What's the max boost for stock Turbo?

[streetknight]

Just wondering how much boost the stock turbo can make efficiently. Looks like I'm gonna be sticking with it for a while and would like a good baseline.

I'll be running one of Razor's alky kits with a stock IC.

TIA

 

[JP112_89]

..

Maybe 21-22#'s. I have heard of 24#'s somewhere on the boards but not sure.

 

[streetknight]

Thanks for the reply. I'd been reading up and saw a few guys had gotten into the 11's with the stock turbo and IC. I new I had a TA60 and stretch IC to go 11.70's a few years ago.

Just hoping to max out what I have

 

[DCVING 6]

Most people run into a brick wall around 22-23 psi where the turbo just starts pumping "hot air".

 

[QUIP'6']

Just wondering how much boost the stock turbo can make efficiently. Looks like I'm gonna be sticking with it for a while and would like a good baseline.

I'll be running one of Razor's alky kits with a stock IC.

TIA

your turbo will be more efficient when running alky unlike racegas so you can run 25 psi and make more power than 21 or 22 just keep upping the boost and tune for mph not et. if you see no gain then go back a pound

 

[dsa87gn]

I run my stocker at 23# with alky. Havent been to the track in a while so dont know about the limit, but it pulls good.

Had to go with a maual boost control to get there tho. the adjustable wg maxed out at around 20# on my setup.

 

[TTA1326]

I've been to 27psi on a stock turbo, stock intercooler, and Razor's alky. It was an accident on my part, but the engine survived thanks to the alky. I had been running 23-24psi and I don't think it picked up anything at 27psi, but at least I can say I've been there! :biggrin: The thread was in the Turbo Trans Am section, but it's gone now.

Alex

 

[GNVYUS 1]

Your intercooler and other inlet backpressure items will alter this answer.

Ditch the intercooler while going mafless and the turbo will be able to hold way more psi. The stock intercooler has about 7psi of total backpressure on the turbo, here is my breakdown.

Gain 2psi by going to Dutt neck
Gain 3.5psi by going to CAS FMIC
Gain ?? by ditching FMIC, I'll find out soon.

Add pre turbo alky and gain 1psi!!

 

[moose]

One thing i noticed when running my stock turbos at high boost levels is that they seem to go down quicker.

 

[RUQWKNF]

Without alky, the stock TBO348 is pretty much done at 25psi. Charge temps are out of control, as well as flow capabilities are maxed. Throw alky into the mix and it significantly helps control charge temps, however, you are still reaching critical flow limits of the rotating assembly at high boost levels. If you were to install a Back Pressure gauge and monitor BP readings at boost levels over 25psi, you would see what I mean. It can only spin so fast before you reach an over speed condition. Ever see what happens to a turbo when it's run at the edge? Or into an over speed condition? Not pretty. IOW, you'd beating a dead horse. Now, if you factor in the turbo being a stock OEM unit, it's at least 22 years old at this point. Can you say grenade with the pin pulled?

I would not run a stock turbo past 25psi myself, even though I'm guilty of doing it a long time ago. (Circa 1994)
Just my O2's worth.

Patrick