Diesel vs gas

[VroomVroom]

I know you can't compare with different transmissions, different size tires, engines......just curious of the comparison between my fathers farmall M, 43 hp , 1953 I believe and the little 2816hst I bought for my mother. As a kid, I was always amazed at what that old farmall would pull. And then discovering it only had 40 hp or there about. Now I see this little engine about 14 or 16 inches long in that Mahindra, diesel powered with 28 hp and wondered how far in pulling power it would have compared to the farmall. Since my father passed away I haven't had the chance to get the farmall out of storage to compare. Or haul any big wagons with the little compact tractor. The shear weight of the farmall, its just a bigger tractor and that's that. The big wheels and probably not far off of over 1.8 times the weight of the little compact. When my father said they got that after using horses it was thought of as a massive powerful tractor. Its a 40 hp gas and the compact is a 28 hp diesel.

Also, the J5 we use sometimes. they have a 115 hp gas engine, flathead 6. Years later they made some of them with a 4 cylinder diesel perkins with 90 or 100 hp. I wondered what the comparison would have been.

 

[buickanddeere]

And turned twice the rpms.

The V10 was not a direct injection gasser and the Cummins was not a tier IV diesel .

 

[buickanddeere]

I don't know where compression plays into it other than to get x number of hp out of a given space. The compression on a diesel generates heat as the air is compressed (compression ignition). The heat is what explodes the fuel vapor since there is no spark plug like in a (spark ignition system). That's why low compression engines, needing overhaul are "addicted" to ether. The older they get the worse the compression the harder to start.....the addiction thing has nothing to do with ether, it's all about compression. Diesels usually are under square with a long stroke and the purpose it to have a long burn period of the fuel to keep the foot-lbs flowing and to help in developing the compression ratio.....that's why 2 strokers are low on torque for the engine size and have to run high rpms.....Old OMC outboards at 25 hp were 30 cu in and ran 4500 rpm. Mercs ran 1 cu in/hp and up and ran at 5500-6000. Half way down the power stroke (every rev on them) the exhaust ports open and out goes the charge. If you didn't get the bang out of your fuel by then you just lost it.

Remembering hot rods of the 60's where they ran 10:1 compression and had to run high test, premium fuel to prevent self detonation, pre-igniton, pinging, or what ever you want to call it. High compression "Edelbrock" for a name got more bang out of a given block due to more compression.

Diesels tends to be under square are the long stoke is required to obtain enough compression ratio. It is much more difficult to obtain 18 to 1 with an undersquare vs and over square engine .

 

[buickanddeere]

87 - octane gas is about $3.50/gal now in CA; diesel is over $4. You prob have to go to Hawaii
to find prices that high in the US.

I notice that the smallest diesel engine sold now in CA (in new excavators) seems to be 3-cyl, Yanmar, Kubota, or
similar, and only about 10 hp and a bit over 700cc. A 420cc gas engine (CARB/EPA-compliant) puts out 15-16hp.

If the tier IV emissions regulations had not been relaxed for diesels under 25 HP . Diesels under 25HP would be very expensive and rarely used .

 

[buickanddeere]

Check you formula and math . The HP does not increase as the engine luggs down to the torque peak.

Well I should have said with natural aspirated diesels and turbo diesels without electronic control . Yes it is possible to tweak turbo boost , cam timing and injection timing to make a diesel 田onstant HP from it痴 菟eak torque rpm to it 菟eak HP rpm.

 

[buickanddeere]

Somewhere the question was raised about a 2018 direst injection gasser vs a 2018 tire IV diesel in medium to HD applications .
The efficient per BTU of fuel would be about a wash with the gasser haviing the advantage at less than 100% load and the diesel with a slight advantage at continuous 100% power .
Diesel Fuel due to being “heavier” contains more carbon per gallon and contains approx 111% of the energy a gallon of gasoline does .
Diesel however does not burn as clean as gasoline . Something similar to propane burning cleaner than gasoline as it’s a “lighter” fuel than gasoline . Something to consider with the cost of particulate filters, urea injection, EGR cooler etc . Plus the fuel filters, glow plugs, , extra batteries etc .

 

[ovrszd]

The V10 was not a direct injection gasser and the Cummins was not a tier IV diesel .

Please explain how that makes a difference?

 

[dfkrug]

If the tier IV emissions regulations had not been relaxed for diesels under 25 HP . Diesels under 25HP would be very expensive and rarely used .

And indeed that is what has happened. A quick search for small single cylinder Tier IV EPA-compliant engines yields 2 makes sold in the US: Hatz and Kohler. Neither seem to be CARB-compliant, so not available in CA. Also, the former, in electric-start, is over $3K + tax and shipping. Very expensive and rarely used! A CARB/EPA compliant gas engine is under 1/10 the cost.

I just went thru trying to import a non-compliant 11hp ChangChai diesel engine in a mini-X. Many folks have gotten around the EPA inspection, but I could not. Attached is the EPA Form 3520.

 

[Snobdds]

Duty cycle on Diesels are much lower than on gas motors.

The diesel can work half as hard to produce the same power, which is reflected in RPM's.

Diesels always win in this debate...

 

[MossRoad]

Duty cycle on Diesels are much lower than on gas motors.

The diesel can work half as hard to produce the same power, which is reflected in RPM's.

Diesels always win in this debate...

That's a blanket statement that is proven incorrect a couple times. See the engine specs on my IH2500b with both gas and diesel engines that I posted earlier. The gas engine is smaller, produces the same power, at a tad lower RPMs.