[Boatcrazy]

I have the chance to pick up a complete side mount Whipple charger with the upper and lower intake included for a really good deal and am not sure if I should go that route or just rebuild my 502 to a 540 and use reliable and tested components? I would like a little higher cruising speed out of my 302 and to be over 60mph on the top end. Currently I cruise at around 35mph @3500 and my WOT is 53mph @4800rpm. I think I can get another 100-150hp out of my 502 and possibly be over 60mph at WOT.

What do you all think?

[ShabahZ280]

Personally, from someone who's supercharged an engine before (not a marine engine though), I'd say you might be better rebuilding the block to a 540 using tried and true performance parts. The stock engines are meant to handle the HP they were originally designed for, and when you add higher torque and HP, those stock components wear down much more quickly, and become a ticking time bomb, so to speak. You'll never know when they'll just give out, and leave you up the creek. If you were hellbent on going the supercharger route, i'd consider rebuilding the block from the ground up with heavy duty parts. At least you know you'd be going with "new" parts, and not just accelerating the deterioration of an already used marine engine.

Also, not sure how they are with marine engines, but on my old Jeep rockcrawler, it was finicky as hell, I could never get the proper air/fuel ratio set, fuel pressure, even with the engine being MPI, I could never get it tweaked to run just right. It gave me an extra 90hp, but threw my gas mileage out the window too. I got 8mpg in my 200hp supercharged 4 cylinder rockcrawler, and 13MPG out of a 310HP Ford V10 Excursion. I'm sure they've made some significant improvements with supercharger setups, but I still think you'd be better off spending the money getting your engine rebuilt up to the 540.

Ultimately it's entirely up to you what to do, just remember, the hulls of the Z302 & Z300's were built to be able to sustain the max HP of the 500EFI and 525SC's (around 470-490HP). Keep that in mind, I don't know that I'd want to go pushing any higher than the structural limits of the boat.

[Boatcrazy]

Thanks Chris as that is kind of where I am leaning to. I can pick up the Whipple setup for $1600 and would probably have to throw some money into having it gone through before even thinking about installing it. I was told that I can pick up atleast 100hp with the Whipple setup but not sure of the internals in my 502 even though it was supposed to be a recently rebuilt block when I purchased it. I am going to contact a couple of engine builders and see what they can do with my 502.

[Boatcrazy]

I think I have decided to not go with the Whipple system but to rebuild my 502 to a 540 with the installation of a new rotating assembly and add roller rockers. I am also looking at installing a 500EFI intake and modified throttle body. The research I have done looking at what others have already done makes me believe that the setup should be around 550hp and be more reliable than adding forced induction.

[ShabahZ280]

Great choice!! Keep us updated on the process!