Wood Splitter Engine RPM's

[XmasTreefarmer]

I've got an old MTD splitter with a Brigg's 6HP engine. What a gem of a machine. I've had it for 16 years now and it's split over 70 cords of wood - what a work horse!

I came across something a while back - it stated that small gas engines like that are designed to run at 3,600 RPM or lower. The article also said that when an engine is on a lawnmower, they have to be set at 3,200 RPM. Something to do with blade speed/lawn mower safety/etc and that all/most engines come out of the factory set at 3,200. Well being the curious guy that I am, I checked my splitter and sure enough it's running at 3,200 RPM.

Now the hydraulic pumps for splitters seem to be rated at X gallons/minute at 3,600 RPM. Doing some math at the higher RPM's I should see about a 12% increase in ram travel time. So, I messed with the governor and have the rev's set at 3,550 now. I timed the ram travel out and back and sure enough it's about 10% faster!

Anyone who really knows engines have any opinions on this? I was quite happy with the performance of the splitter all these years and don't want to cause any problems with that engine with this change to the RPM's. The engine is well maintained with regular oil changes and air filter maintenance.

 

[Zack R]

I've got an old MTD splitter with a Brigg's 6HP engine. What a gem of a machine. I've had it for 16 years now and it's split over 70 cords of wood - what a work horse!

I came across something a while back - it stated that small gas engines like that are designed to run at 3,600 RPM or lower. The article also said that when an engine is on a lawnmower, they have to be set at 3,200 RPM. Something to do with blade speed/lawn mower safety/etc and that all/most engines come out of the factory set at 3,200. Well being the curious guy that I am, I checked my splitter and sure enough it's running at 3,200 RPM.

Now the hydraulic pumps for splitters seem to be rated at X gallons/minute at 3,600 RPM. Doing some math at the higher RPM's I should see about a 12% increase in ram travel time. So, I messed with the governor and have the rev's set at 3,550 now. I timed the ram travel out and back and sure enough it's about 10% faster!

Anyone who really knows engines have any opinions on this? I was quite happy with the performance of the splitter all these years and don't want to cause any problems with that engine with this change to the RPM's. The engine is well maintained with regular oil changes and air filter maintenance.

I don't think a few hundred RPM increase will cause any issues. Worst case you wear the motor out a little bit sooner, but it's already provided 16 years of use so I wouldn't worry.

 

[DodgyNomad]

My opinion: Higher RPM's leading to considerably faster cycle times will certainly put higher stresses on the engine, pump, ram etc.. Is it worth it? Probably! That's a pretty good increase in speed, just for upping the gov.

There's no doubt that given a set amount of time, you'll do more work, and get more productivity, but in that same period of time, you'll wear things out faster.

I have jacked up the R's on many different devices over the years, from a walk behind leaf vac to wood chippers, snowblowers, etc..

I have never once had one blow up on me or have a catastrophic failure because of it. Did they probably wear out sooner? Probably. I can't see how they couldn't. But with best oil and more frequent changes, longer low rpm warm up times to let everything get up to temp and equalize before use, and good quality gas to avoid detonation and give more power (use ethanol free premium if at all available) I would do it if I was you.

My vote: go for it. Sounds like the gov was set to low, and you're just bringing it up to where you want it to be.

I've spun some of my gas powered equipment a LOT faster than that to get more work out of it, and have never had one come apart on me because of it. Rock on.

 

[Woodsplitter67]

a couple hundred Rs really isn't much of a difference 3500 to 3600 is a good range.. it's not like your taking it from 3600 and trying to get it to 4400 Rs.. if that was the case I'd say bad idea and the life of the motor will be shorter

 

[NickW]

I consulted my brother who has been in the engine RD department at Kohler for over 38 years. He says "no problem whatsoever". Small engines are designed to run at 3600 RPM at full load. High idle RPM no load is between 3900-4000 RPM to achieve this. He said you could probably set it even higher... He surprisingly did not say you should replace the Briggs & scrap iron with a Kohler. My response would have been you're allergic to backfires .

 

[XmasTreefarmer]

Thanks to all that replied - all very intelligent and helpful comments which is what makes Hearth.Com so awesome! The information shared really helped to confirm my "mechanical intuition" on this change. And special thanks to NickW for checking with his brother who confirmed the info that 3,600 RPM is the standard full-load RPM and that I could go even higher at full-idle RPM. I will stick with this increase in RPM's at least for now and maybe mess with it a bit in the future.

And I just had to split some wood yesterday. The speed difference is noticeable. I expected that it would be with about a 10% change. It messed with my rhythm at first because I am so synch'ed up with the machine after all these years. I'd complete a split, hit the lever to return the ram, grab the next piece of wood and the ram would be back and ready to go! Nice! After about a half hour I'd totally adjusted to the change.