# Running air-cooled gas engines at full throttle.



## sscotsman (Dec 8, 2010)

Hey everyone..
this came about from another thread, but the thread really has nothing to do with this specific topic, so I thought it deserved its own stand-alone thread.
Here is some information from actual manufacturers concerning the question of running at full throttle, when using various machines.

*Direct from Toro*:


> Why don't I have a throttle control on my mower?
> 
> Most Walk Power Mowers we offer *do not have a throttle control.* A throttle control would allow you to vary the engine speed from idle all the way up to full speed. We have found, *not having it actually increases engine life and product performance. *
> 
> ...


Source:
https://www.toro.com/en/customer-support/faqs/residential-faqs



*Also direct from Toro:*


> What are the benefits of running your riding mower on full throttle?
> 
> *Cleaner cut* on the grass
> *More power*, less likely to bog down
> ...


Source:
https://www.toro.com/en/customer-support/faqs/residential-faqs






*From Ferris:*


> “ALWAYS operate at full throttle when mowing”


source:
http://www.specsserver.com/CACHE/frdaneyeuxwx.pdf



*From Simplicity:*


> Throttle Control
> This controls the engine speed.
> Move the throttle control to the FAST position to increase engine
> speed and SLOW position to decrease engine
> speed. Always operate at full throttle.


source:
https://www.simplicitymfg.com/na/en...llisting.downloadmanual.1757858_B_LO.pdf.html



*From Ariens* 
Ten Ariens Manuals, snowblowers and mowers, variations on "run at full throttle"
https://tinyurl.com/yd5rrg36




*From Honda:*


> Mow at full throttle with the transmission in the desired mowing speed for the best cut quality and performance. Mowing in a medium or low throttle setting will affect the performance and cut quality.
> 
> 2. Move the throttle lever to the FAST position. NOTE: For best cut quality, and performance always use full throttle. Use the shift lever to select the desired mowing speed range.


source: http://cdn.powerequipment.honda.com/pe/pdf/manuals/31763901.pdf




*From Bobcat:*


> For normal cutting the throttle should be set at the full open position.
> Using the machine at less than full throttle in heavy conditions will cause the engine to labor and result in excessive wear.


source: https://tinyurl.com/y8e484qy


Scot


----------



## bigredmf (Jan 16, 2018)

Thank you good info that many will ignore.

Ref


Sent from my iPhone using Tapatalk


----------



## sscotsman (Dec 8, 2010)

Since this thread has the potential to drift into conspiracy-theory land, if you wish to dispute any of the manufacturer-provided info in the first post..thats fine..but the contrary info must *also* be from air-cooled engine manufacturers, or OPE manufacturers. Personal opinion is irrelevant, on both sides.

Thanks,
Scot


Quote from post 29 in this thread:


sscotsman said:


> I wish I had thought to instantly create a "post #2" in this thread, just for the excerpts from manufacturer manuals and documentation that support the opposing viewpoint..
> but I didnt think of it until just now.. :frown:
> 
> So I'll turn post #3 into the post for that..I'll add quotes there..
> ...



---------------------------------------------------------------------------------------------------------


Engine or OPE manufacturer statements, from manufacturer manuals or other documentation, that say it is acceptable to run an engine for extended periods, in use under load, at less than full throttle:

--------------------------------------------------------------------------------------------------------


*From Ariens:*
In reference to a snowblower with an EFI engine:


> OPERATE UNIT
> 1. Rotate discharge chute and move deflector to desired positions.
> 2. Select desired speed.
> 3. Engage attachment clutch.
> ...


source: http://apache.ariens.com/manuals/05136000C_ENG.pdf


tadawson said:


> Note that the "Efficiency" level of the throttle is at about 2/3 of maximum . . . (Image on page 9 of that document - can't cut and paste that . . . ). Note also that the only recommendation is stated to be due to performance - absolutely no statement about engine life.



*From Honda and Briggs & Stratton:*
Also there is documentation that in some counties generators need to be run at exactly 3,000 RPM, this is due to the requirements for generating electricity:



DriverRider said:


> I have made available to the Forum that Honda and B&S sell generators outside of North America to the rest of the world which run at 3000RPM to supply the 50Hz voltage these Countries use.
> https://www.honda.co.uk/industrial/products/generators/specialist-open-frame/specifications.html#
> https://www.briggsandstratton.com/e...nerators/elite-8500ea-portable-generator.html





94EG8 said:


> As far as generators being run at 3000RPM in other countries, they have to be. It has to do with that being the RPM needed to get 50Hz




.
.
.
..


----------



## tdipaul (Jul 11, 2015)

.

lets settle this once and for all...

Can somebody with an infrared thermometer gun point it at the exhaust of their warmed up blower 

while at full throttle for 30 secs, 

then at half throttle for another 30 secs

and see which way the temps go

bonus points for videotaping it

if i had such a gun it'd already be on youtube

.


----------



## tadawson (Jan 3, 2018)

tdipaul said:


> .
> 
> lets settle this once and for all...
> 
> ...



I'd be much more interested in a thermocouple on the head than the exhaust. The exhaust really does not give a view to internal temperature.


----------



## sscotsman (Dec 8, 2010)

tadawson,
I deleted your first post..
you are free to post your link, using the rules outlined in post #3 of this thread.
No rude snotty condescending remarks are necessary.

thanks,
Scot


----------



## tdipaul (Jul 11, 2015)

tadawson said:


> I'd be much more interested in a thermocouple on the head than the exhaust. The exhaust really does not give a view to internal temperature.


Agreed, but who is going to rig that up?

How about the gun pointed at one of the head bolts near the exhaust port?

.


----------



## tadawson (Jan 3, 2018)

Just trying to figure out why the easily verifiable counterpoint that I propose is somehow not valid, despite the fact that the physics invoved *IS*. I think that is a reasonable request . . . 



Ariens manual contradicting this, for the EFI engine: 



http://apache.ariens.com/manuals/05136000C_ENG.pdf


----------



## sscotsman (Dec 8, 2010)

tdipaul said:


> .
> 
> lets settle this once and for all...
> 
> ...


That could be interesting data..
but its not really relevant.
We aren't talking about 30 seconds..we are talking about lifetime health of the engine. (and hydro transmissions)

If you could measure heat, of the engine, for say 15 minutes at both throttle settings, that would be more relevant data.

but! even then, it might be interesting, but its still not really relevant at all. Because the manufacturers say to use the machines at full throttle while *in use*, while actually mowing, or snowblowing, or whatever. Idling a mower in the driveway at half-throttle, even with the blades spinning, is a far different scenario than actually mowing real grass at half-throttle for an extended time. that would need to be the real test, under load while in regular use.


Scot


----------



## tdipaul (Jul 11, 2015)

I assumed 30 secs would be enough but thats just a guess


----------



## tadawson (Jan 3, 2018)

tdipaul said:


> Agreed, but who is going to rig that up?
> 
> How about the gun pointed at one of the head bolts near the exhaust port?
> 
> .



Anyone with a DVM that supports temps and a $5 thermocouple? Not much more work that using an IR gun . . .


----------



## tdipaul (Jul 11, 2015)

whats a dvm?


----------



## tadawson (Jan 3, 2018)

I think I am in agreement with sscottsman on this - long term thermal is more relevant, although that isn't a constant either, since load on a blower is changing constantly. The key would be to look at some known load cases and compare once things are settled into a steady state.


----------



## RedOctobyr (Mar 2, 2014)

sscotsman said:


> if you wish to dispute any of the manufacturer-provided info in the first post..thats fine..but the contrary info must *also* be from air-cooled engine manufacturers, or OPE manufacturers. Personal opinion is irrelevant, on both sides.


I don't disagree with the principle, anyways. But I don't think info should be limited to stuff from the manufacturers. 

If someone wanted to measure their engine temps, ideally with a full load (throttle wide open) at full-RPM, and a full load at partial-RPM, I think that would still be very educational, as an example.

(Oops, sorry, there have been a bunch of posts since I loaded this page. I'm late to the party.)


----------



## tadawson (Jan 3, 2018)

tdipaul said:


> whats a dvm?



Digital Volt Meter. A lot of them (even cheapies) have thermocouple ports, since folks in the trades often use them to measure temps.


----------



## tdipaul (Jul 11, 2015)

but the load (ie the blower processing the snow) can vary from one pass to the next. Would this affect the results?
.


----------



## tadawson (Jan 3, 2018)

tdipaul said:


> Agreed, but who is going to rig that up?
> 
> How about the gun pointed at one of the head bolts near the exhaust port?
> 
> .



Hard to get head temp with the cooling shrouds on, and hard to get cooling with them off . . . 



Thermocouple could just be pushed into the fins on the head past the plug into the fins.


----------



## sscotsman (Dec 8, 2010)

We do have a problem with such an expirement though..
Whichever way it seems to "prove", someone wont believe it..

I have said in this thread I only want manufacturer data..
And tadawson has said he doesnt believe the manufacturer data (in post 1 of this thread) because it isnt specifically from *engine* manufacturers.

So im willing to accept any manufacturer statements, tadawson only wants engine manufacturers specifically. Neither of us will likely believe an unscientific test from someone on youtube! 

Would still be interesting to see, even it probably cant be considered definitive "proof".

But for the most part, yes, we really do need to rely on what the manufacturers say, because they are the only true experts..we are not.

Scot


----------



## DriverRider (Nov 20, 2016)

sscotsman said:


> Since this thread has the potential to drift into conspiracy-theory land, if you wish to dispute any of the manufacturer-provided info in the first post..thats fine..but the contrary info must *also* be from air-cooled engine manufacturers, or OPE manufacturers. Personal opinion is irrelevant, on both sides.
> Thanks,
> Scot



Your argument is with Honda as I stated in the other thread. Honda is running their engines and generators at 3000RPM in the rest of the world with no reported adverse effect, so why is Honda wrong and where is your proof of reduced engine service life?
Generator service is likely the most severe duty an engine will see.


EDIT ONE OF MY POSTS HAS BEEN DELETED ALREADY.


----------



## sscotsman (Dec 8, 2010)

DriverRider said:


> Your argument is with Honda as I stated in the other thread. Honda is running their engines and generators at 3000RPM in the rest of the world with no reported adverse effect, so why is Honda wrong and where is your proof of reduced engine service life?
> Generator service is likely the most severe duty an engine will see.


I have no idea what you are talking about, in relation to Honda.
As I said, feel free to post direct quotes from manufacturer documents, and provide a link to the original document, like in post #1.

Scot


----------



## sscotsman (Dec 8, 2010)

DriverRider said:


> EDIT ONE OF MY POSTS HAS BEEN DELETED ALREADY.



Yes, i deleted it, and you noticed it before I had time to comment on it! 
thats fine..

As I said in post #3, we arent going to have random speculation and wild tangents here..
As I also said, feel free to post direct quotes from manufacturer documents, and provide a link to the original document, like in post #1.

Scot


----------



## DriverRider (Nov 20, 2016)

sscotsman said:


> I have no idea what you are talking about, in relation to Honda.
> As I said, feel free to post direct quotes from manufacturer documents, and provide a link to the original document, like in post #1.
> Scot



I am proving a point from this thread that you stated running an engine less than 3600 RPM is detrimental to its longevity. Manufacturers make engines for all purposes with no ill effects running less than 3600RPM which seem to be just a North American thing most likely tied to a SAE spec of 3600RPM as a standard we stupid Americans are accustomed to.


https://www.snowblowerforum.com/forum/1639977-post29.html


https://www.snowblowerforum.com/forum/1640423-post32.html


----------



## RedOctobyr (Mar 2, 2014)

tdipaul said:


> but the load (ie the blower processing the snow) can vary from one pass to the next. Would this affect the results?
> .


I'd certainly expect it could. I think you'd want to load up the engine as much as possible. Cram as much snow into the bucket as is practical  High ground speed, into deep snow. 



tadawson said:


> Hard to get head temp with the cooling shrouds on, and hard to get cooling with them off . .
> 
> Thermocouple could just be pushed into the fins on the head past the plug into the fins.


But you want to ensure the thermocouple is reading the metal temperature, more than the air passing over it. Many thermocouples don't have a lot of mass by themselves, and are often round. They'd be easily cooled by the air rushing over them, giving an inaccurate reporting of the actual metal temperature. And if the thermocouple probe is round, it's not actually making much contact with the metal. And a small movement of the probe could change its contact with the metal, changing the reading. If you could clamp the probe to a surface, that would at least make it more consistent. 

An IR gun aimed next to the spark plug, or something like that, might work. You couldn't get "live" readings, unfortunately, but it might give a better chance of reading the surface temperature accurately. 



DriverRider said:


> Your argument is with Honda as I stated in the other thread. Honda is running their engines and generators at 3000RPM in the rest of the world with no reported adverse effect, so why is Honda wrong and where is your proof of reduced engine service life?
> Generator service is likely the most severe duty an engine will see.


That's an interesting point. Does anyone know if, for instance, a given engine & generator combo is rated at less watts for 50Hz? 

Though I guess even if it was, I could think of at least 2 possible explanations: 
- the engine simply produces less power when turning more slowly
or
- possibly they had to de-rate it a little to avoid overheating the engine, when running at the lower RPM. 
So even if you did find manufacturer A showing engine B running a higher-wattage generator at 3600 RPM vs 3000, it might be difficult to draw firm conclusions.


----------



## DriverRider (Nov 20, 2016)

RedOctobyr said:


> I'd certainly expect it could. I think you'd want to load up the engine as much as possible. Cram as much snow into the bucket as is practical  High ground speed, into deep snow. .



You would not want to load it like on a dyno.:sad2: Moderate load just like most everyone runs their equipment in the real world.


----------



## DriverRider (Nov 20, 2016)

tadawson said:


> Just trying to figure out why the easily verifiable counterpoint that I propose is somehow not valid, despite the fact that the physics invoved *IS*. I think that is a reasonable request . . .
> Ariens manual contradicting this, for the EFI engine:
> http://apache.ariens.com/manuals/05136000C_ENG.pdf



A little insight, the demise of the carb and points and condenser were due to EPA regulations as the car manufactures could not meet emission standards with those devices. Points and rubbing block started to wear driving out the door and would not meet emission time service requirements of 5yr/50k? miles back then. Carburetors were notoriously dirty especially closed throttle decel where high intake manifold vacuum sucked in a rich mixture. Hence EFI.


----------



## RedOctobyr (Mar 2, 2014)

DriverRider said:


> You would not want to load it like on a dyno.
> 
> 
> 
> ...


I agree that a moderate "fixed" load is probably better. But with different RPM, matching that load "by hand", if you will, is probably difficult. Your ground speed will be changing, as well as the augers & impeller RPM. The simplest thing to do consistently might be to just load up the engine completely. Same throttle position (wide open), and you only change the RPM. Which you'd effectively do by varying the snow load.

If you do something like just use the same gear, and only vary the RPM, then the load on the engine will also change significantly. You'd be processing less snow per-second, if the only change is to slow the RPMs. And a slower impeller & auger doesn't require as much power, so at lower RPM, the engine would likely not open the throttle plate as far. Reducing the heat produced per power-cycle (not just per-second, which also depends on RPM). That seems like a less-balanced comparison.

If you're going to reduce the throttle load on the engine at the same time that you slow the RPMs down, then there's no need to use a snowblower (which can fully-load the engine at a range of engine speeds, depending on your gear selection, and the snow conditions).

You could keep things a lot simpler, and more consistent, by just running a mower at different RPMs (just sitting in-place). At lower RPM, there is less drag on the blade, so less power is needed, and the throttle plate doesn't have to open as far. It's a lot easier to get a mower to a steady-state, with it running in the driveway for 15-20 minutes, than it is to get to a steady-state condition with a blower, where you have to stop and turn around, etc.


----------



## tdipaul (Jul 11, 2015)

I emailed this man to see if he knows. He's done a lot of interesting tests

https://www.youtube.com/channel/UC2rzsm1Qi6N1X-wuOg_p0Ng


----------



## scrappy (Dec 7, 2014)

I just like to idle it down, and hear it idle. 



Something about the sound that I like.


----------



## sscotsman (Dec 8, 2010)

I wish I had thought to instantly create a "post #2" in this thread, just for the excerpts from manufacturer manuals and documentation that support the opposing viewpoint..
but I didnt think of it until just now.. 

So I'll turn post #3 into the post for that..I'll add quotes there..
and i'll also update post #1 with new ones for "run full throttle" if/when they are found.

So if you have any direct quotes from engine or OPE manufacturers that say its fine to run for extended times at _less_ than full throttle,
please write them up! put them in a new reply, then I'll put them in post #3 so they are all on the front page of this thread..
my goal is to make this thread "one stop shopping" for all the pro and con data, so people can easily find it and decide for themselves.

Like post #1, Please provide a direct quote from the document, and also a link to the document itself.

thanks,
Scot


----------



## DriverRider (Nov 20, 2016)

RedOctobyr said:


> I'd certainly expect it could. I think you'd want to load up the engine as much as possible. Cram as much snow into the bucket as is practical  High ground speed, into deep snow.
> But you want to ensure the thermocouple is reading the metal temperature, more than the air passing over it. Many thermocouples don't have a lot of mass by themselves, and are often round. They'd be easily cooled by the air rushing over them, giving an inaccurate reporting of the actual metal temperature. And if the thermocouple probe is round, it's not actually making much contact with the metal. And a small movement of the probe could change its contact with the metal, changing the reading. If you could clamp the probe to a surface, that would at least make it more consistent.
> An IR gun aimed next to the spark plug, or something like that, might work. You couldn't get "live" readings, unfortunately, but it might give a better chance of reading the surface temperature accurately.
> That's an interesting point. Does anyone know if, for instance, a given engine & generator combo is rated at less watts for 50Hz?
> ...



Where in the world are you coming up with this overheating theory of a snowblower operating at 32 degrees F and under? Or overheating of an air cooled small engine at all which should be happening in Saudi Arabia and no reports so far. Here are the possible engine/ pole numbers. Everywhere except North America your typical generator with small air cooled engine is running 3000RPM. Honda included, this is no special engine same one installed on their snowblowers. Come to think of it have you ever seen an over heated failure of an engine not due to chafe? 



https://www.theautomationstore.com/poles-rpm/


----------



## rslifkin (Mar 5, 2018)

There's a few important things to figure out on this issue: even if the engines run hotter at lower RPM under load, do they run hot enough (cylinder head temp, cylinder wall temps, oil temps) for it to be of any concern? And is it possible that some of the "run at full RPM all the time" recommendations come from other factors and not cooling? 

Possible other reasons manufacturers suggest running at full RPM are:


Fixed ignition timing, so if timing is reasonably optimized for normal operating RPM it could be too much under heavy load at lower RPM and cause damage due to detonation. Interestingly, if timing is more conservative, it would be less than optimal at full RPM which could lead to elevated exhaust temps and cylinder head temps at full RPM compared to what might be seen at lower RPM or with more advanced timing.
Poor carb performance at lower RPM, especially when not just idling (could be emissions concerns, carbon buildup)
Poor alternator output for engines with an alternator coil (leading to poor performance of lights, hand warmers, etc.)
Oiling concerns: bearings would likely see plenty of lube even at lower RPM, but oil splash to cylinder walls would be reduced, so there might be concern about putting the engine under too much load (cylinder pressure) with less oil being thrown up at the cylinder walls, wrist pins, etc.


----------



## sscotsman (Dec 8, 2010)

Driver,
Go easy on the speculation..
I wont delete your post outright, but i will if you continue to make up things like:



> Or overheating of an air cooled small engine at all which should be happening in Saudi Arabia and no reports so far.


You are not fit to declare where in the world an engine will overheat, and where it wont.  
And, do you personally get every report of every engine that overheats? No? If not, you are merely guessing, nothing more. Just because you personally havent heard of something happening, doesnt mean it has never happened.

I also havent specifically heard, myself, of specific engines overheating from low throttle. But what I have personally heard or not heard is also 100% irrelevant. The manufacturers say it *can* happen, which is good enough for me. I believe them, not you. 

So lets keep the personal speculation and guessework to a minimum please. I will delete more posts if they are short on facts. 

Scot


----------



## tadawson (Jan 3, 2018)

sscotsman said:


> We do have a problem with such an expirement though..
> Whichever way it seems to "prove", someone wont believe it..
> 
> I have said in this thread I only want manufacturer data..
> ...


No, I said I won't accept statements without backing justification and/or engineering data . . . and that can be from any knowledgeable source who comprehends the physics and engineering (examples of which I tried to offer). A statement without backing data is just noise, and could be for any number of reasons . . . and who knows who wrote the users manuals . . . could be engineering, marketing, legal, or ? ? ?


----------



## tadawson (Jan 3, 2018)

RedOctobyr said:


> I'd certainly expect it could. I think you'd want to load up the engine as much as possible. Cram as much snow into the bucket as is practical  High ground speed, into deep snow.
> 
> 
> 
> ...


Two words: thermal adhesive . . . . Not quite as easy as just measuring head temp, but more consistent. Could always put the probe in the oil as well to get a good overall temp.


----------



## Toro-8-2-4 (Dec 28, 2013)

I have read similar info in Briggs and Stratton manuals.


On an ohc engine could you not just point your IR thermometer near where the spark plug threads in? I am not that curious to try but for those who are.


----------



## drmerdp (Feb 9, 2014)

This is kind of a non discussion. Work at full throttle, reduced throttle under no load. 

Engines without throttle controls SCREAMS cost savings, with the perk of “protecting consumers” who would otherwise foolishly operate their equipment in a detrimental way. 

Conspiracy or truth? Yes 

If one was to test for engine temps, I like the idea of a thermal couple best. All of my meters came with one. More accurate and consistent then an IR gun. Thermal cameras are pretty sweet too.


----------



## DriverRider (Nov 20, 2016)

I am fit enough to observe that the world's No. 1 and No. 2 small air cooled engine manufacturers on which all others designs (clones) are based see it appropriate to run their engines at 3000RPM in generator service outside of North America and yes this would presumably include Saudi Arabia with no reported life expectancy issues. These are the same engines found in your snowblower.:smile2:
50 yrs. ago engine and equipment owners manuals contained a plethora of technical information. Not so today as I suspect lawyers and PR people write them in the climate of American litigation and the dumbing down mentality. . The American operators manual takes the path of least resistance and is contradicted by what the engine manufacturer deems appropriate in other applications. Outsourcing would also be a factor where OPE manufacturers simply specify components

As an example my Honda motorcycle factory service manual contains painfully obvious inaccuracies of the Hitachi built alternator.(Which I rebuild)

If anyone has evidence that running an engine at 3000RPM is detrimental please post here or inform Honda and Briggs&Stratton as to the error of their ways.


https://www.honda.co.uk/industrial/products/generators/specialist-open-frame/specifications.html#
https://www.briggsandstratton.com/e...nerators/elite-8500ea-portable-generator.html


----------



## KennyW in CT (Feb 24, 2015)

My .02. After 20 years with air cooled small engines, I've seen many people that run at low rpm to "conserve fuel". The issues I see are clogged grass screens and engine block fins that no matter how fast you run will not sufficiently cool the engine and will break down the oil and ruin the engine. In my opinion keeping the path of air flow clean is way more important than running the engine fast or slow. Even at idle an engine with clear passageways blows a lot of air over the engine. The only caveat, when mowing in the summer under the load of thick wet grass with dull blades, a full rpm rush of air is optimum for engine longevity as the combustion chamber temperatures under these conditions are way higher than no-load conditions..


----------



## sscotsman (Dec 8, 2010)

Update..I will also add this to post #1:


*From Honda:*



> Mow at full throttle with the transmission in the desired mowing speed for the best cut quality and performance. Mowing in a medium or low throttle setting will affect the performance and cut quality.
> 
> 2. Move the throttle lever to the FAST position. NOTE: For best cut quality, and performance always use full throttle.
> Use the shift lever to select the desired mowing speed range.


source: http://cdn.powerequipment.honda.com/pe/pdf/manuals/31763901.pdf


Scot


----------



## tadawson (Jan 3, 2018)

Since i have not seen it in the top posts, I'll submit my Ariens manual citation yet again. The Platinum 24 EFI manual states on page 12: 



OPERATE UNIT
1. Rotate discharge chute and move 
deflector to desired positions. 
2. Select desired speed.
3. Engage attachment clutch.
IMPIMPORTANT: 
For best snow-throwing 
results, ensure that throttle control knob is set 
to the *Efficiency or higher position.*

http://apache.ariens.com/manuals/05136000C_ENG.pdf

Note that the "Efficiency" level of the throttle is at about 2/3 of maximum . . . (Image on page 9 of that document - can't cut and paste that . . . ).


Note also that the only recommendation is stated to be due to performance - absolutely no statement about engine life.


----------



## sscotsman (Dec 8, 2010)

thanks! I'll add it to post #3.


Scot


----------



## guzzijohn (Mar 31, 2014)

The faster you run it the faster it wears out. I use minimum rpm to get job done. Less fuel & noise too. 60+ years wrenching.


----------



## Lottstodo (Feb 16, 2018)

There are so many variables that go into factory recommendations for throttle position and (RPM) that you cannot take just the stand alone engine to make outside field test to prove that a snowblower or generator or any MFG is wrong for their recommendations. When coupled to a piece of equipment the entire piece of equipment now becomes one, and all of the machine now becomes part of that variable.

If anyone has had the opportunity to see a R&D facility where the actual engine is tested and developed you would have seen that they use everything from heat sensing to vibration, exhaust, intake air, fuel intake, oil temp, out flow air temp, Db levels controlled ambient temps, and hundreds of other readings being recorded during actual development, and testing, and the best information achieved is from the dyno. This is where they are able to find the best Hp/ Torque band for that engine meaning 10hp @ 3600rpm etc. 

These facilities have millions invested in R&D and you will not see any testing data or records being published, these places are like fort Knox, this is why clones are so cheap they dont have the investment into the R&D.
But that is the engine , it still needs to be married to the proposed equipment, from that all the parameters of the ( lets say ) snow blower has to be taken into account and again tested, extensively so that from engine to auger and every piece in between is used to determine the final product MFG operators guide.

So for me I rely on the Torque/ Hp @ xxxx rpms for my running of the engine(stock).
Running a engine faster does not mean that you are building more Hp once your out of the power band your simply wasting fuel. Nor does running a engine slower mean that you are still getting the most Hp and performance from the fuel being used.
That said the exception to that is a fully monitored EFI that has the on the fly capability to change the parameters of timing , fuel, etc.and this is why the EFIs dont have the same operating guidelines as carb engines. 

One thing I did hear in regard to engines with no throttle control was that market surveys showed that there was a market where people liked the SS blowers, mowers etc. with pre set throttle, even though they were not the best size suited for their particular use as a 2 stage would have been, it was simply easier to run and start than one with the controls they did not understand. Many of these being women and as well just people who did not understand mechanical engine use. So they went for that market share,


----------



## UNDERTAKER (Dec 30, 2013)

*This is the 1 and only time and place I am going to post here. I sure as BLOODY Well would not want to go Head on with a big old drift pile at Slow Bore. I might just as well break oot a shovel and do it by hand then. "SR" only has 2 engine speeds off and FULL ON BORE!!!!!!!!. And I have been doing This 4 35 some odd years. :crying: AND THAT IS ALL THE MORE I AM SAYING ON THIS 1!!!!! :smiley-shocked033::smiley-shocked033: *


----------



## tdipaul (Jul 11, 2015)

POWERSHIFT93 said:


> *This is the only time and place I am going to post here. I sure as BLOODY Well would not want to go Head on with a big old drift pile at Slow Bore. I might just as well break oot a shovel and do it by hand then. "SR" only has 2 engine speeds off and FULL ON BORE!!!!!!!!. And I have been doing This 4 35 some odd years. :crying: AND THAT IS ALL THE MORE I AM SAYING ON THIS 1!!!!! :smiley-shocked033::smiley-shocked033: *


i think everyone agrees that when doing heavy work the throttle should be at 75-100%

but for times when you're not, 
like pulling a light trailer around with a tractor, 
or leaving the tractor on while you're unloading the trailer with a shovel, 

will the engine run hotter if the throttle is at 35-74%?

that is the question


----------



## sscotsman (Dec 8, 2010)

tdipaul said:


> will the engine run hotter if the throttle is at 35-74%?
> 
> that is the question



Toro has specifically answered that question:


*Direct from Toro*:


> Why don't I have a throttle control on my mower?
> 
> Most Walk Power Mowers we offer *do not have a throttle control.* A throttle control would allow you to vary the engine speed from idle all the way up to full speed. We have found, *not having it actually increases engine life and product performance. *
> 
> ...


Source:
https://www.toro.com/en/customer-support/faqs/residential-faqs



*Also direct from Toro:*


> What are the benefits of running your riding mower on full throttle?
> 
> *Cleaner cut* on the grass
> *More power*, less likely to bog down
> ...


Source:
https://www.toro.com/en/customer-support/faqs/residential-faqs


Red color emphasis added by me.
Bold emphasis is from Toro.


There is no logical reason to suspect Toro is wrong or lying. They are more than qualified to be THE authority on how their own machines should be operated. So, the question has in fact been answered.

Scot


----------



## tdipaul (Jul 11, 2015)

guzzijohn said:


> The faster you run it the faster it wears out. I use minimum rpm to get job done. Less fuel & noise too. 60+ years wrenching.


+1 

After my 35 years of putting in plenty of work at full and just as many putting around at half, nothing has ever overheated or burned out. In addition to wear, its annoying and extra polluting (emissions and noise-wise) to run a machine at full when it doesn't need it. 

This thread just keeps going round and round until someone can put some head temps out there and put it to rest. . 

No more quoting anecdotal marketing statements from the manufacturers!

.


----------



## Lottstodo (Feb 16, 2018)

Using the word (tractor) is casting a pretty large net that will yield a lot of different fish.
Year, Make, model , type, attachment, etc will have an impact to that question, especially hydro-static units, or true hydraulic units like my old case with a hydraulic pump and hydraulic motor/ axle, and many others so its not really an apple to apple question that has been asked.

Your particular unit may be fine doing that if cooling is only required for the engine only. But your neighbors unit might burn up a $800.00 pump because of lack of cooling to a hydro assy.


----------



## tdipaul (Jul 11, 2015)

Understood. 

Not doubting the manufacturers. They know way more than any of us. 

just looking to see some actual temps 

if they are higher my partial throttle days are over 


.


----------



## Lottstodo (Feb 16, 2018)

I would like to add one other note as far as the lower rpm usage, in a engine that has a oil filter screw on etc, it would have a oil pump, it would be highly important to know how many psi of oil pressure there would be at a different throttle condition and if indeed the required psi is developed and maintained during those periods. Like your car or truck oil psi will increase as throttle does, especially if it has some miles on it.


----------



## 1132le (Feb 23, 2017)

guzzijohn said:


> The faster you run it the faster it wears out. I use minimum rpm to get job done. Less fuel & noise too. 60+ years wrenching.



How do you explain my 26 yr old L head 8 hp tec running 3725 rpm still perfect never apart used hard everytine put away wet 

30 seconds off choke run full tilt in the snow
starts 1/2 a pull everytime
countless other tecs run like that i used to run them 3800 rpm

40 years plus of tecs run like that 1st hand use guess id call that a fact not imo
50 yrs wrenching which means nothing
clean full oil 

start machine every 2 months run 5 min refill that amount of gas with stabul no issues come november
1st tank of new winter gets seafoam for a cleaning
when i pulled the bowl looked brand new


----------



## ColdinMontana (Nov 18, 2018)

Briggs (and Ariens) put a throttle control on my Pro 32, so I figure it was meant to be used. I would never blow snow at less than full throttle. But, I frequently throttle down if I'm going to pause for more than a minute or two. Why keep an engine at full throttle, using more gas and more wear and tear, if its just sitting there not doing any work?


----------



## rslifkin (Mar 5, 2018)

1132le said:


> How do you explain my 26 yr old L head 8 hp tec running 3725 rpm still perfect never apart used hard everytine put away wet


I have a feeling that this may be a case of "even if X causes more or less wear, a properly maintained engine will still last a very, very long time"


----------



## tadawson (Jan 3, 2018)

Or, more likely, that the old L heads were built like tanks . . . just so you kept clean oil in it, they go forever. I've got equipment 40+ years old that still start like new with those engines!


----------



## 132619 (Nov 20, 2018)

that they do! yet they are also the dirtiest motor ever made pollution wise, due to how the gas most flow being more or less sucked over the valve and down make the intake stroke and pushed up and over the valve to make the exhaust stroke, unlike a ohv which is right down and up making for a cleaner burn, plus a more compact engine design. 

which also aids in cooling as the piston and head get more direct airflow opposed to having to flow around more engine block


----------



## Seaweed (Jan 18, 2016)

From a Bobcat Mower Manual. (I was told this, too when I purchased my Bobcat mower)


----------



## 1132le (Feb 23, 2017)

rslifkin said:


> I have a feeling that this may be a case of "even if X causes more or less wear, a properly maintained engine will still last a very, very long time"



so its more about taking proper care 26 yrs rpms are not and issue
same as they say older blowers have thicker metal they will last 100 years
my 28 inch will only last,50 then boo hoo
It's no comparison a much better blower with more power and auto turn and cheaper then 20 yrs ago

what do you buy today that will last as long and works better then older models? Not much

dryers washers electronics lawn mowers over 5 yrs old you are lucky if they do chit the bed its cheaper new


----------



## AL- (Oct 27, 2014)

Maybe the manufactures give basic guide lines as it's detailed and for most of the general public somewhat confusing. ie. The blower fan cools the engine within a large temperature range. ( 32F to below zero) It also seems likely that the flatheads that have been running for 30 or more yrs were not all run at the same RPMs or the same load conditions. Even in this thread snowblower users are not all running thier machines the same way and not having problems. Which is good in that it seems the motors are somewhat adaptable.


----------



## 1132le (Feb 23, 2017)

AL- said:


> Maybe the manufactures give basic guide lines as it's detailed and for most of the general public somewhat confusing. ie. The blower fan cools the engine within a large temperature range. ( 32F to below zero) It also seems likely that the flatheads that have been running for 30 or more yrs were not all run at the same RPMs or the same load conditions.[/QUOTE
> 
> 
> I just said i was tuning 3800 for 20 plus yrs i get about the heaviest snow you will find on the coast of mass
> ...


----------



## 94EG8 (Feb 13, 2014)

Running at low RPM with a load will cause carbon buildup. I used to see this when I worked on OPE professionally. The old guys who thought they were babying an engine running it at low RPM would have ridiculous carbon buildup in the combusion chamber. Idling at an excessively low RPM will cause overheating as well. Is there anything with throttling down an engine while you're doing something else and don't want to shut the machine off? No, but it should be run at wide open throttle while working. I will say I do like having a throttle control to idle a machine before shutting it off, but that more than likely stems from years of running older flathead engines with no anti-afterfire solenoid which would often backfire when shut off at WOT.



As far as generators being run at 3000RPM in other countries, they have to be. It has to do with that being the RPM needed to get 50Hz


----------



## Toro-8-2-4 (Dec 28, 2013)

AL- said:


> Maybe the manufactures give basic guide lines as it's detailed and for most of the general public somewhat confusing. ie. The blower fan cools the engine within a large temperature range. ( 32F to below zero) It also seems likely that the flatheads that have been running for 30 or more yrs were not all run at the same RPMs or the same load conditions. Even in this thread snowblower users are not all running thier machines the same way and not having problems. Which is good in that it seems the motors are somewhat adaptable.



Well said Al.....or said differently, the engines are insensitive to a wide range of conditions.


Keep in mind that most folks on here are the types that change their oil (probable more than they need to) and do basic maintenance. Which all helps prolong the engines life.


----------



## tabora (Mar 1, 2017)

I question what WOT really means in terms of RPMs, though; seems opinions vary...

My Honda HSS1332ATD came new with the WOT speed set to 3,460 RPM.

The service manual specifies a max speed range of 3,550 +0/-150 - That's 3,400 to 3,550 RPM. Confusingly, it also lists a FINAL operating speed range of 50 RPM below that range - That's 3,350 to 3,500 RPM. So, from the factory my blower was set very close to the top end of the specified WOT operating range.

After I upgraded the main jet from #102 to #110 to address low power and surging issues, I also set the WOT to 3,650 RPM based on the recommendations of others on the forum (some suggested setting WOT as high as 4,000 RPM, very close to the coil rev limit). I stopped where I did based on the diminishing torque above that speed. When using the blower last year, I routinely recorded fluctuations between about 3,350 RPM and 3,960 RPM (my tach records max RPM) when initially engaging heavy snow: about a 600 RPM range.

When I received my blower back this year after having the chute and transmission service bulletins performed (different dealer than where it was purchased), they had reset the WOT to 3,300 RPM. Since that speed is closer to the torque sweet spot, I decided to leave it there for the time being as an experiment. In the two storms since then, I've only seen fluctuations in the 3,250 RPM to 3,350 RPM range. It would seem (so far) that the blower is happier at this WOT speed and hopefully is experiencing less wear. If I see larger fluctuations when the snow gets deeper, I'll adjust WOT and continue the experiment.

*Update 01/30/2019: Well, we finally had our first "real" snowstorm of the season. The EOD was a solid 24" - 28" high and about 4 feet into the driveway. Going across the driveway taking a full 32" bite in the middle of the high stuff, the HSS1332 FINALLY bogged down to about 2,500 RPM (peak torque) a couple of times. While it still threw the snow 30-40' back from the road, guess I'm going to put the RPMs back up and see how it compares.*


----------



## DriverRider (Nov 20, 2016)

I have made available to the Forum that Honda and B&S sell generators outside of North America to the rest of the world which run at 3000RPM to supply the 50Hz voltage these Countries use.

https://www.honda.co.uk/industrial/products/generators/specialist-open-frame/specifications.html#
https://www.briggsandstratton.com/e...nerators/elite-8500ea-portable-generator.html


----------



## sscotsman (Dec 8, 2010)

DriverRider said:


> I have made available to the Forum that Honda and B&S sell generators outside of North America to the rest of the world which run at 3000RPM to supply the 50Hz voltage these Countries use.
> 
> https://www.honda.co.uk/industrial/p...ications.html#
> https://www.briggsandstratton.com/eu...generator.html


Thanks Driver,
This info about the generators has already been added to post #3. 
I will add your links right now.

Scot


----------



## Kiss4aFrog (Nov 3, 2013)

I have two Tecumseh engines from the early 70's still running and I'm sure the oil was seldom changed, they were run at various speeds and forty + years later they are still going.
Run your engine at a speed that you feel comfortable with and gets the job done. :icon-deadhorse:

.


----------



## DriverRider (Nov 20, 2016)

sscotsman said:


> Thanks Driver,
> This info about the generators has already been added to post #3.
> I will add your links right now.
> Scot



Thank You Scot. 

Would you like to hear my opinion as a CMAT and CTT Dealership mechanic during the '80's, with first hand knowledge from the Engineers who worked on these projects who taught the schools. From Ford EEC IV that gave us a break out box to determine system faults and C6 to AOD transmissions as to what the climate was during those early years.


----------



## sscotsman (Dec 8, 2010)

DriverRider said:


> Thank You Scot.
> 
> Would you like to hear my opinion as a CMAT and CTT Dealership mechanic during the '80's, with first hand knowledge from the Engineers who worked on these projects who taught the schools. From Ford EEC IV that gave us a break out box to determine system faults and C6 to AOD transmissions as to what the climate was during those early years.


Since none of that has anything to do with small air-cooled engines, and so is irrelevant to this thread: No. Thanks for offering though.

Scot


----------



## tdipaul (Jul 11, 2015)

.

I bought a laser temp gun today. 

With the laser pointed here right near the exhaust port of my Kohler Magnum 18...



and running it for 5 mins at full throttle (no load = ~3570), this is the avg reading...



and then after running it for 5 mins at idle (no load = ~1200), this is the avg reading...




Thoughts???

.


----------



## nwcove (Mar 2, 2015)

now a somewhat true test would be to load the engine and test again at wot and maybe 1/2 throttle under the same the snow conditions. snowblower myth busting.


----------



## tdipaul (Jul 11, 2015)

nwcove said:


> now a somewhat true test would be to load the engine and test again at wot and maybe 1/2 throttle under the same the snow conditions. snowblower myth busting.


I suppose this would be a good test but I wouldn't normally run a (snow blower or mower) engine at 1/2 if it had a _significant_ load on it. We already know that's not good for an engine. 

My test was to determine if a lower throttle setting results in lower temps when under a _light_ load

It does, so have no fear about putt-putting back to the house after some hard work or towing a light trailer around the yard

Less noise, less fuel consumption, and cooler temps now proven out. Its all good! :grin:


----------



## RedOctobyr (Mar 2, 2014)

I may be wrong, but it seems to me like the exhaust isn't the best place to measure. A lot of the discussion has involved the cooling you get at different RPMs. But nothing's trying to cool the exhaust, because you don't particularly care how hot the muffler gets. 

I think measuring on the engine's fins might be more applicable. That's an area that's being cooled, and is arguably more important.


----------



## tdipaul (Jul 11, 2015)

.

I think its safe to assume that everything upstream from exhaust header (the cylinder head and fins, exhaust valve, block, piston, oil, etc) will be cooler at lower engine speeds too, no?

.


----------



## RedOctobyr (Mar 2, 2014)

I don't know. That's kinda been a pivotal part of the discussion  At lower speeds, less heat is *generated*, but how does that impact engine temperature, after you incorporate the reduced cooling that's going on? 

Another possible spot to measure would be down on the crankcase, where you're hopefully kinda measuring the oil temperature.


----------



## russ01915 (Dec 18, 2013)

Take off the oil dip stick tube from the engine and stick a instant read thermometer into the oil.


----------



## tdipaul (Jul 11, 2015)

be my guest!


----------



## Sid (Jan 31, 2014)

It's better that it spins, rather that it lugs. I was having trouble with my pickup pinging under load, and down shifting, and spinning faster, solved the problem. Sorry about being off subject.
Sid


----------



## scrappy (Dec 7, 2014)

Way too late to the posts...


This would be the most reliable way to determine an air cooled engine temperature, along with a probe in the oil.


I have used an IR gun focused on the spark plug base, pretty much useless, due to surface temperature is effected by ambient air temps.


Plenty of info out there using the spark plug probe readings.


https://www.autometer.com/type-k-thermocouple-cylinder-head-spark-plug-probe.html


----------



## RedOctobyr (Mar 2, 2014)

I realized recently that I have an engine that could be an interesting candidate for this. Inverter generators can spin more slowly, or at full speed, while still powering the exact same electrical load. 

So unlike a mower, snowblower, etc, you can: 
- provide the exact same useful output work (watts) 
- do it in a consistent & repeatable way (power a bunch of lights, etc)
- change the RPMs while doing so

I have no interest in sticking a temperature probe into the crankcase while it's running  But if someone with such a generator wants to measure their temps at 2 RPMs, please let us know!


----------



## scrappy (Dec 7, 2014)

RedOctobyr said:


> I realized recently that I have an engine that could be an interesting candidate for this. Inverter generators can spin more slowly, or at full speed, while still powering the exact same electrical load.
> 
> So unlike a mower, snowblower, etc, you can:
> - provide the exact same useful output work (watts)
> ...



Shut er down and stab the probe in. Temperature will be real close to actual running temp.


----------



## Shovel (Mar 26, 2019)

While I may be new to snow blowers,, I have mowed lots and lots of grass as well as repaired many small engines.
I have seen many engines run close to 3450 rpm from the factory.. and many at 3600rpm.
Some may even be lower than 3450 rpm
An engine say rated at 8 hp at 3600 rpm that is set to 3600 rpm will not deliver 3600 rpm under load. 10 to 15 percent governor droop was pretty normal.. The lower the droop the increased chance of hunting. 
An engine that is hunting will rev past it's no load rpm. If we had no load rpm at 3600 rpm and started to hunt we have exceeded our 3600 rpm. We also exceed 3600 rpm for a moment when we turn off the blades. 
Decades ago we didn't have as powerful of engines doin the same work.. A manufacturer that set max rpm at 3600rpm will droop to 3100rpm to 3200 rpm before full throttle has taken place as we can see we don't have that eight hp.
No load rpm of 3450 would get you at around 3000 rpm before full throttle was taking place.
If we reduce rpm farther say no load rpm of 3200 we can have rpm down to 2800 before full throttle.
We had different springs and different holes to use to get our desired droop
Generators needed less droop so had to have an excellent tune or would hunt.
Mowers. Pumps.. compressors and such just ended up with 3600 no load rpm as a standard.. however some engines were 3750 .. 3450.. 3300.
Some of the larger garden tractors were to 3250 rpm.. those shipped to Europe often were set lower than here in the states... We had power to spare we just kept producing more powerful engines as time went by... Horsepower sells whether it is a waste or not.
Personally I don't run at 3600 unless there is a specific need... My snowblower was set at the factory to 3450 rpm for instance..I just will have to wait and see what happens.. I had one snow an inch or so deep this year.
My Gravely equipped with a Kawasaki was set to 3600 rpm.
I turned it down to 3300..The Horsepower curve goes flat on that engine way before 3600 rpm.. Big waste of fuel and unneeded stress
When we double engine speed .. the reciprocating force quadruples.. not double as you would think.. so any mild reduction in speed takes stress off the engine components as long as you aren't lugging it.
Also if you hit an object.. the blade strikes with four times the force when engine speed is doubled. 
4250 rpm vs 3000 rpm has twice the reciprocating force inside the engine or any object you hit.
I got in the habit of slowing the throttle in places with debris so I wouldn't chuck it as far...2000 rpm or so if the load is light.
I have an old Dixon factory setting is 3400 rpm I have it set to 3260.. it's less jerky.. throws grass two stripes wide so My grass is perfectly thrown just by a fine tune of the throttle while mowing
Bearings live longer. Its my current favorite and is 18 years old ..the old Kohler engine just keeps going and going... Are lower rpms hurting it?..Might be .. It's not going to be anything significant though if it is.
3600 rpm standard was something that just kinda happened ...With more powerful engines nowadays ... Many manufacturers slow the engine a little as we are not having to have every last ounce of power the engine can deliver as back in the past.
I don't have any scientific data to show that a moderate reduction in rpm is not harmful... however I have never experienced a problem 




Sent from my LM-Q710.FG using Tapatalk


----------



## tdipaul (Jul 11, 2015)

If the machine throws grass and snow just as far at 3200rpm as it does at 3600rpm there is no reason to keep it up there. 

Sometimes you need max blade tip speed for proper cutting and max impeller tip speed for proper throwing.


----------



## sscotsman (Dec 8, 2010)

Zombie thread returns to life! 

but we've now lost touch with the original point of this thread, which was already thoroughly covered.

no need to resurrect it.



Scot


----------

