Camshafts: What effect does increased lift have on performance?
I haven't read the 4 pages worth of replies, but if you're thinking you'll gain a bunch of performance from increasing the lift, aka: like going from a 1.5 to a 1.6 ratio like a lot of guys do thinking they'll gain 30 HP it's not going to happen. Duration has far more to do with increased performance than .050" -.100" extra lift. Hanging the valve open longer is where you'll get more substantial power gains.
Tom
I was doing some testing on a 340 last week. It has a very small cam in it. Too small but it was picked for “drivability”.
Anyway, when it was last in the car we installed 1.6 rockers. With a geometry correction kit.
The cam was supposed to lash at .028/.032. I never lash anything that loose. But when the rockers went on, I did the math and it came back some big number.
So set them, against my better judgment at .028/.032 and went to the track and it was Sloooooooooooooow. I didn’t want I work on it at the track so we finished the day and left it alone.
On the dyno it was a P-I-G PIG.
I decided since it was on the dyno I’d tighten them up.
I could tell when it lit off it was much happier. Idled better, took load better. It was just better.
First pull was up 40 hp.
In this case the cam is so small that it will respond to anything that makes the cam bigger.
I killed any power gain by opening up the lash more than it should have been, regardless of what the math says.
So between the lash decrease in the lash and the 1.6 rockers it showed a nice gain.
Obvious had the cam been correct, or at least been closer the gain wouldn’t have been as big. If any.