is 5 psi on a small turbo = to 5 psi on a bigger turbo

 

NO, cfm's is the name of the game

 

Thats right, you can be running 13 psi on a small turbo, and be running 4 psi on a large turbo depending on the flow rate etc. to equal the same ammount of power.

 

Do you guys consdier a 60/63 t3 a big turbo?

 

It depends on what engine you plan on putting it on. If you think your going to spool it by 2500 RPM on a D series I'd say it's pretty big.

 

So your saying it wonts spool up on a d series by 2500?

 

i don't think so. 5 psi is 5 psi. the same volume of air will enter the intake ports and the combustion chamber with 5 psi of pressure. The question is whether this 5 psi was produced efficiently (ie cooler). If a turbo has to spin ridiculously high to produce 5 psi, it'll heat up the air more and you won't get as much power. In that case you'd want to go with a turbo that can produce the 5 psi more efficiently (the air would be cooler and more dense). So the short answer is: No, 5psi on a small turbo is not equal to 5psi on a big turbo, but not for the reason you might think. It's more about thermal management than it is about air flow. Also, keep in mind that exhaust back pressures rise when the turbo is making boost in an inefficient range (another power loss).

 

no its cfm. ihi is like 190 cfm. t3 48/60 is like 480. both at 5 psi you do the math as to what turbo will stuff more air into the motor

 

Read again what superpilun wrote.
He is correct... at 5psi in intake manifold, it doesnt matter what turbo is pushing air.
Difference is that bigger turbo will need to have wastegate more open due to better efficency, so more gasses pass by turbo, and air will be cooler he pushes due to better efficency and thus maybe some increase in HP.
As for CFM -> same CFM at 5psi, no matter which turbo.

Please use some common sense.

 

The correct measurement of air flow in this case is mass, not volume. So think about lbs/min or kgs/min rather than cubic feet per minute.
500cfm at 20°C is not the same amount of air as 500cfm at 60°C.
20lbs/min is the same as 20lbs/min no matter how you heat it up or cool it down.