Eaton as in L/HD conversion, not speaking of any other installation.

 

stock highway on my trips from MA to FL, i would get 15.6 ish miles per gallon. since install, highway mileage is 13.5-14 mpg at the most. same driving style. regular maintainance always done.

 

My first tune for eaton was open loop, even thought it was "CUSTOM". Mileage was about 13.5 Second tune from another source was closed loop and mileage went up. Mileage now 15 driving 33 miles to work each way with 3/4 of time 65mph and 1/4 stop and go. The truck has a serious problem and that is I can never floor it off the line, since it will smokes the rear tires all the way through second gear, so I don't do it. What a problem to have.

 

I finally took a trip down the highway and checked to see what I'm getting MPG wise.
I was surprised to see I got about 14mpg. That's at 70mph and turning 2200 rpm with 4.10 gears.
Now around town I only get 5 MPG.

Phil

 

who did the 1st tune? who did the 2nd tune? i might take a trip down to jdm in nj at some point to see what he can do.....my original tuner doesn't return any of my messages.

 

do boosted applications (pro charger or supercharger) require higher octane?

 

YES.

Phil

 

I use my truck (2004 Supercrew 4x4 leveled with 35's) for business which requires a lot of highway miles. Before the Roush install I could squeeze 18-19 on a good day driving what some may call hard @ 75-80mph with the cruise.
After the Roush the best I have ever gotten was a little over 17 mpg. I recently returned to Akron from Detroit @ 80mph with the cruise on and got right at 16mpg. I normally average 14-15 city. I knew I would be giving up mpg in the beginning so it really is not a concern for me.
Ironically, my "01 Lightning which was right at 490rwhp would get 18 on the highway, and my '03 Cobra making 475rwhp could easily get 24-25 mpg on the highway.

 

I can get as much as 21 mpg on the interstate if I control my right foot. Otherwise, it drops to 16 or so.

3.73 diff, 2wd, 5.4L, SCrew, Roushcharger

CW

 

Down hill

 

doing 70 I average 16, doing 60 I average 18-19

 

Don't want to rag on the first tuner, it was a well know name for L swaps, but I believe he is out of business now. Second tune was done by Woodbine Motorsports in Woodbine MD. I did not go dyno tune, so I know there is a little more in the truck, but then this is a daily driver pullied to 16lbs and I do tow occasionally (just had 8,000lbs behind it, no problem).

 

Does having a limited slip diff raise any issues when going with forced induction?

 

i have limited slip....no issues

 

No, its only helpful