RPM Range

[Esox_Magnum]

Whats the typical WOT range on a 91 115 Merc? Finaly have a working tach and back to playing with props.... Currently running about 5500-5600 WOT with 3 people and light gear load, but translates into my regular load when loaded for muskies with 1-2 guys... Currently running a Yammaha 13.25 x 18, but do have a worked Yammi 13.25 x 17 that needs reworked after getting into some gravel.... Top end with 3 guys is about 40mph currently but has been in the low 40's with the 17 and before motor rebuild but no clue on what the RPM's were back then...Both my props are 3 blade Stainless and do have a new merc alum 13.25x17 I keep in the boat as a spare...

[delcecchi]

Is that the 4 cylinder 2+2 motor? or the 6 cyl tower of power?

[Esox_Magnum]

2+2, good holeshot and good handeling but just think it has more in it than what I'm getting....

[delcecchi]

2+2, good holeshot and good handeling but just think it has more in it than what I'm getting....

My copy of service manual says 4750 to 5250 at WOT.

[Esox_Magnum]

Hitting 5500 alone with a light load with the 18p, not sure if going to a 19 will help top end or if it's worth trying... My reworked 17 was better on top end by 2-3 mph but it had some extra cupping done to it... I'm sure I can go up a pitch on holeshot, thats great with both props even with max load...

[tlbigstump]

You really want to keep the rpms on that engine at or below 5250. Those inline 4's would break the crankshaft at the top and the flywheel will turn into a flying saucer and the result of that is never pretty. The harmonics of those engines would cause this.

[WARRIOR 2090]

what tlbigstump says don't over revthat motor it will break the crank

[Esox_Magnum]

Guess I been lucky then the last 3 years, I'm sure my 17p was 6000 or better and ran it for 2 seasons, crank was in good shape when rebuilt last spring no signs of abuse or excesive wear....Boat came with a 17p Alum on it and guessing had been run for years like that since it is a 1991....

[tlbigstump]

Take it for what it's worth, but the magic Rpm for the flying saucer trick is between 5300 and 5500 rpm's. If you really want to twist that thing to 6 grand go for it.