What motor lasts longer

[LD1]

msny times that's a cooling issue.. you can take a sprts car with a 350hp capable engine and a cooling system capable for 160hp... the car only uses that 350hp on the hard accel in traffic.. otherwise it's pulling 100hp for most stuff...

many tractor cooling systems are rated for the 'rated' hp output of the engine..e tc.

Tractors are also governed to a MUCH lower RPM.

Govern that sports car to 2500 or 3000rpm and then yea, it can run for hours on end at "red-line"

How about these old Masseys?
Perkins diesel vs. a Continental gas engine. I'd go with the Perkins, they've been making industrial diesels for a long time.
Which is not to say a properly maintained Continental (is this the same co that makes engines for Piper Cubs and similar?) would not last
exceptionally long, for a gasoline motor...

I am pretty sure he was talking about the PERKINS gas motor.

And IMO, that is the perfect comparison. Since the Perkins Gasser and Perkins diesel share the SAME block. Actually, they share EVERYTHING they can that isnt relevant to the fuel they burn. And that would pretty makes to ONLY difference the fuel.

 

[john_bud]

What about a gas engine on a old tractor? A tractor engine is different than a automotive application, a tractor can be ran full throttle all day long and not hurt.

Yes, you're correct. They can. But there are some internal differences that are important that make it possible. The old tractor gas engines are in the 6:1 to 7:1 compression ratio. The diesel is 16:1 to 20:1 range. Efficiency goes up with mechanical compression ratio. Operating temperatures also go up with compression ratio (or down with lowered ratio). So to get the gas tractor engine to be able to run all day long for years, it must be designed to run cooler. That means lower CR and that's good for longevity, but bad for fuel consumption. Didn't used to be that big of a deal back in the 50's & 60's, but nowadays....

If you compare good running 1960's vintage gas and diesel tractors (same make & model, just gas vs diesel with both having the same power) the gas engine will typically have a little less HP but use 1.5-2x the fuel per hour doing the same tasks.


But with all that said (and the excellent info in the rest of the posts), we need to remember that today's diesels are built much lighter than they used to be. The construction is a lot better, the machining is dramatically more accurate, but they now run 3000-3500 rpm vs the old ones running 1500-2000rpm and make 30-50% more HP out of the same displacement. Guess we won't know the longevity for sure for a long time. But I know my 50 year old tractors will be running good 50 years from now... I'm less certain of my 10 year old one!

 

[john_bud]

Me thinks the underlying perseptions of almost everyone, makes the diesel seem like the answer. Those perseptions are very skewed.
You have to break that train of thought and realize, that it is not a fair comparison to group 2 engine types by internal or external size, which everyone does by nature. The fact is you are comparing a diesel that weighs almost twice the weight of the gas engine, and costs 2-3 times the price.
Compare same priced gas engine to a same $$ diesel, and you will likelyvfind your longevity results will be very even. Because for the same $$ you can buy a much more powerful gas engine that could be run much less loaded.

Interesting thought. I can see your point, but it seems that most tractors with larger engines are only in larger machines. If they actually would build one like that, it may work that way. Plus, the gas engines (in cars etc) last easily 2-300k with many going 400k or 500k miles where the old ones would be smoking like a bug fogger in 75-100k miles. I guess there's a lot of modern progress we need to consider!

 

[Soundguy]

are you sure about that?

many of the tractor engines I'm compairing have esentially the same block gas or diesel...
thus same size...

on a ford 3000 for instance.. I'd take diesel over gas any day. and on;y part of that reason is because the holley carbs are finicky, and the points are hard to get to..

Me thinks the underlying perseptions of almost everyone, makes the diesel seem like the answer. Those perseptions are very skewed.
You have to break that train of thought and realize, that it is not a fair comparison to group 2 engine types by internal or external size, which everyone does by nature. The fact is you are comparing a diesel that weighs almost twice the weight of the gas engine, and costs 2-3 times the price.
Compare same priced gas engine to a same $$ diesel, and you will likelyvfind your longevity results will be very even. Because for the same $$ you can buy a much more powerful gas engine that could be run much less loaded.

 

[Soundguy]

can't speak for other brands.. but that doesn't specifically hold true for the fords. loking at say a 601 gasser and a 601d.. the d is just a hair less hp.. AND 10more CI.. 134 vs 144. etc.

hard to draw a hard straight line thru this conversation..

If you compare good running 1960's vintage gas and diesel tractors (same make & model, just gas vs diesel with both having the same power) the gas engine will typically have a little less HP but use 1.5-2x the fuel per hour doing the same tasks.

 

[JoeBuyer]

How about these old Masseys?
Perkins diesel vs. a Continental gas engine. I'd go with the Perkins, they've been making industrial diesels for a long time.
Which is not to say a properly maintained Continental (is this the same co that makes engines for Piper Cubs and similar?) would not last
exceptionally long, for a gasoline motor...

They are both Perkins engines. The gas uses the same block as the diesel. I know Massey used the Continental gas as well, but they also used Perkins for gas. My question was about Perkins gas compared to Perkins diesel.

 

[94BULLITT]

Yes, you're correct. They can. But there are some internal differences that are important that make it possible. The old tractor gas engines are in the 6:1 to 7:1 compression ratio. The diesel is 16:1 to 20:1 range. Efficiency goes up with mechanical compression ratio. Operating temperatures also go up with compression ratio (or down with lowered ratio). So to get the gas tractor engine to be able to run all day long for years, it must be designed to run cooler. That means lower CR and that's good for longevity, but bad for fuel consumption. Didn't used to be that big of a deal back in the 50's & 60's, but nowadays....

If you compare good running 1960's vintage gas and diesel tractors (same make & model, just gas vs diesel with both having the same power) the gas engine will typically have a little less HP but use 1.5-2x the fuel per hour doing the same tasks.


But with all that said (and the excellent info in the rest of the posts), we need to remember that today's diesels are built much lighter than they used to be. The construction is a lot better, the machining is dramatically more accurate, but they now run 3000-3500 rpm vs the old ones running 1500-2000rpm and make 30-50% more HP out of the same displacement. Guess we won't know the longevity for sure for a long time. But I know my 50 year old tractors will be running good 50 years from now... I'm less certain of my 10 year old one!

I think the main reason the compression ratio was lower was because of poor gas back in the day.

 

[john_bud]

can't speak for other brands.. but that doesn't specifically hold true for the fords. loking at say a 601 gasser and a 601d.. the d is just a hair less hp.. AND 10more CI.. 134 vs 144. etc.

hard to draw a hard straight line thru this conversation..

True, the old fords diesels seem to be weaker than most. But, the gas engine is still sucking a lot more fuel and the amount of work you can do between the two is about as identical as you can get.

(and yes, its about impossible to draw a straight line conclusion ! Too many cases where either side is equally correct (or equally wrong) depending on what reference you look at. )

 

[MHarryE]

Question regarding European cars and the statement that European driving is not relevant to USA. I lived there, owned a diesel, and drove it 90,000 kilometers or roughly 54,000 miles in 3 years. They drive a lot. For example they say Paris is home to one million cars and 700,000 parking spots so there are at least 300,000 cars on the road at all times and having driven there a lot I have no reason to doubt it. The general rule I heard from my everybody living there was 200,000 km for a gas engine car and 500,000 km for a diesel equivalent. I hated to leave my diesel there when I returned to America because of the fuel economy and drivability. A diesel has so much better low end torque that you never want to return to a gas clunker, but alas that is what we are stuck with in America. After returning to America I still had to travel to Europe a lot for my job, but then it was rental cars. I always dreaded getting stuck with a gas engine car due to the poor fuel economy and difficulty driving a gas manual in heavy traffic - the constant shifting due to the narrow torque band. But in Western Europe the diesel is relatively consistent although my car came with a recommendation to buy only specific fuel brands (and they had a list of about 6 for each country) for longest FIP life. In the USA the fuel is very inconsistent. At work I had access to repair data I could break down in any way I could dream of - dealer, state, type of job, region, etc. Selecting one machine I found a 4 to 1 difference in FIP failure rates between the best and worst regions. Analyzing the claims I found the difference to be fuel related. That is what the car Diesel engine makers told me is there reason for not supplying them in America although they may build the vehicle in America for export to Europe (Voyager minivans were very popular in Europe in the 90's, every one I saw diesel equipped).

 

[daugen]

Analyzing the claims I found the difference to be fuel related.
In the USA the fuel is very inconsistent.

boy would that make interesting info to get online...do you mean one brand "worked better" than another, or were there brands with
irregular cetane ratings, additives??

I think I'll keep giving my Kubota a shot of diesel additive. And I still get to pay $3.40 a gallon locally for diesel. Such a deal.