Gas vs. Diesel

[Dugsaws]

Just wondering if anyone ahs ever went from gas engines to deisel engine on the same mill. (bandmill) And if so , what were your results, better cutting, more power etc ?

[D._Frederick]

You can put a gas engine of the same hp. on a mill for less than half of the cost of a diesel. The diesel engine will have more torque for the same displacement as the gas. If you match the horsepower and torque of each engine and get the correct size pulleys there will be little difference in performance. The diesel will run on about half the fuel of the gass engine, but you can never pay the difference in cost on fuel savings.

[Fla._Deadheader]

"D", Down here, there are ads in the paper for VW and Toyota Diesels for $100.00 and up. I REALLY considered one, but, too much environmental crap that I Don'T know how to hook up.

[Neil_B]

Mine came with a turbo diesel on it so I can't say whether it improved the production or not. Diesel would be alright if the cost of fuel came back down but now it's about the same as gas so would take much longer to make up the cost difference. They are supposed to last longer than gas engines so that's one added bonus. I can get coloured fuel cheaper than at the pumps but then would have to put a tank in for bulk delivery. Will consider that later as my mill, edger and backhoe are all diesels. Both trucks are as well but hate to get caught running coloured in them  

[Buzz-sawyer]

A great befit of diesel..... besides producing massive low end torque...
is that a diesel engine gets rughly 2x the mileage...or run time of the equivelent gas engine instantly cutting fuel costs in half.....
sorry just saw D fredrick posted this info already :D ;D

[Fla._Deadheader]

Hey Buzz, could ya 'splain this "Diesel low end torque"???
  Seems to me that a Diesel ain't worth squat, till ya get it wound up???

[Buzz-sawyer]

Hey Harold
Well the differece that you see is probably acceleration...at low rpm ...you are correct ....acceleration is sacrificed in a diesel, for torque (just like we see in gearing ratio's speed vs. torque or amps, volt ratio) you give one to get the other ...
I believe the high compression ratio and mass of the engine componets cause the diesel to have torque at low rpms....
but at idle or low rpms diesel are hands down more suitable for high torque loads...( like running hydraulics or gen sets....also for pulling ...the bottom potion of the torque band curve is where the diesel shines...gas motors I believe shine at 1/2 or farther in the acceleration cycle....(me no expert ..me just simplet cave man ;D ;))
make sense?

[Percy]

I had a LT40 with a Wisconsin 35 hp for about 6 years and now I have an LT70 with the 42 hp Kubota. No difference really cept you dont have to kiss the Kubotas butt to keep it running while it warms up, the Wisconsin was awful. The kubota has more power but with the wood I cut,  mainly(WRC,Spruce, Birch), the blade is usually  the limiting factor here. The Kubota is chinsey on fuel compared to the gas, as stated earlier, and the oil changes are less frequent. I could have rebuilt the Wisconsin in my carport if needed but I sure wouldnt tackle the Kubota.  There is no gas option for the LT70 so I didnt have to ponder that decision when ordering the mill. When Im real busy, I do notice a big difference in the fuel bill(100.00 per month) and I think the diesel will eventually pay for itself ;D

[mhasel]

I have to agree also with Buzz-sawyer, a diesel can just sit there at an idle and still pump out the HP. It was also my belief that the higher compression of the engine contributed to this. When you can choke out a diesel you have done something to be proud of 8)

On a maintenance note, a diesel really shines so long as you keep the fuel filters clean and free from air you are good to go, other than the normal oil and air filter changes. I'll take a diesel any day of the week for HP application.

[Fla._Deadheader]

Well maybe, Buzz. I just figgered that diesels are rated very differently in HP vs gas engines. At idle or very low rpm's, I don't believe there IS much difference unless you have one of them old Cat low speed (800RPM) diesels.

  I had this discussion with Marine mechanics, when I converted an OMC outdrive from gas to Diesel. They claimed "low end torque" would destroy the outdrive unit. I figgered the rough idle (firing) of the diesel, would create surges against the gears, so, we kept the idle up just a trifle, till it ran smooth. ??? ???

[Buzz-sawyer]

Well
 as I am sure you already know many diesels are at 1800 rpm while gas is at 3200-3600rpm...
as far as anything else regarding low end power(torque or twisting force)...I cant offer much more than my previous explaination...I like a diesel motor though ....low maintenace, great fuel economy, last forever with a little love....I have often wanted to put one in a boat ...
did ya go ahead and if so , did you convert to marine heads or just run it standard closed loop coolant...did ya like it?

[Fla._Deadheader]

Buzz, I like diesels also. Rebuilt a GM pickup 6.2 Diesel, NOT the 350 gas conversion. : ;D

  Had the boat hooked up with original heads and a water cooler and anti-freeze, for corrosion. Ran well, same as the 305 I took out. Sold it before I ran it much.

[Buzz-sawyer]

Harold I got one of those 5.7 diesels...was the second one from the factory(of course 1st failed)....besides being built to light in the rods and crank...the big problem with those things was oil change intervels...I got this on with 30k on it and it had been oil changed religiously every 2k....still runs great at 24mpg!

[Fla._Deadheader]

That 5.7 is the gas conversion model. The 6.2 is molded right on the block. Everything is heavier, a "true" : Diesel. Took it out of a van.

  The one I rebuilt was in a pickup, that pounded a bearing out and I got a rebuilt crank for it. Jerk said, "it has a little something making a slight noise". : It seized while I was checking it out.   :  Gave him $500.00 for the truck. ;D

[D._Frederick]

If you look at the torque curve of the big three ( Cat, Cummin, Detriot) diesels, they are a lot flatter than any of the gas engines. The torque is controlled mostly by cam and valve timing, and the injection of fuel over a longer time period. With circle sawmills, the diesel torque makes a big difference in sawing, even if the rpm falls off the cutting rate can be maintained. With a gas, if the rpm fall off, the cutting rate has to be reduced.

[Dugsaws]

The reason I posted this question is the onan 24 hp gas motor that is on my mill blew up, I found the replacement in a new gas 24 hp, but I also found a new 27 hp diesel that the mill manufacture said is the same one that was installed the same year my mill was made, and they said it would bolt in the same as the gas with and a couple minor modifications like heavier chain to suspend the motor and a bigger solenid, anyhow the diesel is factory new and is onlt going to cost about 8 to 9 hundred more than the gas, and was wondering if the extra $ was worth the difference, I have been hearing it will be worth the extra, but wanted to get some more opinions.

     Doug

[Neil_B]

Percy,
Your motor is probably the 36 hp continuous, 42 peak. Is that correct? If so it's the same motor I've got. What rpm are you running on yours? Manufacturer told me to run mine at 3000 which is almost the max for the 36hp. This engines peak torque is around 2500 rpm. I would like to put it down around there and keep it as it consumes a lot less fuel.

Neil

[D._Frederick]

I see the 25 hp. Kohlers engines advertized for about $1500 that WM is now using.

[Fla._Deadheader]

I paid $1500 US for the 24HP Honda.

[Dugsaws]

I found onan the for 1700 and the Deutz for 2500 plus shipping, but I am waiting to find out if it has a cold starting aid or not, and I think that is going to be the deciding factor.

[Frickman]

Dugsaws,

Here in Pennsylvania we pay over 40 cents a gallon road tax on gasoline, and all gasoline out of the pump has to pay it, as you can't buy "off road gas" like you can diesel. You can get a refund if you are a fire department, farmer, etc., but it is a big hassle. I'm sure that around your place you store bulk off road diesel for the farm, so buy using it you are saving over 40 cents a gallon, not counting the performance advantage. It shouldn't take too long to pay off the extra cost of a diesel.

[Percy]

Percy,
Your motor is probably the 36 hp continuous, 42 peak. Is that correct? If so it's the same motor I've got. What rpm are you running on yours? Manufacturer told me to run mine at 3000 which is almost the max for the 36hp. This engines peak torque is around 2500 rpm. I would like to put it down around there and keep it as it consumes a lot less fuel.

Neil

Heya Neil
The manual just says 42 hp, so I dont know about the continuous thingie ;D. Its a V1505 with a little dinky terbo, cute as a button. I dont have a tach so I couldnt tell you the rpm. It was factory set but it sounds about  the same as a Cutting Edge Mill I saw a while back that ran at 2900. A tach would be a good Idea and Ill have to give that some thought.

[ADfields]

Dugsaws when I lived in Arizona diesel was the only way I ever wanted to go but hear in Alaska it has a couple of little ticks. :-/   Can you say jelled up, wont cold start and likes to run so cold that they never get to proper working temps. >:(   So think on this if you work in the cold like 10 degrees out.   Diesel will last 3 times as long as a gas motor so with the fuel savings it's the way to go if the cold weather work is not a problem for you.  Good luck. ;D
Andy

[Neil_B]

Percy,
Yep 1505 is what I've got too. It is 36 continuous and 42 peak. I've got the manual for mine, although not very elaborate, so if you ever need any info just ask and I can scan it for you. I've also got the hp/torque specs somewhere in the harddrive. Think I downloaded it from the Kubota website.
Thanks anyway.