Is it time for a gasoline engine tractor?

[jmc]

Torque doesn't do work. Force over distance with relation to time is a measure of work. When you say torque, are you referring to torque rise when lugged down during an overload condition ? With a hydrostatic or powershift machine the point is mute.

Actually, the units of work and units of torque are the same: pound(force)-feet, for example. Work per unit of time, as you mentioned, is power. Power and work are totally different. A rat in a squirrel cage can plow a field if the gearing is right and we give him enough time.

 

[Oldpath05]

Yes and a pound of diesel weighs more then a pound of gas

 

[jmc]

The other thing about gas vs diesel efficiency, besides fuel BTU content and compression ratios, might be the higher gear ratio to get a gasoline engine's sweet spot RPM down to a useful RPM on a tractor. For example, my old Ford 1920- 34ish engine HP deteriorated to 29ish HP at the PTO. So, say 20% drivetrain loss from gear friction (and churning the oil bath). I think gear train frictional loss is proportional to the gear reduction ratio, so if you have to take 3600 RPM on a gasser down to what works at 1800 RPM on a diesel, you've doubled the frictional geartrain loss- no small deal.

 

[Jerry/MT]

Considering all the angst and disappointment over TIER IV diesel engines and tractors, is it time for a manufacturer to bring back a gas engine tractor? I mean, they worked well for lots of years under lots of conditions.

My understanding is that Kubota currently sells gas engines to repower diesel tractors?

Those of us who farm and ranch are being done a great disservice by the EPA with emission controls for farm tractors. Farm tractors are minimal contributors to air pollution and the expense driven into the purchase cost and the cost of ownership is much greater than any perceived benefit. But if you have regulators their gonna' regulate.

 

[Redneck in training]

This argument has played out over the last 100 years, gas lost a long time ago; more expensive, hard to store, dangerous to use, has less energy, costs more to refine, and gas engines don't produce the toque need to do jobs a tractor performs, gas engines require more maintenance, and are shorter lived. It's a no brainier it's diesel. Oh, by the way a clean diesel produces way less CO2 then gas, just added that for a modern twist. HS

And can run on various fuels.

 

[Redneck in training]

The other thing about gas vs diesel efficiency, besides fuel BTU content and compression ratios, might be the higher gear ratio to get a gasoline engine's sweet spot RPM down to a useful RPM on a tractor. For example, my old Ford 1920- 34ish engine HP deteriorated to 29ish HP at the PTO. So, say 20% drivetrain loss from gear friction (and churning the oil bath). I think gear train frictional loss is proportional to the gear reduction ratio, so if you have to take 3600 RPM on a gasser down to what works at 1800 RPM on a diesel, you've doubled the frictional geartrain loss- no small deal.

I don't think that is correct statement. PTO rpm is set by manufacturer little past of the maximum torque (near best specific fuel consumption) while maximum power is produced at much higher rpm. Google performance curves for the engine to see what I am talking about.
Here is example Kubota EA330 - Kubota Model EA330 Diesel Engines - EA Series Engine

The lowest fuel consumption is between 2000 and 2400 rpm. Maximum torque is at about 2000 rpm. So gears for PTO will provide 540 rpm at about 2400 - 2500 rpm because (for stable operation) you want the torque to rise if rpm start decreasing due to high load.

 

[buickanddeere]

The other thing about gas vs diesel efficiency, besides fuel BTU content and compression ratios, might be the higher gear ratio to get a gasoline engine's sweet spot RPM down to a useful RPM on a tractor. For example, my old Ford 1920- 34ish engine HP deteriorated to 29ish HP at the PTO. So, say 20% drivetrain loss from gear friction (and churning the oil bath). I think gear train frictional loss is proportional to the gear reduction ratio, so if you have to take 3600 RPM on a gasser down to what works at 1800 RPM on a diesel, you've doubled the frictional geartrain loss- no small deal.

Farm tractors all ran similar or identical rpms for the gas and diesel versions.
Just as a point Yanmar has made a 3600rpm single cyclinder air cooled diesel for decades. is it a lousy performer ?

 

[buickanddeere]

And can run on various fuels.

Grandpa's old all fuel AR would run on gasoline, moonshine, paint thinner, kerosene, #1 diesel and #2 diesel. Now that is "flex-fuel". Try those various fuels in a Tier IV EPA diesel.

If the EPA had stopped at Tier II instead of current Tier IV and going to Tier V in 2019. It would be all moot point as Tier II Diesels would be the preferred engine in most applications with gas usually a distant 2nd.

 

[Redneck in training]

Grandpa's old all fuel AR would run on gasoline, moonshine, paint thinner, kerosene, #1 diesel and #2 diesel. Now that is "flex-fuel". Try those various fuels in a Tier IV EPA diesel.

If the EPA had stopped at Tier II instead of current Tier IV and going to Tier V in 2019. It would be all moot point as Tier II Diesels would be the preferred engine in most applications with gas usually a distant 2nd.

I have two diesel pumps in opposite directions in about 12 miles from the farm. One sells both red and normal diesel and the other sells bio-diesel. So once a while I buy bio-diesel because I am in town. Didn't see difference in tractor performance.
Bio-diesel produces much cleaner exhaust than normal diesel. I was working on some equipment my employer supplied to underground ore mine in Canada. Switching to bio-diesel significantly improved air quality underground. Initially it was total disaster because the bio dissolved all the crud in tanks and fuel system plugging filters, injectors etc. but after all was clean they said they will never go back to normal diesel.

 

[daugen]

I'm told running biodiesel can smell like popcorn.
while I believe there is nothing like the smell of diesel in the morning,
popcorn would be ok...

what is the cost difference between Number 2 and biodiesel? More than one type/grade of biodiesel I assume too.
Now if you also owned a restaurant, you could use your old cooking oil after some good filtering.

Those older tractors with the large propane tanks; could they stay out in the fields all day? For most of what most of us do, as not "real" farmers, capacity not much of an issue. And I already have a big propane tank on the property. There are some small handtools that run on those camping propane bottles. Since you can't recycle them, or get them refilled, seems an odd solution. But...I think the propane powered hand tools and small mower were a direct result of gasoline powered equipment not starting. I think the gasoline issue may be more of an issue in the Northern states where mowers, weedeaters, etc get used for a smaller portion of the year. Then they sit.

what there should be is a law where all gas engines have to have a fuel shutoff. Then you could run them dry easily, though I've read that's not a cure-all either.

For point of discussion, could we all agree to comparing gas and diesel for a 50hp CUT? Something most of us might have?
Could the best source of proven gas engines for long term use be the engines they use in propane generators, which are converted car engines?

And don't tractors normally have inline engines versus V for compactness? I know Cat 3208's were used in tractors, maybe not for long, of course no engine could be wider than the tires on a tractor... So what inline gas engines are we thinking of? Are we ready for gas turbo fours in our tractors?

With both my tractor and my diesel lawn mower I have to wear ear protection or it's just really tiring after an hour or two.
Would be nice to have a quieter alternative. But not as nice as good performance and much better fuel economy.

Would be nice to see some stats on tractors currently offered with both gas and diesel in the same hp, and see what
today's real world is like, not what many of us remember from 30 or 40 years ago.