Joe V

Here's what I have:

92 W250 w/3.54 234k miles AT 33" tires daily driver and a popup camper
http://www.dodge-diesel.org/yabbse/g....php?album=107

Before I plopped the camper on I was getting 15mpg city and 17-20 highway. Now All I get is 12mpg.

The fuel pump was replaced before I purchased the vehicle, the only aftermarket under hood item I'm aware of is a K&N air filter, which I cleaned recently. The tires could use balancing and the tranny seems to slip some at take off and my right foot is heavier than my left.

I would like to purchase the 16cm but I'm wondering if it will help my mileage. I'm in the middle of a project vehicle and every dollar needs to go into the project before I start spend money on performance upgrades for the Dodge that will not benefit me as far as fuel mileage goes.

Thanks,
Joe V
Orange, CA

Monty

The 16 isnt going to help mileage substantially. Your poor mileage probably has alot to do with the 33" tires. How long has it been since the valves have been adjusted?

Bob Beauchaine

I would suggest that you check you speedometer to see if it is correct. With 33's that will give you a pretty good error. Try to find a speedo shop near you to see how accurate your speedo is. You can have a correction adapter made to true up the speedo then check your mileage. I will bet that it's better than you think. My average is 18.5 - 60% city and 40% highway at a steady 70mph. My mileage numbers come from 10 years of records and has increased with preformance upgrades. <br><br>When I installed the NV4500HD mine was showing 60+ at 40mph with the correction adapter it is now 1mph fast at 70mph.<br><br>Bob

Jbolt001

With factory wheels when I drove it off the lot in 93 the best I ever got around town was 17.5<br><br>After putting on 33&quot; it dropped to 16 AND corrected the speedo. Speedo is dead on with 33s YMMV<br><br>With all the fueling mods I'm up to 16.5 to 17 around town<br><br>I'd say the big air dam sitting on the back is not helping. I know my 84 D350 gasser went fron 13 to 8 with the camper on. <br><br>I'd start with fue filter, adjust valves &amp; run some high doses of fuel conditioner and see if that helps. Are the injectors stock? Mine were pretty cruddy when I pulled them at 150k<br><br>Jay

Joe V

I've owned the truck for 1yr now and do not know how long it's been since the valves were adjusted. The camper has some serious wind resistance that's for sure.

In 6 months I plan on lifting the truck with some 1&quot; springs so I can run 35&quot; tires. If I re-gear to 4.09 with 35's would that put me back in the right power band? I would have the speedo recalibrated as well.

Even if my speedo has inaccurate mileage readings what is correct is the 5mpg spread. Maybe I should check the valves before buying the 16cm?


Thanks,
Joe V

bigredbrick

FWIW my speed-o-meter is also dead on with 285/75/16s (33in. tall) and 3.54 gear ratio- at least according to them &quot;Your Speed Is&quot; radar signs!<br>bigredbrick

dodgeman01

my speedo with the stock tiers is 5mph slow. been that way ever sense I bought it last year.<br>DM01

jleonard

I'm running 85 series tires and my speedo seems pretty good...<br>3.54 ratio.<br>I get anywhere from 22 to 24.5 mpg and it was the same with the 18 cm stock housing. My foot is the biggest factor in the mileage ;D<br>Jay

furious70

those slide ins kill mpg!!!! my friend's 91 gets 21-24mpg @ 65-70mph empty, he put one of those in (a bit taller, u can sleep above the cab) and the mpg went to 13-14!!! They aren't heavy (he could bury me from a stoplight since i was tugging my Fury -- I got 19mpg behind him towing the fury on an open trailer), but they cut ALOT of wind.

Jeeper

Nice truck Joe. 33's aren't much bigger in diameter than the stock 235/85R-16's. I run 33's and get about 17 in empty daily driving, and about 12 towing 12K lbs. Jay is right, the right foot is the biggest factor in controlling mpg. I could probably get 20 if I could resist the urge to pour on the fuel. Sure, the camper doesn't help, but I've gotten 15 mpg on the highway with a big 2800 lb. slide-in camper in the bed.

IMO, there may be something wrong that's causing the lower than average mileage. Could just be the right foot. The 16 cm housing is not the fix, but is a good upgrade. It may help mpg a bit by building boost sooner than your stock 21 cm housing. I'd start with going over the truck with basic maintenance and checking everything. New filters, set valves, adjust the trans if an auto. Check wheel bearings, u-joints, dragging brakes. Check boost hoses for leaks. Check exhaust for kinks. Don't laugh, they came from the factory with badly crunched bends. Leaking intercooler? Does the truck smoke badly? Some boost/pyro readings might help us help you if you have guages.