I agree with this 200%

The first thing that needs to be done is develop a cylinder head that has a cam or better yet cams over the head and go from there. Get rid of the lifters and pushrods. Then we can start opening the valves up and making some real power.

Mr Maine. Heres a simulation I just ran on my combo. On the left, you have a 240/245 112 Cam. On the right, a 240/252 cam.

What I see here, pretty much backs up my earlier post about the RPM thing. The cam with the extra 7 deg split, only outdoes the 240/245 cam, at 7000+ RPM for power. Up until that point, the extra exhaust duration does nothing. I am going to try the same thing, but with say, stock GM rect port head flow numbers. Keep in mind, this is a forced induction setup, which textbook says you need more exhaust duration/split.

Another sim, no changes except for switching to the edelbrock performer RPM head. Which is much closer flow to a stock GM rectangle port head. A little better , but not that much. What changed? Power across the board went down due to the heads. But, the extra exhaust duration, didn't help again, until 7000RPM.

Heres a sim of a N/A setup, 9.5:1 , Edelbrock performer RPM heads.

On the left, cam is a 236/240 114 LSA, cam on the right, is 236/245 114 LSA (very similar to 525 EFI cam).

The trend changed. Now, the cam with the wider split, is actually making more power in the 5000-5500 range, with almost no loss in torque anywhere, and holds on quite a bit longer in the upper rpm.

What is interesting, is there were alot of guys 10 years ago, building marine 540's, with afr 315 heads, with crane 741 cams. That combo made darn good power. Everyone used to say, the AFR's 315's ex port was super awesome, and that the 741 cam had too much split, and wouldn't work well. Reality proved otherwise. The cam worked very well, and made good power to 5600-5700 in those combos, and usually 650-675HP. Hardly bad for an off the shelf cam that had mild lift, and easy lobes.

Mild, awesome info. So it looks like from these simulations and at least with those heads some extra exhaust duration is more helpful on a NA engine. Let me throw a wrench in, let's say we look at it as running less intake duration to help the exhaust work better? What if you bring up the intake duration to match the exhaust on that last simulation?

Heres something interesting. Cam above, was the combo with

288/296, 236/245 .629/.632 114 LSA cam.

I then used the controlled induction cam software, to spec a cam for that combo, with max rpm of 5700. The cam it spec'd was

293/301, 238/245.5, .606/.634 , 109 LSA.

The controlled induction software, has zero to do with the dyno sim program, separate items. But anyhow, the cam that it spec'd, showed to be an improvement over the 236/245. Note, that the controlled induction cam, is making more power with less lift, and a slightly less aggressive lobe.

236/245 114 on left, controlled induction spec'd cam on right.

The 109LSA vs 114LSA on a NA big block in that rpm range can be significant. The 109 winning. Very good tuned exhaust needed. And yes, this is experience from et.mph in vehicles.

I have GLM exhaust, BUT I had them extended where the water enters the exhaust evack 15 inches from the center of the Manifold/Block to eliminate reversion. I am currently running 350 sm blocks with a Comp Cam of 236 intake and 242 Exhaust at .050 Lobe Separation is 112 - I would like to step it up! Any help on Cam Selection would be Great.....

A lot of cam for a 5.7.
How about more cubes and better heads. Or better heads and less cam duration?

Yes, bigger cubes are not an option rt. now. but I am going to AFR Alum. Heads from Dart Iron 202/160 - I didn't think that cam was so big, it doesn't sound that big and I don't have any idle issues.

I wouldnt expect a whole lot of performance gains going from the darts to the afr heads.

depends on what kind of Darts...so...what kind are they ?

Back to cams, what is your rpm at top speed ? And what is your compression ?

How much lift? Two years ago I built a 355" with Edelbrock E-Tec 200 heads and a hydraulic roller 230/238 on a 112 with .530 lift. If memory serves me I was either 11 or 12:1 compression. I ran Stainless Marine Exhaust. It made 425hp fully dressed with Stainless Marine exhaust on the dyno.

I went from turning 4800 rpm with the original 350 MPI to 5800 rpm with my new 355 MPI. If you want any info on the combo I'd be happy to dig it back up for you.
https://youtu.be/Pykm0boxvdE

PAnther - I remember commenting on your cam being a little too big back then, but I'm sure I didn't know you where running that much compression. WOW !

How much compression?

Jeff

That's what I remember because I think the stock CR is like 9.5:1. Add the extra cubes from the overbore and the flat top piston and I was somewhere around there with 64cc chambers. I could be off a little, I'm just going by memory.

I was afraid the cam was a little big and I thought the E-tec 200 heads were going to be a little big when I was building it but it all worked pretty well.

My Compression is 9.5:1 now and prop for a max RPM of 5800 - My existing Heads are Dart Sportsman II 202/160 ported and polished. I want to up my Compression by a point to 10.5:1 with the AFR Alum. Heads. My Rocker Ratio is 1.5 and again my existing Hyd Flat Tap Cam is 236 intake and 242 exhaust at .050 and the Lobe Separation is 112 - I think I can step it up a notch and I am reaching out for Selection Help. I don't get to a computer daily so please bare with me....

that is to much compression on pump gas

10.5 will be fine on a SBC but you'll just have to run 93. I would change to a hydraulic roller. The compression will make better use of all that duration.