View Full Version : Any modifications to Indmar engines to increase HP/Fuel effi

husky fan
02-22-2005, 01:08 PM
another dumb question.... I'm an incessant tinkerer and cannot leave stock alone.

My boat is a 2004 with the 320 HP Throttle Body FI engine. I see the factory offers a 350 HP engine, which has the same displacement and compression ratio. Supra offers a 380 HP engine with the same displacement and compression ratio.

How did they go about getting an extra sixty HP out of the engine? I know part of it is the different exhaust manifold, and the multiport FI.

Anyway to buy an aftermarket cam and/or exhaust manifold for these engines? Is it possible to remap the FI? I can hook my computer up to my motorcycle and remap the FI no problems, using an aftermarket blackbox and software from dynojet.

Is it possible to increase the HP and/or fuel efficiency through standard modifications?

I've got extensive experience on both automotive and motorcycle engines. I've rebuilt both, and raced motorcycles for a number of years (Suzuki GSXR 750, Honda RC-51).

On every vehicle I've owned I've changed the axhaust and replaced the air filter, etc, for increased HP/better gas mileage.

I would imagine you could do the same to a boat. Can you put a lower restriction muffler or a higher output exhaust manifold? How about changing the fuel injection mapping, or a different air filter.

I know I'm ignorant about boats, so please be somewhat gentle. Yes, I'm aware of the impact it might have on my warranty.


02-22-2005, 03:55 PM
It wouldn't amount to much more than a few HP, but K&N does make high-flow marine flame arresters.