Switch 22hp gas to 18hp diesel, will it be less powerful?

[mopacman]

I think you are comparing car engine with no govener to a diesel engine with a govener, That is the difference.......Larry

 

[Superduper]

I think you are comparing car engine with no govener to a diesel engine with a govener, That is the difference.......Larry

I'm not familiar with a diesel govener, what is that? Would that be something that automatically compensates for increased load by increasing the amount of fuel injected to richen the mixture for greater power?

Do gas tractor engines have a similar device that will increase throttle when rpm drops below preset amount? It seems you can't get max power from a cruise/high-idle type throttle setting.

 

[Blackbird_BX]

Glad to hear that it comes with a radiator. I only asked because the spec sheet mentioned two different radiators; standard and high capacity, so I thought it might have to be ordered separately.

 

[mopacman]

I think all tractors and small engines use a govener. It keeps the engine from over reving and It helps keep the RPM at a stedy speed by increaseing fuel when the RPM drops when applying more load.....Larry

 

[Soundguy]

I -wouldn't- be surprised to fin dthe gasser running near that 3600 rpm range.. that's a pretty standard rpm.. look at gensets.

As for the way a diesel injector pump/throttle interacts vs a gassers lawn mower engine manual cable actuated carb setting.. there is a big difference.. especially once you add load.. a governed diesel will try to maintain the rpm. the gasser will bog down till YOU add more throttle tot he carb... that's the difference in haveing a governor and not.. ever bog down a weed eater and then lift it up.. it's speed maxes out... now set your tractor for a specific rpm while cutting a heavy pass with a mower.. then drive into the open... yeah.. rpm comes up a bit.. but it don't max out. that's cause it has a governor that no longer sees the 'call for power' it just had a few seconds ago.. vs a simple cable operated butterfly on a carb'ed engine with no governor.

soundguy

Regarding the belt and pulley issue, I don't think there is one, issue that is.

The presumption is that the gas engine will be operating at a higher rpm than the diesel therefore the mower blade will be too slow for optimum operation. I looked up the stats and both the Yanmar and the Gasser are rated at 3600 rpm so that shouldn't be a problem. Personally, I don't believe that the gas engine is running at 3600 rpms anyhow when throttle is moved to max position.

I've included a news release article with great info on this engine. Apparently, Yanmar intended it for uses exactly like what i have in mind.

A thought and question did cross my mind though. In a gas powered car, it takes very little throttle pressure to run an engine at 3000 rpm. Put that car in gear and at the same throttle position, the car might go 20mph. If you were then able to depress the throttle further, to WOT, then you might go 100mph. In a tractor, pushing the throttle to max before putting a load on it would be like a 3000 rpm idle, right? It can't truly be WOT because if you were to operate a car engine at a true WOT position, it would blow up in 10 seconds. But in a diesel powered vehicle, there doesn't seem to be much difference in power between a 1/3 throttle to 3/3 throttle, at least not the type of difference you would see in a gasoline powered vehicle. So my question is wouldn't gas powered engines (for tractor type use) be more effective and powerful if they had a automotive type of gas pedal to truly utilize WOT?

 

[john_bud]

I'm not familiar with a diesel govener, what is that? Would that be something that automatically compensates for increased load by increasing the amount of fuel injected to richen the mixture for greater power?

Do gas tractor engines have a similar device that will increase throttle when rpm drops below preset amount? It seems you can't get max power from a cruise/high-idle type throttle setting.

On your tractor, you pull the lever down to open it up (no load), the gov will open the "real" throttle to the max you set with the hand throttle lever in order to meet the load requirements while staying at the set rpm. A governed engine is more easily thought of as one where you set the max rpm and the govener opens and closes to hold that rpm even as the load on the engine changes.

Same deal on a diesel, except there is no throttle (open like a sewer pipe), the govener adjusts the amount of fuel injected to match load.

 

[artfull dodger]

Thats correct guys, the diesel's gov controls the injector rack in the main injector pump. I know when I mow with my diesel repowered and factory diesel engine tractors, the engine just takes on a nice working note to its exhaust as it powers thru the thick stuff, then lesses that note just as quickly as I exit the heavy stuff and back to normal grass. If its really deep and the ground speed is a bit much, it will start putting out the black exhaust, thats when I down shift one gear as mine are not hydro drive. Cheers Mike

 

[David Cockey]

I -wouldn't- be surprised to fin dthe gasser running near that 3600 rpm range.. that's a pretty standard rpm.. look at gensets.

As for the way a diesel injector pump/throttle interacts vs a gassers lawn mower engine manual cable actuated carb setting.. there is a big difference.. especially once you add load.. a governed diesel will try to maintain the rpm. the gasser will bog down till YOU add more throttle tot he carb... that's the difference in haveing a governor and not.. ever bog down a weed eater and then lift it up.. it's speed maxes out... now set your tractor for a specific rpm while cutting a heavy pass with a mower.. then drive into the open... yeah.. rpm comes up a bit.. but it don't max out. that's cause it has a governor that no longer sees the 'call for power' it just had a few seconds ago.. vs a simple cable operated butterfly on a carb'ed engine with no governor.

soundguy

Gasoline engines made by Briggs & Stratton, Kohler, Techumseh, etc used on lawn mowers, garden tractors, snowblowers (at least those with 4 stroke engines), roto-tillers, etc all have governers. The "throttle" control acutually controls the governer, and the governer controls the throttle plate in the carburetor depending trying to keep the engine speed at the desired speed. The air cooled gasoline engines I'm familar with use an air flap governer, with air from the cooling fan blowing against a flap. When the engine speeds slows down due to load the flap moves which opens the throttle. If the load on the engine is sufficient the governer can open the throttle fully to "WOT".Depending on the type of governer the speed will vary somewhat with load, but no where near the amount it would vary without the governer. Of course if the load becomes too heavy even full throttle won't keep the speed up and the engine slows.

Think of the governer as cruise control for engine speed. As an aside "cruise control" on an HST tractor is really just a lock on the pedal control of the transmission, the speed of the tractor is controlled by the governer on the engine.

I don't know how a string trimmer or chainsaw engine is set up, it is probably not the same as the larger, 4-stroke gasoline engines used on power equipement.

I'm a mechanical engineer, and this has nothing to do with my hat size.

 

[MJPetersen]

Some of the smaller engines use an air flap to govern the engine by controlling the throttle plate position. The larger engines use a gear with spinning weights to control the throttle plate position. Gasoline engines and diesel engines in equipment all have governors. It is necessary as the load on the engines vary it is necessary for the engine to be able to maintain a steady RPM. The governor may be built into the engine or it may external from the engine. You can have a governor which senses the speed of a generator or that is spun with a fan belt, but almost all industrial engines will have some sort of governing device.

Mike

 

[john_bud]

Bit of trivia here.

The term "Balls Out" is sometimes thought to be in some way shape or form to do with reproduction and as such can get you in trouble with the fairer sex (or small minded behind covering corporate HR types).

Not true! It has to do with the governors on steam engines. They used fly balls and when they were in the furthest out position - that was full power and maximum speed. Because it was right out there in the open, visible to all, everyone knew you were at full power. So, going "balls out" is steam engine speak for full power full speed. Most of us have seen them without knowing it as they are the spinning things on the top of a steam engine.

The details here may not be 100% as this was relayed to me by a person that had been written up for sexual harassment for using the term "let's go Balls Out on this project". A female didn't like that as she felt it was exclusionary of her gender, not being able to participate in this male only activity. He refused to have that in his file and generated a 10-15 page report with pictures of the mechanism, copies of the original patent drawings, the origins of the phrase, it's contextual meanings and all derivative slang showing conclusively that the phrase had nothing to do with anatomy.

jb