opinions, can retarding/advancing a cam change idle/driveability characteristics
10-21-2004, 09:16 AM
#21
Originally Posted by GrannySShifting
Yeah joel on a singel pattern cam with symmetrical lobes you cna do that, but I dont ever run the same lobe on intake adn exhaust
Its the same analysis whether the cam is a single pattern or not. I just picked that as an example because the math was simple and obvious. I did that analysis with all of the reverse splits I looked at.
If you use the cam calculator spreadsheet, you can calculate the overalp center as:
(EVC-IVO)/2 =X.
If X = 0, then it is centered on TDC.
If X < 0 then it is BTDC biased;
If X > 0 then it is ATDC biased.
My understanding is that centered or ATDC biased provides for a better idle, at least in the case of reverse splits.
10-21-2004, 11:06 AM
#22
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A really good question would be what does moving the overlap period verses TDC do to power? My guess would be that before TDC provides the best power as the piston is moving very slow around TDC and producing the overlap cycle sooner allows more exhaust vacuum to be seen by the intake valve pulling more intake charge in.
10-21-2004, 12:50 PM
#24
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I agree, it depends on your bore, stroke, compression, intake manifold, exhaust setup, intended use, etc. I would think in general my above statement hold true though.
