On a 4094r map. I know how to get the max power it can move with 80lbs. But how do you know what psi it takes to get you there? say running 30psi? is it 30 + 14.7/ 14.7=3.04

So if thats true running 24psi verse 34 psi its only going to pick up 2lbs more in boost?

Here is the map:

http://www.atpturbo.com/root/maps/gt4094r.htm

Just curious were I would be on the map 28psi verse 35psi?

 

Yes that is how you calc PR

and it will pick up 2lbs/min of air.

You dont' run higher P/R just for the turbo maps.

You run that for your engnine based off your VE - to force air into your engine.

So you if you run a P/R of 2 it does not mean your engince can injest the max of what the turbo can flow.

It's like a 4cylc vs 8cyl - they will be able to injest a different amount of air give the same p/r.

The compressor map will tell you how efficient it can deliver that air given the two different flow rates.

Use the VE of your engine to calc how much air you will injest at a given P/R

That is just what the turbo is capable of.

I would post my VE calc but it's on a different computer.

Generally i start off with .9 then move up to 1.1 in the rpm (i have a non-street port) - efficient rotary can go 1.15.

becareful not to miss the displacemnt as we are rotary.

 

These websites explain the process pretty well:
http://www.gnttype.org/techarea/turbo/turboflow.html
http://www.turbobygarrett.com/turbob...o_tech103.html

The x-axis on that compressor map is the flow rate in pounds of air per minute (lbs/min), not to be confused with the manifold pressure which is commonly measured in pounds per square inch (psi). If you fill a container with air until it weighs an extra 2 pounds, you will see that it will require a LOT of air, lol.