thanks

Not sure why the map isn`t more progressive. 32* anything after 3000 defeats the whole purpose of a map
I don`t have experience with NA but 32* at peak tq would be way too high for what I do.

Timing isn't so much about a number vs achieving the aim of combustion with a margin of safety.

As an example in the early days of Hemi NHRA racing, they didn't understand that the massive hemi chamber need ridiculous time to burn. The guy that discovered it was winning...with something like 45° ign timing, until the secret got out.

Different chambers/piston crowns need different timing. Add in the varying exh valve temps and fuel atomization.

Dan's applications see very high air density resulting in high dynamic compression ratios. The extra cyl pressure increases flame front travel speed = less timing required + a safety margin.

NM and HP on the same page is giving me a headache.

I ask without knowing... I find it curious to see MAP +5.8 psi in a normally aspirated engine. Is that good or bad?

MadMax2,

I think you misunderstood Dan's comment. The table is most likely from his engine builds, which were Whippled 555s.

Thanks. Brad.

Going to upgrade My exhaust from stainless marine manifolds to a CMI headers, 1.7/8" primary id/ full lenght primary tubes. I am building custom taill pipes and The question IS what Would Be The desired Id For The taill pipes? I am thinking 3.5" or larger, i could trade few mph at top For better low rpm efficiency. Dyno sheet IS on this thread.

Jani, are these dry or wet flow?

Make a difference for sure.

You need 2.2cfm/hp for unrestricted exhaust flow.

115cfm/ sq in of exh area.

A 3" tube with 7.07" area = 813cfm before restriction.

813÷2.2= 370hp x2= 740hp Dry exh

Important to note... a bit of exh restriction does not shut everything down..it's an exponential graph.

3.25" would be 867hp.

Dry to transom with 4.5" downturns. Not sure how and where exactly to enter The Water. I Would really like to hear some opinnions how to do IT. Also The collector on those cmis IS stupid large, almost 4", i Would really like to replace IT with merge/reverse Coney collector.

Here IS link For different collector shapes.
https://burnsstainless.com/blogs/art...iB7hvfWslzUW2k