Does this prove David Vizard's 128 lsa formula ?

273 said

The question was based on that to run more cr than people are generally willing to run eg 12:1 instead of 10:1 that you would have to run less than ideal timing cause of pump gas. (Wasn’t my assertion)

Say for 12:1 ideal timing was 33 degrees how much less than ideal timing would you run (for pump gas) that it becomes we’re it wasn’t worth going to 12:1, eg. 32,31,30,29,28 etc..

If I remember right that was the basic question.

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Think it through. Compression makes power and it makes power everywhere. Compression makes the chamber packed tighter. A tighter packed chamber requires less timing.

So why not up the compression and unfuck the tune up so you can do it?

On pump gas, a 9:1 engine may want 35 total. That same engine at 11:1 with the exact same parts will maybe only need 30 because the chamber is packed tighter.

Plus that extra compression allows you to use different cam timing. It just works.

Unless of course you are stuck in 1980 and can't get out of it. That means slow cam lobes, coolant temperatures over 180, an all in by 2500 timing curve or worse yet locking it out just makes it much harder to run higher than orthodox compression ratios on pump gas.

I had a 12.5:1 engine on the dyno a week ago. He was bound and determined to run Avgas but it looked to me like it lost power with it. I say with what he was doing I could have easily tuned it for pump gas (safe tune up) and it would have made more power.

And 110 would have made less power regardless of how much timing was jacked into it.

But most guys won't learn because it's too hard and it upsets their lifetime paradigm of what can't be done.