psi and displacement

[zilo900]

Well I remember once seeing a page with a formula for however much psi of boost you run, what your displacement would be because of that. For example, xx psi it would be about the same as if the motor were a 3.8 liter engine. anyone remember or know where this is?

 

[LaN-]

no idea, but i've asked myself this many times.

 

[GSTBlack95]

I think there is something like, for every pound of boost your static compression ratio goes up, maybe you just use that static compression ratio to figure out your "engine" size.

Just a thought.

 

[zilo900]

I think it was a whole chart thing, maybe in excel that you could plug in air temp, psi, rpm, intercooler eficiency %, etc and it would tell you hp and some other stuff, but I just wanted to know the "calculated" engine size

 

[blackGSX2g]

I think there is something like, for every pound of boost your static compression ratio goes up, maybe you just use that static compression ratio to figure out your "engine" size.

Just a thought.

Static compression is not based on boost. It is based on the bore, stroke, combustion chamber size, and head/deck/HG thicknesses. To figure out your static compression, use the calculator tool here:

http://www.rbracing-rsr.com/compstaticcalc.html

You can not base calculations like that on psi alone as 15psi on one turbo is different from 15psi on another, you need airflow figures.

 

[zilo900]

thanks The sheet I was talking about also has input for airflow, I'm hopin I'll find it or remember where it was

 

[slipstream808]

Yeah... you run into all of those dang efficiency issues.

Turbo efficiency, Intercooler efficiency, and engine volumetric efficiency.

Then there's the Baro pressure, temperature.... and tuning.

But I hope you do find it and please post it up. I'm sure its a great tool!!

 

[tstkl]

dude, its incredibly simple,... with our 2 liter engines (1997ccs to be exact) every atmosphere of boost you add is another 2 liters. At sea level, one atmosphere is about 14.7 psi. So at sea level, running 14.7 psi, you have roughly 4 liters. In higher altitudes where the atmosphere is less dense, you need less pressure to use the same amount of air as a 4 liter engine, AT THAT SAME ALTITUDE.