WOT RPM's

[djzyla1980]

Re: WOT RPM's

Like to do it all... I hear you on Manawa if it wasn't so close to me (during trial and error times)I would find other ... Theres really no good lakes around here... they all get crowded.

 

[walleyehed]

Re: WOT RPM's

Cat, You are correct on the specs of 4500-5500.....in 1989, not now. We've spent WAY too much time tearing these down after continued use on todays fuel in many different cases to say 5400 IS NOT lugging it..IT IS, and has been proven. Obviously we have another issue with this engine that is not allowing full throttle operation. Although the plates may be horizontal, if that's been checked, we still don't know if the tach is correct. 2 weeks ago, I had an OMC tach stick right at 5K and would NOT go any higher, even though I knew it was turning near 6K. Do we know the timing pointer has been centered properly?? Do we have a carbon build-up issue in the exhaust ports that will flat not let it develope anymore power??<br />Have we removed the flywheel and determined the key has not sheared??<br />The BEST thing you could do with this engine is take it to a dealer, have them put a test wheel on it, and see if it developes rated power.<br />Set-up for 6000 RPM is not for performance of speed, it's for proper operation at cruise settings on TODAYS fuel...not 1989's fuel.<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 />

Most will not understand the fact that todays fuel does not exhibit the same properties that were typical when this engine was built. I stand behind 5500RPM as the very minumum RPM allowable.<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 />

Your Idea of performance is my Idea of longevity. The Maximum available "performance" is a combination of efficient running with greater longevity due to lower combustion temps because of the lower quality of todays fuel vs. the fuel of 1989.<br />This isn't an Idea....it's facts we've seen over and over.<br />The "Disservice" would be to NOT share our experiences with this exact and very common misunderstanding.<br />When we suggest lower than Max RPM is "Bad", it's because it has proven to be that way over time, again, fuel issues.<br />Run the temps up till the rings lose their tempering, doesn't matter....Load the ring lands 'till a ring catches a port, get after it...<br />That engine running 5400 at top-end, allows(Makes) the engine work harder at cruise settings as well, and that's very hard for some to understand for some reason, and it's beyond me, but then again, the 1978 115 we've had from the box, proped for 5750-5800 only has 4100hrs on it now because it was a fluke...it'll turn 6k on a cold day, easy.<br />The customers we have set up for 5600-up have no problems...the customers that insist on 5200-5300 being OK, we see alot of.<br />Take your pick, it's your investment.

 

[walleyehed]

Re: WOT RPM's

Regarding this statement.... "Per the experts on this board I am trying to get into the 5800-6000 range. But something has to be up." Johnson/Evinrude does not agree, hence the RPM limiters on their late model motors.<br />

Mark, the timing and many of the electronics on some of the newer engines are limited to a specified RPM, because of the electrical components. This being said, replacements are available with NO rev limiter, if the proper components are added.<br />As for these crossflows, they run out of air before any damage can occure...the stock reeds will allow about 6500RPM, and when set up right 8000RPM won't kill the engine. Personally, I think the conditions present are a combination of issues not being looked at...they don't have rev limiters and I think a look under the flywheel may be in order. Maybe a good look at the plugs and wires. I wish I had one here to stick a test wheel on and get that question answered.

 

[umblecumbuz]

Re: WOT RPM's

Looks like there is also a bit of confusion here about the meaning of WOT.<br /><br />As the experts all know, WOT is not the maximum revs the motor will hit. WOT is a rev range or band, within which the motor will perform at its most efficient, which also means that it will last longer. <br /><br />If the manufacturer states that WOT is, say, 4,800 - 5,600, this means that your motor should be able to reach 5,600 suitably propped. If it can't, then even if you run at 4,800, your motor could be lugging. <br /><br />To run efficiently within the manufacturer's recommended WOT band, you also have to be able to hit the top end of that band. Once you've set your motor up to do that, you know that you can run anywhere within the WOT band at maximum efficiency.<br /><br />So even if you never run flat out, it's important to set your motor up so that it will hit maximum recommended revs. Most of us, like CA, can run at the top end, but prefer to ease off a little once we know that our motors are within the efficient operating range.

 

[Dhadley]

Re: WOT RPM's

Performance orientated is indeed related to longevity. And every year when the fuel (possibly) changes you have to re-evaluate everything. Lugging the motor causes increased combustion heat. Not water temp necessarily but combustion heat. Combustion heat promotes coking which sticks the rings. <br /><br />Turning a stock, as produced crossflow 5800 rpm isnt "racing" it. Nor is 6000 to a looper. My 150 is set up at 5800 or so. I cant remember when we've been out and had it past 4000. Normally we cruise at 3200-3500. But at 3500 the combustion temps are as cool as they can get. And we use a bigger prop than most with the same type boat & motor.<br /><br />Hook up an EGT gauge and see what happens with props to change the top rpm. Not at top end but in the cruise range. When youre running on full advance timing and very little fuel. Then youll see how rpm is directly related to longevity.<br /><br />A disservice? I dont think so. I make a living selling engine parts. Parts that tear up from lugging. A disservice would be to preach 5200 rpm so we sell more parts.

 

[vranasaurus]

Re: WOT RPM's

There is no carbon build up in the exhaust ports as it was just rebuilt in the spring and I probaly have 12-15 hours on it.<br /><br />When I said it is not lugging I meant that the prop is not the limiting factor on RPM's.<br /><br />Plates are horizontal. The timing was set by an outboard mechanic. <br /><br />The tach will go above 5400 if I trim it up to the point the prop begins to ventilate.<br /><br />Dhadley and Walleyehed, I think you both understand what I'm getting at.<br /><br />Is there a rev limiter on this motor? Could a previous owner have replaced some of the electronic parts with something that had a rev limiter? Is there any way to test this theory?

 

[djzyla1980]

Re: WOT RPM's

If the prop begins to ventilate, but it runs above 5400 then I would assume theres a set up issue... and not a Timing, or ignition or any problem with the way the engine is running. If there was a Rev Limiter on this I can't see it allowing the RPM's to get above 5400 ventilating or not. A limiter would limit the RPM's wether it was ventilating or not..... It's not like the motor knows it's ventilating...RIGHT?

 

[kevin88]

Re: WOT RPM's

vranasaurus,<br />You are asking if there is anything that could prevent the motor from revving over the stated 5400 RPM's? IMHO the WOT timing could be the reason why you aren't seeing a notable change. If the timing reaches it's maximum before you reach WOT the RPM's will be limited. Aside from carburation this is the only thing possible that could cause your symptoms. May think about having it checked.

 

[djzyla1980]

Re: WOT RPM's

So if I understand this correctly... In 1970 my 115 was rated between 5000-5500 max RPM's. With todays fuels being different and if my mathmatics are correct, My current target for this motor should be 6900 RPM's(I'd blow the rod right out the side of it). Not to question anyones vitality in here but that seems a bit off. I understand that some are Professionals and do this for a living but I personally would rather run my motor at the specs range from that time then to risk harm in the motor. Besides I don't think the problem he has is not worried about his spec ranges... vran just wants to know why his motor won't run above 5400. Don't make much sense to me.

 

[vranasaurus]

Re: WOT RPM's

The timing was set by a shop. It has been linked and synced how could the timing adavance be reached before WOT. I am not understanding. <br /><br />It runs like a freakin' champ it just does not get up in RPM's regardless of the prop. Could there be something in the ignition system that is breaking under a load. As in it will allow operation up to a certain amount of RPM's but will not go any further.<br /><br />I am really confused.

 

[djzyla1980]

Re: WOT RPM's

your advance is going to stop before WOT. the last bit of movemment on the throttle won't affect the timming. That is why alot of people don't "lay" on the throttle.. they will cut back and cruise along. The timming is advanced as far as it is set, at your required degree... which was I believe you said 28. after it reaches 28 it stops moving but your throttle will continue to open up more then that. If it is advanced to far you will ruin your engine.... If it's not enough then your losing RPM's and preformance and take the risk of Lugging your engine. Your timing was checked by a shop... I really doubt it is off unless it has been messed with since then. <br /><br />I must ask though... Since it has not been asked yet... How does the cavitation plate line up with the bottom of the boat?

 

[vranasaurus]

Re: WOT RPM's

I feel like a dumass but:<br /><br />What is the cavitation plate?

 

[djzyla1980]

Re: WOT RPM's

Above the prop.... there will be a "plate" that sticks out farther then the rest of the mid section probably about 2 inches. In most set ups it is right at or even with the botttom of the boat. measure from that plate to the bottom of the boat. Your boat is a flat bottom so I'm not sure it is going to be set up the same.. but in most V's and tri's that is where it is.. Just curious as it very well may be a set up isue "engine to low"<br />and Don't feel like a dumbass... If it weren't for this site... I'd have no clue either

 

[djzyla1980]

Re: WOT RPM's

would like to know how far above or below that plate is from the bottom of the boat..."side veiw"<br /><br />If you have any questions look at this post<br /><br />DHadley, could you look at the pics of my motor height??

 

[vranasaurus]

Re: WOT RPM's

It is probably a two inches above the bottom of the boat.

 

[djzyla1980]

Re: WOT RPM's

Hmmmmmm..... <br />not really what I was wishing for....lol<br />sometimes if there too low it will "lug" the motor... I was having the same prob... But my motor was mounted too low. Made a difference bringing it up to the bottom. I would not move the motor down any.... and before I would move it up any I would get someone elses theory on it... If it's up too high then you can start loosing water pressure, and probs with the prop gripping...the only difference between this and when you trim is the way the prop is in the water. From what I understand (anyone correct me if I'm wrong please) just because it ventilates trimmed up.... doesn't mean it will ventilate not trimmed with a higher mount of the motor, and a more vertical alignment of the motor/transom might allow the prop run properly.<br /><br />Now you said when the prop started to ventilate and the RPM's increased.... How much did they increase?

 

[vranasaurus]

Re: WOT RPM's

It increased about 400 RPM's maybe a little more. But I knew it was ventilating because I lost speed and the RPM's jumped suddenly.

 

[djzyla1980]

Re: WOT RPM's

But if there was a limiter on it.... the limiter would not allow the RPM's to go above what you believe is 5400. So if it starts to ventilate... but reaches lets say 5800 RPM's there would be no limiter on this motor. You were trimmed up.... the prop was at a different angle in the water.... started ventilating...but had increased RPM's<br /><br />You've changed the prop no difference.... <br />I would almost think raising the motor 1 hole very well could make a difference... but good or bad depends on the exact set up. If it wasn't already 2" above the bottom of the boat I would raise it with out a question... bringing it up any more may lead you to too low of water pressure... and ventilation <br />however I am really thinking it is more of a set up issue.... I would verify tach and then go from there.

 

[vranasaurus]

Re: WOT RPM's

You planning on hitting Manawa on the 20th or 21st. I should be in town.

 

[djzyla1980]

Re: WOT RPM's

I am replacing reeds in my motor(waiting for them to come)They should be here by middle of week... If all goes well and she starts running right I very well may be... thats a way's away and with 3 kids and the wife things change daily and sometimes I just go out there just to go...for a couple of hours.<br /><br />I still don't think it is the way your motor is running. I'm no expert, and don't claim to be one but if you found the tach is working right... and theres not much else that can be done to the motor then what else could it be? From what I understand the two go hand in hand... A Finely tuned motor and the set up... If the tunning is off then the top end suffers but turn those around and the set-up is off... the top end still suffers. The two have got to be right for things to go right. It seems alot of people on here have the same problem, and none have mentioned the way there motor is mounted or set up issues in relation with how the motor sits on the boat. Change ignition components, rebuild carbs, motors, change tachs and whatever else but it seems that not one have said anything about moving the motor on the transom, and all have the same problem after money is spent and time is waisted. Coincident...not sure but you cannot rule it out. Another fact is how many of these people with the same problem have rebuilt their motors? What was the reasoning for the rebuild? Motors wear out yes, but what is the reason they wore out so quick? Could it originally been a set up issue? Did it just wear out from time or was it something else? I as well as My dad and grandfather have ran some very old motors for a very long time without a rebuild and so have many other people. If the set up isn't there then you will have probs...if not now then in the long run. I personally would rather raise or lower the motor or look at the set up then dump another $300 into it. If it doesn't work then change it back. You can buy anything you want and spray paint her chrome (if thats what you desire) and still end up with the same results. I would much rather go thru trial and error to get it right then keep dumping any uneeded money into it. I always...no matter what I am working on do everything possible that I can do before I pull out my wallet, Call me cheap or a tightass but if I can fix it for free why spend money? <br />Some input from walleyehed or Dhadely would be greatly appreciated right about now....lol