Given two single pattern cams with different LCA's on a blown engine. (108 & 116)

1. 116 cam will have later intake open/close
2. 116 cam will have earlier exhaust open/close
3. 116 cam will have decreased overlap
4. 116 cam will have snappier throttle response

Now, make the 116 cam a split pattern with 14 more degrees exhaust duration (from 224 to 238)

1. later exhaust closing point
2. Increased exhaust efficiency to make up for "weak" or "overpacked" exhaust ports.
3. slight increase in overlap intake to exhuast
4. Will maintain crisp throttle response due to later intake timing.

All installed straight up for their respective lca's.

Oh, and.......
1. The decrease in overlap would be 16 degrees going from 108 to 116.

BUT, HOW MUCH WOULD BE PUT BACK WITH THE INCREASE IN EXHAUST DURATION???????

 

how do you do that?

are you saying that the cam's LSA is going to change totally, or are you going to change the ECL?

I always thought that the overlap was the reason for the throttle response and not the LSA, but they are directly related.

Bret

 

I'm thinkin it's the decrease in overlap too??? But the intake installed centeline seems to have alot to do with it also. Just trying to figure this stuff out...........
What's your take?

 

Well the intake centerline is going to control the intake closing point true.

I you have a cam the LSA will give you the overlap, that's it. The ICL and the ECL are just a funstion of advance/retard on a cam.

Bret