WOT RPM's

walleyehed

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Jun 29, 2003
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6,767
Re: WOT RPM's

5400 may not kill it today, but milage suffers as does the combustion chamber.<br />As we don't "have" a gear shift to lower the engine load, you must be propped for MAX RPM of 5800-6000 for "BEST" efficiency at any RPM.
 

CATransplant

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Feb 26, 2005
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Re: WOT RPM's

But...5400 rpm is well within the manufacturer's recommendation for the rpm range at WOT. I can't imagine that picking up another 400, assuming that the tach is accurate, is going to make much of a difference in the life of his outboard.<br /><br />In fact, I can't imagine it causing any problem for him at all. I'd have to see some data demonstrating that an engine was damaged from operating within the factory specs for WOT before I'd be convinced that there was a problem.<br /><br />5400 rpm is NOT lugging that engine. Not at all. It's within the published specs from the manufacturer for WOT operation.<br /><br />Lookin for another 4-600 rpm seems a waste of time to me, frankly, again assuming that the tach is accurate in the first place.<br /><br />Maybe I'm wrong, and if so, I'll change my opinion when I see some real data.
 

djzyla1980

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Jul 26, 2005
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Re: WOT RPM's

I have to agree with you CAT.... If my motor was running 400 RPM's lower then it should.. I would be out havin fun. As much as I like to tinker and toy there's got to be a stopping point where one says thats it... It's good enough. <br />Heck, I'd trade them motors any day if they really want to tinker and toy. If your interested let me know... I'll meet you 1/2 way...lol
 

CATransplant

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Re: WOT RPM's

Well, if he got his outboard up to 6000, instead of 5400, he'd gain about 3mph or maybe a little bit more. So, he'd be going 37-38 mph, instead of 34-35 mph.<br /><br />Now, I don't know, but I don't run my outboard at WOT hardly at all. I always back off to 75-80% throttle. I get better fuel economy there, the motor seems happy, and I still manage to get across the lake to my fishing spot pretty much in the same time.<br /><br />Reason says that running your outboard at WOT all the time can't be as good for it as backing off a little and letting the engine take it a little easier. Every outboard I have ever run seems to have a sweet spot...somewhere off WOT, where the boat is skimming along and the motor is running quieter and using less fuel. That's where I run mine 99% of the time when I'm going fast.<br /><br />Of course, my outboard's only 47 years old, so maybe the damage from running it slower will show up later in its life, eh? ;)
 

ddbyrd3

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May 9, 2005
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Re: WOT RPM's

I have to chime in.. sorry.. <br /><br />As for me, I dont fish, at least not yet, I water ski, wake board, etc. If I can, and have, the potential of gaining 400 to 600 RPM, sign me up I will do it in a heart beat... Not everyone is satisfied with par performance, others of us dont mind pushing the limit for performance.....<br /><br />Just my opnion of course...
 

vranasaurus

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Apr 18, 2005
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Re: WOT RPM's

Walleyehed,<br /><br />It's not the prop. The motor just seems to stop at 5400 no matter what the load. I just want the motor running properly. <br /><br />I do not want to speed across the water at 45 MPH. 35 is fast enough for me and I will continue to enjoy my boat. But something is definately up. It is not, I repeat not the speed that I want it is proper functioning. I don't believe the motor is being lugged but that something is limiting the R's. <br /><br />I am loathe to go out and start replacing expensive parts before I know whats wrong. <br /><br />My next step is to verify my tach readings and go from there. <br /><br />Does anybody know a good place to get an OMC/BRP tach and am I go to have to give an arm and a leg for it?
 

djzyla1980

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Jul 26, 2005
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Re: WOT RPM's

But what is 3 miles per hour...really? The skier is not going to come off his ski's and say "WOW that 3 miles per hour extra made all the difference." To me if I could get a skier outta the water in a decent time, and keep him there who is really going to notice the extra 3 miles per hour? Except the gas tank... <br />I understand everyone trying to get the best outta there boat but sometimes the best isn't worth all the hassle's and changes. <br />If your boatin' and havin a good time... why take the possibility of makin things worse?
 

djzyla1980

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Re: WOT RPM's

And this still doesn't say wether or not the Tach is working properly... just thought I'd add that in
 

CATransplant

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Re: WOT RPM's

ddbyrd3,<br /><br />Sure...if that's your goal...go for it. Tinker all you want. The original poster isn't in that position, if I read him correctly. He doesn't care about that extra 3mph or so. He just wants to make sure he's not damaging his outboard.<br /><br />I've seen no evidence that operating a Johnnyrude within its factory specs for WOT operation is harmful to the engine. If it were, all those folks out there who don't bother switching props and hunting for the maximum RPM would have busted engines. They don't. <br /><br />For most people, wringing the last possible bit of performance out of their outboard is not a serious goal. They're using their boats for what they were intended and not worrying about it.<br /><br />In fact, I'll wager that most boat owners spend very little time at WOT in the first place. Most folks back off a bit and cruise along happily.<br /><br />My guess is that all those old Johnnyrudes that are running very nicely after 20, 30, or 40-some years were treated that way by their many previous owners. That's why they're still running today.<br /><br />But, that's just me. Performance-oriented folks will continue to tweak and tune and go for the max. And so they should, if that's what they want.<br /><br />I just question the validity of telling folks who don't really care about peak performance that they'll damage their engine if they don't run it at or beyond the max rpm recommended by the manufacturer. The manufacturers provide a range of rpms for WOT operation. Within that range, an owner should be comfortable that they're not damaging their engine.<br /><br />In reality, the ones who will get the longest life out of their expensive outboards are the ones who perform all the proper maintenance and run their outboard below WOT most of the time. That much I can guarantee. There is no piston engine that gets its maximum durability by being run at full throttle and full load most of the time. Not a single one....outboard, automotive, or any other.<br /><br />I have the greatest respect for Dhadley and Kenny. They're the masters at getting the maximum performance out of a Johnnyrude and a boat. But, when they suggest that anything other than maximum RPM and WOT operation is bad for the outboard, then I think they're doing a disservice to those who are not performance-oriented.<br /><br />The original poster can safely operate his outboard at 5400 RPM. He will not damage his engine. He's well within the manufacturer's specs.
 

ddbyrd3

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May 9, 2005
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Re: WOT RPM's

Dave, if that 4 to 600 RPM can add to your hole shot, it is less strain on the skiier, boat, etc.<br /><br />Who cares about top speed, its just making sure we are getting all of what the motor has to give... SAFELY!!
 

CATransplant

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Feb 26, 2005
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Re: WOT RPM's

The guy's got a 22 foot jon boat, ddbyrd3. A jon boat. It goes 35mph, and he says the hole shot's fine. I don't see the problem. He's worried that he might be damaging his engine.<br /><br />Personally, I think his tach's probably off. Most are. He's happy with the hole shot. He doesn't care if he goes 38 instead of 35. You might care, but he apparently does not.<br /><br />His engine's running at 5400 at WOT. Again, it's within specs. Not every outboard of a particular model will perform as well as every other one. Maybe his is not perfect. It's also 16 years old.<br /><br />I have a 16-year-old car. It doesn't go quite as well as it did when it was new. It has 156,000 miles on it. I don't ask it to perform at WOT...ever! I'd like to keep it a while longer.<br /><br />If you want the 3mph, then tinker until you get it. But please don't tell others that they should do the same thing. I'm betting that his engine will outlast yours.
 

djzyla1980

Chief Petty Officer
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Jul 26, 2005
Messages
640
Re: WOT RPM's

Correct me if I'm wrong, but that 4-600 RPM's won't be there Until you actually reach WOT... so your whole shot should not be effected if you add 4-600 RPM's at WOT
 

ddbyrd3

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Re: WOT RPM's

I appologize for getting on a rabbit trail.... <br /><br />Sorry VRAN... I am sure we are all sorry for high jacking your thread.....<br /><br />I am curious to know what you find out though....<br /><br />Keep us posted...
 

vranasaurus

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Apr 18, 2005
Messages
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Re: WOT RPM's

This motor actually has better hole shot on the 17 pitch. This motor gets up and goes faster than a guy who realizes that his date wasn't as pretty as the night before. This motor has plenty of gumption. If I wanted to pull a skier I believe I could.<br /><br />A jon boat at 35 MPH will get you wetter than a bus load of fat girls on their way to see a Ricky Martin Concert. And it is scarier too.<br /><br />Just remember outboard motors have got to be the second goofiest thing on this planet.
 

jameswilson95

Seaman Apprentice
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Jul 27, 2005
Messages
43
Re: WOT RPM's

If you have an engine with max rpm (5400)and try two props - one with a low pitch and one with a coarse pitch. The one with the coarse pitch would make your boat move further thru the water with one complete revolution of the propellor, therefore, this would give you greater speed for the same 5400 rpm. Hense, a prop with less pitch would cut less water which would slow your boat down. Is this not right ?? :confused:
 

djzyla1980

Chief Petty Officer
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Jul 26, 2005
Messages
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Re: WOT RPM's

Hey vran... where do you drop your boat?... In Omaha Myself and need to find somewhere better then the mucky shallow waters of manawa.. Hows Icara if you've been there... Haven't been there since I was a kid
 

CATransplant

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Feb 26, 2005
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Re: WOT RPM's

"A jon boat at 35 MPH will get you wetter than a bus load of fat girls on their way to see a Ricky Martin Concert. And it is scarier too.<br />"<br /><br />I'll bet it will. 35 is really fast in any jon boat. Watch those squared off corners, too, in turns.
 

vranasaurus

Petty Officer 2nd Class
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Apr 18, 2005
Messages
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Re: WOT RPM's

I fish a lot at Manaswamp it gets pretty crowded though. <br /><br />I live in Ames now and go on Saylorville quite a bit. big lake plenty of room.<br /><br />Icaria is nice but it to gets crowded. I don't think it is worth the drive for you. <br /><br />If they don't do something about Manawa soon it will fill in in 5-10 years. <br /><br />What kind of boating do you do?(Fishing, Skiing, Cruising)
 

vranasaurus

Petty Officer 2nd Class
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Apr 18, 2005
Messages
105
Re: WOT RPM's

CAT,<br /><br />I get some relief because it is a mod v but that isn't quite enough at times.
 
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