test does list a lsd as standard equipment.( I've got the original magazine in front of me)...But then they also reckon the wheels are 8" wide too!...And they get confused between 228bhp and 225ps power outputs as well!

Personally I prefer to quote the 'What Car' performance figures from their Dec 1988 group test, against the Supra and Renault GTA!
....The in-gear acceleration times are better and the 0-60 and 0-100 times are better too, at 6.7 and 18.6secs!...makes my car feel faster!
Cheerz,
JEZ

 

[SeanDezart]

Well, I lit up the tyres all the way in 1st at the weekend so Mike sIS right and Autocar IS wrong, shame as I'd liked them to be right !

So Mike, with standard turbo wheels and 225/5016 tyres, if I change the diff to a 3.7 and assuming 5600 revs, what mph readings will I have and at how many revs, ie at 80 mph, how many revs in fifth ? Please !

This is assuming tha the N/A 3.7 diff will fit into the Turbo and is strong enough ?

Over here, top speed is becoming less interesting but short-term sprints are !

 

[neil300zx]

Hi
I did'nt realise that it was going to be that involved, having second thoughts now as my mechanics is very limited especially electrical works, i dont know if im up to that sort of project.

Big dilema