Mercury 150 Fuel Mileage - 1971 20' SF

[Bigshrimpin]

Originally Posted by YeA 20sF

I didnt know you could run these motors safely beyond 5k. I will look into your other suggestions thanks.

Mercury 2.5L block is still the base for almost all F1 racing outboards.


http://www.youtube.com/watch?feature...&v=9ofyoovc6h8

http://www.youtube.com/watch?v=71pUV...ure=plpp_video

up to 7000rpm in stock form is not a problem . . . The manual for our fishing motors suggests 5800 for the max recommended RPM. You can go to screamandfly and read all you ever cared to know about these motors.

[YeA 20sF]

Originally Posted by Bigshrimpin

Mercury 2.5L block is still the base for almost all F1 racing outboards.


http://www.youtube.com/watch?feature...&v=9ofyoovc6h8

http://www.youtube.com/watch?v=71pUV...ure=plpp_video

up to 7000rpm in stock form is not a problem . . . The manual for our fishing motors suggests 5800 for the max recommended RPM. You can go to screamandfly and read all you ever cared to know about these motors.

Oh man you should of never linked to the screamandfly site....... New reading addiction lol

[Fr. Frank]

I ran a '92 XR4 150 motor on my 20' Seafari for a number of years. Remanufactured by AAA Outboard and Machine and produced 192-194 hp on the hydro-dyno.

I had a prop custom made by Powertech, 15.25" diameter, 16.5" Pitch, fairly aggressive rake progression, 3-blades, polished. I changed my lower from the original small gearcase to a large gearcase off a 225 Merc, 1.65 ratio, with nose-cone and low-water pickup from Bob's (already on the lower when I bought it)

Amazing hole-shot, planing in just about 3 seconds lightly loaded, and still under 6 seconds with 9 people on the boat (4 adults & 5 kids).

Slow cruise was 28 mph at 3300 rpms and achieved 2.7 mpg on a Navman Flow meter. Fast cruise was 34 mph at 4000 rpms, 2.3 mpg. My normal average usage over all as 1.9 mpg.

WOT in the right conditions (45*F, downwind in 8kt breeze, light chop, only 12g fuel on board, was 48kts (53-54) mph at 6050 rpms

BTW, I now get 5.3 mpg with the same hull, at 24 mph, running a 90 Optimax.WOT 33-34 mph.

[Blue197320]

i have a prop you can try. i get 5700 out of my black max on my 20 sf.

[eggsuckindog]

Originally Posted by YeA 20sF

Oh man you should of never linked to the screamandfly site....... New reading addiction lol

That Mirage is a big prop Dia and aggressive pitch and cup, as mentioned too much - with a 17 Mirage for example you will get right at 400 more, raise the motor and anothe 100/150. I have a similar prop - Stilletto - smaller dia but similar that I just raised mine to 2+ inches above the hull bottom - still can't get it break loose = don't be bashful LOL the marina guy will look at you funny and try and talk you out of it but go 2+ trust me

see my post on the other prop thread for numbers, quite remarkable difference and I was already over an inch above.

BTW - Pipers Marine in Tampa had a used 17 Mirage+ for about 225, might still have it, good props but that makes them hard to find used - tell Ron or Chris the goofy SeaCraft guy sent you