Was browsing Truck Paper.com and got to wondering: what is a good horsepower/tranny combination for just general purposes and optimum fuel mileage? Would 500 HP and a 13-speed with a 3:37 rear be okay for general hauling or maybe 475 HP with a 18-speed? If special ordering a truck what are some combos that would work considering maybe five or six loads a year in the mountains of the western states? 8)

 

475hp with a 13spd and 3.37-3.55 gears would be a good general purpose combo, at least from what I have seen. My uncle owns a few car haulers and that is the setup he uses in his pete 379's.

 

Yeah, either the 13 or 18. I've always liked 15 over, too.

At work, we have 350 come aparts, Straight 10(Meritor). Not sure about the rears, but they have the motors governed down to 68. Fuel milage averages around 4.5 - 6.0 mpg. Sometimes, when pulling a single, it gets more around 7 or so mpg. What's funny, my buddy has a 550 CAT in his 379, with an 18 speed. He gets around 5.5 - 6.0 mpg. :lol:

 

8) So maybe the folks at Cat are improving the fuel mileage in their engines? From what I've read that setup your buddy has is about ideal for the Cats as it seems the more horsepower engines with 18-speeds and lower rears (3:37-3:55) is about the peak for fuel economy. 8)

 

Yeah.
As long as you can get the right transmission, rears, you can get as good or better fuel economy with bigger motors. Just because you have a motor that runs like a scalded ape, doesnt mean bad fuel milage. :P

 

Well it has more to do with how you drive them and not "as" much as how you set them up. When you put an 18spd tranny on anything it will get good fuel mileage as the rpms stay low while making the power.

Oh and just a heads up the lower the number for rear end ratio's the taller the gear. A 4.11 gear is much "lower" and will produce much more pulling power than a 3.55 but it's top speed will be reduced greatly compared to the 3.55.

 

You don't need an 18-speed. Much heavier Tranny.
10...or 13-speed is all you need.

Those 18's are for Heavy Hauler's, or Livestock, off road applications, etc.
They only help you in lower speeds, and stiff terrain, triple-drives...what-not.

I just delivered a load of Drive axle-housings to Arvin Meritor in Heath, Oh.

Ohhh Baby... :P That new gear smell.... :lol:

 

I dont even think they make a 15 for hwy trucks anymore sense the 18 is doing so well!!

 

Eaton still lists the 15 speed transmissions in it's sales literature section so I would assume you can still order one. The problem is that it's only rated to 1650 lb/ft of torque so if you're in the market for a big HP engine with 1750lb/ft or torque or better, the 15 speed isn't an option.

 

275HP Mack and a 7spd.