Volumetric Efficiency
11-26-07, 11:29 AM
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Volumetric Efficiency
A few words from a frustrated student of engineering... Does ANYONE out there have real numbers from testing the N/A 12A's through 85? How about the 13B? It's obvious why this info is hard to find, because if I was designing and selling a motor to a mass of consumers, I wouldn't want to admit that my engine only hit it's peak chamber filling efficiency at 6000 rpm, or whatever it may be... but I'm tired of not knowing.
I have an '84 gsl that I built a blow through system on a budget for, and I guess I'm looking to see how badly sized the cheap turbo that I nabbed for it is. If you have any real numbers, or a link to a sheet of values that you have from testing your own setup, please post! Also, if you could include what intake you were running and what carb/throttle body, it would be so helpful!
I have an '84 gsl that I built a blow through system on a budget for, and I guess I'm looking to see how badly sized the cheap turbo that I nabbed for it is. If you have any real numbers, or a link to a sheet of values that you have from testing your own setup, please post! Also, if you could include what intake you were running and what carb/throttle body, it would be so helpful!
11-26-07, 04:05 PM
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I'm not sure if this is what your looking for, but Sterling sent this to me as a little lesson in VE
12a rotary max RPM = 9000
12a rotary cid = 70
That's 70 cubic inches each rotation, times 9000 RPM, = 630,000 cubic inches per minute.
12 inches x 12 inches x 12 inches = 1728 cubic inches per cubic foot.
630,000 cubic inches divide by 1728 cubic inches per cubic foot = 364.58 cubic feet per minute.
That means that theoretically, a 365.58 cfm carb would be maxed out on a 12a rotary running at 100% Volumetric Efficiency @ 9000 RPMs.
Now I say "theoretical" because the carburetor would have to be absolutely perfect - a "theoretical" perfect, at that. And no carb is perfect.
12a rotary max RPM = 9000
12a rotary cid = 70
That's 70 cubic inches each rotation, times 9000 RPM, = 630,000 cubic inches per minute.
12 inches x 12 inches x 12 inches = 1728 cubic inches per cubic foot.
630,000 cubic inches divide by 1728 cubic inches per cubic foot = 364.58 cubic feet per minute.
That means that theoretically, a 365.58 cfm carb would be maxed out on a 12a rotary running at 100% Volumetric Efficiency @ 9000 RPMs.
Now I say "theoretical" because the carburetor would have to be absolutely perfect - a "theoretical" perfect, at that. And no carb is perfect.
11-26-07, 04:35 PM
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fde2blk, check your PM. I think the people who can best answer your question don't lurk in this particular section. On this forum, search in the General Rotary Tech Support section as it has been discussed there. Type in volumetric efficiency and select general rotary tech support section, and you will get a number of results.
Or search/ask in the rotary engine building and porting section of the "other" forum.
Or search/ask in the rotary engine building and porting section of the "other" forum.
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