Re: Sizing your prop
 

If you compare the performance tests of a large number of outboard powered boats you will find that best fuel economy is almost always @4000rpm (cruising) or 1000rpm (trolling). 3000rpm is most often the worst for fuel economy. This all is effected by the fact that most boats are struggling to be on a plane @3000rpm and not in the engines designed power band.

Re: Sizing your prop
 

I'm running a 165 HP 4.3L v6 chevy i/o. Anybody know the max operating rpm's at WOT?

Re: Sizing your prop
 

I know as a rule of thumb your RPMs won't be as high as a 2cycle outboard +- 5000 to 6000....I think you should be somewhere around 42-4500 MAX, but you can't quote me on that

Re: Sizing your prop
 

Sounds about right phester.

Re: Sizing your prop
 

I'm in the ballpark, turning a 141/2 x 21 prop.
Thanks,
Rev

Re: Sizing your prop
 

Rev, didja ever find out the max RPMS for your motor?...

Re: Sizing your prop
 

No, not officially. I was hoping someone here would know. I'll do some research and post what I find.

Re: Sizing your prop
 

http://boards.trailerboats.com/cgi-b...c;f=6;t=000851

Looks like 4400-4800

Re: Sizing your prop
 

And w/ a light load, good conditions, trimmed up, etc, will she turn those numbers w/ that prop?...if you can try a Merc Mirage in that size, I think you'l keep it...

Re: Sizing your prop
 

I'm not sure of WOT rpm's but I know I'm over 4000.
I'm a little gun shy of full throttle but next time I'm out I'll check it out.