Posted by Alan Bowes on January 06, 1999 at 21:22:19:
In Reply to: 3500 Dodge Diesel or F350 Ford Diesel ??? posted by Terry on January 06, 1999 at 17:44:39:
I've been eyeing these models a bit myself of late and I've test driven several variants of both. I haven't tried the Dodge diesel with an automatic yet, but I've driven both the 6-speed manual and 4-speed automatic Ford diesel. My opinion is that with the diesel, get the six-speed manual transmission. The diesel develops good torque, but over a fairly narrow RPM range. The six-speed manual helps keep engine RPM within the optimum section of its torque curve. Also, the diesel might be better with the 3.73 rear end...do some research on this.
High engine torque is all good and nice, but you can't forget RPM and how a transmission acts as a torque multiplier. Since gasoline engines tend to have a much wider torque curve than diesels, you can still deliver as much (or more) torque to the wheels with a gasoline engine due to gearing. For example, if you are going X miles per hour with a diesel at 2000 RPM at 1:1 through the transmission, you won't be able to produce as much torque at the wheels as you can with say, the Ford V10 when the V10 is in a lower gear and running at a higher RPM, such as 3000 RPM and a 1.5:1 ratio through the transmission. This ratio would give you the same road speed, but more torque at the rear wheels. And at that RPM, I believe that the V10 is farther from its redline RPM than the diesel, though I'd have to check the specs to be sure.
Everyone is talking about "torque" these days, but don't discount the value of "horsepower," which is an indicator of how much "work" an engine can do. Horsepower is a function of torque AND RPM.
If I were you, I'd go out and do a thorough test drive of several different engine and transmission combinations, both gas and diesel, and see what you like the best. Find some long, steep grades and take some notes.
As to which engine will last longer, well, only time will tell on these new models. A diesel has the advantage of running at a lower RPM, which lowers certain inertial forces, but on the other hand, diesels are very highly stressed engines, with (in Ford's case) a 19:1 compression ratio, naturally high combustion chamber pressures, and a turbocharger to boot, all of which increase stress considerably on the block as well as on the reciprocating parts. Diesel engines have to be built heavier to stand up as long as gasoline engines, RPM difference notwithstanding.
As to fuel economy, I think that the new GM 6.0 liter Vortech looks like a winner, with economy comparable to the Ford diesel, but without adding thousands of dollars to the price tag. It looks like a good mill with a lot of racing-quality components (which I won't list here). It also has an extremely wide, flat torque curve...very impressive!
Still, I do like the feel of driving the Ford Powerstroke with the 6-speed, even if I do have to shift a lot.
One other thing: Unlike in the past, there isn't much difference now between the new Super-Duty F250 and Super-Duty F350 other than suspension, is there? I think they have the same drive train, including the AXLES, just some different springs/shocks and ??? But don't take my word for it. Double-check to be sure. It might save you some money if you get what you want with an F250 instead of an F350.
Alan