Hey guys, I was reading jrp's cam guide and had a question regarding what effect the lift has on the cam performance? Does a higher lift produce more/less HP or Tq? Does it effect the idle? The section from jrp's sticky is below...

B. Lift:


- Lift is defined as the difference in height between the radius of the circle and the height of the eccentric. This is called lobe lift.

- When viewing cam specs the lift portion is the gross lift, meaning its calculated with the 1.7 stock rockers.

- To get the lobe lift you take the advertised (gross) lift and divide it by 1.7. If you follow the T1/X2 cam card you’ll see that they list both lobe lift and gross lift.

- If you want to add higher ratio rockers and want to know your new lift you do the following using the T1 as an example:

.559 / 1.7 = ~.329, you then take that lobe lift and multiply it by whatever rocker ratio you want. With SLP 1.85 rockers your new lift specs become .329 X 1.85 = ~ .609

 

all these smart people and no one knows??

 

Increasing cam lift and performance is a function of how well your heads flow. More lift can mean more power if properly matched to the heads/intake. Remember its the sum of the parts, not just one aspect in particular.

 

More lift will move the power curve up all things being equal, higher lift will accelerate valve train wear as the rate of valve acceleration will increase. Should not change the idle quality unless the overlap is changed.

 

That makes sense. My thought process was that when comparing two cams with the same duration and lsa, the cam with the higher lift would make a little more power. I figured it was due to the fact that the valve would be more open to allow more air in and out. Does that reasoning make sense?

 

im no mechanic, but seeing the higher lift numbers means the valve goes up higher, and thus is open longer. I would agree with your reasoning, but I have no 'actual yes or no answer.'