Performance

[clasavi]

I have a 1998 mercuries 350 EFI MPI
Engine Serial
Sterndrive OL153367

at the moment I have all stock parts but I would like to improve performance (top speed). what are some parts I should (if any) look in to changing?

 

[bonzoscott]

Re: Performance

Other than waxing your hull and bumping your prop up a pitch, nothing.
Nah.. that's not all you can do. If you have deep pockets, you can take it to a performance boat shop, sink $10k and get 20 MPH more.
Is it at 50 MPH now?

 

[agallant80]

Re: Performance

Boats are not like cars in the sense that you can bolt on this and that. You are pretty much stuck with what you have unless you want to spend major money putting in a larger motor. I was looking at 8.1L yesterday and I think they are about 12-15K for the conversion.

 

[haulnazz15]

Re: Performance

Don't know what boat you're in. Aside from a possible prop change, nothing short of bolting on a supercharger is going to get you more than 2-3mph better if everything is running as it should. It costs a lot of money to go fast in the marine-world. Speed costs money, how fast can you afford to go?

 

[QC]

Re: Performance

Agree, blower or engine. That's about it for anything significant.

 

[Volphin]

Re: Performance

Please do not strap blowers to engines that were not specifically built for this modification. To do so is inviting reduced engine life expectancy.

 

[clasavi]

Re: Performance

Thank you for the replies.
The boat is a 220 sx made by stingray. The current speed is 60 mph.

 

[agallant80]

Re: Performance

60mph is not good enough? My stingray I could get 50-55 out of it. I bought a cruiser and its 35 at WOT crusining at 25.

 

[clasavi]

Re: Performance

No it is fast enough. I wasn't sure if replacing the distributor cap and plugs would have given me better performance. Or adding a kit for $500-$700 would have improved the speed. I'm definitely not sinking $10,000 in it ...

It sounds like she is good the way she is.

 

[Walt T]

Re: Performance

Thing about a boat is a tune up improvement isn't noticeable. It probably is running better and producing a few more ponies but that isnt noticeable on a boat. The load on your engine pushing all that water aside is huge. 20-30 hp gain by changing cams, intakes, exhaust wont change much. The guys are right, if you want 70-75 mph you will need about 225 more HP. The Stingray is a good speed hull, but I wouldn't use it. If you want to go 70+ start with the right hull and work your way up from there. 500-700 on an MPI which is already performing pretty darn good, I really am not sure what to do with that. There's no magic trick, if there were we'd all be using it.

I spent 2800.00 and did my own labor, got a substantial increase in power and maybe 5 mph top speed improvement. Bottom end torque is awesome though. 22 foot cuddy, not really a speed hull like yours.

I wish my boat would do 60.