What is BHPc & BSFC?

[Tbone]

Received my test cell data from superior on my I0-360-B1AD2 and was curious what those terms mean in reference to the engine data?

[AltonD]

From Wikipedia

Brake horsepower (bhp)

Brake horsepower (bhp) is the measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump, and other auxiliary components. Thus the prefix "brake" refers to where the power is measured: at the engine's output shaft, as on an engine dynamometer. The actual horsepower delivered to the driving wheels is less. An engine would have to be retested to obtain a rating in another system. The term "brake" refers to the original use of a band brake to measure torque during the test (which is multiplied by the engine RPM and a scaling constant to give horsepower).

Brake specific fuel consumption

Brake specific fuel consumption (BSFC) is a measure of an engine's efficiency. It is the rate of fuel consumption divided by the rate of power production. BSFC is specific for the piston engine known as the reciprocating engine. The general term is specific fuel consumption (SFC). There is also thrust specific fuel consumption (TSFC) for turbine and rocket engines.

[Kevin Horton]

Originally Posted by Tbone

Received my test cell data from superior on my I0-360-B1AD2 and was curious what those terms mean in reference to the engine data?

I suspect (but am not certain) that BHPc refers to the brake horsepower reading from the dyno, corrected to standard conditions of pressure altitude and temperature. The power produced will vary with pressure altitude and temperature, which are pretty much outside the control of the guys in the dyno. If you want to be able to draw any conclusions from the dyno results, you need to correct them to standard conditions.

Note: I am not sure exactly which standard temperature the dyno guys would correct to. The international standard atmosphere says the standard temperature at sea level is 15 deg C. But, I believe automotive dyno guys use a higher standard temperature, IIRC. It is possible that aviation dyno guys correct to 15 deg C, or they might use the same formula that was created to correct automotive dyno results.

[rv6ejguy]

Originally Posted by Tbone

Received my test cell data from superior on my I0-360-B1AD2 and was curious what those terms mean in reference to the engine data?

Most dynos will correct data for atmo engines to 29.92 inches ambient pressure, 15C and 0% humidity. Referred to usually as corrected hp.

BSFC is Brake Specific Fuel Consumption usually denoted as pounds of fuel per corrected brake hp. This may be noted at several different mixture or air fuel ratios or EGTs. Best power will be at around 12.5 to 13 to 1 AFR and result in a relatively high BSFC figure. The lowest BSFC will be LOP in the 16.5 to 15.5 to 1 range in most cases.

What were your figures?

[Tbone]

My figures were... Intake air temp 86f, baro 29.9, rpm 2643, MAP 29.26. The BHPc is showing 160.44 and the BSFC is 0.6102. Not sure what that means but out to the side it shows in the comments section (Acceptance Test: BHPcn=180.15, BSFCn=0.5763. Are those the corrected numbers for horsepower and fuel consumption ratios? Just curious to know....

[hevansrv7a]

Originally Posted by Tbone

My figures were... Intake air temp 86f, baro 29.9, rpm 2643, MAP 29.26. The BHPc is showing 160.44 and the BSFC is 0.6102. Not sure what that means but out to the side it shows in the comments section (Acceptance Test: BHPcn=180.15, BSFCn=0.5763. Are those the corrected numbers for horsepower and fuel consumption ratios? Just curious to know....

In the Superior manual it shows SFC for peak EGT and for a specified number of degrees (50 or 75 - don't recall which) ROP :.43 and .50 respectively. They say full rich SFC is >.55. Keeping in mind they were testing a completely new engine, that would suggest they were running rich. I'd call them for a better explanation of the test cell sheet.