I have a quad-rotor 565 with the 3.3 that we had builded at Paul Pfaff I used the Lunati Pro billet crank and rods on mine, it runs to 6000rpm. At 8# it is 1021HP and at 18# it's running 1387HP Did not run it with race gas just 100oct. You will need to go to a solid lifting cam if you want 1500HP.

Sorry for being so vague ,what I meant was when pitching your boat for peak torque at wide open do you think there would be a significant speed drop compared to pitching for top hp.The reason I ask is I would like to keep the rpm below 6000 possibly as low as 5500 then bump the boost up for more grunt.The jet pumps dont like rpm s. I was going to carb my motor,will this pose a fuel distrbution problem on extened runs?

mark @ precision www.pmefi.com is currently building another set of 565ci quads for a customer. manley rods, callies cranks. no hype builder. there is one coming of the dyno that did 1247 with 112 but i don't know the ci on it

In my experience, if you prop for peak torque, you will lose speed rather dramatically. Carbs will work fine, EFI is just better if you can program well.

FYI I was wrong scat does not make crower billets .

ZT260, I use a wide band o2 sensor for full throttle tuning,what afr reading on your engine would you consider safe in a race application?

I'm not sure you will get enough fuel through the carbs for that kind of hp even with blocking the high speed air bleeds. Start thinking about 55mm roller bearing journals for the cam and oversize diameter lifters for longevity. 18726543 firing order will help with fuel distribution as well as aiding in crankshaft life. If you really want to be leading edge on longevity, think 55mm roller bearing journal and 1" diameter flat tappets with 1.9:1 or 2:1 rocker ratio

My A/F ratio is at 12.5 +/- 0.3
It's somewhat conservative, but I'm not trying to squeeze every last HP out. As long as your at or under 13, I think you'll be OK.

BTW, nothing's safe in a racing application. Just hold on and pray.

My A/F numbers were only 11.3 at their peak, all were 11.1 below 6200 rpm. Does this seem to conservative.

That's probably very safe. Do you get any black crap on the transom? To know if you can go up, we need all the specs on the engine.