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

[Soundguy]

You apparently missed the very last line of my message.. or didn't read all the way to the last word. my comment was related to the gas engines that have the user operated throttle control that connects directly down tot he carb butterfly.

I'm not talking about the more advanced gas run engine.. .. just the plain jane push mower and other engines that are NON governed... except by your right hand. IE.. I specifically said to follow the cable to the carb butterfly. common sense would dictates that if the user operated throttle cable don't go to where I said. then my comments didn't apply to that application.

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.

 

[Soundguy]

Seems to me I wasn't talking about a industrial engine.. just a carb stuck on a jug with a crankshaft..

soundguy

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]

Sounder,

Have to agree with David C on this one. The plain jane B&S mowers and Techumseh's all have a governor on them. It is a spring loaded deal that is pushed by air from the top of the crank fan. Take a close look. The cable goes to the throttle that is first in the carb, the governor goes to the second throttle at the bottom of the venturi. They have been that way about forever.

 

[David Cockey]

I did carefully read your message all the way through.

Even the cheapest gasoline lawn mower has an engine with a "governer" system. Have a good look at the carburetor and the other connections of the carburetors to the rest of the engine. The "governer" system on an inexpensive, "plain jane" lawn mower engine is generally very basic, some might say crude, and usually allows noticeable speed variation as the load varies on the engine. But nothing like the speed variation which occur without the system.

If the engine in a mower wasn't governed it would be very difficult to mow with. Unless the throttle was open most or all of the way the mower would bog down in heavy grass. But as soon as it was not cutting grass (over a previously cut area, bare spot, etc) the engine would overspeed and destruct unless the throttle was closed.

You apparently missed the very last line of my message.. or didn't read all the way to the last word. my comment was related to the gas engines that have the user operated throttle control that connects directly down to the carb butterfly.

I'm not talking about the more advanced gas run engine.. .. just the plain jane push mower and other engines that are NON governed... except by your right hand. IE.. I specifically said to follow the cable to the carb butterfly. common sense would dictates that if the user operated throttle cable don't go to where I said. then my comments didn't apply to that application.

soundguy

 

[Soundguy]

My weed wacker has 1 linkage connection to the carb.. from the manual trigger on it.. is it governed?

soundguy

 

[MossRoad]

Is your weed whacker a 2 stroke or 4 stroke?

Every 4 stroke I have has a governor.

 

[Soundguy]

2 stroke.

soundguy

 

[Superduper]

I'm pretty sure most weekwackers DO NOT have a governor. Unlike the industrial engines that has a lever type throttle where you set it and ignore it while operating, most weedwackers, at least the ones I own, all have a sprung finger trigger. You throttle the engine as needed for more speed and power while you are cutting, and yes, the engine revs up when the load lightens up and bogs down when it hits a dense patch.

 

[David Cockey]

My weed wacker has 1 linkage connection to the carb.. from the manual trigger on it.. is it governed?

As I said in a previous message, 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.

My guess is the small, 2-stroke engines usually used are designed to run safely at the unloaded, wide open throttle speed, and under load slow down. The lack of valves, cam, etc makes this simplier to achieve.

Lawn mower, garden tractors, etc with 4-stroke engines are different beasts.

 

[john_bud]

2 cycles are usually not governed. They fly right up to 10 to 12,000 rpm.

But, weren't we talking about B&S and T 4 cycle engines ? And hey, maybe even putting a diesel into a tractor that was originally gas? Come to think about it, wonder how that project is going?

jb