Another pulley size question

[rleonard]

Gentlemen of the group;
I am in the process of belting up my 16-2 Lister to a ST15 generator head that I just received.  Now I know that the engine cannot pull a full 15KW load.  I do not need nearly that capacity at this time.   My average load for the house is 2500W over the month.  That goes to 3500 in the summer with AC.  I do not know my peak loads (note to self - get a Kill a watt meter ordered). Lets estimate 30A @240 = 7200W momentary load when the AC kicks on.

The engine is rated at 16HP @ 850 RPM.  I have 23" heavy flywheels on the engine.  To sipn the generator @1800 I'm looking at a 10.86 dia. pulley. 

In the interest of fuel savings, I do not need that kind of output on a regular basis.  To pull the avg. load of 3500W, someone here will suggest that I throw away my 16-2 (a nice origional one!) and replace it with a 6-1 + ST5.  This would be a plan, but I had another idea. (LOL)

Why not slow the engine down to reduce fuel consumption.  In very general terms, if a 16-2 @850 rpm becomes a 12-2 @ 650, then at 500 rpm, HP is roughly 9.  Using ~2hp/kw gets me closer to my average load while hopefully enjoying some fuel savings.  I can drop the pulley size to 6.39" to get 1800 on the generator.

I am going to use a serpentine belt and can machine my own pulley. 

The local expert with at least 40 years experience with Listers said that they run these engines slow as needed with no detrimental effects whatsoever.  The Lister manual says to run the engine at rated speed or contact them.

Ant thoughts or comments?  Something I have overlooked?

Thanks,
Bob
   

[GuyFawkes]

I personally would not load a genuine lister above half rack opening at 325 rpm, and would not personally run one slower than that under any sort of appreciable load.

think lubrication.

[rleonard]

Good point.  I want to try 500rpm.  There should be enough speed to sling the oil around.  I suppose I could install a plastic window temporarily to watch it.  Might be interesting to see the splash patterns.

Bob

[binnie]

Any picts Bob? Originals are rare on this forum. I am sure we would all like to see what you have.
I have a 12/2 "roid" not set up yet. But have been giving thought to the idea of flexibility too along the sames lines as you are proceeding. To go up to 16/2 I would have to have another set of flywheels but to go down, it is doable. binnie

[rleonard]

I just did another round of cleaning before building up the framework.  This would be a good time to shoot pictures.  I'll snap some this weekend and upload.

Bob

[Jim Mc]

Not sure if there are significant differences between the 16-2 and 10-2, but this sheet shows data down to 500 rpm, so presumably it's OK at that speed.

http://www.oldengine.org/members/diesel/Technical/102P3data.htm

[rleonard]

Excellent!  Thank you

Bob

[hotater]

The geometry of the governor weights are different at different RPMs.
     It might not make a difference....or it might make a BIG difference, but the weights ARE at a different attitude at lower speeds.
   Since governors are balancing acts between inertia and a springs they may have to be made heavier for lower speeds to work correctly.

[cujet]

I guess that all will be fine at the lower RPM's as long as you have enough lubrication.

There was at least one Lister clone that failed at low RPM due to lack of oil.

Chris

[rleonard]

Frame construction was this weekend.  Far from complete but work in progress.  I posted some pictures in the coppermine gallery. 

Bob