I'm not sure if you'll be able to help me for sure or not but I'll give you as much information as I can. The build is a 396 cid with a set of Canfield 220cc heads that flow 275cfm @ .400, .290cfm @.500, 303cfm @ .600, 312cfm @.650, and 317cfm @ .700. The .700 lift number is really irrelevant because the springs are only setup for .650 lift. I'm probably going to run somewhere around .620 lift. This is a max hp effort so I will be running a SR cam. My question is what duration do I need to run in order for the horsepower to peak at 7000rpm with this cubic inch and size head.

Thanks

 

~250-255 degrees @ 0.050"on the intake side. The LSA will also have an effect.

Rich

 

I was planning on running a 117 lsa since it is a turbo application. Maybe a 116 lsa. What do you think? Does a wider lsa increase the rpm or decrease the rpm power band of a cam?

Thank you for the reply Rich.

 

LSA will make very little difference in the rpm band with a turbo.

Rich

 

I would just contact a cam grinder and have them spec you out a cam.

 

Typically what does closing the LSA do to powerband of a cam on a N/A setup?

Take a 224/230 xtreme engergy as an example if it has a 6200 rpm redline with the 112 lsa what would a 110lsa do to that cam?

 

generally speaking, a more narrow LSA will increase overlap. This will generally push the rpm band up slightly.

 

Excuse me for asking but how much rpm is slightly 200 rpm, 400rpm?

 

How much? I don't have that info on me. I'm sure its different for different engines. Maybe Rich or Fred have that info.

 

Right, I'm sure cubic inches and runner size of the heads plays a role in how much increase in rpm will be seen. This question is for a kid at work whom is kinda making me crazy. I've told him to go with an AI h/c combo and he'll be happier but then he just gives me the impression he really just wants a really choppy idle. So if he doesn't do the heads (big mistake on his part) I've picked lobe # 3014 for his intake and lobe # 3035. I was also thinking about lobe #3190 for the intake but didn't really want to split the durations by 10 degrees. All of these ground with a 110 lsa and 4 degrees advance ground in. Along with a pcm tune of course. I figure this will give him the sound he wants without going past 6200 rpm.

 

The width of the powerband doesn't increase or decrease with LSA changes, it just moves up or down in the rpm range. A higher LSA will have less overlap and will move the start of the powerband down, but also fall off earlier. A lower LSA will move the start of the powerband up, and fall off later. The catch-22 in your situation is that you're running a turbo in an engine with high piston speed, so it's going to be tricky coming up with a cam that'll allow the engine to breathe in the range it wants to without wasting too much boost out the exhaust valve because of overlap.