<VV> corvair air fuel appetite

djtcz at comcast.net djtcz at comcast.net
Tue Dec 25 22:24:52 EST 2007

A 4 stroke engine's piston takes a gulp every other down stroke.  The other Alternate downstroke is the power stroke, and I would not want to give that one up.

Then there is the matter of volumetric efficiency which rarely exceeds 80% or so in street engines, unless a supercharger is involved. 

SO, I believe the answer to your original question of the volume of air/fuel mixture per revolution is engine displacement X 0.5 X volumetric efficiency/100.

When the question turns to cubic feet per minute for carb selection purposes, the rpm must be included, plus a factor to go from cubic inches to cubic feet or whatever.
rpm X engine displacement X 0.5 X volumetric efficiency/100
Various online calculators allow plugging in rpm, VE, and displacement to derive a cubic something per minute estimate.

Holley carb website has a chart for those of us who would rather connect the dots.
Dan Timberlake

-------------- Original message -------------- 
> Message: 2 
> From: Bob Gilbert 
> Subject: Engine Question - Some Corvair 
> Today we had a lively discussion on the volume of fuel/air mixture consumed 
> by an engine per crankshaft revolution. 
> We are talking normally aspirated 6 cylinder and V8 4 cycle gasoline 
> engines. 
> Is it engine displacement X .5 X RPM, engine displacement X RPM , engine 
> displacement X 2 X RPM or something else? 

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