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Registered
Join Date: May 2009
Location: Tennessee
Posts: 42
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Quote:
Gordon Blair, Design and Simulation of Four Stroke Engines DE Winterbone, Theory of Engine Manifold Design
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Cheers, Vince -1997 993 Cabriolet, Arena Red, M030, Bilstein HDs, RSR exhaust, HIDs "'Safe?' said Mr. Beaver...'Who said anything about safe? 'Course he isn't safe. but he's good. He's the King, I tell you.'" |
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10-28-2009, 03:06 PM
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Join Date: Mar 2006
Posts: 1,107
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psalt - sorry, but what is VE?
Hello David, Volumetric Efficiency. An expression of how much of the cylinder is filled or the ratio of actual volume to ideal volume as a percentage of displacement. Most N/A engines are below 90%, because of restriction like the intake valves, ports, manifolds, etc. Supercharged engines can exceed 100% VE, the more mixture you can put into the cylinder, the more power you can make. VE is low when there is vacuum in the manifold and VE is highest at the torque peak under WOT. This is when cylinder pressure is highest and the probability of detonation is highest, requiring the knee in most ignition advance curves. Resonant intake tuning (velocity stacks) is all about raising the VE above what it would "normally" be at a specific rpm.
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Paul |
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10-28-2009, 03:09 PM
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Join Date: Sep 2007
Posts: 500
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Some good discussion of inlet dynamics (and simulation) can be found here, with graphs showing effect of inlet dymanics at various engine speeds
It also raises an intersting (and rarely discussed) point - residual exhaust gas in the cylinder charge. It's all well and good to get VE above 100%, but you also need to ensure that you've eliminated as much of the exhaust gas as possible (through valve overlap and exhaust dynamics) They go hand in hand. See page 2&3 of the PDF http://www.bosch-motorsport.de/content/downloads/Software/lapsimengine.pdf Last edited by jcge; 10-28-2009 at 06:50 PM.. |
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10-28-2009, 06:43 PM
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