Good gen 3 hemi NA street power?

[digger]

is this it?

https://www.hotrod.com/articles/dyno-te ... -iii-hemi/

[BLSTIC]

Out of curiosity, how does the average port area compare between the two heads? And what about mixture motion? How does ignition timing compare between the two?

Between stock 6.1 and the Thiteks? I'll take those measurements and get back to you. IIRC optimal ignition timing was pretty similar, but I don't have any of my old 6.1 maps.

I was referring to the LS vs Hemi. I have no idea between the different types of head for each, but I do know that if the hemi ports are too large there simply won't be the energy in the port to get particularly high VE. Also that if the hemi combustion isn't very efficient you won't get the same power from the same VE either.

[Ron E]

The ports are generous. But, I doubt that's an issue especially considering the good flow rates. There are good performing engines with larger port (per valve area) that run fine. The mixture motion will be similar to a non-ski jump/tumble 4V head. The chamber is pretty snug around the valve offering good diffusion rates on the sides. Typical timing on the few hot street builds I've seen are in the 18-20° range.

[Grant]

I ended up sending my motor off to Chris Seidle. He's done a lot of work with these aluminum blocks, and even has a fix for the porosity issue. I'll post dyno results when I get them.

[In-Tech]

Thanks Bryan, I was hoping there was a better solution like the valley cover AoS on LSes. However looking at the motor I don't see where I could pull directly from the crankcase. When you start pulling over about 1.1 g the factory AoS in the 6.1 manifold turns your catch can in to an oil grenade. I think a taller, vertical-path (factory is horizontal) AoS is needed.

I understand the IR 8-stack intake by Speedmaster is a big boost over what you have . All I remember is 30-40 more peak HP with more everywhere. I think the closest intake was -30 to it. Several were tried. It was a milder engine than yours. A 40 CFM loss by adding the intake "concerns me.

Any idea where you saw that test?

Richard Holdener has tested the Speedmaster stacks (https://www.youtube.com/watch?v=G_DZSvJiFaA) and an unported SRT8 intake (https://www.youtube.com/watch?v=O6_GeHl-77U), but on slightly different motors (5.7s with different cams).

Speedmaster uses 50mm throttles; those come out to about 80% less surface area than my port opening. From what I'm gathering this is probably too small for me? I'm also kind of skeptical ITBs are meaningfully different from plenum intakes, once you put filters on them and route cold air to them.

I've been playing around with CodeQuery and may see if I can print an intake to test with.

mag_intake.jpg

Although you do have a "hemi" problem with those cam specs, it is the runner length that is limiting you(not just a hemi problem) longer runners appreciate a later intake closing event but still "stall" even with supercharging. It's "time travel" at this point, larger runners of course help but still won't fix.
Exhaust is critical with NA hemi and that will be your next fight after you fix the intake fight. There's at least 100hp waiting for you

[Rowdy Yates]

Place a 4500/4150 carb intake on it and be done cheaper.

The only problem with the hemi is you can't place much cam lift with the rockers....


No port work and you losing 25 to maybe 80 Hp with non Ported heads and not using a carb style Intake @ 420+ cubic inches....