SB

iTrader: (1)

BSFC is not really a good measurement of lean or rich. Yes, it's #'s can be swayed by lean or rich but that, again, is not the true nature of BSFC.

It is how much fuel it takes to make each HP.

Peak torque usaully has lower BSFC's then rest of the rpm curve because that's when the engine is usually most effecient....thus the peak torque.

Rattlesnake Jake

iTrader: (2)

My 500 EFI with Cam similar to a Crane 741, 315 cnc AFRs, 9.6:1 JEs made 572hp @ 5400.
BTW was a 509

MILD THUNDER

iTrader: (3)

The intake was prob costing you some power. A full cnc head with that cam, shoulda did a little better than that. The 525 almost makes that with similar cam, cast edelbrock heads and less compression.

Either way still a big gain from stock 500EFI. The OP engine has as cast 305 heads

SB

iTrader: (1)

MT , Different Dyno SAE standards, but that was another thread. Regular 607 Standards and would be 600 plus/minus a few.

Anyhow, well known, looking for 600+ time to move on to something else. Holley Single Plane EFI intakes get nod by many at this point.

Rookie

iTrader: (4)

I was also correlating it to the High AFR's that is saying that it is lean. Almost stoichiometric burn.

SB

iTrader: (1)

Me comprendo.

Issue with the A/F readings on this sheet along with a million other sheets that the dyno does not read A/F Ratio from wideband is that they are wrong. Suks huh ?

When dyno's don't use a wideband they calculate A/F ratio from air entered thru the Airflow Meter Hat vs the fuel going thru the fuel flow meter.

Not exact by any means. Many dyno's I have been at with both have showd Wideband reading of 12.8-13.0 while the Airflow Meter Vs Fuel Flow Reading showing well into the 14.0's.

Even though widebands can throw you for a loop once in a while , this really shows how important Widebands have been in all our lives.

FYI: I am assuming his #'s are not wideband because I mentioned it earlier and was not told otherwise #1, and #2, who would leave a dyno seesion with those #'s. LOL.

SB

iTrader: (1)

I would like to mention, while on the subject of BSFC's, be very warry of other dyno sheets floating around internet land where all are in the .300's. Very, very good chance it's because of inflated power #'s.

Remember, BSFC is derived from how much fuel per horsepower an engine uses. It is a measurement of effeciency only. If the fuel use remains the same but the HP magically is up, the result is very low and quite unobtainable (in the real world) BSFC's.

Unlimited jd

iTrader: (5)

The air/fuel numbers were calculated. Good catch sb. A close eye was kept on egt's and we kept jetting up until we did not gain any power. On this dyno mid to high 13's seems to be the sweet spot for power on bbc's and equates to low 13, high 12's when measured with a wideband. I have the wideband and bungs ready for the tails to fine tune it in the boat. I'm pretty confident the actual air fuel in the boat will be very close to mid 12's.

I'CE

Jammie avg. egt,s @ 1468 seems a bit tall, yes ? __ did you guys try 32* on the clock?

Unlimited jd

iTrader: (5)

No, by the time it richens up into the 12.4-12.8 range egt's are going to drop 100* or more. Lowering timing will increase egt by starting the burn later and causing the burn to still be on going while the exhaust valve is opening. Could go to a -8 plug but I prefer 7's and running 93 octane