Sawmill Engine Diesel vs. Gasoline

[JPAC]

I am looking to purchase a woodmizer bandsaw mill. I would like some input on the engine, I know the pros and cons between gas and diesel for trucks but not for a sawmill.

Right now the base motor is 19 HP Kohler Twin Cyl. Gas Engine. I can upgrade to a 10 HP Yanmar 1 cyl. Diesel Engine or a 25 HP Kohler Twin Cyl. Gas Engine.

Which one would be better to have? I would like to do the upgrade when I don't have to play full price for a new one.

[rjwoelk]

I have the 19hp no problems.

[Dave Shepard]

As much as I like diesels, 10 vs. 25 is too big of a jump. 25hp is a really nice number for a manual mill. I didn't run into anything I couldn't cut with the 24hp Onan I used to run.

[sawguy21]

The diesel really shines when it comes to torque, that is what gets the work done. It will also be more economical on fuel. The downsides are weight and cost.

[POSTON WIDEHEAD]

With all the problems I've had with a Kohler...I would go diesel if I were you.

[Dave Shepard]

The diesel really shines when it comes to torque, that is what gets the work done. It will also be more economical on fuel. The downsides are weight and cost.

But it it making as much torque as a 25hp gas? 10 vs. 25 is a big spread.

[Magicman]

Here is a LINK to Marty Parsons reply on this same subject a couple of months ago.

[MartyParsons]

Hello,

With all the problems I've had with a Kohler...I would go diesel if I were you.

One, different animal. 25 hp is non computer.
We sure do have many of these engines out there in the field. I hate to condemn every piece of equipment for one or two Kohler engines that may have had issues.

You can throw stones at me or say that is not correct. But there is dust on my Kohler computer and the pages on the service manual are not even worn in yet.

Marty

[POSTON WIDEHEAD]

You can throw stones at me or say that is not correct. But there is dust on my Kohler computer and the pages on the service manual are not even worn in yet.

Marty

I can not throw stones at you brother because you are worth your weight in gold....but my Kohler computer is clean as a whistle and the pages of my manual are starting to wear.  :D

[esteadle]

Can't comment on Diesels as I don't have one, and haven't used one. But I have a Kohler CH730 on my Timber Harvester. It works fine, and Kohler supports their customers well. But folks with EFI engines seem to have more trouble than those with carburetors, mostly due to what appears to be low quality Throttle Position Sensors. My suggestion would be to call a couple of the Kohler dealers in your area, and ask them about the specific model of engine on the mill. Ask them if other people have problems with the TPS, and if they stock those parts. Lots of Kohler dealers everywhere, so if you don't like one of them, call the next, and find the one you like.

Read this thread https://forestryforum.com/board/index.php/topic,94318.msg1454119.html#msg1454119

If you get a gas engine, always run it dry at the end of the day. I never leave fuel in fuel lines or carb anymore.

[caveman]

We have Kohlers on our Gator, Lt-28 and our Dixie Chopper-all have performed as they should for many years/hours.  The 25 hp engine on the mill does a respectable job although I have never run a diesel mill or tried to earn a living cutting boards.  David seems to have gotten a lemon, similar to our Suburban (another thread).

[Chop Shop]

Diesel is nice but ya got to get good at topping off the fuel.

Im pretty good at sawing till the mill sputters out (both are gas).

Lucky for me I just pour gas in and pull the choke and it fires right back up.  Run a diesel dry and you will have fun bleeding it out before starting it.

[4x4American]

Diesel is nice but ya got to get good at topping off the fuel.

Im pretty good at sawing till the mill sputters out (both are gas).

Lucky for me I just pour gas in and pull the choke and it fires right back up.  Run a diesel dry and you will have fun bleeding it out before starting it.

Thats true on the older diesels, these new ones aren't a problem at all.  Even after a fuel filter change on my yanmar diesel or on my 2015 dodge cummins, just crank her til she roars and they will.  Just somehting to keep in mind, you don't want to go cracking the lines on a commonrail system, then you'll really have problems. 

[RazrRebel]

I'm still gathering parts for my sawmill build, hopefully soon I'll start. My engine is a Yanmar diesel from a reefer truck. Specs say 19hp. Hopefully it will be a good engine for the mill.

[barbender]

TypicallybI would say diesel all the way, but my experiences with small 1 and 2 cylinder diesels haven't impressed me very much. They rev very slowly, and if bogged down, recover rpms slowly. I don't have any experience with that particular engine, though. Now it was a 20 hp yanmar triple cylinder or something, I'd probably say go diesel.

[moodnacreek]

Diesels are better but its just an engine. I would be much more concerned  about the machine ; size of wheels,blade size,set works,feed  capacity etc. These things are hard to change later.

[scully]

Go with the big gas on that mill I think you would be much happier , But if you go up to a 40 or better well Diesel is the way to go IMHO !

[Grower]

I fitted a Mitsubishi K3H 24hp diesel engine and it runs well! I couldnt have made a better choice, she lugs away in heavy going ie 3 foot diameter logs make her blow a bit of smoke but she always wins the battle. I want another K3H for another build but can't find one, anywhere in the country (NZ).

[jpassardi]

First off: I love diesels, my pickup and all equipment are diesel.
Based on description, it appears you're looking at an LT15, I recently upgraded mine from 15 hp to 25 hp Kohler (non-efi). Made a huge difference.
Go with the 25 which makes 39 ft#, the 10 diesel won't make that and being single cylinder will shake like a dog pooping peach pits.
The name of the game is power: the more the merrier. More HP allows quicker feed rate which prevents trapping sawdust in the gullet and kerf and cutting into fine powder = wasted energy.

[rusticretreater]

The right choice is the 19hp Kohler or for $500 more, the 25hp Kohler

Kohler 25 HP, 39.9 ft.lbs torque at 2800rpm
Kohler 19 HP, 35 ft.lbs torque at 2850rpm
Yanmar 10 HP, 20.1 ft.lbs torque at 2700 rpm

The Yanmar has a very flat torque curve up to 2700 rpm and then it drops like a rock.

If you expect to do the occasional 25" log but most of the time smaller diameter logs, the 19hp will do just fine.  The Yanmar will limit you to much smaller logs.

[Southside]

Torque is king when running a sawmill.  HP is a good measure of how fast your band will be moving when you enter the log, torque will decide how fast that band remains moving after you are in the log - and that's all that actually matters. 

[Peter Drouin]

That's why I like my 52-horse cat on my 40 Super It will cut almost as fast as a 70

[Ianab]

Diesel is probably worth 1.5 times the HP of a gas engine in the sawmill scene. That's because it's torque curve is pretty flat. When you bog the saw down with a tough knot, the torque doesn't drop much, and the saw doesn't bog down, lose speed and make a wavy cut.

But the engines are more expensive and heavier. For a small manual mill will you see enough advantage? For a commercial operation, the diesel is certainly a decent option. For a smaller hobby, part time mill, the gas engine will get it done,  and run for years. 

[Southside]

That's why I like my 52-horse cat on my 40 Super It will cut almost as fast as a 70

My Super 70 has the 55 HP turbo, but it's also running a hydraulic pump all the time so you might have more torque to the wheels with your set up, I can see why it cuts so fast. 

[SawyerTed]

Is the juice worth the squeeze?  Added price of the diesel might be hard for some to justify, especially a hobby sawyer.

Looking at the Woodmizer mills, I wouldn't even bother with a 10 hp diesel on a small sawmill. Too costly for the performance difference.  The 10 hp diesel is $1,200 more than the 19 hp gas on an LT15. The 16.9 diesel at $3,800 more would be money better spent IMO, IF a diesel just has to be on the mill. 

The comparisons should be between a 19 hp gas and 16.9 hp diesel, price versus performance.  And then comparison between 25 gas and 24 hp diesel, price versus performance.   The price on those smaller diesels isn't too bad but a hobby sawyer might not have the budget for an added $6,000 plus for a 24 hp diesel. 

Having run a 25 hp Kohler gas engine on an LT35, those things can saw lumber just fine but probably not at the speed a 24 hp diesel would.  There would be a lot of satisfaction in running a diesel on a smaller mill especially if the money isn't a big concern.

On the bigger mills, the LT40 Super and LT50 , the diesels put those mills out of the "high end hobby mills" for most people.  The up charge is $11,500 to go from 38 hp gas to 36 hp diesel.  I just have to think Woodmizer is guiding buyers toward the gas engines with their prices on diesels.

Nobody has ever said "this band sawmill has too much power".  So the largest hp and highest torque one can afford is the way to go. 

[ladylake]

 I went from a 27hp Kohler gas which was underpowered in wide cuts to a 30 hp Isuzu diesel which cut almost twice as fast in wide cuts and uses 1/2 S MUCH fuel plus I have over 12000 hours on it now.  If you saw a lot get a diesel .  In those 12000 + hours I've saved  6000 gallons of fuel or $18000 .  Steve