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 | Paul Bookbinder
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1999-08-22 7212
I own Kubota B1700, and am quite impressed with what it will do with 17 horsepower. However, I wonder why all of the compacts, and even some high end garden tractors, are diesel. Diesels seem from what I have read to be more expensive, more costly to repair, less tolerant of impurities which get by the fuel or air filter, and more cantankerous with regard to cold start-up and warm-up. My garden tractor starts up in any weather, and as soon as I feel heat in the cylinder heads I'm off. Kubota recommends a 20-30 minute warmup in cold weather, and sometimes that is longer than the job I have to do. If I had two otherwise identical machines, one my B1700, and the other a B1700 with a 17 horsepower Briggs and Straton gas motor, would they both perform the same? Will the diesel inherently do more or better work, and is that what makes it worth it?? If the only advantage is longevity, I know I could replace the motor in my garden tractor for less than $1000, so I could do that 4 or 5 times before I paid for a small diesel motor.I don't regret my purchase, but I wonder why the market doesn't have an excellent quality, heavy duty, air cooled gas compact to compete with the current crop of diesels.Thanks for educating me,Paul
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| MichaelSnyder
Join Date: Jun 1999 Posts: 0
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1999-08-23 7233
Paul,I'm sure many will add to this posting. No use in re-writting what is already well written. www.turbodieselregister.com.Kubota's 25-30 minute warm-up sounds a little long to me. Even Cummins only states 5-10 minutes. ....
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| MichaelSnyder
Join Date: Jun 1999 Posts: 0
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1999-08-23 7248
Paul,The webmaster of turbo diesel register just informed me that he has not put those articles back onto his new webpage as of yet. He is in the process, but that doesn't help you today. If you've ever used a 17hp gas & a 17hp Diesel, for the same tasks, I think you would be able to answer quite a few of your questions. Diesels are not only naturally more efficient, they are that way in design as well. One of the reasons is BTU. A gallon of diesel fuel is quite a bit higher in BTU's than gasoline. Thus more power can be produced with the same amount of fuel. Secondly, a Diesel varies its fuel to air ratio with the amount of load placed on it. Meaning that a diesel idles at about 100:1 fuel to air ratio, and still maintains a miserly 25:1 ratio under load.Gasoline engines are a constant 14:1, regardless of load. Secondly, Tractors are generally machines that are required to be strong in the area of turning shafts. Otherwise known as Torque. Take the Dodge ram for example, a 5.9L gasoline engine puts out 335ft lbs of torque, the 5.9L Cummins is 460ft lbs of torque. Taking it one step further, My brother-in-laws 5.9 gasoline and loves it...I mean gas, he gets 12 mpg. My Cummins averages 17-18mpg.His truck in tow dies on a hill, mine seems to enjoy the ride. The 5.9 gas could be made to put out 460ft lbs of torque, but then you would be more interested in finding the next gas station, rather than the hp it puts out. Gasoline engines are great for getting groceries and moving things from A to B.Diesels were made for work, and work for a real long time. As far as problems with dirt in the fuel, its no different than a fuel injected gasoline engine.Stop by that page I mentioned, when he has those articles back. ....
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| Paul Bookbinder
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1999-08-25 7326
So the chief advantage is torque per unit of fuel consumed? What about the old classic farm tractors, which I would guess had plenty of torque judging by the antique tractor pull I went to last weekend. Do they achieve this at the expense of fuel economy, or via gearing??Lets now create a second fictional machine, my B1700 with a 25 or 30 horsepower gas motor. How would it compare with the B1700 I have?If you think I am better off waiting for the articles on the turbodiesel site, I will, but if you have the time I find this discussion quite interestingThanks,Paul ....
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| MichaelSnyder
Join Date: Jun 1999 Posts: 0
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1999-08-26 7340
Paul,I'm no expert, so I'm not sure its the "chief" advantage. The mistake that people often make, is stating that a 17hp Diesel is more powerful than a 17hp Gas. 17hp is 17hp regardless of how or what makes it. The thing to remember is that a typical 17hp gas powered engine makes that hp at 3/4 throttle or more, with significate loss in power below that. A diesel usually makes most of its "power" at 1/4-1/2 throttle. And when its all said and done.the Briggs will need re-fueling, and the Diesel will still be at 1/2 tank or greater. As far as the old tractors as concerned, Take notice to the size of the engine, in relationship to the hp output, including the fuel consumption. But fuel consumption probably wasn't an issue back then. And +150hp engines didn't exist in a tractor platform. But imagine if it did? Your old IH or JD would have been the size of a train. Not just in engine, but to also support the 500 gallon fuel tank, needed to finish a field without re-fueling. ....
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 | lsheaffer
Join Date: Jun 1999 Posts: 1082 Northern Illinois 
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1999-08-26 7341
Back when the old classic farm tractor were made, the diesels were not very advanced. Technology has improved immensly. When it was cold those old farm tractors weren't always the easiest thing to start either. Going to diesel did away with the 2 biggest tractor problems--ignition system & carburation. If you plug a diesel in with a water heating device it will start just as easy in winter as summer & you don't have to worry about choking it too much & flooding it. Fuel consumption was a big factor. A gas JD4020 used 8.3 gals/hour & got 10.5 hp/gal. The diesel used 6.4 gal/hr & got 14.2 hp/gal. (Nebraska tests). Another factor becides less maintainence (no plugs or points) was longer overhaul interval. Rule of thumb- gas farm engine 2500 hours till overhaul, diesel 5000hrs. I have a 135 hp diesel with 7700 hrs & never been bored or sleeved. The other factor that has been explained is torque. As long as rpm's are up the gas does fine. If rpm's drop the diesel will keep going, The gas won't. The diesel has more luggng ability. One note. The old farm tractors you saw at the tractor pull were probably finely tuned & were probably putting out a lot more hp than the way they came from the factory. If they were hooked to a plow & ran 18 hours a day, I doubt, they would last very long. ....
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| MichaelSnyder
Join Date: Jun 1999 Posts: 0
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1999-08-26 7348
Excellent posting, LenGood point about the gas "pullers" ....
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| Paul Bookbinder
Join Date: Posts: 1
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1999-08-26 7352
Thanks for all the input. I guess I should just use my tractor and stop wondering about why they made it the way they did - the engineers must know a lot more than me. One thing I will attest to is fuel economy. I go 10 hours on 5 gallons, heavy loader work, dragging my horse ring. whatever. Uses a lot less fuel and does a hell of a lot more work than I figured it would when I bought it( gee, guess I answered my own question didn't I) ....
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| David
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1999-08-26 7355
There is a pretty good comparison of diesel and gas engines here.--Regards,David ....
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| David
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1999-08-26 7356
Whoops. url didn't post.http://www.cummins.com/ram/ramqa8.html--Regards,David ....
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