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As diesel mills leap forward into the modern era lets take al ook at this classic debate. I want to preface this by saying my knowledge is rudimentary compared to many of you on he boards so there may be a few open ends you can help tie up...



Power/Torque

Conventionally petrol produces more horsepower and diesels produce more twist. This all comes down to use cases. Does your Promaster spend the majority of time around town where a quicker start off the line would be valued. However thats for an unloaded vehicle.

If capacity and force are needed in your repertoire (for most i think so!) then diesel should be your avenue. higher compression ratios needed to ignite diesel means peak power and torque come lower down in the rev band.

Economy

One gallon of diesel contains 147,000 BTU's of energy while petrol only carries 125,000 BTU's. So more gasoline is needed to equal the output of diesel.

But where i always get hung up is on additional costs. If gasoline will go the job is there a point in putting up the additional premium required to equip a diesel, maintain a diesel and pay the higher fuel costs per gallon? And how does this all relate back to towing?

 

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.....cut.........

Power/Torque

Conventionally petrol produces more horsepower and diesels produce more twist. This all comes down to use cases. Does your Promaster spend the majority of time around town where a quicker start off the line would be valued. However thats for an unloaded vehicle.

If capacity and force are needed in your repertoire (for most i think so!) then diesel should be your avenue. higher compression ratios needed to ignite diesel means peak power and torque come lower down in the rev band.

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In my opinion performance differences due to engine torque versus power ratings are so subjective that it leads to much misunderstanding. And it doesn't seem that objective test data makes much difference. And then there is the subject of how do we compare a small diesel versus large gasoline engine, or vise versa. On what basis do we compare gas versus diesel? When engines are of equal power? Equal torque? Equal displacement? Equal weight/mass? Equal fuel economy? Equal cost? I honestly don't know how we can compare on general basis. Only when we compare two known choices like that offered for PM can we get started. But in that case they are so dissimilar that it's hard to compare anyway.

The torque that should really matter is what is delivered to the drive wheels, more so than what is produced at the end of the crankshaft.
 

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City or highway? light load or heavy? Pick an engine based on these.
Max out both vans and go for a long mountain drive or a head wind.
This is where the numbers will change drastically. My opinion.
You WILL get bad mileage on the gas with max payload,the diesel not so much.
 

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You got your answer in the other thread do you think it’s going to change in this one?

If you want a diesel buy one. We’ve given you our opinion!
 

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This guy has been banned for obvious reasons!
 

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Plus DEF fluid cost.

By my math, it's equivalent to paying 0.14/gallon more for fuel.
I get 1500 miles per gal of DEF and pay $3.15/gallon so it is .0021$/mile for DEF NOT 14¢ but 2/10 of a cent per mile or about 5¢ per gallon YMMV
 

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RD, that’s a good way to look at it, and puts DEF cost in perspective. If a van gets driven 10,000 miles a year, the +/- $20 gets lost in the “budget” noise.

By comparison, diesel at $3/gallon would cost $1,200 at 25 MPG. What has always concerned me most about vehicles though are repair costs once out of warranty. For example, $500/year in repairs, if spread over the same 10,000 miles, would be equivalent to an extra $1.25 per gallon. And today it’s easy to blow $500 per year on repairs once a van gets around 200,000 miles like my Ford E-Series if you don’t do much of it yourself.

This is one reason I prefer simplicity over performance and or fuel economy. I prefer to minimize risks of expensive repairs even if I have to pay more monthly in fuel costs. It’s like spreading the cost out monthly.

Buying a new diesel PM is currently a moot point, but the idea of ignoring the little stuff like DEF that doesn’t affect total cost of ownership significantly is still valid. I’m personally most interested in simplest engine they can come up with.
 

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City or highway? light load or heavy? Pick an engine based on these.
Max out both vans and go for a long mountain drive or a head wind.
This is where the numbers will change drastically. My opinion.
You WILL get bad mileage on the gas with max payload,the diesel not so much.
Ours is pretty close to max payload and we were pleasantly surprised by 21mpg on our trip last fall (mainly highway driving).
 

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Last year driving home to VA from FL with just us in the van. (2014 136 ht gasser) About 800 miles. Our PM was averaging 23 mpg driving it gently. Only about half the time spent on hiways, rest was all blue line back roads at 55 mph. That trip was a real pleasure. Funny thing was it only averaged 19-20 mpg on the trip south. I did a few controlled "Italian tuneups" on it using entrance ramps and rolled on power to let it rev up. I have to wonder if that cleaned the cobwebs out of it. It sure felt more effortless on the way home.
 

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When I left Tucumcari NM on my trip I traveled on Rt 54 right into a hard wind and climbing thousands of feet as well. I was distraught that I seemed to be getting only 22mpg! It all depends on your point of view. When I get a couple of free hours I’ll do the complete trip’s calculations. I don’t believe I got my usual 26 mpg. The diesel did pull up there in 6th gear and drove wonderfully as it always has. I’m getting past the mileage that lots of posters here have had transmission and engine problems with their gassers that due to the shorter warrantees, cost them thousands of dollars. All of us will have repairs if we keep our vans long enough.
 
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