Ok so when I bought my car, I was told it had uprated turbos and that they were turned right down (I assumed adjustable actuator), 0.4bar was what he told me, he also didn't know what they were and reckoned he'd spent thousands on the engine, which I don't believe, because half of it is tacked together really poorly I'm now finding out.

 

I finally fitted a boost gauge last week before the car came off the road and nailed it a few times, aside from a few boost spikes which I reckon means I've got a leak somewhere, the needle seemed to sit somewhere between 0.4 and 0.5.

 

I've also noticed, that the car doesn't seem to boost much, until really late on in the acceleration curve. Around 3.5K to 4.5K revs usually, I've also noticed, that the boost only really kicks in properly, if I floor the crap out of it.

 

Now previous cars I've had, haven't suffered from quite this much lag. The GTR had proper twins as well, not staged, yet the lag was negligible, almost un-noticeable in fact, the Supra only had one turbo, which was up-rated, but it didn't seem to have much lag either.

 

I know my car definitely needs some work, and the Mines ECU definitely improved the cars performance ten fold, so giving it that more aggressive profile helped a lot, but I'm really starting to wonder if my turbos are genuinely up-rated and are quite a bit larger than standard (Causing the lag and massive boost described below).

 

One day last month, I was driving along and came from a 30 to a 50, so I put my foot down (I was already in 3rd I think) and the back end went nuts and actually nearly threw me off the road, but only after a second or so of my foot being on the floor, it lit the tyres (255, 40, 18s, which usually stick REALLY well) at around 35mph. Of course this could have been one of the spikes I mentioned earlier, but baring in mind from what I've been told, if a standard turbo goes over 1.0bar, it has a tendency to blow it's ceramic wheel out the exhaust and I'd say the boost would have to be over 1.0bar, to go as nuts as it did, bleh I just don't know.

 

Anyone elses experience of uprated turbos or just how mental the turbo kick in is supposed to be standard would be appreciated. It's not like I can stick my head in the engine bay and see a model number on the turbos lol.

I dont get wheel spin in 3rd no matter how much i try. infact i get very little in 2nd. I am boosted to the limit of the tubs as well. So i would say you have somthing else under the bonnet.

 

Your getting lag and im at full boost at about 2500/3000rpm off the top of my head

Cheap tyres!

LMAO! I had to buy the rears the day I picked up the car, because the previous owner was a drifter and they are definitely not cheap.

 

If I launch the car properly from standing, I get spin, then into second I get spin, then into third I get spin (Driving very aggressively), what was really surprising on this occasion though, was I was already in third and all I did was put my foot to the floor and it lit the tyres so hard, the back end actually went sideways about half a meter, to me that's REALLY odd.

 

The other day I was driving and watching the boost gauge and it definitely wasn't boosting until well after 3K revs. I'm going to be removing the plenum in a few weeks and replacing it, so I'm going to try and get a better view of the turbos while I'm down there. The odd spike that I've seen since having the boost gauge on there, hasn't gone above 0.8bar, but then that's because I've been watching it and have backed it right off when I've seen it go that high, before having the boost gauge in there, I really had no idea how high it was boosting.

about the same boost as me then. I only get a little chirp in 2nd gear. If im in 2nd already and boot it, it just goes but it will spin if the road is uneven.

 

Im running 275 on the rear

I've just been to the garage to look at mine, they're 265. I remember I had to go a size lower than he had on the rear, because he'd already used all the 275's in the garage lol.

The stock Z turbos suffers from less lag than most turbocharged cars. Small turbos, big engine = minimal lag.

 

It does'nt really have a strong kick-in, its more of a smooth progressive power delivery.

 

If you were on standard turbos and getting 0.4-0.5 bar (6-7psi) then you would either have a boost leak or the car is in safety mode. Either of these would cause Increased lag.

 

That would'nt explain, what sounds like good performance your experiencing though. Although either you were on a patch of oil or your mistaken about the gear or speed, because 3rd gear at 35mph is only about 2300rpm.

 

The Z standard turbos dont have ceramic wheels and are fine at over 1bar (14.5psi) , and produce power up to around 1.25bar (18psi), before they produce too much heat to be efficient. Stock boost is 9.5psi(0.65 bar)

 

Check to see if the turbos have a 4 or 5 bolt connection from turbo to downpipe.

Edited May 1, 201114 yr by Yowser

what brand tires out of interest?

 

If the turbos have been changed, they could quite easily be mismatched for the engine and end up with laggy/spikey performance without actually producing that much extra power.

Not sure on the brand of tyres and I cba going out to the garage again tonight, I did notice a lot of `A` ratings on the tyres though, for traction and blah blah blah. Turbos mismatched could definitely play a part, but I've also recently (While fiddling this last few weeks) found out that the balance bar isn't seated properly (Threaded bolts on the passenger side) and I think it's leaking on one side of the plenum at high revs, not quite sure WHAT that would cause exactly, but am pretty positive it would cause the engine to not run properly under load and have a strong suspicion it would cause boost issues.

 

3rd gear at 30 - 35 for me, is nearer 3K revs upwards, so maybe I have an altered differential as well? There was definitely no oil on the road and it was a dry day.

 

I thought the Z tubs were the same as the 200SX and Skyline Tubs, Garrets with ceramic compressor wheels for faster spooling, but limited to around 1.0bar safely, but glad to hear they're not to be honest.

 

The one thing I can say about the car, just by looking at the brakes it has on the rear (The previous owner took the fronts out and fitted them to his S14 before I bought the car), the rock hard lowered suspension and the state of the ignition block when I saw it the other day, and a few other things, I reckon this car was once, REALLY fast.

 

When I get the chance to get anywhere near the turbos I'll look at the downpipe connection, what's the difference between 4 and 5 bolts exactly?

 

Kind of glad I'm going to get to strip the car down and build it back up really, it'll give me a chance to find out what's really in there.

As an added fault finding exercise, how would I find out if the car was in safety mode? Could it even be in safety mode being a manual with a Mines ECU?

Tyre brand (or model really) definatly plays a part. Their is a big difference in traction between something like a Nankang and a Goodyear F1.

 

A balance bar not seated properly would cause boost and vacumn leaks. Affecting boost pressure and fueling, and subsequently increasing lag/spool up.

 

3000rpm in 3rd gear is 48mph. The highest ratio diff available on the market for the Z would still only be at 3500rpm at 35mph in 3rd.

 

The Z uses smaller turbos than the Skyline, 200sx...etc They are Hybrid Garrett TB22's, which are similar to T25's but smaller.

 

Got a pic of the rear brakes ? Im curious as to what they have fitted.

 

The number of bolts on the exhaust housing to downpipe gives an indication of size. Bascially if its 4bolt then its either stock or stock with machined internals at best. Anything larger turbo will have a 5bolt setup really.

 

If you do have larger turbos, then the Mines ECU you have fitted would also have incorrect mapping for the turbos.

 

You can test for error codes from Safety mode like this or this.

....double post..

Edited April 30, 201114 yr by Yowser
double post

If i were you chief I'd get it to a rolling road and let someone set it up for you, but not before you get the balance bar an other little things sorted.

 

Before I bought my car I had a test drive in an auto with a boost controller. With the boost in its lowest setting the lag was unnoticeable, but in its highest setting it was wait... wait... there you go, you barsteward :helpsmilie: Span its wheels all the way upto 80mph as I seem to remember. AND that was from an auto, running standard tubs but with a boost controller.

 

I was a little surprised at the performance, it was certainly quicker than my Zed, but boost lag was very noticeable when the wick was wound up.

 

PS, never believe anything that a 300zx owner tells you, we are all compulsive liars :tt2:

 

"that'll last forever, made of granite that is"

 

"I've spent thousands on this engine (in my dreams)"

 

"had a race with this porsche the other day..."

 

etc etc :2guns:

Besdt thing you can do if you're only in Leicester is get it to Zedworld and let them give you the low down on it

 

It'll be the best trip you ever make (for the car that is !)

The stock Z turbos suffers from less lag than most turbocharged cars. Small turbos, big engine = minimal lag.

 

It does'nt really have a strong kick-in, its more of a smooth progressive power delivery.

 

If you were on standard turbos and getting 0.4-0.5 bar (6-7psi) then you would either have a boost leak or the car is in safety mode. Either of these would cause Increased lag.

 

That would'nt explain, what sounds like good performance your experiencing though. Although either you were on a patch of oil or your mistaken about the gear or speed, because 3rd gear at 35mph is only about 2300rpm.

 

The Z standard turbos dont have ceramic wheels and are fine at over 1bar (14.5psi) , and produce power up to around 1.25bar (18psi), before they produce too much heat to be efficient. Stock boost is 9.5psi(6.5 bar)

 

Check to see if the turbos have a 4 or 5 bolt connection from turbo to downpipe.

 

bloody hell tubs the size of dustbin lids 6.5 bar :ohmy: ( 0.65 bar ) cant you get underneath and see what the tubs are ?? sound like something a bit bigger than stock to me if they are boosting that strong your lighting up in 3rd

Mine can light in third if it's really floored !

 

Not always, but last year met up with FunkySi and we had a play, He drove mine and spun the wheels in third with two of us in it, Mine had Apexi front intakes, chipped and boosted to 1 bar and mongoose exhaust. Oh and was Avon zz3s with good tread

 

I don't usually drive mine that hard and it only happens when turbos sre on full chat going through the gears, doesn't happen if you floor it in third to start with

 

But it is quick all the same :wink:

Edited May 1, 201114 yr by TonyB

does it have an electronic boost controller? maybe the Gain is set way too low, or maybe you do have a boost leak. how do you know it's spiking? what boost does it go up to when it does?

Well unfortunately I'm not just in Leicester, not sure why you think I am lol, I'm about an hour and a half away from Leicester.

 

When I've sorted out replacing the plenum, which in turn sorts out the balance bar, and actually fitted an EBC (It doesn't currently have one), and have fitted some de-cats (I discovered the other day when squeezing my head underneath the car it still has it's cats) and changed my suspension, to the set I've bought from Mikey, replaced the Cam Belt etc.etc.etc. which will be some time in June because of being away from home for the next two weeks, it will be going to Jeffs to get it sorted out and set up properly. Thankfully it's off the road for the next 4 - 6 weeks now, while parts get fitted and things get sorted for the MOT, like the sills being welded etc. So I have some time to try and sort these things out.

 

I'm well aware of tyre brand making a big difference, that's why these ones cost me over £500 at a discounted "Cash" rate from the tyre garage in Milton Keynes, as opposed to a set that would only have cost me £200 - £300 el-cheapo budgets.

 

The highest ratio diff available on the market for the Z would still only be at 3500rpm at 35mph in 3rd.

 

Well that's just about exactly what I said mine sits at, so that makes me think even more, that the diff might be aftermarket as well. Like I said before, the guy who had it before me was a drifter, I know he locked out the hicas, it wouldn't surprise me if he changed the diff as well to increase its drift-i-ness. I think the owner before him likely had it as more of a track car, because the suspension is more of a race suspension than anything else.

 

The back brakes are nothing majorly special, the calipers are standard, but it has brembo grooved discs and EBC yellowstuff pads, it did have them all the way around before I bought it (I saw the discs and pads on the front of his S14 and he confirmed that he'd swapped them over), which is what makes me think the car used to have lots more in it than stock, because although brakes are important to uprate, along with other things, I know very few people that would fork for Brembo discs and EBC pads for a stock car (I bought some brembo discs and EBC pads from Liam second hand, but only did that because I think the car is not stock and would like it to stop quicker).

 

Also over the last few weeks I've pulled various other things from the car, wiring for speed sensors down by the wheels, usually used for a digital speedo, a random disconnected piece of vacuum hose which still ran from the cockpit to the engine but wasn't connected up (Now connected up and running my boost gauge), tonnes of wires hanging off the back of the stereo and off the ignition, which look very familiar to me as wires from an EBC, a Turbo Timer and one that even reminds me of an Air-Fuel Mixture system an old friend of mine had running in his 300ZX mounted in his glove box. This is all as well as pulling a full snooper system out of the car. It also has screw holes in places that you would normally find these devices, such as just above your left knee under the steering wheel.

 

All I was really concerned with when I first made this thread was peoples experiences with and without bigger tubbies, do your tyres light up through the gears, anyone else experienced lighting the tyres by just putting your foot down at around 35mph, in 3rd gear, which for me was around 3K+ Revs, does anyone else get what seems like a lot of lag etc. The car has it's moments where it just won't run properly and do what it should, then others, it's simply awesome. I can't wait to get it all sorted out and back on the road running properly, because I think it's going to be REALLY fun.

Sorry , I meant to say 2500rpm, not 3500rpm for a 4.10 diff. Was a typo.

 

You may well be correct about the turbos , i hope you are. If it's spinning in 3rd with good tyres it would suggest so, but I think your reading a little too much into the cars other upgrades though. Upgrading discs and pads is very typical , it's a basic modification with most owners complaining about stock brakes. Many owners even fit full big brake kit conversions on z's with standard turbos. Things like brakes and suspension are very common upgrades , turbo upgrades are quite rare.

 

If you get the issues sorted you could have a real animal on your hands :)

Edited May 1, 201114 yr by Yowser

That's what I'm hoping. I don't really mind if it turns out that it's got stock turbos to be honest. My reasons for thinking that they had been changed were numerous, the previous owner telling me so obviously, plus the lag and bang way of them working, but then I found the balance bar bolts are chewed, so it isn't properly sealed, which could cause that, then there was the noise they make, which sounded just like my GTR did which had uprated Steel Internal turbos (They sound very different to the stock ceramic ones), but now I know they don't have ceramics in them anyway, so we'll just have to see.

 

The Mines ECU made a massive difference to the noise, the performance, the way it felt etc. so it's possible that the turbos are up-rated and the ECU made the difference from standard, it's also equally possible that as was said earlier in the thread, the ECU might be completely mis-matched to the turbos and causing the problems.

 

I suppose we'll see.

Don't why I thought Leicester, must have misread it or from a later post !

 

Good to see it's going to Zedworld though, they look after both of ours and we go down there from NE Yorks !

Yeah it'll be going down there once I've done all the stuff that needs doing to it for the MOT and stuff I want to replace like the suspension and fitted my front discs and pads etc. Hopefully Jeff will be able to tune it up and make it the way it should be.

Don't why I thought Leicester, must have misread it or from a later post !

 

Good to see it's going to Zedworld though, they look after both of ours and we go down there from NE Yorks !

 

its cos Leo and Hollow have similar avatars Tony (except facing the other way!) :sorcerer: