Originally Posted by Dizings2k

Sorry - should've included this in the other post. I'm on a 3.4" pulley, Novi1200, AP2 8400rpm redline

Originally Posted by Car Analogy

No one directly answered your question. No, the tune doesn't affect psi.

Its strictly a mechanical function. This size pump, pumping this fast, into this big an air tank = this psi.

Now realize something important. You might have the same size pump as others (same head unit blower), at same speed (same pulley sizes, same rpm), but you don't have the same size tank.

In the analogy, air tank is your motor. While its same displacement as others, same engine rpm, a bunch of other variables are there.

Exhaust system, engine health, etc. The size of the air rank is also always changing. With rpm, woth throttle position.

Actually, its more like pumping air into a tank with a small hole in it. So it never fills up.

Also understand psi is NOT a direct correlation to power.

So for example, today someone gets 15 psi. They only change exhaust, to something freer flowing. Now they make more power, but now they are at 12 psi.

They didn't change anything with sc setup. Yet they make more power, but less boost.

Basically, same pump, at same speed, but now the air tank has a larger hole in it. So it reaches less psi.

Also realize your car in different places will make different psi. So you can't directly compare someone at a different elevation psi with your psi. Their car in same place as you might make same psi as you. But since they're somewhere else, they make different psi.

The blower is locked in to spin at a set blower rpm for a given engine rpm. Its mechanically driven. So the air its able to compress will be more dense, or less dense, depending on elevation.

14.5psi of atmospheric barometric pressure at sea level means a magic one inch square tube, the length to reach up from sea into outer space, when you collect all air in tube and weigh it, its 14.5 pounds. Go higher, mountains, etc, tube shorter, less air, less weight, less starting psi. Less dense air (because less air on top squeezing it), means blower can't boost it as much.

So same car, same sc setup, less psi in mountains (turbo doesn't suffer as much, since less dense air means less wind resistance, so same engine rpm, turbo will spin faster, partially making up for less barometric pressure. Turbo isn't mechanically linked to engine rpm.)

Originally Posted by Mobias

Just to help, on my 3.2 griptec pulley with stock exhaust, I am still seeing 16psi at 8300rpm on an ap2. So I don't think it's your exhaust unless you have some serious blockage. I'm in Ohio and at similar elevation to you.

Originally Posted by Mobias

Just to help, on my 3.2 griptec pulley with stock exhaust, I am still seeing 16psi at 8300rpm on an ap2. So I don't think it's your exhaust unless you have some serious blockage. I'm in Ohio and at similar elevation to you.

Originally Posted by flanders

Stock cat as well?