Just finished up my cam install today. Comp Cams X-ER 224/230 .581/.592
I added an U/D pulley and a 160 t-stat for drag race consistency. I still have to get the tune dialed in. Based on my logs the car is making about 45-50 more HP. I guess we'll see at the track.

I still don't have headers, but I'm still debating whether I'll go turbo or max NA effort.

I have it idling at 800 rpm and it's pretty nice so far. I still have some more tweaking to do. Overall the sound isn't too different, except for a more noticeable lope. Nothing like if I had headers on the car. This may be a nice sleeper if I can pull out mid 12's this weekend!!!

What's the LSA and the ICL of the cam?

114 lsa 112 icl

Very nice.

You have the stock exhaust manifolds or shorty's? Was your chain dampener broke? What springs did you go with? Any surprises with the install?

Thanks

114 lsa 112 icl
Man, I just don't understand these LSx cam numbers. The ICL seems like it's retarded about 4 degrees from what it should be, and the exhaust is advanced 4 degrees. Are they doing it to decrease overlap, maybe? Maybe the ports are just so good they don't need to optimize the cam timing, and so they spread the lobes to get a little better driveability?

Good cam article (http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/index.html)

Very nice.

You have the stock exhaust manifolds or shorty's? Was your chain dampener broke? What springs did you go with? Any surprises with the install?

Thanks

- Stock exhaust manifolds for now. Not sure on my long term plan yet.
- My damper was fine. Car has about 3000miles.
- I'm using the comp 26918 single coil beehive springs.
- No real suprises. I'm pretty familiar with the LS1 motor, so this wasn't really different. There is actually a lot of room in the car.

Man, I just don't understand these LSx cam numbers. The ICL seems like it's retarded about 4 degrees from what it should be, and the exhaust is advanced 4 degrees. Are they doing it to decrease overlap, maybe? Maybe the ports are just so good they don't need to optimize the cam timing, and so they spread the lobes to get a little better driveability?

Good cam article (http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/index.html)

Actually the cam is already 2 deg advanced. I would normally prefer a single pattern cam, but these heads have a ton of intake flow and so so exhaust. The car actually has a nice powerband now vs. the peak at 5500 and stay flat it had before. The only thing now is I'm shifting at about 6900 rpm and really need some gear.

Actually the cam is already 2 deg advanced. I would normally prefer a single pattern cam, but these heads have a ton of intake flow and so so exhaust. The car actually has a nice powerband now vs. the peak at 5500 and stay flat it had before. The only thing now is I'm shifting at about 6900 rpm and really need some gear.
Yes, I understand that it's already advanced. I was thinking it needed to be advanced even more. what I was trying to say was, if you use the old rules, the ICL should be somewhere around 107-108, with the LSA modified from that based on the exhaust duration.

We ran into this very same issue with the LT1 HOT cam. It was 218/228 on a 112 LSA, with 3 degrees advance ground in (ICL at 109 deg). On the LT1/LT4, it screamed at high rpm, liked to shift about 6800, but was a dog down low. We found that on a heavy street/strip car like the 94-96 impalas, it went from an OK cam to an excellent cam if you installed it 2 degrees advanced, for a total of 5 degrees of advance. It dropped the shift point down about 200 rpm, but made up for it with 10-20 lbs more torque from 2000 rpm on up.

There's a great article by David Vizard that has a lobe centerline calculation chart (http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/photo_11.html). If you keep in mind that he's talking about LSA for single pattern cams ground straight up, you can use this chart to calculate the correct LSA (he calls it LCA) for a dual pattern cam by adding all of the extra exhaust duration to the opening side of the lobe. What you end up with is a cam with an ICL at about 108 (based on the chart) and an ECL at 112, which works out to 4 degrees of advance (which is the typical amount of advance the gen I and gen II smallblock cams have, although the exhaust lobe is usually spread an extra 2 degrees to improve the idle).

I guess the flow on these heads is so good that you can retard the intake lobe for better idle quality and still make plenty of power.

I'd really, really like to know where GM times their LS stage 2, stage 3, and ASA showroom stock cams. Looking at their specs in the GMPP online catalog, they use LSA's of 108, 107, and 106.5, respectively. Presuming these are the most optimized for pure performance, I'd love to know where the intake and exhaust centerlines are.

Ok I see where you are giong with this. I agree, advancing the cam another 2-4 degrees would definitely bring the cam on sooner. The only issue I'd be worried about is P to V clearance on the intake. I think with the older SBC motors it had more of an effect. The other thing to consider is the ramp rates. These XER lobes have a pretty aggressive ramp, so the total overlap area is relatively small. If I didn't care about idle quality I probably would have tightened up the LSA a bit.

I'm pretty shocked that it actually idles as well as it does with a stock converter. These PCMs are pretty good at handling the idle duties.

Since I replied last time, I've been playing with the L92 heads in Desktop Dyno, and I was definitely surprised to see that the engine really cares a whole lot less about exactly how much the cam is advanced or retarded than the old style heads. The flow on these things, especially the intake side, is just phenominal, it seems to make the exact cam specs much less critical than on the old style heads.

Of course, that's probably because I don't fully understand the new rules for these heads. I really need to find out what the factory racing cam centerlines are.