Both cams actually have the same amount of overlap (within 1 degree), so there's nothing wrong with the 112 LSA. Also, I'd recommend against Cam Motion (note my location). Their hydraulic roller lobes are lazy. Plus, they (Terry) told me my XE 224 intake lobe with .605 lift (1.6 rocker) is impossible and does not exist.

 

engineermike,
So out of those two cams, which would you choose for my set-up and why? Thanks for the info, i'm learning tons!

 

I tend to think a tad differently than most about supercharger cams. You see. . . supercharged motors have a higher compression ratio than NA, but a lower expansion ratio. So, you have more cylinder pressure and volume, but don't take advantage of it on the power stroke by opening the exhaust valve too early. The biggest difference between those two cams is Exhaust Valve Opening timing. The 224/230 has a later EVO, so it has a higher expansion ratio. It also has an earlier intake lobe which is usually good. Long story short. . . I like the 224/230-112, +4 cam, but I'd get it from Comp using Extreme lobes. That would be #3314 intake and 3315 exhaust lobes giving you .536/.544 lift. If you want, you can get a little wild and go with the 3192 intake lobe for .605 lift. With a very similar cam, Mike Licht pulled 148 mph with a Procharger at 18 psi on a 355 with stock ported heads.

Mike

 

One LT4 Corvette I was involved with went consistent ~1 tenth quicker down the track with nothing more than a cam swap. Swapped from a 3196 lobe XE grind (after trying a few different springs) to a comparable Cam Motion grind with 237º duration vs the 236º XE lobe. The Cam Motion cam also had ~.030 less lift.

Faster lobes aren't always better. If you can't do things right in the valvetrain (lighter valves etc) you might just end up with a lobe that tosses lifters and bangs out valve jobs.

-Mindgame

 

You are right, Mindgame, in that you HAVE to have the valvetrain set up properly for the ramp rates of the Extreme lobes. I'm running 145 lb on the seal and 420 lb open.

Mike

 

with my head flow numbers stalling out at .525 lift, how will that (or will it) affect my port flow with 6 lbs of boost? And is there any way to ballpark calculate that? And since it is forced air, do I even really need to be overly concerned with intake head flow numbers since this will not be the actual volume of air moved?

Nick at Chapman racing noted that the flow began to back up above .525 on his flow bench. Wouldn't deterning how the F.I. affects port flow primarily dictate cam selection? I'm probably getting into this way deeper than I should, but I'm just doing my best to educate myself and select the best OBDII compliant (with tuning of course) cam that will complimant the mods I have.

 

O.K., per my porters recommendation, it looks like i'm going to go with the CMS cam. Any reasons why I shouldn't?

 

Yep. Go back and read my posts.

 

The 224/236 is a commonly used blower cam for LT1’s. I had Bret Bauer grind me a custom blower cam that should still pass emissions. I was going to be running a vortech S trim’d 383, but decided to go turbo. I have since sold the cam which is significantly bigger in duration and lift then the 224/236. I suggest a custom grind for max power for your application. If not, the 224/236 wont give you any surprises. Many people have made good power with it. Its like the cc306, oldy but goody.

 

I just happened to look on LPE's site and they also have a blower cam available. How would this cam perform compared to the others?

350 – 383 CID SBC Engine Supercharged Applications Cam # 74220
215/220 duration @ .050 .534"/.544" with 1.6 rocker 114 LSA

 

it is smaller then the 224/236 and it would be a real small cam in a 383. I am surprised that no one has told you to go xe218/224. I know there are a few models with the lift numbers increasing each one. Going for a custom cam wouldn't be a bad idea either, you have all the infomation from the heads and you know what the rest of your engine combo is going to be, why not? I know that combination,ls1speed, Joe Overton, Bret Bauer, Lloyd Elliot, all grind cams. I would talk to more than just combination motorsports before you make a decision.

 

Since this is a street car, i'm concerned about the power brakes. At what ponit does the duration negatively affect operation? I read on a cam tech page that above 224 @ .50 duration, power brakes do not work properly.

 

I've had 234/242-112 work fine with power brakes, but that was 383 cid and 11.5/1 compression, which help.

 

I am going with More Performance to have a custom cam made to fit my application. Once everything comes together, I'll post up the dyno numbers and cam specs.

This thread has taught me more than I ever thought possible about camshafts. Many thanks to everyone who helped enlighten me (and a special cheers to engineermike).

 

I have seen OVER 300cfm on a stock casting, had to have offset rockers for the intake, but hey call BS if ya like. Car ran 10.40's on motor with a 383@3350 lbs, had a couple of tenths left in it but it got wrecked at the track.

Just a little 411 for ya.

David