How long at WOT?

[QC]

Re: How long at WOT?

Merc used to say forever, in print. They also mentioned shortened engine life . . . So there it is.

 

[haulnazz15]

Re: How long at WOT?

I can tell you that piston airplane engines are not rated to run at continuous WOT. They aren't designed that much differently than automotive engines.

Convince a renter of a 172 about that, lol. 2450rpms is still less than 2500 redline.

 

[Philster]

Re: How long at WOT?

Yes, if its a closed loop fuel injection system. Otherwise, fuel is delivered as a function of the amount of air.

Accordingly, you must claim a 2-stroke engine can never experience a running lean condition???

 

[Philster]

Re: How long at WOT?

You and I are in agreement, Frank. Load is the variable, but valve float doesn't care . . .

I have no idea what my point is other than most of this stuff is speculation. The impact of load on engine life is variable, the impact of RPM is variable, so what do we have to base any of our positions on? Nuttin' . . .

Sooo... what?? Let's not have a healthy discussion to flesh out some conclusions?? Am I the only one comfortable with this thread, even if it's not 100% based on statistically valid studies?

 

[QC]

Re: How long at WOT?

Just a reminder, and this is factual. Otto cycle (4 cycle, throttled, with spark plugs) engines' efficiency is best at WOT for any specific RPM. A little at odds with some positions here

 

[QC]

Re: How long at WOT?

Sooo... what?? Let's not have a healthy discussion to flesh out some conclusions?? Am I the only one comfortable with this thread, even if it's not 100% based on statistically valid studies?

I love this thread. I have an issue with some of the speculation. Ultimately without data we are debating opinions. Always frustrating. Doesn't mean we can't keep frustrating each other. That's what we do best, Phil . . .

 

[bruceb58]

Re: How long at WOT?

Accordingly, you must claim a 2-stroke engine can never experience a running lean condition???

Fuel injection system? Normal cylinder operating temperature?

 

[QC]

Re: How long at WOT?

Yes, if its a closed loop fuel injection system. Otherwise, fuel is delivered as a function of the amount of air.

Both closed loop and "open" engines determine fuel delivery based on air . . .

 

[Philster]

Re: How long at WOT?

We were discussing carbed, 2-strokers, Bruce.

 

[bruceb58]

Re: How long at WOT?

Convince a renter of a 172 about that, lol. 2450rpms is still less than 2500 redline.

True. I was always conservative when I flew so I always followed the guidlines my instructors taught me.

 

[QC]

Re: How long at WOT?

QC, Phil and Bruce should not be allowed to post before counting to 5700 cc's.

 

[bruceb58]

Re: How long at WOT?

We were discussing carbed, 2-strokers, Bruce.

We started with 4 strokes(OP) and then somehow switched to 2 strokes. I couldn't keep track.

 

[bruceb58]

Re: How long at WOT?

Both closed loop and "open" engines determine fuel delivery based on air . . .

Agreed. I was saying that a closed loop system can make changes based other than just air.

 

[Philster]

Re: How long at WOT?

I love this thread. I have an issue with some of the speculation. Ultimately without data we are debating opinions. Always frustrating. Doesn't mean we can't keep frustrating each other. That's what we do best, Phil . . .

Well, you'd win hands down, QC.

There are some intelligent conclusions you can make. I am not so sure of running at WOT as an issue at all, because it's usually lower than the kablooey point (where an engine might go kablooey).

If the fuel/air and timing hang in there, and the engine's oil and overall cooling system are making out fine, then there is more load, but we'll need a metallurgist to tell us how the metals get softer and more prone to wear when under more load/stress... or not.

 

[Philster]

Re: How long at WOT?

Just a reminder, and this is factual. Otto cycle (4 cycle, throttled, with spark plugs) engines' efficiency is best at WOT for any specific RPM. A little at odds with some positions here

Well, only if it doesn't have to push an object through air. Or are we going to hear some distinction between efficiency and economy (MPG, etc)?

 

[QC]

Re: How long at WOT?

Aerodynamics have nothing to do with that statement. I didn't say Marine application or Automotive. The real world gets in the way of all of this stuff, but . . . Otto cycle engines are most efficient at WOT. Not WOT RPM as we use it, WOT.

Here's a clue for you, diesels are always at "WOT" . . . cause they ain't got no stinkin' throttle.

 

[Philster]

Re: How long at WOT?

I'm applying everything to engines in vehicles here and how they are used by people.

 

[Philster]

Re: How long at WOT?

Aerodynamics have nothing to do with that statement. I didn't say Marine application or Automotive. The real world gets in the way of all of this stuff, but . . . Otto cycle engines are most efficient at WOT. Not WOT RPM as we use it, WOT.

Here's a clue for you, diesels are always at "WOT" . . . cause they ain't got no stinkin' throttle.

It's also 2012 and throttles are now being incorporated to control emissions.

 

[QC]

Re: How long at WOT?

OK then if the vehicle is a boat, assuming a planing hull and efficiency is the goal, then just onto an efficient plane is the best, no matter what the RPM is.

In a wheeled vehicle it is 58 - 62 MPH and smallest engine, highest gear = most wide open throttle.

 

[QC]

Re: How long at WOT?

It's also 2012 and throttles are now being incorporated to control emissions.

For EGR control