Speed with new blower
 

I posted pics a week or so ago. Boat is a 24 Lightening tunnel built by Wyatts Performance Boats. It ran 77 on GPS with two aboard and about half fuel at around 4700 RPM (I never look real close). Engine was a stock 454 Mag spinning a 28 pitch bravo 1 four blade. Now it has the same 454 Mag with a B@M 250 EFI blower. I am starting with a 30 pitch Bravo 1 four blade. I also added external steering and some other stuff. I will also try a 32 pitch Bravo if this wheel isn't big enough. I want to keep the RPM's down if possible. How fast will it go? B@M said 8 to 15 mph gain. It seems like I saw someone on this board a couple of years ago who picked up 17mph on a 22 foot tunnel. Mine is actually barely less than 23 in fiberglass. I think it is going to see 90 at least. What do you think?

You should be spinning that motor up to 5000 rpm. That is where the H.P. peak is. I picked up 14 mph on a heavy V hull at 6 psi boost so I would think 90 is not going to be a problem.

Do you have a GPS unit for speed? If not I would get one and have your passenger call out the speed numbers that way you can drive and trim up or down to get max speed.

I have a hand held GPS. Also, at 77 my liquid filled Gaffrig and the GPS read the same (actually the speedo is a few tenths less). I have a tattletale on the speedo and the GPS will recall the highest MPH reached. On this hull I need a lot of positive trim to reach 77 but have been told into the eighties and nineties I will not need near as much positive trim. I just haven't had enough HP to air it out right. By the way, my boat is one of two with a stock 454. All the others built have had blowers, big stroker motors, or twin outboards.

Heres a pic:

And another:

That's an awesome looking setup. Get that boat in the water and let us know what it runs!! Sounds like you have the speedo thing well under control. Just make sure to spin that motor up!! Mine is a 454 Magnum and I run it up to 5000 alot!!