Full throttle rpms

[droach77]

I was finally able to get out today and switch to my new boat trailer and run the boat after everything i have done, THE BOAT RAN GREAT!! The rpms at full throttle were at about 5200 without trimming and i was just curious how many of you guys run your motor close or past the recommended full rpm. I am running a 17p prop the boat was factory rigged with a 21p prop. BTW thanks for everyones help the past couple years helping me get this thing straight.



dave

 

[Frank Acampora]

Re: Full throttle rpms



On my 21 foot cuddy with a 140, I am propped to run about 5000 even. On my 15 foot Glastron V153 with a 90 I run right about 5400. On my 14 foot go-fast with a 125 I can run 5900 with a 21 pitch cleaver but with a 21 pitch Ballistic, RPM drops to 4500 yet top speed stays the same. My 10 foot go-fast runs about 5000-5200 with a 50.

 

[roscoe]

Re: Full throttle rpms

I try to go max or more, without spending money on props just to gain the last 200 rpm..

My 95 70 hp Force with an empty boat, 5600. it dropped to 5300 when I put all the gear in it.

My 2002 Merc 50 elpto ran at 5600, but never ran it there because the boat was unable to handle that speed..

Merc 115 1985 runs at 5500.

Merc 75 hp 1984 runs at 5300

89 Force 35 hp runs about 4500

 

[jerryjerry05]

Re: Full throttle rpms

My twin/85's can run at 5400.I NEVER run that fast.Most time it's about 42-4400. Easier on gas and not too hard on the motors.

 

[fucawi]

Re: Full throttle rpms

swopping props can be a waste of time ...to rev the motor more you need less pitch ..less pitch gives less speed only compensated for by the higher rpm so you are back to square one...If you want go go faster get a bigger motor /eat less burgers/ get a smaller lighter boat.

 

[droach77]

Re: Full throttle rpms

fucawi, i was knot asking a prop question....no pun intended. I was just asking how much people turn there motors without failure at recommended specs @ wot. Not trying have a speed boat , but a good running vessel that will not blow up at WOT if I choose to open up once in a while....BTW don't be such a di(k


dave

 

[jerryjerry05]

Re: Full throttle rpms

Way to go Dave!!

 

[maverick974]

Re: Full throttle rpms

fucawi, i was knot asking a prop question....no pun intended. I was just asking how much people turn there motors without failure at recommended specs @ wot. Not trying have a speed boat , but a good running vessel that will not blow up at WOT if I choose to open up once in a while....BTW don't be such a di(k

dave

Sheesh droach77, Don't get your panties in a wad. He was pretty much stating fact. I'm no mechanic but I'm pretty good with motors and such.
Outboards in particular are designed to run best and most efficiently at certain rpms. Specially two stroke engines.
If you motor is running within the manufacturers specified rpms then the only question is where in that range you want to be. If your engine is propped to run in the rpm range closer to the top as recommended by the manufacturer, you'll have more holeshot. A slightly higher pitched prop will cause slightly lower rpms but usually a little more speed but at the cost of slower hole shot.
If you want to pull skiers and tubes, go with a bit lower pitched prop. Better out of the hole but lower top speed.
Go up in pitch and the hole shot suffers but more top end. Stay within the rpm range the manufacturer suggests. You and your engine will be much happier in the long run.
BTW, who's the di(k? No insults were thrown out there until your post. Lifes to short to be bitchy. Take your boat out and have a good day.

 

[droach77]

Re: Full throttle rpms

Thank you frank, roscoe, and jerry for answering the question i asked.

 

[bentle]

Re: Full throttle rpms

I have a 94 120 force with a 15 pitch prop. It turns about 5400-5500 wot. Haven't had any problems. I believe these motors were made to run more efficiently at 5300-5500 wot. May not be a huge fuel saver, but this is the life of boating we're talking about. Forgot to add the motor sits on a 18ft Maxum.