1990 merc max rpm & best pitch prop

[Hooked22]

i just picked up a rebuild merc 175 199 model to put on my 1992 alumacraft 185 competitor and i have a 19 pitch vengence prop on it and im getting 43 mph and i was getting 41mph with my 115 merc and im not sure what the max rpm is for 175 it jumps right out of the hole with NO problem but the top end is not there , i have to trim it way up to rn at 43mph at 5600 rpm WHATS THE PROBLEM HERE?? THANKS FOR ANY HELP HERE. HOOKED

[hooked]

with all the knowledge of boats on this board i figured someone would've replied by now

[miksup]

Something's wrong here. That 175 shoudl get you more than 43 MPH and you darn sure should be able to turn more than a stainless version of a 19 inch aluminum Black Max, which is what the vengeance is. You should be able to turn at LEAST a 21 Trophy or Tempest and maybe a 23 pitch. What is the max RPM and what size gearcase is on the 11 year old motor? Where is the motor mounted on the transom? Something not right.

[Hooked]

this motor has less 100hrs on it, its been totaly rebuilt from top to bottom . its mount on the top holes and with the 20inch formula to center of hub its right there i had a 21 pitch on and lost even more top end . the vengence is cupped stanless prop if i dont tuck the motor all the way down it blows out . once im on plane and trim it up and imean up she holds good even on turns . it throws a low long rooster tail im not sure what that means. does this mean i need a adjustable jack plate ??

[miksup]

I'm in over my head here with this set-up. Come on guys. Somebody ought there should be able to give this guy the info he needs.

[hooked]

SOMEONE has to have a idea whats going on here ???

[Tom P]

Is your throttle plate opened fully on the motor?? Check your timing with a timing light and a good shop manual. Find a dealer with a engine dyno to how much HP you are puting out. Do the latter after all above has been looked at.

[REW]

I agree with Tom.
It certainly doesn't sound like your engine is putting out 175 hp.
It sounds like it is putting out about 100 hp.

As Tom suggested, is the throttle linkage set up correctly, so that you are really getting wide open throttle, and that the carb plates are really wide open.

Also, does the timing advance to the correct spot, with the throttle wide open.

Also, what is the RPM that you are able to turn with this engine.
I assume that with the throttle wide open, you are able to get to about 5500 rpm. If not - you have a problem.

As Tom also suggested, I would have your local dealer put on a load wheel, and see how much hp your engine is developing. When you get things set up on this engine, so that you are putting out a true 175 hp, and able to spin a "good" 21-23 pitch prop at 5500 rpm, you will be running your rig in the mid to high 50's.

Take care

REW

[Hooked:to REW]

REW its turning 5600 with 19 pitch merc.stainless Vengenace 3 blade prop i cant get anymore rpm out of it. we checked timiming and it was right there. could it be the hull just isn't made to move. i was at hergerts on sat. and he says that going from a 115 to 175 i should only pick up maybe 8 mph best , thats just hard for me to beleive that 60 more horse is going to get me only 8 mph. maybe trim tabs??or a hydrafoil?? Hooked

[miksup]

Now we're getting somewhere. If you're only able to turn a 19 Vengeance 5600 revs with that set-up, either your engine isn't putting out anywhere near 175 ponies or your hull is SEVERELY hooked. The Vengeance is just a stainless copy of the Black Max aluminum. You should be revving that thing past the limiter, about 62-6300 revs would be my guess. Like the max said, have your mechanic put on a load wheel to check it out. If the engine checks out fine, have an expert check your hull. I can turn a 10 Trophy woith a 150 on a Crestliner 1750 at 58-5900 revs. Yours most certainly should be able to turn that wheel a whole lot faster that 5600.

[miksup]

My mistake. That should have read 19 Trophy, not 10. Sorry guys.