I was thinking big block was 1200lbs, why I came up with what I did. O well it really don't matter lol. Ran a mirage 21p yesterday and hit 70mph at 6000rpms.

That speed right in the ball park with the hp you have. Was it biting good when trimming up and without any blow out???

Yes, it kept taking trim without any blowout.

I just now noticed I said mirage 21p but it was a 23p mirage that i was running. I dont know why i was thinking a 21p because that actually throws my prop slip off. Guessing lack of sleep at some point lol. Prop slip is not 12% it's 20%. So at this point I think I need to go up in pitch. Since I could most likely go on past 6000 rpms with the 23p mirage with more trim, maybe I'll try to find a 24p 3 blade prop to test.

turn it up to 7000rpm and see how it behaves if you have good guts in it!

I'm just looking at staying 6000rpms max.

Try to find a 23 Mirage PLUS prop. They spin about 200rpms slower than a regular Mirage, but they bite better and propslip is a little lower.

You will have to go to 25 pitch Mirage or Mirage plus or a 24 Bravo one. Bravo one is a 4 blade and the boat will handle way better. Not as fast as a 25p mirage though. Still probably 75+mph.

Chris

Your engine has a lot of power, but less torque than the bbc, the solutions are as follows:
1.) Instead to gear 1.5, use gear 2 and you will get a super drive with a prop pitch over 30".
2.) A cheaper solution, which is not as efficient, is the use of a propeller, which will leave the engine above 6,000 rpm. I think you need to use arround of 22" pitch propeller, not to bigg. I have on MSA Marine drive a Signature SL five 22 but will buy another with 21" to spin the motor all the way up to 6.200 rpm.

These make no sense...