Maximum safe BHP for stock 1.5 with turbo

[thebarber]

its likely more about the psi you're pushing with the turbo or superchager vs the actual at-wheel hp

i think 9-ish psi would be the max max on our already 10.5:1 compression engines...

[mightyMax95]

Originally Posted by thebarber

its likely more about the psi you're pushing with the turbo or superchager vs the actual at-wheel hp

i think 9-ish psi would be the max max on our already 10.5:1 compression engines...

hate to do this to you :hide: but psi is irrelevant, flow is key here.

little bitty turbo can run high pounds psi and big turbos less pounds psi without blowing. this is coming from a Maxima forum where some guys reliably run 15 pounds of boost while others blow at 10, all on a stock 10:1 cr motor (vq30). the key thing is to use an appropriate size turbo with flow characteristics that will fit the application.

however, by far the most important thing is a good tune.

[cdydjded]

Originally Posted by thebarber

its likely more about the psi you're pushing with the turbo or superchager vs the actual at-wheel hp

i think 9-ish psi would be the max max on our already 10.5:1 compression engines...

9lbs on with a T28 (what Im using) is not the same as 9lbs with a GT2554R (what Garm is using)........

[Evangelion335]

Originally Posted by cdydjded

9lbs on with a T28 (what Im using) is not the same as 9lbs with a GT2554R (what Garm is using)........

Can someone explain this to me?

It was my understanding that the # measurement was accurate right untill it passes trough the throttle body.

Flow is an important matter, but only because you can create a bottle-necking effect that will rob you of available o2 into the engine.

The 9lb rating is going to be 9lbs no matter what the size of the turbo is. In the same sense that you can have a gallon of water thats pressurized at 9lbs as well as having an oz of water pressurized at 9lbs. Turbo sizes are relevant to the volume of air intake the engine requires not so much the #s required (this isnt a hard an fast rule).

Smaller turbos are ideal for smaller engines because:
1: A smaller turbo has less mass at the turbine meaning that it will take less force to achieve maximum rotations and therefore less time to achieve desired pressure.
2: Because you engine is smaller (1.5l) the actual internal volume of the cylinder requires less oxygen to reach the desired pressurization.
3: a large turbo and a small turbo running at identical pressures will produce the same horsepower gains. The "power loss" becomes an issue because you have selected a turbo that is limiting your maximum flow rate and spooling time. This can wildly effect torqe curves and produce a torqe curve that will become murder on trackday.

Can someone read that and tell me if ive got the theory right?

[cdydjded]

Originally Posted by Evangelion335

Can someone explain this to me?

It was my understanding that the # measurement was accurate right untill it passes trough the throttle body.

Flow is an important matter, but only because you can create a bottle-necking effect that will rob you of available o2 into the engine.

The 9lb rating is going to be 9lbs no matter what the size of the turbo is. In the same sense that you can have a gallon of water thats pressurized at 9lbs as well as having an oz of water pressurized at 9lbs. Turbo sizes are relevant to the volume of air intake the engine requires not so much the #s required (this isnt a hard an fast rule).

Smaller turbos are ideal for smaller engines because:
1: A smaller turbo has less mass at the turbine meaning that it will take less force to achieve maximum rotations and therefore less time to achieve desired pressure.
2: Because you engine is smaller (1.5l) the actual internal volume of the cylinder requires less oxygen to reach the desired pressurization.
3: a large turbo and a small turbo running at identical pressures will produce the same horsepower gains. The "power loss" becomes an issue because you have selected a turbo that is limiting your maximum flow rate and spooling time. This can wildly effect torqe curves and produce a torqe curve that will become murder on trackday.

Can someone read that and tell me if ive got the theory right?

Practice always beats theory:
http://www.turbobygarrett.com/turbob...ch_center.html

Read the above & all your questions will be answered....