Slow running engine ?

[Kai Thomsen 17]

This may sound like a wierd idea..  but i am fascinated by old engines with their massive flywheels and low rpm.

Would it be possible to "do something"  to a 12hp  K301 to make it run slower and still have reasonably power and a lot of torque ?   

I know i could just change the governor settings and get a lower top speed, but that is not quite what i am looking for.

 

If i want it to idle really low, and have a top rpm of, say 1200 rpm, what would it take to accomplish this ? if possible.

My quess is it requires an even heavier flywheel, maybe even add one to the pulley side of the crankshaft.  Maybe some changes to the camshaft too = shorter duration and lift.

 

Beeing a splash lubricated engine, i guess it would need some sort of oilpump to lubricate the bearings also.

 

Could it be done ? 

 

 

 

[rmaynard 16,268]

Kohler recommends an RPM no lower than 1100 for lubrication purposes. Since there are no ports for directly pumped oil, I don't know how you would lubricate properly.

 

Just my   worth.

[Kai Thomsen 17]

I was thinking of a small gearpump / oilpump driven by the engine, and some sort of spray nozzle inside the crankcase that would spray oil "everywhere"   or just route a small pipe to the main bearings inside the case and drip oil into them. But the big end of the conrod will be a problem.

 

It's just one of those crazy ideas that pops up from time to time   don't take it too seriously

[groundhog47 347]

The torque of the engine might increase with weight at a specified rpm, but it may remain below what the original spec rpm torque is/was. 

That tells me HP could go down. Recovery time would be somewhat affected (rpm loss due to added work load like heavy grass) which would reduce operation ground speed. A good example is how a wood chipper bogs when a larger limb is knawed up. With flywheel and rpm matched to torque it could work fine. I can't find any values to show what weight and dia plays on kinectic energy, but found these two formulae to play with: HP=(rpm X torque)/5252 and KE=1/2 x m x v 2 (squared) (ke + kinectic energy, m = mass and v = velocity).

 

Have always loved those old poppers and a smooth idle at low rpm, sounds like a fun project!

[Kai Thomsen 17]

I had a long talk about the subject with a friend of a friend of mine, he has been working his hole life in a engine rebuild shop and knows a lot about engines.. he said it sounded like a fun project..but he wouldn't do it.. as he said to me:  "you will twist or even break the crankshaft.. maybe not the first time you start it up, but it will break if you put another heavy flywheel onto it, it is not strong enough to take the force of two massive flywheels that the old large bore and long stroke engines had"    

 

I'll take his words for it, and wont try it.