496 HO Mags. everything is stock w/28 pitch props. I am having MPH issues and only see 72. I have only owned the boat for a year. I am in the midst of numerous checks in determining the problem, but what should I be seeing for top MPH? I'm not talking about a day in a year when the stars are lined up correctly, but what I should see on GPS generally when everything is running correctly?

At least high 70s. 72 is a perfect scenario speed for the 6.2s.

I'm curious. I have 23p props on my Dominator with 383s. What about the big block Sunnys makes such a difference messing those much bigger props?

Three words: Torque is King

30p on mine

Sure, but that's a little simplistic.

Certainly and I can believe they make great use out of a big prop from down low. But, after you start getting in to the mid-range and high end, I'm making more HP and torque than a 496 Mag or 454. But jumping to a 28 sounds like a huge change despite similar power at fast cruise. I'm curious if the X dimension is different.

Just trying to learn! Prop is definitely my next thing Don't mean to hijack the thread.

Love your boat

Not simplistic at all, Evan. Torque carries the weight, period. Not quite sure where you're getting the idea that you're making that much more power than an HO. (based on the dyno sheets that Bob posted. maybe I misread but I thought your numbers were on the stand) A 496 will make nearly 100ft lbs more than your small blocks at the prop, not the flywheel. That alone will allow a big block boat to spin a bigger wheel. If your boat were mine, I wouldn't hesitate to bolt a pair of 24p Hydros on it and see what happens. I think you might be pleasantly surprised. If you're making that much torque you may even be able to go bigger. X dimension will play a part but there are numerous other factors involved as well. If you've been able to get slip numbers with your current setup it's very easy to see theoretical improvements with the calculator by changing prop size. I seem to recall you were getting 30% and then -5%? Something doesn't seem right with your input to the calculator. (Not trying to be a dickinsee in any way)


CATF800 - there could be numerous details that are slowing you down. Anything from power loss, bottom hook, knicked blades and/or skegs, down to the way you're running the boat. For instance, Capt Y and I have a mutual acquaintance who has a 32 that had those ****ty stainless skeg guards on his boat and while they look cool to some, they were costing him nearly 4mph. Every little bit helps.

Oya 496 HO kills me for sure, I've driven a Dominator with them. I was referring to a 496 Mag 375 hp. More power across the range with those, but if we're talking WOT top speed my 383s have more torque.

I tried another calculator and got 11% slip if I remember right.

Maybe I'll give those hydro 24s a shot and see how it goes. After my next bonus I'll call BBlades to get a pro perspective and get a couple sets to try.

11% sounds a lot better and likely correct. Not a bad number at all, either.

Brett will set you straight. It's only a couple hundred bucks, if that, for a set to test.

Don't own one but 28s seem kinda small. But like said so many thinks come into play. I put drive showers on my boat and lost 1 1/2 MPH.