Just remember that engines, gas or diesel, are air pumps. In higher elevations a power adder, supercharger or turbo, supplies the extra, needed oxygen to keep power levels constant.
Having driven NA EFI gasoline , turbo gasoline and turbo diesel's in mountains, a turbo gas engine performs as well as a turbo diesel. But, since no OE offers one and you'll void your warranty and spend a lot of money adding one to a new truck. So, to get the best performance in the mountains, the turbo diesel if the best choice.

 

It's not just the high altitude where CTDs have an advantage, and I agree that they work well up high, but it's the grade itself where they really shine.
When you hit a grade under load and keep your foot in it you can just let it roar. They sound like a locomotive and there's no reason to downshift unless it just won't pull the grade. No winding it out, no stiring the box, just a wonderful roar. I guess the thing that impresses me the most is how a CTD makes a big job look effortless. And most of the time, when it's not at its max, it just seems like a Sunday drive. In the same situation, one of my old gassers would be screaming away and I'd be hunting for the next gas station

Wetspirit

 

They work GREAT at altitude and will pull the pAnts off a gasser, same elevation and do it longer to boot.

Big Jimmy

 

Guys, CTD's work great in the mountain and hills....but, when you cool off the engine very quickly after a long hard pull, can cause a number of problems. I would make sure you use synthetic oil if you do a lot of Mountain driving, especially when towing.

You might also want to get yourself an exhaust brake.

 

I would NEVER shut down my truck right after a hard pull! Even an unloaded run on the highway and then a stop for fuel, just let it run. Is that what you mean by cooling it off quickly? Of course, shuting it off right after a hard pull overheats the turbo bearing. So how do you cool it off too quickly?

Also I can't put an exhaust brake on because, as I understand it, the early 48REs don't have the roller thrust bearing required for braking. Isn't that why Dodge won't OK them for the '04s? I haven't decided if I should kick myself or not about not getting the six speed. I guess the grass is always greener..........

Wetspirit

 

Shutting down without letting the turbo cool down isnt what Im talking about....Im talking about towing a 28 ft fiver up a five mile mountain pass. Believe it or not, when you crest the hill, mountain, etc., things can cool down REAL quick. Oil can coke in the turbo and cause problems - the deposits in the oil can plug the piston cooling ports - which could mean a cylinder job. Which is the reason I mentioned the synthetic - it breaks down at a much higher temp than dino and likely wont coke like the dino either.

 

Turbo charged diesels do much better than naturally asperated engines at altitude, but still suffer a loss from lower altitude power levels.

 

two words sum this one up:


FORCED INDUCTION

even gassers do alright at high altitude with forced induction....

like say....... a Rolls Royce Merlin V12

 

I agree, but how would you address that characteristic in your towing style?

Take the top portion of the grade at a lower speed/egt's and higher rpm's??

Or is there a way to slow down the cool off after the summit and coasting the other side?


Thanks

Big Jimmy

 

i dont understand the oil coking on cool down. understand engine cooling too fast. oil should coke when exhaust is extremly hot?

 

Normally, oil is flowing through the turbo and it takes the heat away. If you shutdown a hot turbo, the oil flow stops, and the heat in the turbo is more than the residual oil inside it can handle. As a result, the oil carbons up, formish either "coke" or a hard varnish like sibstance, both of which are bad for turbos.

This was a real concern a long time ago when turbo bearings had different designs, and oil was not as good as it is now.


Turbo coking is pretty much a non-issue anymore. The only time I'd worry about letting the turbo cool is if you've been running the truck hard-- towing heavy or using a lot of loud pedal.

If you're just putzing around town, there's not really a need to let the turbo cool off, even with regular petroleum oil.

jh