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OK So it seems the only way to figure my engines BSFC efficiency will be by testing:
To calculate BSFC, use the formula
B S F C = r P {\displaystyle BSFC={\frac {r}{P}}} BSFC={\frac {r}{P}}
where:
r {\displaystyle r} r is the fuel consumption rate in grams per second (g/s)
P {\displaystyle P} P is the power produced in watts where P = τ ω {\displaystyle P=\tau \omega } P = \tau \omega (W)
ω {\displaystyle \omega } \omega is the engine speed in radians per second (rad/s)
τ {\displaystyle \tau } \tau is the engine torque in newton metres (N⋅m)
The above values of r, ω {\displaystyle \omega } \omega , and τ {\displaystyle \tau } \tau may be readily measured by instrumentation with an engine mounted in a test stand and a load applied to the running engine. The resulting units of BSFC are grams per joule (g/J)
Commonly BSFC is expressed in units of grams per kilowatt-hour (g/(kW⋅h)). The conversion factor is as follows:
BSFC [g/(kW⋅h)] = BSFC [g/J] × (3.6 × 106)
The conversion between metric and imperial units is:
BSFC [g/(kW⋅h)] = BSFC [lb/(hp⋅h)] × 608.277
BSFC [lb/(hp⋅h)] = BSFC [g/(kW⋅h)] × 0.001644
With my 03 Ford Explorer's 4.6 there may be a readout of its engine's BSFC efficiency but it has to be of the Explorer as they are reported to have special intake manifolds and other systems to promote high torque at 1500RPMs. So I believe they are not the same as say a 03 P71's 4.6.
As as for my 383 with all its special features I build in and how I built it for a torque peek at 2000 and at 3000 the only way will be on the road.
I have found all engine and all car dynos DO NOT read torque and torque below 2500RPMs and only at Full throttle.
My engines will be running at 1500 to 2000RPMs at as little throttle as possible.
So the only way to figure anything out will to fully gauge my SUV and Van and fully test its MPG at the speeds I will want to drive is to record its MPG and at Various MPH.
I believe I can do this, with the 2000 Mercury I used a section of the I17 Freeway, which showed on GPS a slight incline north, and my tests show a loss of 1 MPG northbound and a gain of 2 MPG southbound.
I would make full up and down this strip at a cruse controlled speed of 65MPH and on each run changed it's A/F ratio by 1% from 4.7 to 7.0 and noted that the cars MPG peeked at 16.4 and dropped with any higher ratios.
I also mentored the engines exhaust gas temperatures during these tests and saw no real changes.
Rich
PS and with all manufactured engines every engine is NOT the same, so as the old joke goes: YOUR MPG may be different.
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