MAF lb/min vs turbo efficency
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From: orlando, florida
MAF lb/min vs turbo efficency Can you use your MAF lb/min reading at a given RPM to map the efficency of a turbo? Say on my car at 6000rpms i`m pushing a little over 40lb/min through my MAF can I assume the turbo is also pushing 40lb/min and map that by my pressure ratio to find out what my compresor efficency is?
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From: Las Cruces, NM
The only way to get the efficiency of the compressor alone, you would have to test it with a housing and compressor alone. Same goes for the turbine and housing. What you are talking about will essentially give you efficiency, of the engine, (turbo - both compressor and turbine) and intercooler, aerodynamics, roling restance, etc,etc. This is not going to happen unless you know the thereotrical efficiency of all the different parts.
You can get a sorta get an efficiency of the turbo and intecooler and engine by performing a test at 6000 rpm, what ever boost you want on a constant load. The constant load means you need to not be accelerating, you could do this on a mustang dyno or on the road. You would need to know outside temperature (really you want temperature at turbo inlet) and barometric pressure. You need pressure at the maf (something you can log data from) and temperature at the maf (if your IAT has not been relocated that will work). Again you have to be at 6000 rpm, fixed gear, no acceleration, same mph during al the time you want data. This way its considered steady state and the mass flowrate will be constant.
So you log a bunch of data. There are several ways to get the efficiency. The easiest to me would be to caclulate the therotrical temperature rise based on on the pressures and flowrate using ideal gas laws (PV=MRT). Compare this temperature to the actual temperature and you have sorta a efficiency. It wont be of the turbo, but more efficiency of the engine, compressor, tubing, intercooler,etc. In reality this is more what you are looking for.
Hope that helps.
Gary
You can get a sorta get an efficiency of the turbo and intecooler and engine by performing a test at 6000 rpm, what ever boost you want on a constant load. The constant load means you need to not be accelerating, you could do this on a mustang dyno or on the road. You would need to know outside temperature (really you want temperature at turbo inlet) and barometric pressure. You need pressure at the maf (something you can log data from) and temperature at the maf (if your IAT has not been relocated that will work). Again you have to be at 6000 rpm, fixed gear, no acceleration, same mph during al the time you want data. This way its considered steady state and the mass flowrate will be constant.
So you log a bunch of data. There are several ways to get the efficiency. The easiest to me would be to caclulate the therotrical temperature rise based on on the pressures and flowrate using ideal gas laws (PV=MRT). Compare this temperature to the actual temperature and you have sorta a efficiency. It wont be of the turbo, but more efficiency of the engine, compressor, tubing, intercooler,etc. In reality this is more what you are looking for.
Hope that helps.
Gary
Originally Posted by MYTURBOT/A
Can you use your MAF lb/min reading at a given RPM to map the efficency of a turbo? Say on my car at 6000rpms i`m pushing a little over 40lb/min through my MAF can I assume the turbo is also pushing 40lb/min and map that by my pressure ratio to find out what my compresor efficency is?
