You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Export thread
Run at Full Throttle?
#1
T
TJohnD
T
TJohnD
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?
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?
#2
7394
7394
Yes full throttle for air cooling of the engine, but also if you have hydro trans, they need the revs to run proper with the fluids.
#3
M
MParr
M
MParr
When the engine manual say run at full throttle, there are reasons for that. Engine cooling is one reason. Maximum rated horsepower being reached at full throttle is the other.
#4
Tiger Small Engine
Period.
Do some additional research and reading as to why if you are interested. Older men are notorious for running equipment at say 3/4 throttle.
Tiger Small Engine
Wide open throttle.When the engine manual say run at full throttle, there are reasons for that. Engine cooling is one reason. Maximum rated horsepower being reached at full throttle is the other.
Period.
Do some additional research and reading as to why if you are interested. Older men are notorious for running equipment at say 3/4 throttle.
#5
M
MParr
M
MParr
This doesn’t apply to me. I always run at full throttle. My Gravely was delivered running at 3,300 rpm at no load. I adjusted it to run at 3,600 rpm with no load.Wide open throttle.
Period.
Do some additional research and reading as to why if you are interested. Older men are notorious for running equipment at say 3/4 throttle.
#6
StarTech
StarTech
And we all do a cool down of the hydros. Personally I replace to many plastic fans especially on the Hustler Raptors. I got to where I just stock them and the drive belt they break.
Running them at lower speed just allow the blade to heat up, curl up and set, continue to do this each time until they get into belt path.
Running them at lower speed just allow the blade to heat up, curl up and set, continue to do this each time until they get into belt path.
#7
B
bullet bob
B
bullet bob
Hmmmm, first I've heard of this. How do you do this?And we all do a cool down of the hydros. Personally I replace to many plastic fans especially on the Hustler Raptors. I got to where I just stock them and the drive belt they break.
Running them at lower speed just allow the blade to heat up, curl up and set, continue to do this each time until they get into belt path.
#8
E
etbrown4
E
etbrown4
At full throttle the engine is not wide open because for the last 75 years all modern engines have used governors. A governed engine is running 500-800 rpm below what would be wide open. You can relax, and don't give a thought to plastic fans.
#9
StarTech
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.
StarTech
Air pressure and plastic softening on the side next the hydros so it stretches.Hmmmm, first I've heard of this. How do you do this?
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.
#10
thesilentone
thesilentone
We don't always run full throttle when mulching in damp conditions. As long as the cut is good, we run as slower engine speed as possible, we find the deck clears much better than flat out.
#11
T
toolboxhero
T
toolboxhero
Running full throttle gives you the proper bade tip speed so the mower will cut at its best. That's one of the reasons push mowers no longer have a throttle - too many people complained that the mower wouldn't cut well. It was because the mower was too loud at full rpm so they would throttle the engine down to reduce the noise and then complain the mower didn't cut well.
#12
StarTech
StarTech
Personally I think it was a cost cutting by the manufactures as consumers just demanding lower cost equipment. There was one push mower engine setup by Briggs that would auto idle and then power up when it ran into a load. A very picky engine for its governor spring had to be the correct one or the engine would overheat.
#13
P
peejo50
P
peejo50
I like all the input about throttle position and made it made me wonder about non-hydro tractors. I have some older equipment that have Kohler K-series engines. Full throttle in 3rd gear is sometimes too fast and in 2nd gear it's too slow, so I use the throttle to adjust my speed. I'm not always using these tractors to mow but for other chores. Bad idea?
#14
M
Mattmotors
M
Mattmotors
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.
#15
B
barny57
B
barny57
That’s me, maybe lucky but never had a problem one of my J D is 41 years oldWide open throttle.
Period.
Do some additional research and reading as to why if you are interested. Older men are notorious for running equipment at say 3/4 throttle.
#16
L
lowmow
L
lowmow
Air flow is not linear with speed.Double the speed,and you cube the air flow,so higher speed gives a much higher air flow than low speed,and the engine will run cooler,even though the engine is producing more heat,overall,the engine and oil are cooler.
The old air cooled beetles could run from coast to coast in 2nd gear,pedal to the metal and not overheat,but don't lug the engine at low speed,same with the old Porches.
Most diesels are also designed to run wide open throttle also.
Lugging a diesel is a death sentence for longevity.Truckers know this.
I am an old timer,and I have had a 16HP Briggs single cylinder MTD garden tractor since 1979.It was sold by JC Penny as a Model 1853,but made by MTD before they had their own brand.
Hydrostatic drive,hydraulic lift(Converted to 3 point cat 0 hitch by me.Replaced the front axle spindles with boat trailer axles and Bearing Buddies,no other problems since,and I hardly ever ran it at full throttle.Must have been a different fan design back then.
Some progress isn't progressive.
The old air cooled beetles could run from coast to coast in 2nd gear,pedal to the metal and not overheat,but don't lug the engine at low speed,same with the old Porches.
Most diesels are also designed to run wide open throttle also.
Lugging a diesel is a death sentence for longevity.Truckers know this.
I am an old timer,and I have had a 16HP Briggs single cylinder MTD garden tractor since 1979.It was sold by JC Penny as a Model 1853,but made by MTD before they had their own brand.
Hydrostatic drive,hydraulic lift(Converted to 3 point cat 0 hitch by me.Replaced the front axle spindles with boat trailer axles and Bearing Buddies,no other problems since,and I hardly ever ran it at full throttle.Must have been a different fan design back then.
Some progress isn't progressive.
#17
thesilentone
thesilentone
On many new pieces of equipment the ' Certificate of Conformity' can dictate engine speed. irrespective of performance.
If the equipment exceeds any of the following: Noise, Emissions, HAV (hand are vibration) or WBV (whole body vibration) the easiest solution is to reduce engine speed to a level where it does conform.
That is why, after purchasing a new piece of kit you find you need to set the engine revs higher, or remove a throttle stop that has been added to gain the performance level that is satisfactory.
If the equipment exceeds any of the following: Noise, Emissions, HAV (hand are vibration) or WBV (whole body vibration) the easiest solution is to reduce engine speed to a level where it does conform.
That is why, after purchasing a new piece of kit you find you need to set the engine revs higher, or remove a throttle stop that has been added to gain the performance level that is satisfactory.
#18
L
Laabk2
L
Laabk2
Another reason to run at full throttle is that the alternator is designed to produce the required voltage to recharge and maintain the battery at that RPM. I have replaced many batteries because the mower wouldn't start after a month or two of mowing with a new battery installed. I got it running and then asked them to try it out, they hopped on, cranked it up and took off mowing at 1/2 to 3/4 throttle. I explained the whole RPM to charging concept. I got a deer in the headlight look and they said ok. Couple of months later, battery replaced again. Some people just refuse to listen and enjoy spending money.
#19
D
DinosaurMike
D
DinosaurMike
From your original post: "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." Period. End of answer. That is all you need to know. <You should apply for a job with Cub Cadet (MTD?) if you think you know more than the engineers. LOL>
#20
grumpyunk
grumpyunk
If you run at slower rpms, the cooling effect of oil being splashed everywhere is reduced. You may starve parts of lubrication they would get at full operating rpm. Additionally, the cooling of the flywheel blower is also reduced at lower rpm. Does lower rpm produce less heat? Probably. Does the blower produce less airflow? Definitely. The higher rpms are designed into the engines, so do what you will, but there is a detent in the throttle control that was also designed into the machine.
They were not designed to be 'babied' which a lot of us like to do. I was 'babying' my Kohler, running @3/4 throttle to be 'nice' to my engine. Wrong. It likely didn't hurt it permanently, but continued running at lower rpms and lowering for the run back to the shed are not really good ideas, and are likely not recommended by the manufacturer. As a matter of fact, some recommend to not lower the engine control/rpms prior to killing the ignition. Suspect it has to do with back fire/back fire out the exhaust.
Have fun.
tom
They were not designed to be 'babied' which a lot of us like to do. I was 'babying' my Kohler, running @3/4 throttle to be 'nice' to my engine. Wrong. It likely didn't hurt it permanently, but continued running at lower rpms and lowering for the run back to the shed are not really good ideas, and are likely not recommended by the manufacturer. As a matter of fact, some recommend to not lower the engine control/rpms prior to killing the ignition. Suspect it has to do with back fire/back fire out the exhaust.
Have fun.
tom
#21
R
RevB
R
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.
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.
#22
T
tadawson
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).
T
tadawson
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.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.
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).
#23
7394
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 ..
#24
T
tadawson
T
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 . . .
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 . . .
#25
R
RevB
Don't know much about engines, do ya.
But of course, you know way more than these guys......
R
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.
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).
#26
B
bullet bob
B
bullet bob
But but but, is there a way to actually cool down the hydros before just shutting 'er down?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.
#27
R
RevB
R
RevB
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....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.
#28
R
RevB
R
RevB
Think of them as turbos.....two minutes at idle, no load. Marginal help but can't hurt.....But but but, is there a way to actually cool down the hydros before just shutting 'er down?
#29
M
MParr
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.
M
MParr
Why would you want to cool them down?But but but, is there a way to actually cool down the hydros before just shutting 'er 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.
#30
T
Tried_it
T
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?
#31
T
Tried_it
T
Tried_it
I didn't need the manual to figure out my Scag 61" Turf Tiger w/same engine had to be run at full throttle. Otherwise it failed to keep all 3 blades spinning fast enough to cut, plus hydraulic pump required RPM, and it cooled better.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?
#32
T
tadawson
again, due to air resistance, etc. you dom't get best fuel economy at higher speed . . . the physics says so.
Then there is the minor little detail that purported "efficiency" is largely irrelevant in power equipment, since you can't seriously be saying that a machine that can do a job at say, 2400 RPM and part throttle will burn more fuel than running wide open, at who knows what speed? (The typical 3600 still isn't wide open, it's governed . . .true "wide open" would likely overrev and blow it . . .) So, it's really comes down to part throttle vs. part throttle, and I find it comical at best to claim the superiority of one over the other . . .
I stand by my statement (and published docs) that non adjustable throttles are in the same category as limiter caps . . . EPA mandates that have *ZERO* to do with use cases! And, why do folks always seem to duck the point that EFI engines, with thier far more accurate metering and ability to meet emissions over a far wider range of settings, don't seem to have this restriction, rather tending to have full throttle control. If the argument thr full speeders are making is true, induction system type should benirrelevant, hut it appears to not be the case either . . .
T
tadawson
I know I am a licensed pilot, and can read both Continental (Lycoming is the same) and Cessna's docs, and with both, you are told to generally avoid full RPM/throttle other than takeoff . . . and I trust them a lot more than these derps . . . (who I also note are from the eperimemtal world, where some things are viewed differently . . . I'm talking amout commercially produced aircraft, whether it be jet, turboprop, or piston . . . and even if the claims are true for the engine alone, youmdom't fly just the engine, you fly the entire aircraft where,Don't know much about engines, do ya.
But of course, you know way more than these guys......
again, due to air resistance, etc. you dom't get best fuel economy at higher speed . . . the physics says so.
Then there is the minor little detail that purported "efficiency" is largely irrelevant in power equipment, since you can't seriously be saying that a machine that can do a job at say, 2400 RPM and part throttle will burn more fuel than running wide open, at who knows what speed? (The typical 3600 still isn't wide open, it's governed . . .true "wide open" would likely overrev and blow it . . .) So, it's really comes down to part throttle vs. part throttle, and I find it comical at best to claim the superiority of one over the other . . .
I stand by my statement (and published docs) that non adjustable throttles are in the same category as limiter caps . . . EPA mandates that have *ZERO* to do with use cases! And, why do folks always seem to duck the point that EFI engines, with thier far more accurate metering and ability to meet emissions over a far wider range of settings, don't seem to have this restriction, rather tending to have full throttle control. If the argument thr full speeders are making is true, induction system type should benirrelevant, hut it appears to not be the case either . . .
#33
H
heyinway
H
heyinway
Do as the operator manual says. Period, end of conversation.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?
#34
R
RevB
R
RevB
So...you must be that guy that just stays below 3000 feet MSL, never venturing above to watch the ambient pressure decrease requiring more throttle to maintain a climb or cruise at 8 to 12k feet until you're at full throttle anyway. I also find it comical that you either can't read and learn or refuse to do either.I know I am a licensed pilot, and can read both Continental (Lycoming is the same) and Cessna's docs, and with both, you are told to generally avoid full RPM/throttle other than takeoff . . . and I trust them a lot more than these derps . . . (who I also note are from the eperimemtal world, where some things are viewed differently . . . I'm talking amout commercially produced aircraft, whether it be jet, turboprop, or piston . . . and even if the claims are true for the engine alone, youmdom't fly just the engine, you fly the entire aircraft where,
again, due to air resistance, etc. you dom't get best fuel economy at higher speed . . . the physics says so.
Then there is the minor little detail that purported "efficiency" is largely irrelevant in power equipment, since you can't seriously be saying that a machine that can do a job at say, 2400 RPM and part throttle will burn more fuel than running wide open, at who knows what speed? (The typical 3600 still isn't wide open, it's governed . . .true "wide open" would likely overrev and blow it . . .) So, it's really comes down to part throttle vs. part throttle, and I find it comical at best to claim the superiority of one over the other . . .
I stand by my statement (and published docs) that non adjustable throttles are in the same category as limiter caps . . . EPA mandates that have *ZERO* to do with use cases! And, why do folks always seem to duck the point that EFI engines, with thier far more accurate metering and ability to meet emissions over a far wider range of settings, don't seem to have this restriction, rather tending to have full throttle control. If the argument thr full speeders are making is true, induction system type should benirrelevant, hut it appears to not be the case either . . .
#35
Tiger Small Engine
Most of the push and self-propelled mowers I check RPMs on, are running from 2800-3000 RPM. I bump it up to about 3150.
Tiger Small Engine
We went from outdoor power equipment, to airplane engines.So...you must be that guy that just stays below 3000 feet MSL, never venturing above to watch the ambient pressure decrease requiring more throttle to maintain a climb or cruise at 8 to 12k feet until you're at full throttle anyway. I also find it comical that you either can't read and learn or refuse to do either.
Most of the push and self-propelled mowers I check RPMs on, are running from 2800-3000 RPM. I bump it up to about 3150.
#36
Scrubcadet10
Scrubcadet10
This question was practically answered on the 1st page. It's served its purpose. Now we're on to airplanes....on a lawnmower forum.