Brake Specific Fuel Consumption of UZ motors.....

[JDMfantasy]

This may be a bit out there, but would anyone know the Brake Specific Fuel Consumption (BSFC) of the UZ series motors? Or care to calculate it?

Its basically a measure of the motor's efficiency...

• BSFC = (observed fuel flow) / (observed brake horsepower)

• Units are observed.
• Fuel flow is pounds per hour
• Observed BHP is used because it is impractical to correct fuel flow. Correcting BHP for weather, as is typically done to compare engine output (SAE J-1349), is inappropriate for BSFC. Using corrected BHP would only lead to the next question which is, what would the fuel flow be under the corrected weather conditions, requiring yet another data correction creating more ambiguity in the data.

Why I'm interested:

Honda's ( in general or specific motor....of that I am not sure) have a lower BSFC than Supras, 0.45 compared to 0.50 ( numbers I've found), and therefore make more power from the same size compressor.
Honda's are making close to 800 whp on a GT4088R, where Supras are topping out at around 700 rwhp. (778 vs. 700) Again, I do not know which specific motor/s these numbers were achieved with for the Honda.

I do know that the number 0.45 was brought up for the Honda's BSFC. From what i've read, 0.44 is almost as good as it gets for the reciprocating piston engine.

I'm guessing as its a toyota motor, we would share similar numbers with the Supra, but then again...maybe not....

I wouldn't mind getting a bit more out of my snails. :veryhappy

Anyone have any thoughts???

 

[madmont]

I posted a graph on this page which might help
http://www.lextreme.com/forums/showthread.php?t=3126

 

[turbotwig]

A well sorted out racing engine can drop into the .40-.42 range.

-Kirk

 

[turboandrew]

I am no expert on BSFC, but I would guess that you want more energy from combustion to go into turning the crankshaft and less energy into heating the exhaust and coolant. You can help some of this by coating the pistons and combustion chamber with material which inhibits heat transfer. You could also probably run a hotter thermostat, so there is a smaller temp delta between combustion and coolant, lowering heat transfer. All of these come at a reliability price -you are increasing the combustion temps in hopes of increasing combustion pressures (to push the piston down with more focre) so your internal parts are subject to more abuse.

Other areas that might help are absolutely perfect ignition timing and incredbily short time between ignition and complete burn (to avoid "negative work" when the piston is moving upward, BTDC, but right after ignition).