ToyoII

Ok, that was informative, just spent the last, however long since my last post, doing some primary research for us. So here's the facts. The stock boost actuator for an auto turbo cracks at 0.35 Bar and my new actuators crack at 0.55 Bar. I'll convert that because my gauge may say bar but I'm really a psi man. So according to google the stock is 5.08psi and my new one cracks at 7.98psi. So a stock car would be 10.16psi (assuming that the actuator I used has had no wear and tare over the 1000's of miles of use and the spring hasn't lowered it's K value.) And with these new actuator I would be running at 15.96psi (assuming I have no leaks or faults with the system.) Well that does sound more like it I guess.

In all fairness I've just read this from the same site: (Z1) A stock 300ZX Twin Turbo produces only about 10 psi of boost pressure. The orifices in the boost jets sold with the popular JWT ECU upgrade are around .040" resulting in about 12-13 psi of boost. and this - The Z32 factory wastegate actuators start opening at 7psi, allowing boost to drop off. Don't add up. But I honestly am finding it hard to comprehend that all my Z'd have been modded to run at 13-14psi? But I'm starting to believe you. Just paid for them to be set to that though. :no: ok I'm willing to pay more money and get them lowered . . . 16-18psi?

True, I know my stock gauge is accurate, because I have an aftermarket gauge to check against as well and when it was dyno'd last it read 13.5psi and so did the dyno machine. I got 330hp @ flywheel, with uprated de-cat, exhaust, manifolds, downpipes, uprated filters, re-map and tuning. Well from past experience and a lot of study, this is what's going down. I'm aiming for 400hp. Which I may get. On the actuator front I'm still not in agreement as I tested the cracking pressure of the stock actuator and it opened at 6psi (auto actuator) so that confirmed what I have been told elsewhere. either way I'm upping the pressure from my stock actuator by 3psi (each) and we'll see what happens. I think people really underestimate the quality and durability of these cars. They don't get enough praise in my opinion.

Well these are the actuators I bought and they say: "The Z32 factory wastegate actuators start opening at 7psi, allowing boost to drop off. These units replace the OEM actuators, and will allow you to hold higher boost pressures from spool up to red line. You will be able to hold boost past 6000 RPM with little drop off. Other benefits include reducing the amount of boost spike, as well as eliminating the oscillation that is common with light spring wastegate actuators. This kit includes a custom made bracket to mount up to the factory points on the back of the compressor housing and start opening at 10 psi but are fully adjustable for preload. We recommend running a boost controller with this unit and upgrading your fuel system. Z1 Motorsports Upgraded Wastegate Actuators work with all OEM heat shields." Also mathematically how can you get such a high power gain from such a low compression? 4.5psi (each turbo) 9psi combined on a TT 3.0L is awful. A stock Rover runs at 8psi.

Well this is my 4th Z now they have all been stock and they all boosted to 14psi on the dash gauge, also my 300ZX book says it's 14psi and all the online tech sites state 12-14psi, (depending on model). So are you sure it's 9psi?

But 7psi each turbo is stock pressure! So your saying if I go above what it came out of the factory, it will blow?

I don't think anyone read the first line of my first post . . . "Just to start with can we stick to combined pressure or it just gets confusing." But to elaborate combined means both turbo's . . . combined. so when I say 20psi I mean 10 psi each turbo, i.e x2 thus 20psi. I know the stock on the auto is 12psi and the manual is higher at 14psi. (The gauge on the dash says 14psi . . . combined) The new turbo's I'm putting on are stock auto turbos because they have a smaller A/R and they will spool faster, but have peak boost at 21psi (each turbo) so they shouldn't over spin running at 10psi each. So is this a sensible boost?

Just to start with can we stick to combined pressure or it just gets confusing. So is 20-22psi ok on stock setup? Because in a few weeks that's what I'll have. I've done my research and most say that after 28psi you need to seriously start thinking about internals. So I thought a 3-4 psi increase each turbo wasn't over the top. But should give me that little extra kick. And I was just wondering what other people where running. Before anyone asks one of my turbos is shot and while I was changing them I thought I might as well do a few mods and get a little more power. I should be getting 400bhp @ flywheel at this pressure . . . if my maths is right :tongue_smilie:

OK will do, cheers.

91 as well, need to replace one of the turbo's, doing it in July.

Hi, SWB TT Hardtop. Whats yours? Sorry for the double post earlier, I think the server went a bit weird.

I'm in Portsmouth

I'm in Portsmouth.

When and where is this happening?

Does anyone know where I can get some replacement coilover rings for some HKS coilovers? Or anything that would fit?

No Nistek have checked all the pipes and sail no leaks or blockages. Defiantly turbo . . . unfortunately. :pinch:

If the turbo's cooked then it's going to have to come out anyway, also I can replace any other coolant/oil lines that look on the way out, and maybe a few mods if I'm not too frustrated with getting it out and just wanting it done and dusted. :taz: It's being sorned in feb anyway so i'll have all spring to do it, so no rush. Probably will be asking lots of questions on here throughout :tongue_smilie: Hopefully be back on the road for the summer.

That had crossed my mind but I though I'd just do it myself, not only will it be cheaper, but once I've done it, I'll know how too. So if I ever need to do it again in the future it'll be a doddle. :thumbup:

Ok so I took it to my local gaarage, told them all i knew and a day later they said that it's: 1) Rocker cover gaskets leaking oil 2) Sump gasket leaking oil 3) Turbo oil feed pipe leaking oil They said it's a specialist job so recommended it to Nistek (Nissan Specialists) After going to Nistek they said nope it's none of those its: 1) Likely turbo's knackered 2) Head gaskets leaking oil But neither garage want to touch it cos it's too difficult for them, with their manuals and hydraulic ramps and specialist tools. So it looks like I'm going to have to pull the engine and have a look on my drive with just a jack and some spanners. If I can do it, why can't they? How do mechanics seriously get a job I'll never know? :no:

Are these the oil lines? (Circled Red)

You don't need to start the car, it just pours straight out :scared: I'll give that a go tomorrow and see if I can locate the problem. Does anyone know where the oil feed pipes are then?

Just looked at what I believe are oil feed lines which I've circles blue. Dry as a bone. The oil is sitting on the turbo circled red but under the shield. Could there be a leak from above circled green. Any ideas? :crying:

Hope c**p no need for a drive put in about a pint of oil and half of it has landed on the drive dripping out from under the RHS turbo. Feed/return pipe seal??? Surely can't be anything else!!!

Good news . . . kind of, I've found the problem. Yes it is the turbo and the reason it's make the noise is because I have no oil. Checked it on the 31st Dec was on the high mark, now 2nd Jan doesn't even register on the stick. Going to top it up now and drive, if noise is gone we have an answer. So the question now is . . . any likely culprits?

Another development, was driving the car today and no noise what so every for about 3 minutes, then as the car was warming up, it started and as it was getting warmer it got louder. Till up to full temp it was the loudest, also on full boost it gets very quiet. Only around -3 to +3 psi it makes the noise really.