Compression Ratio per Camshaft Size
There are many variables that are going to determine if the engine detonates; two seemingly identical engine builds, & one detonates & the other doesn't.....
My GTO is a great example. With a 4 bbl intake, I would get occasional det on a hot day with 98 octane fuel. Did it with different intakes & carbs. Switched to IR induction system about 18 years ago & I have not been able to get it det on 91 octane fuel.................!
Stick to a sensible CR. Worst thing you can do is go too high in CR.....& then have to retard the timing to stop the det. You will lose a LOT more hp that way than if you started with a lower static cr [ don't bother with dyn CR, it is a waste of time ]. As CR increases the HP gain become less.
There are many variables that are going to determine if the engine detonates; two seemingly identical engine builds, & one detonates & the other doesn't.....
My GTO is a great example. With a 4 bbl intake, I would get occasional det on a hot day with 98 octane fuel. Did it with different intakes & carbs. Switched to IR induction system about 18 years ago & I have not been able to get it det on 91 octane fuel.................!
Stick to a sensible CR. Worst thing you can do is go too high in CR.....& then have to retard the timing to stop the det. You will lose a LOT more hp that way than if you started with a lower static cr [ don't bother with dyn CR, it is a waste of time ]. As CR increases the HP gain become less.