We took my silver zed out to a private road ( genuinely a private road) to run some tests on it,

 

Baring in mind I'm running on actuator pressure only, and the clutch is slipping ( yeah I know not the best idea to test but I've only time we could use the road for a month or 2) I'm having trouble getting it to put its power down, worst was when the boost came on at 120mph it spun the tyres again, I need advice tips on how to counter this, It needs a big wing that's a given to help with the high speed stability, thinking of getting wider wheels maybe some 10.5 j to help, would softening the rear suspension help? Feels like it's jumping around a bit too much,

 

I'm completely scared of it, certainly don't want to turn the boost controller on ( can do double its current boost) it's probably more my lack of experience with the power but I'd appreciate any advice anyone has.

What tyres are you running and in what condition/age are they?

500 mile old 245/35/18 mid range tyres on the rear, ( summer tyre technically) but with good displacement.

 

I've a set of federal rsr to go on but after the winter. 265/35/18

 

My rotas are 9.5 so in theory could try to get the 285/30/18 rsr tyres,

 

Can't go to drag radials as it's a been built for circuit mainly.

Edited December 12, 20169 yr by (adl) phoenix

Some of this does not make sense, basic actuator boost is the same as safety boost, around 5.5 psi, making heavy work of getting the power down and with a slipping clutch at such low boost would seem odd, unless of course it is boosting more than you think or the "new tyres" are bad, also a slipping clutch at low boost is also unlikely unless its is completely worn out.

 

Another point, you mention "when the boost came on at 120mph it spun the tyres again" again 5.5 psi of boost would feel crazy poor at 120 mph, and quite why did it go and come back? do you mean when changing gear?

 

Unless I have misunderstood what your saying, non of it adds up.

 

Jeff

Sorry should have clarified this is my silver slicktop actuator pressure is 14psi, on GT675RS turbos. it's been built for 600-700 bhp, still on an oem clutch hence slipping, ( my fault needed the engine back in but couldn't afford the new sz clutch at the time), there seems to be a bit of lag before the turbos spool properly, probably due to the r5 race cams not performing lower in the Rev range, that's what I ment as it spooled at 120 it spun up

:oops:

Did it spin up or squirm? Reason I ask this is because if some of your suspension isn't up to task it may feel like/you may be fish tailing. Scarey shit, mine did the same when the sub frame bushes were shot and I was only chucking 370 odd BHP out there. Traction is way better now.

You've got undersized tyres and dump loads of power. If the clutch is slipping though how can you be spinning at 120mph? Think logically about that.

Check the condition of what you've got but the bottom line is you need more grip and a clutch. A BGW might help but I think that's the end not the beginning grip wise. Also was it wet. It's been raining here all day, that thing is going to be murderous on cold wet roads.

Edited December 12, 20169 yr by Stephen

Your waaaaaaay undersized on the tyre for that power level. Look at it like this, would a manufacturer release a RWD car with 6-700hp on 245 width rear tyres? Never in a month of Sundays! Never mind the fact we don't have the pleasure of TC or ESP!!!

 

To give you an idea, on my old engine build (570hp/480lbs ft) with 295/30/18's on FL453's i could get full power down in third on a dry road with the tyres up to temp, in the wet I'd get wheel spin in 4th regardless of the speed IF I booted it.

 

With regard to suspension setup (and if your on coil overs) I'd reduce your spring preload a couple of turns to help with softening the weight transfer to the rear. Stephen also makes a very valid point around the bushings on the rear end

 

- - - Updated - - -

 

(FK453's not FL's)

And this is from 150hp odd less than you're running :)

 

335 on rear

Thanks,

 

It definitely spun up, was about 15 degrees from straight had to fight it straight again. The mechanics helping me test thought I was about to lose it, ( so did I hence why I'm scared of this car now)

 

Thanks for the input, will dial down my rear coilovers, and get the wider rsr ordered, the bushes were good, no sign of wear, the zed has been solid and planted on its previous trackdays ( prior to the power modifications) but it's always been really stiff,

 

Think I went too far to fast with it should have gone in stages as aposed to 350bhp to 600+ in one jump...

Ok not standard actuator boost, that explains the higher boost level, you know there is a valid point that you can have too much power for a certain chassis set up, lower boost in your case may actually feel more controlled and ultimately quicker on the road, as whilst you wheel are spinning your getting less forward push as it were.

 

A good boost controller with individual gear boost parameters / level`s would almost certainly make the car feel quicker and more controlled overall as it will match the turbo / engine / boost build time in relation to how the engine can build and retain boost, of course as other`s said some tyre and suspension work needs attending too also.

 

Jeff

He would need to fit lower rated wastegates for that though Jeff. 14psi is wastegate pressure, you can't trick a wastegate open earlier as far as I'm aware.

He would need to fit lower rated wastegates for that though Jeff. 14psi is wastegate pressure, you can't trick a wastegate open earlier as far as I'm aware.

 

Of course yes you are quite correct, I was thinking stock wastegates again, usually after market ones have adjustable rods to preload the spring, if so these could be backed off I guess but would need checking with a vacuum pump and gauge to ensure they are both the same.

 

Jeff

TBH Alex very few people in this country have any first hand experience of Z32s in this power band. Some trial and error are required and speaking to people who know thier apples on the subject. Hopefully Bob, Pete or Jaffa will be along to make some suggestions. As you know Nick has experience of owning a big power Z and he's given some good advice.

The long and the short of it is you have 300hp worth of tyre there and you need more grip, however you get there.

TBH Alex very few people in this country have any first hand experience of Z32s in this power band. Some trial and error are required and speaking to people who know thier apples on the subject. Hopefully Bob, Pete or Jaffa will be along to make some suggestions. As you know Nick has experience of owning a big power Z and he's given some good advice.

The long and the short of it is you have 300hp worth of tyre there and you need more grip, however you get there.

Alex :lol:

You only met him last month :P

 

Ashley is the name you were looking for

Your apparent problems don't make it an easy answer. Not quite sure how you manage to spin it up with a slipping clutch surely it would slip before spinning?? But here's my input (for what it's worth).

 

I doubt very much you are too stiff at the rear and in reality it shouldn't provoke spinning up. I have 500lbf/in springs at the rear and think they're about right (though further testing is required to be certain). You are a little under tyred but more likely they were cold and it was a little damp I suspect. The drag tyres I used for my 10.92 quarter mile were only 265. It does sound like you have a fair bit of lag and the set up means the boost comes in with a bit of a bang. I have a similar set up and if I don't use the nitrous the boost hits hard. I suspect the combination of damp conditions, cold tyres, and late boost has caused the problem.

 

I can probably lend you a set of rear wheels to try out. I will be taking my race car out testing if not this month certainly early January. Not sure where as yet but you are welcome to come along to discuss with Eurospec they will be able to advise better.

Alex :lol:

You only met him last month :P

 

Ashley is the name you were looking for

 

It's not the first time I've met him either! :lol: I'm just terrible with faces and names, it's part of my blend of antisocial and ignorant attitude that suits the vast amount of time I spend outside solitary. Coupled with the amount of new faces I meet every day of the week at work. I can't keep track of who is who. I responded and got the first letter right what more do you want? :lol:

Thanks for all the advice,

 

The clutch is odd, first noticed it on the boxhill-brighton run, it's filled the zed with clutch smoke and went nowhere when I tried to put my foot down, seems my zed either slips the clutch or the tyres what ever it feels like at the time...

 

 

but I've a long list of issues to resolve before I goes out testing again, needs a better map and the new clutch as a priority, also had some smoke under boost which looking at the afr gauge was running rich, but going to replace the pcv valves as a precaution as it looked slightly blue, but compression and cylinder leak is good,

 

Aim is to have it ready for some proper runs in March-April,

 

would be good to test/run along side you bob, you have far more experience would appreciate a chance to learn from you and eurospec.

 

 

 

it's OK Stanley not offended you got my name wrong, was only a matter of time before Alison and the grammar police picked up on it, wasn't going to say anything :innocent:

We took my silver zed out to a private road ( genuinely a private road) to run some tests on it,

 

Baring in mind I'm running on actuator pressure only, and the clutch is slipping ( yeah I know not the best idea to test but I've only time we could use the road for a month or 2) I'm having trouble getting it to put its power down, worst was when the boost came on at 120mph it spun the tyres again, I need advice tips on how to counter this, It needs a big wing that's a given to help with the high speed stability, thinking of getting wider wheels maybe some 10.5 j to help, would softening the rear suspension help? Feels like it's jumping around a bit too much,

 

I'm completely scared of it, certainly don't want to turn the boost controller on ( can do double its current boost) it's probably more my lack of experience with the power but I'd appreciate any advice anyone has.

 

 

fit link ecu with built in traction control

I'm completely scared of it, certainly don't want to turn the boost controller on ( can do double its current boost) it's probably more my lack of experience with the power but I'd appreciate any advice anyone has.

 

Think I went too far to fast with it should have gone in stages as aposed to 350bhp to 600+ in one jump...

 

It looks like you have already diagnosed some of your problems.

And it takes a brave man to own up to that.

Testing at this time of year is pretty meaningless as you cant get enough heat in to the tyres all round.

 

Take up Bobs offer of meeting up with him and Ben from Eurospec. You will learn a lot in a very short time Im postive..

 

It will take many sessions testing at a proper track before you get the car to your liking.

As already mentioned a 245 width middle of the road tyre just wont cut it now on your car.

 

Hopefully Bob, Pete or Jaffa will be along to make some suggestions.

Its nice to be mentioned but I dont have any experience of BIG power cars. Both Bob and Jaffa have offered me drives in the past which I have declined.

My experience is centered on making a lower powered car punch above its weight on track and on the 1/4 mile. I like to think I have been reasonably successful in that area.

What you need to bear in mind Ash is the devil is always in the detail. Its not easy to turn a 300 into a fast track car........just look how few have done it in the UK.

Its very easy to make a powerful 300 and crash it......lots of people have achieved that.:scared:

Thanks everyone for their advice, got a while before I'll be driving it properly again, I've ordered the wider 285 tyres anyway, shame as I hadn't even fitted the 265's I'd already bought for it.