cooltoys61

piston mfg Co. will give you the ratio for whatever CC head you use. I would shoot for 9-9.5 then your cam will kill a little of that if it's very hi-perf.. What are the #'s at 50 thou? If it's a cam thats close to stock you better stay under 8.75 if you want to run 87 octane. Since your already doing it I'd hate to pass on the chance to raise comp and pick up HP and torque for just the diff in gas,,,you'll wish you did when the boat is running XX and your buddy is running XX + 3 mph

formula31

I wouldnt go bigger than the L2399F if you need to use 87 or the 89 at the marinas. Others I know have gone higher but I prefer to be conservative since I am stuck with marina fuel.

danielthelen

Then cam is 218, 224 @.050 Comp Marine cam
I'm looking at H693CP with .210 dome. It says 9.3 to 1
Also H426CP with .100 dome wich is 8.56 with the 119 chamber.
Looking at the hypereutectic. seem to be cheeper. Just wish there was one at 8.8 to 1 with 119 chamber.
I looks like the l2399f mayb close to that. I found out 9.0 to 1 with 116 chamber. They are a little more pricey and have to run them looser.

what should I do?

thanks