Theory Question, Comp Wheel Flow
Theory Question, Comp Wheel Flow 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?
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?
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
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.
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.
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.
At 40k there is no pressure, basically a vacuum. Just looking for a jump start to where to start the calculations etc.
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
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
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
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
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
Interesting though, I will keep at it
