Pressure between engine and turbo

[turbometh]

Does anyone know what the pressure reading should be if I take a reading before the turbo.(between manifolds and turbo) This is on a v8 single turbo application.

[xrattiracer]

on most stock setups it will be between 2 and 3 times the intake pressure (boost). on a custom setup its hard to tell without knowing the engine size and turbo size, and having a bit of experience. The closer you can get it to the intake pressure, the better.

[turbometh]

Thanks, I ended up finding my notes late last night. We were setting at 50+psi with 15 lbs of boost. Bigger turbo is on the way. Thanks again!!!!

[xrattiracer]

ouch, you certainly are in need of something larger alright!

[igotaneed4speed]

1.5 times intake pressure i would think is optimal

[xrattiracer]

optimal would be as low as you can get it
some race setups will have exhaust pressures that are less than the intake pressure, but also are designed to run within a certain powerband so would not be much fun on the street.
I am aiming for as close to 1:1 as i can get, since that is the secret to running a good cam. make the engine act more like an n/a engine and you can run really wild n/a cams.

[turbometh]

Our problem with this truck was that it started out as a stock 383 Jasper crate motor. Made 380 on our Mustang dyno with the small turbo that was sized for that application. The customer wanted more power so we built him a good 383 with 4 bolt splayed caps and turbo roller cam 8.8:1 forged pistons and brodix race rite heads. We just neglected to think that this turbo was not sized right on the exhaust for the new application. The compressor was still ok if the thing could spool. We just decided with the new motor to get a bigger turbo on both sides. PT76GTS