Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Cams: SVT vs. Regular

Changing just lobe orientation on the camshaft would not change duration though.
Just changing lobe position (valve opening and closing points - earlier or later) would not alter duration (shape of the lobe)

How come they say the SVT cams have more duration then?

I do agree that the lobe seperation angle is different. (110.5 degree for SVT & 116 degree stock - BIG difference!) However so is the duration. The power curves are too different to not have different durations. Just advancing the entire set of points would not change the curve; just move it up the rpm band. It is more of a change than that.

I've seen big differences in powerband and power in tuning the lobe centers. Big time power on alot of Hondas. My brothers friends car made an extra 11hp to the wheels when he had a set of JG 301X cams on his LS Integra tuned. I can get to a set of stock 2.5L cams and a set of SVT cams. I could have them measured to make sure that these measurements are correct. I have heard that the only real difference in cams was the timing between them also.

Roger

Duration can be changed if you view the cams as a 'leading and trailing' valve,without changing any grind the leading intake cam could be given an early opening and the trailing cam a late closing...that increases duration of the whole cylinder intake period.....IF you could move the cam lobes on the shaft!!!

Terry,

That makes more sense. If this was done, I would assume that the primary lobe would be the one that would be advanced on the intake side, since advancing the cam increases low end power. Since retarding the cam tends to increase upper RPM power, it would seem natural the the cam lobe that controls the secondary intake valve would be retarded.

On a similar note I have often wondered how it would work to have a hotter grind on the secondary intake lobes. This valve isn't passing near as much air when the secondaries are closed. I've also wondered if it would help for the secondary intake valve to be larger as well.