Boost fluctuating after 2g bov switch

[Nonrml4]

I recently switched to a 1g bov after pulling the bcs insert and having my boost gauge peak at 12 psi (I believe that the plastic boc was leaking because it would sputter around 12 psi and I would hear air escaping) Now after I got the 1g bov installed the boost gauge will peak at 15 psi and as it pulls to redline lower to about 11 psi. Do you think I have a boost leak? I dont understand if I would have a boost leak since it will hold 15 psi in the beginning and just not the end of the gear. Is something wrong here . Any help would be great, John

 

[luvmygst]

You might have a boost leak, what turbo are you running? When I still had the T-25 I also had problem with the boost dropping at higher rpm's. The turbo might not be flowing enough air to keep up with the motor. I would still check for leaks, it cant hurt to look.

 

[blackGSX2g]

You have discovered the limitations of the stock T-25 turbo. Upgrade to a 14b or 16g variant for constant boost to redline.

I agree, it never hurts to do a boost leak test, but the symptoms you describe fall right in line with anyone trying to run 15psi to redline on a T-25.

 

[Nonrml4]

You have discovered the limitations of the stock T-25 turbo. I agree, it never hurts to do a boost leak test, but the symptoms you describe fall right in line with anyone trying to run 15psi to redline on a T-25.

What is a better boost level to run on a T-25? I have a home depot manual boost controller and havent put it on yet due to the 15psi after pulling the bcs. I read that 15psi is the highest to safely run on the stock fuel management. Would lowering the boost level lead to better performance or just a smoother powerband? thanks for the replies. John

 

[S_Ranger]

I wouldn't go anything past 13 until fuel upgrades have been done. No use working that little turbo w/out some nourishemnt to keep it going.

 

[Ultimatedsm]

Well you know why did your boost jump from 12 psi to 15 psi? Your stock 2g BOV can't hold boost past 12-13.5 psi. So once you dropped in your 1g BOV which can hold around 18 psi, there was no boost leaking from the BOV. Why does it drop to 11 psi at redline? T-25 can't product enough air pressure to support over 5000 RPM engine speed. If you put in a 14B TDO5, I noticed it can hold 18 psi or even higher to redline (personal experience). If your on a budget, get the 14B, if you have the cash, get the EVOIII 16g, then you will no longer suffer the 11 psi at 7000 rpm drop .

 

[Ultimatedsm]

What is a better boost level to run on a T-25? I have a home depot manual boost controller and havent put it on yet due to the 15psi after pulling the bcs. I read that 15psi is the highest to safely run on the stock fuel management. Would lowering the boost level lead to better performance or just a smoother powerband? thanks for the replies. John

15 psi on the T-25 is fine, you will drop to around 11-12 psi at redline regardless. With 15 psi, you will have more low and mid range power, but your top end will not notice much of an improvement. Just shift around 6000 rpm and you will always be in the T-25 power band. Once you add an exhaust system I recommend getting a MBC because your boost will spike to around 17 psi or even more depending specially with the BCS mod.

 

[blackGSX2g]

What is a better boost level to run on a T-25? I have a home depot manual boost controller and havent put it on yet due to the 15psi after pulling the bcs. I read that 15psi is the highest to safely run on the stock fuel management. Would lowering the boost level lead to better performance or just a smoother powerband? thanks for the replies. John

There is nothing at all wrong with that boost level, but the turbo can't hold the raised boost level in the higher RPMs. Once I put a 1g BOV on my otherwise stock car, my 'stock' boost level was about 15psi with no aftermarket boost control. Its completely normal, its just a limiting factor when you are trying to get more power out of your car.