horsepower

[mkast]

Re: horsepower

So according to the formula it is only a 2 mph increase for 20 hp? Seems like a lot of work for 2 mph. I am going to start looking for a 350 to throw together



"Rule of thumb" instead of formula 1 MPH per 10 engine horsepower increase, each MPH, (more) takes a tad more than 10 horsepower and so on.
Owner/operators speak of "More horsepower", what they want is a seat of the pants "Feel".
That will require either large amounts of money or another boat (read large amounts of money).


My first marine engine was an inboard flat head V8, as in:

http://www.youtube.com/watch?v=g9NBvk8mXoY

Aluminum SOHC 427(up to 542 cu.in.) weigh in at 450 LBS. dressed, 800+ hp. @7200 RPM naturally aspirated.

 

[letsgo19]

Re: horsepower

Was originaly just looking for a little better holeshot but after reading all advice here I think I will stick with present setup I can deal with slightly sluggish holeshot after all the boat is throwing off an excellent sized wake

 

[mylesm260]

Re: horsepower

yup, I'm going to echo what everyone has said here, drop in a 350.

Here's a couple other thoughts.

Turbo's and boats don't work well together (generally). It is virtually impossible to build a DIY turbo kit while keeping it safe and legal.

problems include: Water jacketed exhaust and turbine housings, as well as corrosion resistance of the compressor housing and compressor wheel.

*IF* you were willing to go dry exhaust with a wide open engine compartment and were prepared to have a very very short turbo life, then you COULD do it.

You would also NEED efi as any kind of carbed turbo setup is just garbage (I'm sorry, blow-through or draw-through turbo setups are just absolute crap!)


If I was in you're situation, I would do this.

Pull you're engine
Remove and inspect you're exhaust manifolds
Go buy a low milage 5.7 from a Chev/GMC 1500 pickup (1998 or newer)
Use you're manifolds and ignition system with the 5.7
Get a new intake and use you're carb (will need to be vortec)
Use you're starter and alternator (may have V-belt to serpentein belt issues)
Install a heat exchanger (it's either that or, change you're water pump and head gaskets)

The vortec 5.7 will give you an honest 280-300 HP in a boat with a 4bbl, and the motors can be had with low milage for 500 bucks if you look around.

 

[mkast]

Re: horsepower

Was originaly just looking for a little better holeshot

Then look for a two speed or shifting propeller.

 

[45Auto]

Re: horsepower

From letsgo19's thread in the prop forum:

I have a 20ft bowrider with a merc 305 220hp we usually have 6 or 7 people and about 700lbs ballast for boarding

You need a LOT more boat in a runabout, or a dedicated ski/wakeboard boat like Natuique, Moomba, Tige, etc.

 

[Don S]

Re: horsepower

Was originaly just looking for a little better holeshot but after reading all advice here I think I will stick with present setup I can deal with slightly sluggish holeshot after all the boat is throwing off an excellent sized wake

Maybe what you should have done originally, is explained what you are looking for with your boat. Not just a cheap way of increasing horsepower.

I have to assume you are pulling a wakeboard and when to get going, but top speed isn't what you are looking for. Am I corroect?

 

[CheapboatKev]

Re: horsepower

Was originaly just looking for a little better holeshot but after reading all advice here I think I will stick with present setup I can deal with slightly sluggish holeshot after all the boat is throwing off an excellent sized wake

Glad you see what these guys were saying...Use what you have, and when you move up to your next boat, you'll know to look for a bad ol 5.7 lol