Best emmissions legal blower cam?

I'm thinking about a new combo and am considering reinstalling my procharger. Unfortunately, I need to go through the sniffer test so I will need to consider that when selecting a cam. What do you guys have or what would you suggest?

Use whatever you would NA. In LT1's, a blower cam and a NA cam look an awful lot alike.

Mike

Use whatever you would NA. In LT1's, a blower cam and a NA cam look an awful lot alike.

Mike

Mike,
Would your opinion change if it was a turbo instead? I'm in the same position, but with a turbo on an LT1.

Joe

I'm currently running the gm846 cam. Is that blower friendly on a 112 lsa?

Mike,
Would your opinion change if it was a turbo instead?

Same opinion.

112 LSA isn't as bad as most people think. It's the 104-108 you need to stay away from.

I just passed CA emissions with the CC 224/236 at 114 lsa blower camshaft, in fact it wasn't even close. Pretty much stock programming except for the bigger injectors. This or the smaller 218/230 cam should do it. Stay away from 112 lsa if emissions is a concern. I think my cam worked so well because it doesn't have much overlap. The motor will also have a smoother idle with a 114 vs 112.

My previous cam was the gm hotcam, the CC 224/236 blows it out of the water. Mean sounding idle, the motor runs smoother, and it is designed for use with a supercharger.

Stay away from 112 lsa if emissions is a concern. I think my cam worked so well because it doesn't have much overlap. The motor will also have a smoother idle with a 114 vs 112.

Duration determines overlap moreso than LSA. The old Buick GN cams were on a 106 LSA! For instance, 224/236-114 has 5 deg more overlap than 218/224-112, even though it's on a wider 114 LSA.

Duration determines overlap moreso than LSA. For instance, 224/236-114 has 5 deg more overlap than 218/224-112, even though it's on a wider 114 LSA.That was one of my arguments for steering away with the LSA mentality this site holds on to. You're one of the few that supports that position. LSA means little. It is more of an effect than a cause. IOW, it is not the dog, it is the tail.

Thanks, Gary - I've been beating that drum for a while now.

Now this one will really stump you. . . assuming a set amount of overlap, say 10 deg, is it better for power to have the overlap occur before TDC, during TDC, or after TDC? Secondly, how would that change if you had more intake pressure than exhaust (i.e. supercharger), the same intake and exhaust pressure (i.e. naturally aspirated), or more exhaust pressure than intake (i.e. turbocharger)?

Mike

I also agree with Mike...its overlap that your looking for...LSA is just a small part of it. Here is a quick formula to help those interested in finding overlap:

intake duration + exhaust duration = total duation
total duration / 4
then subtract LSA
then multiply by 2

Example 218/218 112LSA versus 224/224 on 114LSA

218 + 218 = 436
436 / 4 = 109
109-112 = -3
-3 x 2 = -6 degrees of overlap

224 + 224 = 448
448 / 4 = 112
112 - 114 = -2
-2 x 2 = -4 degees of overlap

As you can see, the 224 cam has more overlap (worse for emissions) then the 218 cam despite the 224 cam's "blower friendly" LSA.