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:

not sure where u been reading but 28psi !! u blow the engine up ..

 

Stock boost is 9psi .. with a remap u can up the boost to 13/14psi ish

 

after that u will need other mods

intercooler

injectors

diffrent remap

turbos

 

all the boost spec is shared between both tubs

Hi, 14 psi is about the max the standard turbos can handle, so unless your running non standard tubs and IC's etc theres no point in turn it up pt 20psi unless you want your engine to pop!

 

I was running 14 psi with boost jets and upgraded chip, on the dyno it maxed out at 370bhp, hth

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:

 

Not sure where you read that 20 to 22 PSI is good on a stock set up, id say you are actually heading to blowing something up with that amount. 14 to 16 on stock is what ive heard countless times. the stock turbos cant handle above that and you will get in to all sorts of problems.

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?

yes we got what u said and we gave you PSI spec in combined pressure ... 14psi Max so that would be 7psi each turbo

 

DO NOT RUN at 20psi

No mate!! We actually mean 14psi combined!!!

 

Stock boost for both manual and auto is only 9psi combined; there is a balance bar to even out pressure between the turbos and 9psi is standard boost in the whole system.

 

Yes, the gauge does go up to 14psi (on both manual and auto cars) but unless the car has been modded (or the gauge is not accurate - and after 20 years the consensus is that it's probably not), you will rarely see the needle above 10psi.

 

Richard:surrender:

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

Nope Stock Boost is 9psi .. Combined

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

 

No - 7psi is not stock "per turbo" the combined boost pressure in the system of 9-ish psi.

we will get there soon .. :)

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?

you may have got lucky and all your Zeds been slightly modded with controller or boost jets and remaps ..

 

as Most drivers that own Zeds its one of the first mods to be done ... More Power

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?

 

Positive mate - 9psi stock combined boost pressure and 7psi on safety boost. You may see slightly higher pressures on the gauge - as said the gauge may not be so accurate after 20 years. Also low ambient temperatures can raise boost pressure slightly; along with light mods like an aftermarket air filter and exhaust. The improved breathing "might" have a small positive effect.

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.

Because the wastegates will operate based on the combined pressure in the whole system; and not just per turbo.

 

Each turbo operates just one bank of cylinders remember - so you have one turbo generating 9psi as if running 2 separate engines; the balance bar will even out slight differences to ensure smooth power delivery.

its not all to do with how much Pressure the turbo can Provide ....

 

Volume of air is the key factor in performance and using one turbo for 3 cylinders = more volume of air from that turbo per cylinder

but all so your referring to a 2.0lt engine and one tub

it will need more PSI to hold the volume of air for the 4 cylinders

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.

Quote I think people really underestimate the quality and durability of these cars.

 

 

do u want to see what happends running at 20 psi ?

 

we are only advising you so u dont Lean your engine and blow it ...

 

 

 

looks nice dosnt it .. i did this 2 weeks ago to much boost + running to lean = Fooked engine

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?

did u ask them to make them work at 13/14psi each .... ? think thats where its all gone wrong for you ... as u didnt know the act work on the combined PSI

 

you would of been better sticking with the stock actuators and just getting a boost controller to sort it for u

I dont know where to start here....

 

First of all, theres no individual and combined boost. One turbo feeds one bank, the other turbo feeds the other bank. You do not add the boost pressures together. The Balance tube simply equalises out the pressures in the intake before they enter the combustion chamber.

 

The stock turbo's run 9psi each (or about 7psi in safety mode).

 

Do not run more than 12psi on the Stock ECU, the mapping is not there for extended boost and you can all sorts of fueling issues. With a remapped ECU , 14psi is a safe maximum raised boost level with Stock Injectors. Beyond this and the Injectors are at 100% duty for extended periods and the the mixture leans out, resulting in increased detonation issues.

 

With larger injectors (and a remap to suit) and aftermarket Intercoolers you can run them up to 17/18psi before they make too much heat to be efficient. However they wont last long and neither will a 20year old stock engine.

 

Beyond 14psi on stock turbos, most will opt to then go for an aftermarket turbo setup, and since the engine is coming out at this point it makes sense to fit Forged pistons, new bearings and freshen up the rest of the engine. This is where it starts to get expensive.

Edited June 3, 201213 yr by Yowser

I dont know where to start here....

 

First of all, theres no individual and combined boost. One turbo feeds one bank, the other turbo feeds the other bank. You do not add the boost pressures together. The Balance tube simply equalises out the pressures in the intake before they enter the combustion chamber.

 

The stock turbo's run 9psi each (or about 7psi in safety mode).

 

Do not run more than 12psi on the Stock ECU, the mapping is not there for extended boost and you can all sorts of fueling issues. With a remapped ECU , 14psi is a safe maximum raised boost level with Stock Injectors. Beyond this and the Injectors are at 100% duty for extended periods and the the mixture leans out, resulting in increased detonation issues.

 

With larger injectors (and a remap to suit) and aftermarket Intercoolers you can run them up to 17/18psi before they make too much heat to be efficient. However they wont last long and neither will a 20year old stock engine.

 

Beyond 14psi on stock turbos, most will opt to then go for an aftermarket turbo setup, and since the engine is coming out at this point it makes sense to fit Forged pistons, new bearings and freshen up the rest of the engine. This is where it starts to get expensive.

 

 

 

This ^^^^ is how I've always understood it

Quote I think people really underestimate the quality and durability of these cars.

 

 

do u want to see what happends running at 20 psi ?

 

we are only advising you so u dont Lean your engine and blow it ...

 

 

 

looks nice dosnt it .. i did this 2 weeks ago to much boost + running to lean = Fooked engine

 

i used to run 16psi boost on stock tubs

remapped ecu

 

upgraded intake

zorst

upgraded intercoolers.

 

mind it wasnt for long and all the time,most of time just 14psi boost

 

after looking at that pic i might think twice now :)

 

them boost controlers are so bloody tempting tho,you are always tempted to to just wind it up grrr

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.

To many people saying to many different things, I asked JKM to set my actuator to 10psi. If what Yowser is saying is true and "The stock turbo's run 9psi each (or about 7psi in safety mode)." then 10psi is only a fractional increase over stock.