25 daytona Max speed
 

I recently bought a 1999 25 daytona. It has a 540 with brodix heads, little over 8 to 1 compression with a BDS 8-71. The timing is set at 25, and boost peaks at about 6lbs. It has an older bmax drive, that is 1.30 ratio with their standard length lower. Prop is a 28 Bravo 1 that was slightly worked on, and has a 29 stamped on it.
It pulls about 52 or 5300 rpm and best I have seen with it is 88 on GPS.

I see people on here claiming to be running near or over 100 MPH with Less Hp than my setup. (I'm guestimating i should be around 750-800hp)

Do I have something setup wrong?

That setup should run triple digits. First of all, your timing is way late. Should be closer to 35deg. You are probably 100hp down at that timing setting. Next, check to see how far below the hull your prop shaft is. Might be too deep causing way more drag. You can always speed up the blower if need be.

Thanks for the reply! I was thinking the timing is a bit low too. The spark plugs look like the tune is pretty good, GUESSING it was dyno tuned. I run it on 91 octane, so I may increase the timing slowly over time but don't want to break the engine.
I also have a sportmaster -2 lower, but cant put it on until I get a coupler for BMAX to Bravo/Imco. I thought Eliminator installed the drives at the same height on all 25s. Using the plastic rub rail as reference, to me it looks the same height as other 25s.

Tried posting some pics, but Im new to offshoreonly and wont let me until I have more posts.

For speed reference I drove Eliminator’s latest 25 Speedster (twin step bottom 25, i think it’s the same bottom as yours) powered by a Mercury 565 ITS Sportmaster -2 shorty lower 1.50 gear ratio Merc Bravo1 32 pitch 5400rpm 92mph.

I recently bought a sportmaster -2 with a 1.26 ratio that I want to try out. Problem is I need an adapter to go from Bmax to standard bravo (so im told). Hopefully that will pick up a few MPH. Also bought a whipple supper charger I plan to take off the roots blower and add a bit of boost. Changing the blower is probably going to be a winter project, as im going to fuel injection. Really would like to dyno the engine before and after, but really dont want to pull the engine at this point.

Typically the 25 Daytonas like -2 lowers, but before you go through all the hassle you need to see where the bullet of the drive is in relation to the out side sponsons. Some drives are mounted at different heights from the factory.

The sport master is a mercury lower not a IMCO. Either way I’m would think BMax makes an adapter. The Bravo props seem to work the best, but with your gear ratio dropping to the 1.26 you might need to prop down a bit.

After you get the engine tuned to a comfortable place you might want to work with a prop shop like BBlades. They are very helpful and have a try before you buy program. Run stock bravo props if you start with a tweaked prop might give you bad feedback to determining your setup.

Did you get the top speed worked out? Seems like a ton of slip. I haven’t experimented with mine, but it was under 10 percent the way I bought the boat. 26 daytona

Curious to see what happens after I change power and have to start changing props, possibly gear ratio as well

I ended up getting a bmax -2 lower with the same gear ratio.(1.30) It struggled to get on plane, but the boat was MUCH faster. GPS said 102, the prop also got dinged from hitting bottom so thinking there might be a couple more mph there.

This summer I spaced the lower down 1/4 of an inch and installed a cav plate from max machine. It now gets on plane a lot better. It's not as good as it was with the standard lower but definitely acceptable.

Does anybody have suggestions for what prop I should run? Considering a max 5, or maybe a rev4 now that they offer a 27p 15.25 in version.