Adv. duration??
04-04-2003, 03:53 PM
#1
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Adv. duration?? what effect does the adv duration have on a cam?? if two cams had the same 0.050 and lift specs, but one had less adv. duration, what would the effect be??
04-04-2003, 05:16 PM
#2
Re: Adv. duration?? The one with less advertized duration would have steeper ramps. This would give it more "area under the curve" so would produce a little more power but would need roller lifters. It would have a better idle because there would less valve overlap. But it would also be harder on valve springs and have more valve train noise. It's a world of trad-offs out there. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
04-05-2003, 08:30 AM
#3
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Re: Adv. duration?? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Z28sRock:
<strong> what effect does the adv duration have on a cam?? if two cams had the same 0.050 and lift specs, but one had less adv. duration, what would the effect be?? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">If both cams were from the same manufacturer, and both hydraulic rollers, or both solid flats, etc. there might be slight differences in area under the curve, but if they were from different companies, the .050 duration and lift tell the tale.
Different companies rate advertised duration at different lifts. One might use .006 lobe lift, and one might use .010. That could make cams which perform identically appear very different based on advertised durations. This is one of the main reasons .050 lobe lift point was generally accepted as a way to compare cam durations.
More telling would be the .050 and .200 durations, which some companies publish. Compare them(and lift), and if they are very close, the cams should perform the same no matter what the advertised duration.
Advertised duration is just that because many folks think "bigger is better" when it comes to cam timing. Unfortunately this isn't necessarily true, but big numbers sell.
<strong> what effect does the adv duration have on a cam?? if two cams had the same 0.050 and lift specs, but one had less adv. duration, what would the effect be?? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">If both cams were from the same manufacturer, and both hydraulic rollers, or both solid flats, etc. there might be slight differences in area under the curve, but if they were from different companies, the .050 duration and lift tell the tale.
Different companies rate advertised duration at different lifts. One might use .006 lobe lift, and one might use .010. That could make cams which perform identically appear very different based on advertised durations. This is one of the main reasons .050 lobe lift point was generally accepted as a way to compare cam durations.
More telling would be the .050 and .200 durations, which some companies publish. Compare them(and lift), and if they are very close, the cams should perform the same no matter what the advertised duration.
Advertised duration is just that because many folks think "bigger is better" when it comes to cam timing. Unfortunately this isn't necessarily true, but big numbers sell.
