Quote:
Originally Posted by Malaki86
Next question: what gear ratio & engine size would be considered "ideal" for general otr, hauling a mix of freight, in a variety of areas?
For example, right now I primarily run the northeast. The company truck I'm in has a 425hp Detroit and gets piss-poor mileage. My previous truck had a 465hp ISX (pre-EGR) and averaged 6.5mpg hauling the same freight in the same area.
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I've done lease/purchase on two trucks, and outright bought one. Seems like the most popular transmission you can get your hands on these days is a straight 10 speed. Really not a bad tranny, and I've pulled a whole lot of freight with them.
Of the trucks I've driven, I've gotten good fuel economy with two of them. But the key seems to be in the rear-end ratio. With 3:55 and 3:73, the economy was crap. With 3:42 and 3:43 (with 22.5 tires) the economy ranged from the low 6s into the high 7s. Depending on the load, terrain, and wind direction. Running westbound across NE (into the wind) and getting 6.7 miles per gallon was nothing to sneeze at in my book. Not when other guys were telling me they were getting 4 and 5. My best mileage was with a 3406 CAT and an N-14+ Cummins. Both rated at 500 horsepower.
Buying a truck today, things to look at besides fuel economy (a very big issue, without a doubt) are durability and cost of repairs. Cat is one of the highest on repair costs, not to mention the fact that Cat is getting out our engines. Good service, but not much future. Cummins seems to be a bit cheaper to have repaired than Detroit, and I had far less problems with the Cummins than any Detroit I've ever driven.
So, if I were going to spec out a truck to buy today (instead of collecting my Social Security), I'd be looking at a Cummins, about 500 Hp. Either a 10 or 13 speed, and rear ratio somewhere around 3:40 to 3:48. I've found that 3:42 drops you right about in between gears at double nickle. But, in normal running, the lower you are able to get the rpm, the better the fuel economy, as long as you are not lugging the engine.
Wife and I pulled a load of laminated redwood beams out of OR. Going up one of the hills, we passed a 500 Cat and really impressed the owner of that truck. Our fuel economy on that load was around 6.5.