Foxfan88 said:higher the powerband(higher duration) = lopey-er idle
It's possible for a relatively smooth idling cam to make a lot of power, but I can't imagine a cam with a stockish idle making *optimal* power on a high rpm engine. Ideally for a street engine you'd want to maximize lift with less emphasis on duration to produce a decent idle and good power. It so happens that our 2v 4.6 engines respond very well to more lift due to the design of the heads.tjm73 said:I'm curious if a smooth idleing cam can make the big power numbers that some cams like the big comp cams XE grinds can?
Yes, the LSA and duration both affect the idle, but the LSA needs to be to a specific size to get optimal results with a given duration. For example, the LSA could be widened to get a better idle, but the power curve would be negatively affected.84blkstang said:...I understand the LSA and LCA determine the idle characterstics, as does the duration, someone correct me if i am wrong. ..
I would say a N/A engine can benefit from MORE overlap than a boosted one. I'm saying this because my Comp 270's have a good amount of overlap based on the idle quality (specs: 234/238 @0.50, 113 LSA). The dyno showed a big difference in the upper rpms (initially 430+ rwhp, up from 378), and improved all the way up the curve from 2700 rpms. My fuel system can't safely keep up with the cams beyond 6000 rpm though . Even de-tuned with a lower rev limiter it is obvious the cams are in there when I go WOT .Rick 91GT said:..Boost combo's need ver little overlap or your pushing the boost out the exhaust.
90mustangGT said:Like anything else, it depends on the whole combo, cams only controll the lift of the valves. The cam is ground to promote cylinder filling at certian engine speeds and many different things determine the grind to do that. So a cam engineered to operate from 4000rpm to 7000rpm was not engineered to operate at 800rpm, so of course it won't run right. Lets say that cam was engineered for a 408, it won't do the same thing in a 306.