Eco-diesel

I purchased trucks for a company years ago and an engineer developed a formula to help decide if diesel was the right choice.  These were 3/4 on pickups that made deliveries and pickups within a 200 mile radius.  No trailer pulling.  The main decision point was miles driven per year.  If it exceeded 50,000 then diesel was the choice.  They were traded every five years.

This is far different duty that my personal truck.  If there was less up front premium with a diesel I would like one, but I am not sure I could build the economic justification.

Originally posted by ToolmanJohn  Diesel can't be justified on fuel economy alone. Especially if it's going to be the daily driver as well. A diesel holds the advantage for towing because of the high torque output at lower RPM's. This is why they last a long time and get decent fuel economy. If a gas engine was also kept at low RPM's it would get good fuel economy. Fewer RPM's, less fuel used.

Part of the reason for diesel engine longevity is because of the crank/connecting rod/piston fortification required to deal with the rather high compression ratios used in diesel engines. If you look closely at the Ford EcoBoost engines, you will note that they have been "beefed up" in those areas. Of particular note is that they use 6-bolt main journals. 2-bolt are "standard" in gas engines, and 4 are "performance" modifications, 6 are almost unheard of in a gas engine. You will find that 4-bolt are common in diesel, with higher-end diesels sometimes have 6-bolt. You will also note that EcoBoost (turbo charged gas engines) produce almost 100% of their torque at only 2000 RPM, and are producing 90% of max at only 1700 RPM. That torque curve is virtually flat all the way to redline.That used to be diesel territory, but is one reason why EcoBoost engines are so great for towing.

Originally posted by DavMar Interesting thread and its sparked an interest in me learning more about diesel motors that were used in buses and RV's such as the old Cat 3028 and Detroit Diesel's 6V92 and 8v92. Though what has really caught my interest and completely confuses me is what is the best late model diesel pickup truck sold today? Fords Power Stroke, Chevy Duramax, or the Dodge Cummings and what size engine? Now I don't want to start a flame war but it seems we have some members here that are much more knowledgeable then I that can enlighten me and we can have a informed discussion. So what's your opinion as to the best truck and why?

Those are all good these days. The early GM diesels were "converted" gas engines that did not last long because of the aforementioned issues with the weak lower end (crank/connecting rods/pistons) that they grew out of. I believe those issues have all been worked out. I have yet to see a "bad Cummins".

That said, I think diesel is headed for a long, slow decline in popularity. After the VW (and other Mfgs) "cheating" scandals, it's clear that diesel fuel has a big problem in the long term. Perhaps not as bad as coal, but not far behind. One of the issues is sulfur content of diesel (note that most US diesels aren't sold in Mexico because of their high sulfur content diesel fuel). Mexico may eventually fix that issue, but I think the handwriting is on the wall long term.

Does diesel have 5, 10, or 15 years? I don't know. I think 15 years is probably as good a guess as any, but I'm not placing any bets.