Topper - killing fuel economy?

[TPringle]

I have a 1992 Dodge W250 with a tall topper. It has a lip, kind of like a spoiler on the back. I have oftened wondered if this is destroying my fuel economy. It isnt easy to pull this topper off to compare. Any experiance or "been there, done that"? I have thought about cutting it off and glassing over it.

 

[JDiehl]

How many mpgs are you getting right now?

 

[brods]

I've noticed a small reduction of mpg with a cab high topper, less than a 1 mpg difference at highway speeds. It is a safe bet with a taller one you're getting some mpg reduction.

 

[steved]

I had a Leer cab high on my 99, got the best mileage with the cap on...



Not sure about the raised roof, as long as its not an abrupt change, it should not really affect it that much...

 

[jgillott]

I had a wedge style Leer cap on my former '92 years ago. I honestly never had it off of the truck for extended periods of time to see if there was much of a MPG difference. I would assume that it would be more of an advantage having it on if anything else.

 

[jeepit]

I have had a topper on for 5 years and have had it off for the past year now. I don't see any change in mpgs. If anything, the mileage went down while towing my Jeep on the trailer. I think the height of the topper blew the air resistance over the Jeep. .

 

[TPringle]

The truck used to get low 20's (not towing), but the mileage has dropped down to around 12-13. I used to have a lower, cab high topper with a hump in the middle. I wore it out, so I replaced it with a taller topper. I often tow when I run the interstate, usually a travel trailer or flat bed trailer with a car or something. I am investigating the injection system, but didnt want to start throwing parts and money at it if it might be as simple as the topper. I am usually conservative on the highway, around 58-60, but when the fuel ecomony went south, I cranked up to 70 with very little change.

 

[Andy Morrison]

I doubt that your topper is causing that much of a MPG drop. I think I would have the injectors tested... nozzels are likely worn and just dumping fuel into the cylinders.



Hope this helps, Andy

 

[brods]

I doubt that your topper is causing that much of a MPG drop. I think I would have the injectors tested... nozzels are likely worn and just dumping fuel into the cylinders.



Hope this helps, Andy

X2



An 8 mpg decrease is huge. A topper is likely to have a small impact on mpg, either slightly better or worse. Some of the manufacturers claim an increase, such as Snugtop who claims a 1. 32 mpg gain at 45 mph on a Dodge with the hemi Snugtop - Fiberglass Truck Cap & Tonneau Top Covers, Camper Shells Tops, Customized Truck Toppers, Pick Up Truck Canopy

 

[surfbeetle]

How's your power? With that much of a loss in mpg, I would start with boost pressure and see if it's less.

 

[Midnite]

Could it have anything to do with winter fuel? If you got in the low 20s with summer fuel, 12-13 in the winter isn't beyond the realm of possibility, although mine normally only drops to 16-17.

Mike

 

[JLEONARD]

I had a raised up cap on my 91 for most of my time with the truck. It never changed the lieage. I would 23/25 mpg in almost any condition . . minus 2 mpg on winter fuel of course.

 

[Buffalo]

If anything, the "spoiler" on the back is probably helping the aerodynamics of your vehicle. A number of the new trucks now install a small "lip" or spoiler on the top of their tailgates for that reason.



Do you have a flat front that sticks above the top of the roof of your cab? If so, creating a "slope" in that area may help your aerodynamics. Just a thought!!!



My '91. 5 W-250 (with a cab-high shell) is starting to lose mileage, also. I'

ve got 183,000 miles & think something is not quite right. I use it to drive to work, every morning. Only about 3 1/2 miles & I think it never gets warmed-up. Power seems to be good, though.



Joe F.