I whant to put a S/C on my car but im running the LT-4 "HOT" Cam 218/228 .525/.525-1.6's, 112LS do you guys think I will have any problems if I keep this cam? Does any one have this came in a s/c car?

 

This cam has a little to much overlap in my opinion for a supercharger. I would run a ZZ4 cam 208/221/112LS-.487/.510 W/1.5 rockers. This cam has good lift, short intake duration, a s-load of exhaust duration, and a relatively small amount of overlap. It would be even more lift with your 1.6 rockers. Another consideration is some of the computer cams out there. I believe comp has a 210/220/114LS cam that would work very well also. In general look for a wide LS and a dual duration pattern profile with more duration on the exhaust side. The LT4 hot cam would work very well if it had a wider LS. You may wonder why the ZZ4 would be better even though it has a 112LS like the LT4 hot cam. Look also at the duration. As duration increases on a given LS, so does the overlap. So to counter overlap as duration increases, LS must also be increased. Also you do not need lots of intake duration with a supercharger, it gets forced in. However you want additional exhaust duration. The exhaust is still leaving in relatively the same manner as a normally aspiratied motor.

 

Do not base a cam's ability to run with a supercharger solely on lobe separation. Obtain the valve timing events, then calculate overlap. Case in point: My Crane 2032 cam. It has 112 LSA, which in most eyes would eliminate it as a blower cam. However, if you examine the valve timing, it has absolutely zero overlap -- perfect!!

Bottom line: Get the specs and do NOT base your decision on LSA alone.

------------------
Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://members.optushome.com/au/downunder1/rides/willie/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

Yes that cam will have no overlap at .050, but there is still overlap below .050. When evaluating overlap you also now have to observe seat to seat timing. Your cam would most definitely have overlap. However, it is relatively small so as not to be a big concern. I agree not to just look as LS alone, like I said in the first responce, you have to look at duration AND LS together. When looking for overlap, it is important to now look at seat-to-seat timing. For example the cam I put in my Dad's GN is 206/206/110LS. Notice the tighter LS angle, but there is also less duration than a lot of other cams. Therefore there is also less overlap. By the way Willie's cam would also be a good choice.

 

............If his cam is the emmissions computer cam I was thinking of. 214/220/112LS?

 

Yes, it is. Very nice power naturally aspirated, with nitrous and/or with a supercharger. I've track tested it with every combination. It also passes Arizona's yearly mandated tailpipe sniffer test.

Willie



[This message has been edited by Willie (edited February 07, 2001).]