Best Maximum boost pressure for a GTA Turbo ?.

Hi all,

My GTA has the Renix ECU upgrade, and supposedly has uprated boost pressure. Allthough it did not seem any different from other GTA's i had driven.

I will be fitting a quality 1 bar Boost Gauge to my GTA, as i have done with all my turbo cars. As I like to keep an eye on the pressure, and ensure its set correctly.

I have read on some sites that the recomended max pressure is 0.85 bar for reliable running. And factory is 0.65 bar.

But what is the census here ?.
What is the max boost pressure to set, given an engine in good tune and condition.

Cheers !.

I ran 14 psi on a BBR chipped std GTA with slightly bigger injectors and turbo .Any more and I think you'll be pushing it a bit .
12psi I would say is the limit to keep it all safe as it will tend to spike .


Have you sent off for your membership yet

Yep, Sent of the forms and payment just before christmas....

That's all right then

My Saab 9000 Aero, Maptun Stage 3 was running 23psi (1.6bar).

Guess i better not try that much then, or goodbye PRV !.

Even on aftermarket management, much beyond 1bar and it'll just make more noise

and a lot of heat

I dont think the Garrett T3 can go beyond 1bar anyway.

Back when i used to tune Saab 900 Turbo 8v's, they would not go beyond 1 bar, and they used the same turbo. Even with Water injection, and forced cooling on the intercooler, the turbo just makes too much heat.

We used to have some good success with Motorbike radiator cooling fans on the Intercooler. They would greatly help reduce intercooler and hence intake air temps.
Anyone on here tried anything similar ?.

My modded T3 is maxed out at 18psi poss even at 16 ...But it is the heat that is the real killer .I put a water spray on ,not injection ,but that was only good for short bursts as it soon runs out .

My modded T3 is maxed out at 18psi poss even at 16 ...But it is the heat that is the real killer .I put a water spray on ,not injection ,but that was only good for short bursts as it soon runs out .

I have heard that the 21 turbo T3 is acually slightly higher spec than the T3 on the GTA I was wondering if it could be fitted as a very cheap way of getting just a little more from a basically stnadard engine set up. I am guessing that the lag experienced on the standard car is the reason they put a slightly lower spec T3 on the PRV so that it spins up a little easier.

Has anyone tried it, or is such a small difference its not worth the effort I know it runs out of puff at about 230bhp, maybe a hybrid T3 is the way to go in the first place. I guess a modern roller bearing turbo would help reduce the lag too.

si21

21 T3 has a .48 exhaust housing as std doesn't it ? That'll be it I suspect ...GTA .36
My modded one is good for around 260 .It's running a .63 but that is very laggy .
RATS will be listing some good Garrett rebuilds and upgrades soon

21 T3 has a .48 exhaust housing as std doesn't it ? That'll be it I suspect ...GTA .36
My modded one is good for around 260 .It's running a .63 but that is very laggy .
RATS will be listing some good Garrett rebuilds and upgrades soon

Any anti lag for those of you with stand alone nothing like suirting neat fuel into the turbo to feck it up

No seriously is that an option?

si21

I wonder if a Garret T25 from a Saab 9000 lpt would fit.

The lpt's (low pressure turbos) ran at 6psi. But will run at 12psi without issue. The turbine itself is tiny. As a consequence lag was practically non-existant. Just instant boost.

The GTA's lag issue is not helped by the long exhaust manifolds and runners to the Turbo.
Using a Manifold wrap, and Turbo wrap, will help keep EGT's up and reduce lag.

Anyone tried this ?.

[stephendell]

Have you got a water cooled turbo on your car?

No, the T3 is not water cooled.

However, the T25 can be used without the water cooling. Alot of people with old Saab 900's. (The classic 900 as its called), fit the T25 as a replacement for the T3, but without using the water feed and return.
Provided the normal cooldown procedure is followed after a drive the life of the turbo seems unaffected.