Cams timing and all that

[Gary Derian]

Spark ignition engines loose efficiency at part throttle because the engine
has to suck vacuum against the throttle.  Its like a big vacuum pump with a
leak.  The lowest fuel consumption is at WOT without fuel enrichment.  BSFC
at WOT will generally be minimum at the peak torque rpm but driving down the
road at part throttle, mileage improves as rpm is reduced ant throttle
opening is increased and vacuum is reduced.

Gary Derian <gderian at cybergate.net>

>Clare Snyder wrote:


>Bernie Jacobsen wrote:
>>
>> Does anyone know if there is a relationship between a torque curve and a
>> BSFC (fuel consumption) Curve?
>>
>> On many diesels, the peak torque corresponds to the lowest fuel
consumption
>> per brake horse power hour.
>>
>> On gasoline engines???  where can I  get BSFC curves for gas engines (454
>> Chev)?
>>
>> ^Bernie


>Maximum fuel mileage on a stock 454 will be acheived at 2800RPM - which
>is the max torque RPM for the engine. on the 350 diesel, it would be
>1600rpm