Shownomercy

iTrader: (1)

Don't kill me, very off the wall question.

Lets say you had a good data collection on a comp wheel, and you wanted to see how much flow it would do at say 40k ft.

Temp, Density and speed would be known, is that a possible calculation given you have a proper map?

JoeNova

It shifts the compressor map around.

Compressor maps aren't labelled in kPa or PSI, but pressure ratio. If you take it high enough so that ambient pressure becomes 12 PSI, then each full digit increase of the pressure ratio on the compressor map is only 12 PSI instead of 14.7.

It also shifts the choke area to the left a bit because the air is moving much faster in order to create the same pressure ratio, so it will choke earlier. I'm sure there is a calculator or some ratio that can be figured up to find the choke line at a given boost pressure if you have a compressor map.

Shownomercy

iTrader: (1)

I am more concerned with mass flow than pressure, although they are related.

At 40k there is no pressure, basically a vacuum. Just looking for a jump start to where to start the calculations etc.

JoeNova

I'm not sure if there is a calculator out there for that exact thing, but you could probably use something like this to get close to what you need.

http://www.motorgeek.com/?fullpage=true&page=flowcalc



I really like this one. Get everything set to where it needs to be, and change the altitude to watch its effect on CFM.

www.turbos.bwauto.com/aftermarket/matchbot

Shownomercy

iTrader: (1)

Neither says a turbo would work at altitude

Interesting though, I will keep at it

sbcgenII

iTrader: (1)

If there is no air then what are you going to compress?

Shownomercy

iTrader: (1)

Axial style fan will create high and low sides, which moves air mass, at 40k ft.

Just a work conversation that came up and was looking to get more info.