Boost drop T25

[Juanjo07]

I Have the stock turbo and I noticed that in 2nd gear when I accelerate the car it goes all the way up to 15 psi and then drops to 10 psi

I have been reading and I found that at higher RPM the engine require more air so the turbine cant keep up(choke)

My question is what would be better or more efficient when racing shift gear at lower rpms so I can keep boosting 15 psi or go all the way to 7000 even that the boost will drop

 

[partylikeits82]

I would recommend actually fixing the problem, rather than trying to work around it. Your t25 should be able to handle 15psi (not much more though). What sort of boost control are you using?

 

[chrysler kid]

No the t25 only holds 12 psi to redline. A member on here last week forgot to hook up the actuator and the most it will spike to is 21psi then drop to 12psi. My car with the boost solenoid not connected spikes at 15 then backs down to 12 on its own

You can get a downpipe and exhaust to free up some back pressure but what you are describing sounds normal

 

[oneslowwdsm]

Yeah T25 would not be able handle 15psi all the way to redline. When I was on the stock turbo back in the day I found shifting at 6K RPM would be efficient enough. Shifting at 7K just felt like I was wasting time.

 

[doubleclutch]

Since more air>more fuel>more power, you are better off to take it to red-line or close to it if you want to be nice to the motor. Boosting at 15 at lower RPMS just means there is more power to be had. Once the pressure has stopped dropping you know that you are getting the max airflow out of the turbo. It doesn't feel as fast since you don't have the "pull" of when the turbo is spooling, but you will be making more power in the higher RPMS. Not to mention short shifting leads to more off-throttle time and more turbo spool time because you are shifting more often.

Probably should just do yourself a favor and go get a 16g.

 

[Juanjo07]

Yeah T25 would not be able handle 15psi all the way to redline. When I was on the stock turbo back in the day I found shifting at 6K RPM would be efficient enough. Shifting at 7K just felt like I was wasting time.

Yea that its exactly what I'm experiencing. it feels like the car is not moving any morecompared to when is boosting 15 psi

Since more air>more fuel>more power, you are better off to take it to red-line or close to it if you want to be nice to the motor. Boosting at 15 at lower RPMS just means there is more power to be had. Once the pressure has stopped dropping you know that you are getting the max airflow out of the turbo. It doesn't feel as fast since you don't have the "pull" of when the turbo is spooling, but you will be making more power in the higher RPMS. Not to mention short shifting leads to more off-throttle time and more turbo spool time because you are shifting more often.

Probably should just do yourself a favor and go get a 16g.

I haven't drive to hard since I noticed that the boost was dropping I thought that something was wrong, then I read a lot and it seems to be normal. So I never have shift to 3rd gear at high RPMs.

Getting a new turbo is one of the next mods that I'm going to get. My goal is 350, should I get a 16g or something bigger?


Thanks to all for the responses

 

[EvilGST]

A big 16g at full tilt will get you to 350whp provided you have the supporting mods. A 68HTA will get you there alittle easier.

 

[J Fresh]

Just filled out my profile and have been reading threads like crazy... I too have a stock T25 setup and am slowly adding mods to support a bigger turbo which will hopefully happen this summer. Definitely leaning towards the Evo3 16G over the 68HTA since ill never take it to the track and everyone says the FP68HTA only really comes to life when boosted over 23ish PSI... Im actively searching for a used MHI 16G that I can have rebuilt vs buying a new one although a new one would be great for peace of mind in the long run!

 

[Kryndon]

With N/A cars, you'd want to go as high up in the RPMs as possible (until airflow becomes a restriction due to intakes/piping).

For our stock T25 "hairdryers", you will be maxing its airflow up to 5700-6000 RPM. Anything above that is negligible.

Also, if it goes up to 15 psi (overboosting) and drops down to 10, you could have a boost leak somewhere.

 

[90TSIAWDTALON]

I was playing around with upping the boost with Link and noticed my boost would come up to 16 and immediately drop to 10psi no matter what changes I made in Link. I ended up pulling the boost signal from the wastegate and got the same results. I figured my stock 2g plastic BOV was blowing open at that pressure so I capped it off and voila, it would hold boost higher than stock. This could be your issue as well if it is indeed an immediate drop in pressure. It was a cheap test, just ensure you don't overboost it.

Edit: Just realized someone resurrected this thread from last year. Ooops.