I'm thinking this year I will end up rebuilding my engine, expecting to get high 70's with my single step 29 but hoping for 80.

My 27’ fountain with a 600hp stroker goes about this fast with my wife riding shotgun. 60 plus "I hate you" 70 plus "your never never getting laid again" 80 plus I didn't hear anything... Weird... Coast guard said she was really mad at me about 4 hours later. I stayed at a buddy's house.. Just to forewarn ya!!

Does anyone look at the dates on post before commenting? Just asking.

Yes it will mine has a 540 NA and does 84 gps and we are still testing props. And that is with full tank of gas (135 gallons) and all stuff still in boat and water tank about 1/4 fuel. Before you go crazy I know it will go faster will less fuel ( and my engine builder has already complained about me filling it up ) but I wanted true numbers cause that is how I keep the boat.

not trying to hijack the thread, kickin32 did you just 540 the bottom end of your hp500 or did you go with aluminum heads and the different cam?
im curious because we have two hp500s, one going in a 29 and one going in a 27 and a 540 has crossed our mind instead of a blower

540 bottom, custom cam, Brodix bb2x heads, Brodix intake, dominator 1050 carb. Would have liked to do a blower but too many of my friends eat drives and that gets costly.

Spinletto I was wondering how you were making out with that new IImor motor. I hadn't heard much from you since you started that project.

I know this is an old thread, but can I ask what propeller did you use?
I have an 29 fever with a MCM-HP500, upgraded to 548 (602 hp at 6000 rpm) But the speed is about 69 mph. with a 4 blade bravo one 15 1/4 x 26p (5300 rpm) If I trim more the rpm increase, but not the speed.

New test yesterday with new spark plugs. Got 74 mph. at 5400. trimmed out, but can not get more than 5500 rpm.

I was running a hydromotive 28 left 4 blade
Now we are messing with a hydromotive 27 left with a 5 blade

Ok. The sterndrive broke last week. Before it broke I actually got 76.8 mph at 5600 rpm. Best speed measurement I've had. But I think and hope there is more to be gained with a little research on the propeller and gear I am considering buying Bravo 1 XR sports master short. Someone who has experience with these drives of Fountain 29? I belive I have to buy 5 blade propeller with shorter drives. Hoping for a little more speed and increased stability. What do you think?