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S2 Stagea Boost Fall Off.

GorGasm

By GorGasm,
in Four Door Family & Wagoneers

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GorGasm Collaborator

GorGasm

Posted
Posted

Howdy.

Ive noticed lately that my S2 turbo seems to fall off boost at high RPM. It happens regardless of boost controller settings (profec b s2). It seems to lose about .1-.15 bar in the last 1500 rpm before redline.

Just wondering if this is normal?

Perhaps it is just whacky boost control or is it the turbo running out of huff?

Boost is currently set at .8 bar if that means anything.

Has anyone else noticed this?

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https://www.sau.com.au/forums/topic/107603-s2-stagea-boost-fall-off/
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darrinspencer Grand Master

darrinspencer

Posted
Posted

I am no turbo expert

Does it do it on stock boost?

If it doesn't, your problem could be the wastegate creep, not staying fully shut at the higher boost setting and increase rpm.

Fix. need to put more tension on the wastegate.

Either put a bend in the factory actuator rod or fit a adjustable wastegate actuator

You can get a new garret for under $200 or a HKS one for over $200

And if you want to run a higher boost setting ALL the time you can buy a actuator set to eg 10 or 12 or 15PSI, that way the EBC does not need to bleed off so much air.

Maybe talk to GCG or someone.

That is my guess

GorGasm Collaborator

GorGasm

Posted
  • Author
Posted
I am no turbo expert

Does it do it on stock boost?

If it doesn't, your problem could be the wastegate creep, not staying fully shut at the higher boost setting and increase rpm.

Fix. need to put more tension on the wastegate.

Either put a bend in the factory actuator rod or fit a adjustable wastegate actuator

You can get a new garret for under $200 or a HKS one for over $200

And if you want to run a higher boost setting ALL the time you can buy a actuator set to eg 10 or 12 or 15PSI, that way the EBC does not need to bleed off so much air.

Maybe talk to GCG or someone.

That is my guess

Interesting ill have to check that. It is fine at low rpm and full boost, it just falls off up higher.

Dont think its pipe leak as it will hold 0.8bar at low rpm...

Thanks for the ideas.

Sydneykid Grand Master

Sydneykid

Posted
Posted

12 psi with the standard intercooler?

My guess is restrictions in the inlet and the turbo running out of airflow to hold 12 psi at high rpm

Or the boost controller is not controlling boost properly.

Try it at 10 psi, the standard turbo will last longer anyway, and see if it still drops boost. If it doesn't, it's airflow restrictions.

:biggrin: cheers :biggrin:

AlexCim Grand Master

AlexCim

Posted
Posted

Ive only been on this forum for the last 10 months, but the ammount of times that i have seen that question asked.

The turbo can run 22psi daily (as seen on chris's stagea, exagerated example) BUT, it will shit itself. Its not RPM that kills the turbo, its HEAT. You can safely run say 15psi all day every day, if you boost it 5 times off the lights a day or whatever.

Lots of people have 12psi road tunes which seem OK, but when 12psi it run in track/hills, the turbo WILL shit itself and you will get ceramic in the cat disease. ~SAFE boost is 10psi for track/hard use. Stock boost is about 5psi and stock no solenoid boost is about 7psi.

Oh, and to me, the turbo above just sounds like its running out of puff. Get a boost controller which you can tune accuratly like a jaycar unit. The profecs only have "gain" which is a pretty poor attempt at boost control for restricted turbos. Or, as SK said, inlet restrictions

AlexCim Grand Master

AlexCim

Posted
Posted

Yes, I have an S1 but there is no realy difference between the turbos, some will say there is because of the plastic compressor wheel in the GTT vs GTST, but who cares, we are talking about the turbine wheels which are both ceramic.

I havnt heard anything in specific, but think of it this way. The turbo was made for the car in stock for, designed for it in stock form. So it was ment to run lets say 7psi daily. Now, you boost that to 12-14psi, thats 80-100% MORE then what it is stock.....in my experiance anything pushed to double "reccomended/designed" has not been as efficient/capable etc.

Also, the same goes for the flow of the intercooler, but a GTT intercooler is good for around 200awkw so word goes.

Its not just boost which brings power, its the flow of a turbo. Thats why people say "it flows 450hp". If the turbo can physically flow more air, you are removing the biggest bottle neck in the system (lets say the pipes are the upper limit). So, with a bigger pipe (assume turbo has reduced the bottle neck) for the same pressure you can flow more air....more air is what causes more power. Thats why GCG bore out the turbo compressor/turbine housings to fit bigger steel wheels. If you just replaced the stock turbo wheels with steel units, you wouldnt get much if any benefits.

Tangles Grand Master

Tangles

Posted
Posted
If you just replaced the stock turbo wheels with steel units, you wouldnt get much if any benefits.

Just reliabilty to be daily driven at 12psi, and maybe pushed to its limits of efficiency at ~13psi.

But it still costs around $1200 to put steel wheels in (non-highflow)

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