9.6 compression and boost
 

My most recent boat has 572 NA's with aluminum heads, and 9.6 compression ratio. Would like to discuss adding boost to these engines without lowering compression ratio, or using intercoolers so I can fit under the current blower scoops on the hatch. I guess my knee jerk reaction is 8-71's or a 10-71 if they would clear a distributor without an intercooler, and e85. Before everyone goes down the e85 and boats don't mix road, I have done a lot of research and let's just assume it's not a problem. I can't use centrifugal chargers because I have tall deck blocks, and there simply isn't room to build out, I have to build up. I can't afford new fuel injected whipples, so roots style it is. These motors make 650hp as NA's, and the goal would be 800-850hp. The only negative to e85 for me would be burning more of it, and availability of fuel when I leave my local stomping grounds. I could put a 100 gallon aux tank in the truck to combat some of that issue, but wondered if my goals could be reached on pump 93 fuel. I love being different and unique, and actually want to build e85 engines, but I am wondering if my goals could be made on 93 pump?

It's not ideal but you can add .060 head gaskets and then run low boost 5psi or so. I think that would get you to your goal. An 8:71 would work but a 10:71 is better.

I thought about thicker head gaskets as well, how much static compression can be dropped by go this route?

The only issue we've had running E85 with a Procharger for the last 3 years would be wear on the exhaust seat. The motor idles cleaner and runs stronger across the board. With the E85 you will burn 35 to 40 percent more fuel. You could try 93 with a water or methanol injection system. You can run lake water through a stainless filter and have an unlimited supply for free.
Correction 4 years running E85.

I ran a home made 3 stage water injection system on my motor with 93 octane before the E85 was available.

My buddy runs 9.5:1 with 7 lb intercooled pro chargers, approx. 850 hp no issues if timing is under control...

I'd need to know more about what you have to tell for sure but making some assumptions on my part, it should put you around 9.2:1+/-

With the E85 you shouldn't need to worry about an intercooler. In fact, if you're 5psi or less you don't need it either way. The 9:1 is sorta like having a N/A engine with a blower as a helper. When I bought my boat, the engines were setup this way. I changed it later on but that's how it was set up.

.030 will give you -.1 compression

I run the Snow system on mine! Saw roughly a 1 mph gain on the juice!

I had 1 stage set for 5psi, 2nd came in at 10 and the 3rd at 15, never saw any signs of detination. I didn't pay enough attention to know if it added any speed. The compression was a little over 9 to 1.