I am thinking of supercharging a pair of new hp525efi I have in my 42 Executioner. Has anyone done this yet?

Yes I have. Installed a set on a 39' ft velocity. Boat ran 82mph before and with everything dialed in ran 102 best on gps.

20mph thats crazy do you have any pics and did you do any mods to the comp because that comp does not read boost.Laz Mesa

Thats an amazing increase in speed. What about performance throughout the rpm range. Any other mods? I am running Bravo XR drives. I know I should do something about that. Not sure what though. Any suggestions? Thinking about Max Marine upgrade. Any idea on cost?

I did some drive height adjustments, and some prop changes. Like I said I did the full set up and got the boat fully dialed in. This is also saltwater. I will get some pictures for you. The velocity factory claimed this boat did 91mph from the factory with stock 525 efi. We never saw that.

Just watch the additional heat load due to turning up the H.P. The stock heat exchanger on a closed cooling system may need to be upgraded.

We have cold water up here in the Puget Sound around 54 degrees. I ran it ten minutes at wot and the temp stayed right were it needed to be. The key is the intercoolers they are working extremely well. Air temp runs around 90-100 under boost. Yes, we did mods to the computer and it does read boost know. Cut the map signal wire and ran it to a second computer that has a 2 bar map.

Congrats for exceeding 100 mph. Sounds like you have a good setup on everything in the boat. Love to see pictures.

How much boost are you seeing and what would you say was the mph gain of the blower alone without any other prop and drive tweaking?

Cold water temps will help the intercoolers as well as the closed cooling heat exchangers, but when you read manifold air temp on a positive displacement blower it also includes the effect of fuel evaporation so the numbers are difficult to compare with systems where the fuel is added after the intercooler.

I am glad to hear that the closed cooling system kept up to the increased HP output. I'm working on a system for that engine and I was worried about the cooling system. I still may install a larger heat exchanger just to be sure that it will work with the 90F lake water that people see in places like Havasu.

Here are some pictures of the 39' Velocity with twin whipples. PowerboatsNW Contact Cameron. We do more than just build motors. We will dial in your whole set up.

Do you believe me know?