Let's talk G3 hemi cams
Thanks for your reply. Good to see someone with some actual knowledge chiming in.
For a little background on what I'm doing- I have a running/driving car with a EFI 408 in it right now. (I'll be using the same stand alone for the G3.) I've decided to move over to the G3 world and I had a 06 5.7 sitting in my garage. I've already done some hand porting on the heads and I plan to get an "off the shelf" cam for use with the stock bottom end. I'll likely put a torqstorm supercharger on it. I considered doing the eagle head swap, but didn't think the increased compression or doubled up head gaskets would be a good idea with the supercharger. Also, the ultimate end goal would be to build a larger displacement hemi in the future. I just want to get the car swapped to this platform with what I have on hand already. There's plenty of info on my car in my build thread. If you don't want to read through it, I'm not a drag racer, more of an autocrosser and street driver. I'd be more interested in a cam that makes really good mid-range torque and HP vs max HP at 7500RPM.
Here's a couple "supercharger" cams I've looked at:
Texas speed
223/232 @.050, .582/.582, 115+3 (appears to be only a touch larger than a stock 6.4 cam)
226/235 @.050", .582/.582, 117+4
Comp
221/233 @ .050", .594/.594 116 (very similar to the TSP cam)
229/241 @ .050", .635/.635, 117
As you mentioned above, I don't know why TSP is limiting the lift on their cams. While the large Comp cam seems very healthy, I just wonder if that duration will kill low end torque. Any thoughts on this? Given I have a smaller valve and the lowly early head, wouldn't the increased lift be beneficial?
Well, when it comes to the application of most any source of boost, the dynamics that effect a NA motor goes sailing out the passenger window. Things like tuning effects of intake manifold runner length, or even Exh primary tube length become inconsequential. Also too, the flow dynamics of port CSA (cross sectional area) of the port and it's relation to valve size, is also null-void. (so long as it's not ridiculously restrictive)
This boost, that is several atmospheres higher than what you and I breath, cancels out the NA motors ability to utilize tuning factors of port shape, size, and flow coefficient. Or the ability of Int runner length to work in concert with the headers. And also explains why there's an astronomical difference between NA cams vs boosted counterparts.
That being said, you don't have to be concerned with loss of low-end. It was 'made up for' as soon as the boost crashed the party.
Keeping it simple... the last cam in your list (.635" lift) would be the best choice. But, your torque curve and consequent peak HP with that cam will be done by 6000 rpm with boost. You could extend that range some by installing the cam 'straight-up'. Getting to 7500 rpm would require a cam much bigger... probably in the 270° @ .050 range. But then the EFI wouldn't be able to 'self - learn'.
P.S. I did explain the lack of lift in the above post..
As I stated in a earlier post, in this thread, I'm going to be testing a pre eagle head. Probably next week. (see post) I may even do a write up on my findings, like I did on the Magnum heads a few years ago. (?)
I'll be up front, I'm not a boosted sort of guy.. I spent decades honing my abilities in making HP by learning how to do it, (successfully) with natural atmosphere. I don't intend this to be a poke in the eye, but to offer a glimpse into my perspective. The reality is, if I were to add boost to any of my builds, it would be a betrayal of my long experience.
