I was guessing at the cost....but 7.2mpg for 2700 miles is 375 gal @ $3.50 a gallon is $1,312...... 7.85mpg is 344 gallons for a total of $1,204, so roughly $100 a week to go 4-5mph faster for the whole trip. Now, going 67mph for 2700miles nets me 40.3hrs of non-stop driving (which nobody does LOL) and 62mph gets me 43.5hrs of driving. So for 3 more hours on the road, I'd make an extra $100. And with the price of stuff today, looks like it's gonna take me an extra 3hrs!

The mufflers is under bunk on mine....

http://i6.photobucket.com/albums/y21.../DSC000252.jpg

Yeah, I have the one under the bunk, then 2 in the back. One on each stack :c

What year is your truck? Maybe one is a regeneration system seeing the only trucks I know that have 2 under the cab are 07+ emissions motors. Is that it?

What engine/transmission/rear-end combo are you running in that truck? I'm somewhat surprised that you're getting better mileage at 62 than at 65. For me, it was the opposite... then again, that was a computerized governor, not the sole of my right boot doing the governing.

C13 @470hp/Eaton 13spd/3.36 rears

well, this last week was a bust. I had STRONG headwinds for about 200+ miles of my trip to Texas. I wound up getting 6.75mpg going down set at 62mph.

My trip back home was the same headwind for 200+miles, then nothing. I fueled in MO and was at 7.25mpg set at 65mph.

Looks like this is going to take some time, but I will admit, at 65mph (1325rpm) the engine seems to run smoother and pulls hills much easier.

The truck is currently at peterbilt having the shift-tower busings replaced (stick is sloppy as could be) and having the overhead ran since I'm sure it has prob never been done, and at 517k miles, I figured it was a good time for it. I'll update next weekend if it has improved at all.

I also am looking at going straights on the rear, and leaving the factory resionator/muffler underneath and seeing how that does, then might measure it up and see if I can get a high-flow replacement for it on down the road :smokin:

great thread, lots of good methodology and business thinking in here. Better than $30 an hour paid to you for 3 extra hours on the road...

Thanks, like I said, I get bored with my run and this gives me at least a little something to do in the meantime. And the 3 extra hours is saying you were to get up at say 5am and drive for 11hrs w/o stopping AT ALL. And we all know we need oour coffee, bathrooms and leg breaks, so really it just lowers it to about 1.5hrs less. With my run, I leave Mon morning at 7am and I'm back home in the garage by noon thursday going 60-62mph. Not too bad if I might say to make an extra $100 each week to spend on something better than fuel ;)

Personally, if I had pipes behind the sleeper I'd go to single straight. Less weight and less wind drag.

But then it would like every freightshaker-volvo-IH out there LOL....I like the duals and none of it is exposed to cause wind-drag since I shortened the stacks to roof level ;)