489 with only 14 hrs compression #s
 

#1 170 psi
#2 160 psi
#3 175 psi
#4 165 psi
#5 155 psi
#6 155 psi
#7 160 psi
#8 160 psi

Cold engine, throttle wide open.

Boat runs strong, but disappointed with top end of only 50mph @500rpm, 20 pitch Turbo 3 blade. 89 Chap 2550sx. May try a 23p mirage i have lying in my garage. Do these #s indicate a motor that is in the process of being broken in, therefore more power is on the way, or something amiss!

what rpm?

sorry meant to say 50mph @5000rpm.

What kind of rings did you use? Also assuming you have a fresh grind on valves and seats? Was it bored or honed? Heads and blocked surfaced? 14 hrs is plenty of break in time. Mine typically take less then 14 minutes. Doubt you'll see any more gains. I would do a leak down on a couple of your lower 5 and 6 and see where its going? 100% on, would be nice but not always realistic. Your within or close to being within 10 % but so do several engines with over a three or four hundred hard hours on them. I've seen cylinder rings seat quicker than others on the same engine however with that kind of time you should be set. Have you built multiple good heat runs in it during the 14hrs and let cool good btwn? If you don't have a leak down tester go rent or borrow a good one. At the very least it may ease your mind a bit. Give us a little more info your recent build and who did it etc?

I would definately start the process of elimination. That is enough to be a little concerned.

not sure on the rings, my engine builder picked them. Engine was bored 30 over, heads and block surfaced, all new valvetrain. To be honest I really have only had it over 4500rpm 2 times: once last summer, and then 2 days ago. I guess I need to get on it some more

Well that hull is not very fast); 45 with a stock 330. It's very heavy. Not trying to knock the boat I had one but they were built like cruisers. I would try that 3 blade. Your motor numbers look fine.

I know, its not a performance hull, its a deep vee and very heavy. It's just I really spent a lot of money on the engine, stroker crank, 500hp heads,cam from Bob Madera, roller setup, and to only pick up 2-3 on the top end seems like I wasted a lot of money, could have just done a stock 454 mag rebuild or something for probably half of what I spent. Will see what the 23p does and then go from there. Maybe a 4 blade with more lift would help.

What carb, intake, and exhaust are you running? Was any work done on the heads in the valve bowls or combustion chambers? A lot of the 2550's came with thru-prop exhaust - are you running yours out the transom?

What is your initial and total timing set at?

Little things like incorrect timing and jetting in the carb can make a huge difference on the power output of an engine.

BTW, I almost bought a 2550 years ago that had a stock 330 in it. When I test drove it, I got it up to an easy speedo-indicated 55 mph without even playing with the trim for best top end. Of course, that was speedo-indicated and not GPS, but if 50 is all you are getting with a warmed over 489, something is wrong.

Running exhaust out the transom. Using a demon 850 with edel air gap. I have my initial timing set at 8 deg, not sure of total.