WOT, how long is too long to keep 'er pinned?

[palace]

Re: WOT, how long is too long to keep 'er pinned?

I clean my carb while the wife runs her WOT. It cleans up nice!

I disagree here. Fouled plugs are most likely caused by running low rpms for extended periods. I would assume, though that running WOT occasionally will help clear plugs that are starting to load up.

Running WOT(whether often or just periodically) will also help clear deposits in carbs, injectors etc. It's good to put the hammer down in your car also for the same reason.

 

[Oshkosh1]

Re: WOT, how long is too long to keep 'er pinned?

"India Delta Ten Tango".

John

Ah...in the Navy we called them "ID-10-T's"...reminds me of having new lookouts scan the sky looking for "GU-11's"!

And like most here...I cruise at about 3/4 throttle. Gives me around 30MPH...and my tank will last all day. When I need the to steer clear of the aforementioned boneheads, I have a little extra.

 

[V153]

Re: WOT, how long is too long to keep 'er pinned?

clean my carb while the wife runs her WOT

I'm gonna leave that one alone ...

 

[Tail_Gunner]

Re: WOT, how long is too long to keep 'er pinned?

Running a GM or Ford v8 at wot for long periods is not a good thing. They are not very well balanced and imbalances grow tremendously at rpm increases. The valve train reaches it design limit's at 5000 depending on cam type.. there are so many variables. Are there exceptions always there still built one at a time and each and every one of them are going to vary slightly and all of them are going to have imperfection's.

Maybe someone who blue prints engine's will come along and share some insight but our boat engines were desinged for car's and modifyied for boating ....not internal mods either. As to time.....well cross your finger's that's half the thrill

 

[coolguy147]

Re: WOT, how long is too long to keep 'er pinned?

Good examples there. Lawn mowers are run full throttle their whole lives and are mistreated by 99% of all owner's. They are lugged(mowing tall grass to fast) often and operate in very warm weather. Not many people EVER change the oil in them either.

lol....i'm one of them....

 

[H20Rat]

Re: WOT, how long is too long to keep 'er pinned?

this is a option based issue. just fyi. lawn motors chain saws, weed wakers.ect are carberated. not fuel injected. there is no governer or wot restricor. there is just open and close. unless you own a fancy john deere or hi end lawn mower there is no engine govener. most boat motors are the same way. if there carberated then they are not governed.

umm, no... I've taken apart and rebuilt more small engines than I can count, and every single lawn mower engine had a governor. You don't need a high end one to have a governor, every single lawn mower sold today has one, from the cheapest push mower you can get at walmart to the cub cadet. (weedeaters and chainsaws generally do not have a governor, as there is no way to overspeed them) In fact, its nearly impossible to mow grass without a governor. The engine would rev it up to 6000+ rpm, and as soon as it hit grass, it would load down to 1500. (btw, most small engine governors are set to maintain no more than 3600 rpm at WOT, irregardless of load) You would constantly have to move the throttle in an attempt to mow grass.


Also, boat motors sometimes have rev limiters. Its a tiny little black box on the ignition, and keeps your engine from blowing itself to high heaven if the prop leaves the water.

 

[McLoki]

Re: WOT, how long is too long to keep 'er pinned?

Growing up my father had a 7.5hp evinrude. He had the motor for 35 years (he just recently got rid of it). For the entire 35 years, it had essentially 2 speeds:

Fast idle: (to move away from the dock or while trolling)

WOT: (anytime more than 20' from the dock to 20' from where we want to fish. (unless trolling))

It did not seem to cause any issues (and certainly did not lower its life span to much). With that being said - I do not plan on running my new optimax at full throttle all the time - mainly because I am happy with the MPH, MPG and volume levels at about 3,200 - 3,400 RPM. My 9.9 bigfoot motor (once broken in) will almost always be run at full throttle though (kicker motor sitting right next to my optimax).

All depends on what you purchase them for I guess....

Michael

 

[sasada]

Re: WOT, how long is too long to keep 'er pinned?

I run WOT frequently...HOWEVER...I'm propped so that WOT is around 4k RPM...not MAX RPM. I run different props for different loads/tubing/cruising etc...

I throttle back to "cruise" at around 30 MPH to save fuel.

This simple straight 6 is as near to "bullet proof" as an engine can be though.

FYI...you ABSOLUTELY want a prop that is at the max rpm when trimmed out and normal load is in the boat. Ask any marine mechanic. I am NOT trying to prove you wrong whatsoever but every rpm below your max (when running the correct prop) is much easier on the motor and more efficient. My I/O for instance has a recommended max RPM of 4600-5000. Ideally i want to prop it to top out somewhere between 4800-5000. I VERY rarely run it there but at every point below that the motor is working much less to sustain its current rpm. For instance i would put a 30" pitch prop on it and have it max out at say 3000rpm at WOT but that would be very hard on the motor as a hole and especially the head gaskets.

 

[V153]

Re: WOT, how long is too long to keep 'er pinned?

Fyi one thing I've learned is my motor is significantly less 'efficient' at high rpms ... Anybody else experience this phenomena?

 

[foodfisher]

Re: WOT, how long is too long to keep 'er pinned?

Quite a number of posts. Aside from the damage to his pocketbook, gas, I still think you owe him a beer.

 

[NYBo]

Re: WOT, how long is too long to keep 'er pinned?

Running WOT(whether often or just periodically) will also help clear deposits in carbs, injectors etc. It's good to put the hammer down in your car also for the same reason.

Back in the day, we used to call that an "Italian tune-up" (as in Ferrari, etc.). Totally unnecessary with modern fuel injected cars.

 

[brewern]

Re: WOT, how long is too long to keep 'er pinned?

Jerk or not, I'm with the "You owe him a beer" crowd. Sorry.
Put a beer in your trunk for a week during the summer. Then give it to him.

Boat motors are designed to be at WOT, they simply aren't like car motors. Maybe if you put a 1 pitch prop on it ....

 

[pootnic]

Re: WOT, how long is too long to keep 'er pinned?

Back in the day, we used to call that an "Italian tune-up" (as in Ferrari, etc.). Totally unnecessary with modern fuel injected cars.

Shhh,my wife might find out,then I'd be in trouble.

On the question,right or wrong I seldom cruize.
Idle or WOT,for only about 30mins though,our freshwater lakes/rivers are small.

 

[Lyle29464]

Re: WOT, how long is too long to keep 'er pinned?

To believe that piston speed has no affect on engine life is a different way of thinking.

 

[brewern]

Re: WOT, how long is too long to keep 'er pinned?

To believe that piston speed has no affect on engine life is a different way of thinking.

Of course it does, but, as already mentioned, WOT isn't operating at the actual top end of the engine. WOT is below what the engine is capable of.

 

[BonairII]

Re: WOT, how long is too long to keep 'er pinned?

Fyi one thing I've learned is my motor is significantly less 'efficient' at high rpms ... Anybody else experience this phenomena?

EVERYONE experiences this. Every motor has a "sweet spot"(where gas mileage is at it's peak). As rpms go up from there, the motor is less and less efficient...and gas mileage goes down.

 

[Oshkosh1]

Re: WOT, how long is too long to keep 'er pinned?

I am NOT trying to prove you wrong whatsoever but every rpm below your max (when running the correct prop) is much easier on the motor and more efficient.

My motor is designed to run WOT between 39-4300RPM...according to Merc.

 

[coolbri70]

Re: WOT, how long is too long to keep 'er pinned?

Fyi one thing I've learned is my motor is significantly less 'efficient' at high rpms ... Anybody else experience this phenomena?

i have noticed i use gas faster at wot however efficiency i still ? example, i went up river at wot 15-20 minutes used 3 gallons, linkage to my timing advance broke, turned around and idled back as timing advance isn't needed at idle, the trip downriver now took 3 hours to cover the same distance and my 6 gallon tank ran out at the launch i left from, the least amount of gas i have used yet on an outing.

 

[Mischief Managed]

Re: WOT, how long is too long to keep 'er pinned?

There is a huge difference between operating 2 strokes and 4 strokes at high RPM. 4 strokes really load the connecting rod in tension when they are on the exhaust stroke since there's hardly any resistance to the gases flowing through the open exhaust valve. This means the rod alone (pretty much) has to stop the piston at TDC. On the compression stroke, the compressed air in the combustion chamber acts as a brake to slow the piston down at TDC and that reduces the tension on the rod dramatically. 2 strokes are always on a compression stroke when the piston is moving up, they don't have the same kinds of tension loading and can deal with higher piston speeds.

The lack of valve train in a 2 stroke makes huge difference in the number of parts that can fail too. I'd be fine running a 2 stroke at WOT all the time, a 4 stroke marinized car engine, however, is just not built for that. That said, it will still "last" quite a long time if well maintained, just not as long as it would if used at 75% power most of the time.

 

[sasada]

Re: WOT, how long is too long to keep 'er pinned?

My motor is designed to run WOT between 39-4300RPM...according to Merc.

Sounds like you are right on the money then