I know stock boost is around 19 psi, but my question is what boost is "safe" with a stock turbo/ motor? Of course, this would have to be done along with a tune, but coming from DSMs any 25+ psi would have to be on an after market turbo. Granted the Evo stock turbos are bigger than t25s/14b's, so I'm just wondering what some of you guys are boosting on a stock turbo/ motor setup?
Thanks

 

I remember reading somewhere that the turbo efficiency is reduced after 26 psi, after that you are blowing warm air.

 

I just feel like 25 psi is a bit high for a stock turbo/ motor, even with a proper tune. Am I just being over protective of the car, or can it actually cause some damage? Its not like I'm flying around WOT everywhere, I actually drive like a grandpa, but it still feels like a little much..

 

I'm not the resident tuning expert.. but boost seems relitive around these evo's. Seems to me it's all in the tune and what you've done to your car. by making your car breath better you can up the hp/tq while lowering the required boost. by raising the boost.. you basicly are heating things up.. the hotter you go the more knock you get. thus using higher octane / e85 meth injection etc to cool things off. do some porting, higher air flow inter cooler, etc etc making your engine breath better will cause less friction with less boost pressure required = less stress on the engine. (did i get that right?)
seems to me i saw a video of a race engine doing like 11000rpm with like 10 psi or something... doing 700+hp not sure about the torque...

my car boosts to 24psi at my altitude..(Calgary is 1150m ). when i drive to edmonton it's 668meters above sea level i boost 26-27psi on a cobb stage 1 93 ots. the engine seems to be running fine with no ill effects so far. i'ts a high pressure turbo engine for a reason.. in the uk they make the fq 300,360,400.. they're all high boost and sold as factory. the main thing is they all require high octane fuels..

if we're talking about the juke which is what 9-12psi stock and people are running them up to 18psi, then theres the cruze which is about 15-17psi and ramping them up to 20psi
bunch of others are the market in and around the same range. my volvo v70R was running 19psi , and the GTR runs a factory 10-12psi and ramp it up to 14psi with the cobb maps

Also if you have checked out some of the dyno's on these forums with people using bigger turbo's their pushing 27-30+ psi with built and non built motors. obviously the later may not last long.

push the car to what ever you feel is safe.. if it's your daily driver.. then keep things safe.. if it's a bit of a toy then do what ever you want. I'm sure there are cars on this site that while at the track keep with cars 2-4 times the price.

 

Thanks, that actually helped a lot! I will be running e85 again in the near future, so that'll make me feel a bit safer with running higher that stock boost.

 

I'm on a 9 turbo and set at 24psi on 93oct and 28psi on e85. Little guy keeps spooling like day one. I have basic bolt ons liek you too.

 

I know the 9 turbo is a little bigger than the 8, which would mean you're flowing a bit more air than I would be at that pressure. I cant wait to start filling it up with e85 again. That makes me feel a bit better running that boost. Thanks!

 

Proper tune is usually key

 

Well it depends on what mods you have I run 32psi on e85 on my stock turbo.

 

i'm on pretty much stock, with the exception of the e85 tune. I'm boosting and holding about 24 psi. going with head studs to boost a bit more. From the previous post, tune is def. key.

 

run e-85 and some good bolt ons (especially cams, dont forget springs) and you should get 350-380whp on a mustang dyno