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Re: lowest reasonable highway rpm for a 440?
[Re: hooziewhatsit]
#1058375
08/22/11 08:52 AM
08/22/11 08:52 AM
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Joined: Jan 2006
Posts: 8,162
USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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Quote:
360View, I crunched some numbers real quick...
Assuming a BMEP of 100 psi, we can figure the needed torque to be roughly 275 ft-lbs, at that 1700 RPMs.
So, does it make sense that if we build an engine with that amount of torque at that rpm, adjust the rest of the gearing as needed to get a good highway speed at that rpm, that we should get the optimal mileage out of it?
Of course, depending on the air & rolling resistance, I guess we may still need more power to move along though...
We need the vacuum gauge readings of the actual engine to
'gues-ti-mate'
a BMEP.
1 inch of manifold vacuum showing on the gauge would be 'about' 110 to 120 BMEP at 1700 rpm
6 inches of vacuum showing on the gauge would be less, maybe 50 to 70 BMEP
20 inches of vacuum showing on the gauge would be about zero BMEP,
or what you get idling at 1700 rpm
If you figure up the total square inches of eight pistons on the engine,
you can run your finger down the near vertical lines marked
'HP/SQ In'
to find horsepower at any given BMEP
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