Running: WOT, or 4/5ths throttle???

[Alaninga]

Been a boat family since I was too little to...well,.I was little.
Dad always taught me to run our 1960s era Merc 90 [straight 6] up to full throttle, then ease back to approximately 3/4 to 4/5ths throttle to 'cruise' down the lake. Loved living in Orlando in the early 1960s [I'm 61 now]. Ran a good ways up and down the Butler Chain of lakes out of the Orange County Sportsman's Club. Hardly ANY houses on those lakes back then. Drove there through Windemere from McCoy AFB [ok, reminiscing now!]

ANYWAY, I now have a 2006 Merc 40 EFI 4 stroke on a 16' Triton 1653SS [stick steer]. Talking to a Mercury mechanic about motors and running habits, he said my Merc was DESIGNED to run WOT! I said "cars are 4 stroke and you don't run those at wide open throttle!" He said something like "is your Mercury mounted on a car or a boat [ha!]"
We discussed about how a 4 stroke [or 2] on a boat is really designed knowing that most will run it wide open, and that everything about the motor is made to run that way. Talked about carbon buildup in the heads/valves, etc., if it ran at 3/4 throttle all the time. He also said it would be a good idea TO run it at slow speeds when first cranking it up as some do a car. Let at least the block get some temperature buildup before running WOT.

I LOVE a 4 stroke, especially after getting used to it 'not' having a power peak at mid range rpm like all the 2 strokes had.

What think? How do you run yours??

 

[Bondo]

Re: Running: WOT, or 4/5ths throttle???

Been a boat family since I was too little to...well,.I was little.
Dad always taught me to run our 1960s era Merc 90 [straight 6] up to full throttle, then ease back to approximately 3/4 to 4/5ths throttle to 'cruise' down the lake. Loved living in Orlando in the early 1960s [I'm 61 now]. Ran a good ways up and down the Butler Chain of lakes out of the Orange County Sportsman's Club. Hardly ANY houses on those lakes back then. Drove there through Windemere from McCoy AFB [ok, reminiscing now!]

ANYWAY, I now have a 2006 Merc 40 EFI 4 stroke on a 16' Triton 1653SS [stick steer]. Talking to a Mercury mechanic about motors and running habits, he said my Merc was DESIGNED to run WOT! I said "cars are 4 stroke and you don't run those at wide open throttle!" He said something like "is your Mercury mounted on a car or a boat [ha!]"
We discussed about how a 4 stroke [or 2] on a boat is really designed knowing that most will run it wide open, and that everything about the motor is made to run that way. Talked about carbon buildup in the heads/valves, etc., if it ran at 3/4 throttle all the time. He also said it would be a good idea TO run it at slow speeds when first cranking it up as some do a car. Let at least the block get some temperature buildup before running WOT.

I LOVE a 4 stroke, especially after getting used to it 'not' having a power peak at mid range rpm like all the 2 strokes had.

What think? How do you run yours??

Ayuh,.... I look at a motor as a Bank, full of rpms,...

If ya run it at 5500 rpms all the time,...
Yer bank will be empty, long before it would be if run a 3500 rpms when cruisin'....

 

[Chris1956]

Re: Running: WOT, or 4/5ths throttle???

Alan, I also agree with Bondo. Most Outboards reach full spark advance before they hit full throttle. You will get better economy if you back the throttle down to the spot where you get full spark advance. On the distributor motors it was easy to see. As you advance the throttle, the distributor would swing. After a while it stopped advancing and pushing the throttle more simply opened the carbs more.

 

[Georgesalmon]

Re: Running: WOT, or 4/5ths throttle???

I sorta agree with your mechanic except,,,,,,,,I do believe that the motor was designed to run WOT all day long. But if you think about it doesn't nearly everything that turns wear faster when it turns faster? I really like Bondo's bank analogy. Makes perfect sense to me.

 

[Alaninga]

Re: Running: WOT, or 4/5ths throttle???

Actually I don't prefer to run WOT. The boat feels best at about 2/3rds throttle and is loafing along on plane. I'm wondering if the mechanic is thinking more like 'idle speeds' for a long period of time?? But with EFI and a properly operating thermostat, and pure fuel burn - not a 2 cycle mix of oil,...it should be able to idle for a good while, too.
I'm glad the 4 strokes have become practical motors. I worried a good bit with a 1982 40 Johnon. It had VRO-1 oil injection...and those had problems!

 

[H20Rat]

Re: Running: WOT, or 4/5ths throttle???

Outboards aren't designed to run at WOT for extended times, and doing so will dramatically increase wear and shorten the life. Your fuel burn also goes up by a huge margin vs speed at WOT. Your mechanic did have one thing sort of correct, most 2 stroke outboards don't like idling for long periods, but that doesn't mean you have to go WOT.

 

[rallyart]

Re: Running: WOT, or 4/5ths throttle???

Four strokes can run at WOT as well as two strokes, and for as long. WOT has more to do with the quality of components and cooling system than engine type.
However, almost all engines work at optimal levels that are below WOT and Bondo's point is really valid. Every time a crank turns or a piston goes up and down you have increased the wear. Run any engine too slow and you create other problems and running at the same RPM exclusively for vehicle engines can also create some funny wear. Your point about "feels best" is actually a pretty good indicator of the right speed. Your body is a pretty sensitive instrument for sound, vibration, and force.
The only engines that I know of that are designed to run at WOT are constant RPM industrial engines like a diesel locomotive or a compressor station

 

[generator12]

Re: Running: WOT, or 4/5ths throttle???

With all due respect to all posters, I'll never understand the questions about WOT versus cruising RPMs.

It's a mechanical device, with moving parts separated by petroleum lubricants. What machine can you name would last longer when run at full speed? Your car? Your lawn tractor? Your weed eater? Your wife's kitchen blender? Your 3/8 inch drill? The 747 you rode on when you last visited grandma?

It's an ENGINE, driving a set of GEARCASES. Of course you'll reduce its life running it constantly at full speed. The lubricant will degrade at a faster rate, the metal making up the moving parts will contact each other at an increased rate, the higher temperatures resulting from WOT will degrade all materials involved at an increased rate - all resulting in a decrease in service life.

If it were designed to be operated at full speed ONLY, it would be a throw-away/disposable/single-use item. I doubt that a marine I/O fits that description.

 

[ewenm]

Re: Running: WOT, or 4/5ths throttle???

im with generator12 who wants to run around flat out, if thats your thing maybe you need a faster boat, my understanding of WOT is that it serves the purpose of ensuring the boat is propped correctly, however like your car ( and yes i know its not) but who drives there car at WOT

sure theres going to be occasions when you may need to nail it to get out of someone way or in the face of a storm, or what ever, but as stated throttle it up get on plain and then back her down to a comfortable cruise, for me thats around 3000 rpm, giving a 20 something mph speed, yep i can go faster if i need to but at that speed the co pilot is happy (know what i mean, yep)

all that said, i do give my boat a quick burst at wot, usually on the return just before i get to the ramp, (safely of course) just to ensure everything is working well ( oh and for the buzz, well it is the end of the day, im not dead yet hehehehe)

 

[ondarvr]

Re: Running: WOT, or 4/5ths throttle???

Some posters seem to be a little confused as to what the mechanic said. He didn’t say WOT is the best place to run the motor, or that it’s the most economical place, only that it is designed to do so and will most likely do it for very long time and not blow up.
Most any other motors will self destruct in short order if run at WOT.
But like Bondo said, it will wear faster at those high RPMs

 

[emoney]

Re: Running: WOT, or 4/5ths throttle???

I agree there's a little confusion as to what was said. It's only logical to assume any motor was "designed to run at WOT". Think about it, if it was "designed to run at 1/2 rpm range" what do you think would happen to it at WOT? However, I think the mechanic may have been just a little misinformed. If he's recommending to his customers that it's better to run your 4stroke at WOT all the time, for wear, he's definitely mistaken. Unless they find a way to get around the "internally combusted engine" thingy, it's never going to be better to operate constantly at WOT, because like Bond-O said, there's only so many little "explosions" in there and the more you use today the less you'll have for tomorrow.

2stroke or 4stroke, doesn't matter, they were BOTH "designed" for WOT otherwise we'd all be in a heap of trouble on most hole shots. However, to think anything man made is best operated at maximum capacity constantly is a little misguided at best.

 

[ondarvr]

Re: Running: WOT, or 4/5ths throttle???

I agree there's a little confusion as to what was said. It's only logical to assume any motor was "designed to run at WOT". Think about it, if it was "designed to run at 1/2 rpm range" what do you think would happen to it at WOT?

2stroke or 4stroke, doesn't matter, they were BOTH "designed" for WOT otherwise we'd all be in a heap of trouble on most hole shots. However, to think anything man made is best operated at maximum capacity constantly is a little misguided at best.

Again Outboards are run by many people at WOT for hours on end, this is not something your car or truck can do for more than a short time, their systems aren't designed to handle the stresses for very long. But yes, for a short time they are designed to run at WOT.

I don't run any of my OBs at WOT for more than a minute or so, I don't like the idea of the extra wear and tear and the reduced mileage when doing so, but they are designed to do it.

 

[Bamaman1]

Re: Running: WOT, or 4/5ths throttle???

You can run your engine anyway you want to. But it'll get the best fuel mileage (2 or 4 stroke) just after your hull planes off.

There is a difference between 2 and 4 strokes. Both are loud at full throttle, but the 4 stroke will be much quieter and smoother at normal cruising speeds. 4 strokes will get better fuel mileage, but the difference is offset by having to buy outboard motor oil.

But, aggressive boat drivers, like tournament fishermen, might do better with a 2 stroke as they're running full throttle much of the time. People that run their boats at slow or mid range speeds do better with 4 strokes.