Run at Full Throttle?

[RevB]

Piston aircraft engines with variable pitch props are almost always run full throttle unless the pilot doesn't understand altitude may be your friend or is just potting around with no mission or destination in mind. Unobstructed intake is always more efficient than one partially blocked off by a throttle plate....

Not really applicable to terrestrial engines unless stationary or operating in a constant loading condition sufficient to keep the engine below max RPM with wide open throttle.

 

[tadawson]

Piston aircraft engines with variable pitch props are almost always run full throttle unless the pilot doesn't understand altitude may be your friend or is just potting around with no mission or destination in mind. Unobstructed intake is always more efficient than one partially blocked off by a throttle plate....

Not really applicable to terrestrial engines unless stationary or operating in a constant loading condition sufficient to keep the engine below max RPM with wide open throttle.

Not sure where you get this, but as a private pilot that has been flying "piston engines vith variable pitch props" that is false! The *ONLY* time you run full throttle and high rpm is takeoff! As as you get to cruise, you set a prop rpm and manifold pressure for cruise, which is well below full anything.

On power equipment, you used to get a real throttle on everything, and nothing broke. With the increasingly strict emissions rules and inherent crudeness of carbs, and lot of the "full throttle only" nonsense comes from that being the only setting that meets emissions (and also why it seems that EFI engines still have variable throttles and carbs do not - EFI is far more precise and capable of meeting the regs).

 

[7394]

Speaking of lawn mowers, like this started as. The Hydros need to be air cooled by fan as well. Thus the WFO as per the OM ..

 

[tadawson]

Ironically, though, cooling efficiency likely gets *worse* at higher throttle settings. Friction and combustion heat rise faster than the throttle setting (friction is square of speed), and cooling duct air resistance gets worse, as does fan efficiency, so cooling airflow gets disproportionally *lower* based on RPM as speed increases, and really race plants if the tips of the fan cavitate and stall . . .

And you *can't* run full power at lower speeds duento 14:1 fuel/air, and reduced airflow at lower speeds limiting fuel intake, so don't bother with that nonsense argument . . .

 

[RevB]

Not sure where you get this, but as a private pilot that has been flying "piston engines vith variable pitch props" that is false! The *ONLY* time you run full throttle and high rpm is takeoff! As as you get to cruise, you set a prop rpm and manifold pressure for cruise, which is well below full anything.

On power equipment, you used to get a real throttle on everything, and nothing broke. With the increasingly strict emissions rules and inherent crudeness of carbs, and lot of the "full throttle only" nonsense comes from that being the only setting that meets emissions (and also why it seems that EFI engines still have variable throttles and carbs do not - EFI is far more precise and capable of meeting the regs)

Don't know much about engines, do ya.

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2012-10_flying-efficiently.pdf

But of course, you know way more than these guys......

Not sure where you get this, but as a private pilot that has been flying "piston engines vith variable pitch props" that is false! The *ONLY* time you run full throttle and high rpm is takeoff! As as you get to cruise, you set a prop rpm and manifold pressure for cruise, which is well below full anything.

On power equipment, you used to get a real throttle on everything, and nothing broke. With the increasingly strict emissions rules and inherent crudeness of carbs, and lot of the "full throttle only" nonsense comes from that being the only setting that meets emissions (and also why it seems that EFI engines still have variable throttles and carbs do not - EFI is far more precise and capable of meeting the regs).

 

[bullet bob]

Air pressure and plastic softening on the side next the hydros so it stretches.

And apparently you have never work on Hustler Raptors. I am constantly replacing fans on them when drive belt are broken along that little 2 inch idler pulley that bearings are failing in.

And I came across a new problem to compound the problem transaxle mounts breaking. Loose screws was bad enough now the brackets are breaking too. Hustler is selling a beefed up repair kit but should be doing a recall instead. Of course these are out of warranty unit so they don't care.

But but but, is there a way to actually cool down the hydros before just shutting 'er down?

 

[RevB]

Being older, I prefer an engine that is quiet. It would really be nice if a manufacture could make a quiet engine. I took the ear plug route. Full throttle. Cool engine.

Not to dispute your assertion about cool, esp air cooled cool, but now I'd like to instrument one for cyl head and EGT temp and see what the numbers really are. I've got a 4 cyl Westach analog EGT kit that never got used but the thought of drilling a hole in the exhaust pipe just for curiosity kinda bugs me....

 

[RevB]

But but but, is there a way to actually cool down the hydros before just shutting 'er down?

Think of them as turbos.....two minutes at idle, no load. Marginal help but can't hurt.....

 

[MParr]

But but but, is there a way to actually cool down the hydros before just shutting 'er down?

Why would you want to cool them down?
The most important things are to keep the fans and hydros free of debris, maintain the proper fluid level, change the fluid and filters at recommended times.
Blow your mower off with compressed air or a leaf blower, after each mowing. Pay extra attention to the engine and hydros.

 

[Tried_it]

I bought a new Cub Cadet XT2 Enduro Series GX54D lawn tractor with the 25-hp Kohler engine.

According to the owner's manual, the engine should be run at the fast setting of the throttle, a/k/a full throttle, wide open.

It goes against the grain with me to run an engine wide open if I don't need that much power for the job at hand.

Why is it recommended to run at full throttle? I know the engine is air cooled, and there is a fan atop the transaxle. Is full throttle recommended for engine and/or transaxle cooling?

I'm not much of a small engine mechanic. I'm using this thing to mow and to pull a 50-inch wide, wheel-powered sweeper to pick up pine straw.

It was expensive, and I want to take good care of it. If full throttle is the way to go, then so be it. I just don't understand why?