I know you all know I use my ScanGauge II for getting the most MPG's from my vehicles as in the other thread I kept going over here. So here is now the last few trips to McCall, ID now in my 2002 Dodge Cummins... http://g.co/maps/ezxhe

I think his kit was around $300 off of ebay plus the tank. He said he should have bought the better kit that you could adjust the injection because it only does it above 6psi.

That is where I like my regulator. The more boost the more propane added. I have mine set to come on at about 2 PSI boost.

I have always wondered what it would be like to run propane . Anyway, I have been averaging a steady 18 mpg's. This is in town and/or freeway travel at 65 mph. I saw 20.2 once but that was on a very flat highway going 55 mph for the whole tank. I think 18 is very good considering my injector/tire situation. Going to some rv275's soon!! Here in Yakima, WA diesel is hanging around $4.00 a gallon.

Eventually I am going to be able to get on a dyno to see just how much power propane gives me. There is a noticeable power gain with propane.

Filled up yesterday because I wanted to get my the mpg on my ultra-gauge settup. I only had 144 miles on the tank but when I put the math to it, it came out at 19.5 mpg. Just put a topper on the truck and cant wait to see if it helps.

I have not able to see anything I could identify as an mpg improvement.It seems logical that the topper would eleminate the airflow swirling in the bed and thus help reduce drag on the truck.But I haven't seen it yet.Good luck on yours.

I have not able to see anything I could identify as an mpg improvement. It seems logical that the topper would eleminate the airflow swirling in the bed and thus help reduce drag on the truck. But I haven't seen it yet. Good luck on yours.

If you think about it you now have a huge "vacuum" at the rear of the truck now. Maybe some sort of air foil to direct some air down to 'fill the void'?

Ya, that is true but I am not sure that is worse than no top where you get all the drag from the open bed.With my driving style I just haven't been able to see any measureable difference either way.There is even a difference of opinion as to whether the airfoil or something like Airtabs really make any measureable different either. Will keep the back window clean and will help with the disturbance caused by passing large trucks at freeway speeds.It would be nice to find something that reduces the aerodynamic drag of these trucks enough to improve the mpgs.

If you think about it you now have a huge "vacuum" at the rear of the truck now. Maybe some sort of air foil to direct some air down to 'fill the void'?

I think the vacuum thing is a benefit.. That shelby cobra that whoever designed was chopped off flat on the back to eliminate all the turbulence and it worked wonders. This was the 1960's or who knows when.

Keep in mind that when you have an open box on your truck there is an air 'bubble' that forms in the box. Air strikes the tailgate and gets moved to the front of the box and then up the back of the cab. Once there it gets moved to the back of the box again. the air "sees" the bubble as part of the truck and that is why leaving the tailgate up nets the best mileage. Think of the way smoke from stacks gets pulled down to the road and you can envision the bubble. ISX, you are correct about the flat back end, however, the shear size of the back of a truck with a topper is big enough to cause more drag.

98 2500 Extended Cab 2x4 bone stock (as far as I know)Mileage 17300Fueled up drove from Home going to Baker City for CoffeeDeparture Temp: 10* Arrival Temp: 15* Wind : Still Cruise Set: 65 MPH119 Miles 5.7 gal = 20.87

98 2500 Extended Cab 2x4 bone stock (as far as I know) Mileage 17300 Fueled up drove from Home going to Baker City for Coffee Departure Temp: 10* Arrival Temp: 15* Wind : Still Cruise Set: 65 MPH 119 Miles 5.7 gal = 20.87

Mileage isn't too bad for the winter fuel but that's an expensive cup of coffee.

Mileage isn't too bad for the winter fuel but that's an expensive cup of coffee.

it wasn't as bad as it looked I had two cups,, But I was grinning

I'm down to right at 1/2 tank, and I've traveled 98 miles... W... T... F...?36gal tank, 98mi been all city speeds, mostly.. I hate this truck.

O-U-C-H!!! My needle is barely moving at the 90 mile marker! (Country driving) Something cant be right!?

I'm down to right at 1/2 tank, and I've traveled 98 miles... W... T... F...? 36gal tank, 98mi been all city speeds, mostly.. I hate this truck.

Time to kidnap ISX and have him fix your truck... Like I know this winter been rough on my truck and been varying between 14-19 MPG. Depends if I'm bucking head winds, driving with a heavy foot, or short trips that don't ever warm up completely. This winter I've been staying at home more than previous winters.

I wish I could afford to get him here for a weekend..

I'm down to right at 1/2 tank, and I've traveled 98 miles... W... T... F...? 36gal tank, 98mi been all city speeds, mostly.. I hate this truck.

Did someone steal your truck and replace it with a Ford 460

LOL I sure hope not!

I got 20.9mpg and 19.6mpg on a hunting trip to Arkansas Christmas week with the 2 tanks I went thru. Right at 600 miles one way.