Say you have two identical trucks EXCEPT one is a W250 auto and the other is a W350 DRW stick. Everything else the same.

Now, would the extra weight & rolling mass of the DRW ton offset the mileage gained by losing the 518 automatic?

 

Teh 518 IMHO is better for fuel mileage because it has a .69 overdrive

and the getrag has a .77

So the W250 should get better fuel mileage for two reasons-

Less Weight
Deeper overdrive

 

theoretically that is correct. But lets not forget that many auto's are running around with some pretty poor torque converters.

the majority of the MPG threads that i read on here stick trucks almost always report better MPG than auto's.

 

the majority of people don't have this-

366 gov. spring, fuel screw maxed, home cut fuel pin, potentiometer controlled OD, 5" miter cut stacks, gillett stage 2 (60mm wheel/housing), BHAF, coal train EDM 435 injectors, piston LP
Fall Brawl 08 304hp/525tq

A good tranny/converter should out MPG a good getrag 5th gear/good clutch on the highway running 65 in my opinion.

A getrag truck will probably get better mpg on the highway TOWING because the O/D would probably be off in the auto truck. This is all theoretic though.

 

It shouldn't make any difference whatsoever, because when we was in grade-school, our science teacher had two kids go up on the gym roof and drop two round *****, one a big heavy bowling-ball, the other a hollow plastic ball; both ***** hit the ground at exactly the same time.

According to our scientific findings, since both truck-bodies are the same shape, they should go the same distance with the same amount of gravity, regardless of one being heavier than the other.


I won't go into all the complicated equations and theories that back up my reasoning.

 

Im gonna agree with that.

 

I can solve this whole problem,this is the solution....KEEP YOUR FOOT OUT OF THE GO PEDAL!!! There, you now have the solution to your hypothetical dilemma. But not many of us can't do that. I still have the 4:10 in my truck from my conversion. I did add a 47rh with a rv rated tq, i did a trip from North Carolina to Illinois 805 miles. I kept it at 62 - 65 mph. and averaged between 22 and 25 mpg. This is an 85-D350, 2wd, crewcab shortbed,running 265/65/16 tires. My engine has over 200K. No matter what power upgrades you throw to these trucks they still give the biggest bang for your dollar. To many variables are involved here but keep one thing in mind...the solution is above Now, the fee for my solution to your dilemma is a set of POD'S or a bigger turbo so i can go faster.

 

Now I'm confused.

 

yea many people may not have quite the mods i have. The best mileage i got from my truck was with all my mods.

if you do all the "free" tweaks that can be done to these trucks the stock trans (designed to slip behind the power of the cummins) will be hurting and hurting you mileage. And the majority of the members here don't keep there truck stock for long. So without sinking more than a grand into your auto it will be hard to keep up with the MPG of a stick truck IMO.

but like stated above keeping your foot out if is the biggest difference.

 

you beat me to it. lol.

He proved a point then reversed it with the "don't"

 

I just got burnt.

 

Even if you keep a light foot I still think a manual trans will get better MPG.

 

At 55-60mph I was able to out mileage a W250 with a manual by a good shot.....27mpg vs 23.4mpg. And I have a 727 (no overdrive) drive slow.

Oh PS, I have an aftermarket converter which picked me up a few mpg.

 

More weight = more friction between the tires and the road = requires more power (fuel) to push down the road. Of course then you can factor in tire type etc... but if you kept those variabes constant, the heavier truck requires more power to go down the road.

 

Thats what I was getting at. Both trucks may fall at the same rate off the top of a cliff , but hauling a load (two extra wheels +?) eats at mileage. I guess those fenders add some drag too? Both trucks are geared with the 3.54s.

I figure that the sloppy torque converter cancels out any gains from weight reduction, etc?

I'm still trying to talk myself out of that W350 (although my bank account is doing a pretty good job right now ). The frames seem identical. Even the springs look the same. Only difference is the front sway bar (do all tons have that?) and training wheels. Oh I would reckon a Getrag is lighter in weight than the 518?