My 04 Hemi quad cab 4x4 is averaging 9-10 miles around town at best and not
a heck of alot more on the highway. I have modified it as follows. K&N cold
air intake system ,Gibson dual extreme exhaust system. Tonneau cover. I did
add a set of BFG All Terrain TA/Ko tires. The tires are 265 size up from 245
70/17 I think about an inch taller and inch wider. I don't go peeling out
at lights or really pushing it. Is this common or should I be checking
something? Truck has about 35k on the speedo. It's a beautiful truck but gas
mileage sucks big time.
The good folks at the local Dodge Dealership Foss Motors in Exeter,NH
reset the computer for the new tires. At a cost of $40-50.00 I'm getting
my info from the overhead computer. The truck runs good and has plenty of
power. Does anyone know if the computer they use to reset the trucks
computer is the same one that other garages have or is it a propriety system
that only Dodge has for Dodge vehicles. He plugged it in under the dash.
I'll also check for info at www.dodgetruckworld. I'm a member of the NH
chapter. Thanks hpage3
In response to Ed H. 's post. I thought everyone should know:
Yes they are, but this one sounds close enough to me. my 8.0L got about 8
to 10 mpg 11 if i was real nice.....but yall know me, im not that nice =)
several friends with the 5.2 and 5.9 are claiming the same neighborhood up
to 13mpg so 10 out of a HEMI wouldnt surprise me much.
oh yea best my wifes durango ever did was 15 on a long trip at 60 to 65
mph on the interstate. 13 with her long trips to work was the average.
sorry just my eperiance.
It's a big heavy truck with a big'ish engine.
Mileage is going to suck. But I agree with you, it
shouldn't be that bad.
You've made a couple of engine mods, have you
checked your actual air:fuel ratio? Ask around in your
club, someone must have an LM-1 or something similar.
Have you used a tuner like Haltech or Jet? The
highest setting will give you a tad more performance
than the mid setting, but your mileage will defiantly
Have you checked for proper air pressure? If
you're lucky, you can find someone with a tire
pyrometer to set the pressure more accurately. If you
can't find one, just add 5 psi to your current pressure
and see what happens to your mileage.
On my Ram 5.2 Magnum 4X4 it has the first two that you did and then added
the Mopar performance computer (you may already have this on the Hemi??),
spacer on the intake and an MSD ignition system. Milage went from 12 to 17.5
if you are easy on the accelerator. I also have slightly larger tires as you
do and my speeds are raised by about 5mph at 70. At 70mph I am actually
doing 75mph so actual milage might be slightly higher. I doubt you will see
as large an increase with the Hemi as I did with the 318, but it may help
some. I did add a shift kit to the OD tranny at about 170,000 miles when it
needed a rebuild (damn those Dodge trannies just don't last....:-) and it
now has close to 175,000 miles on it and it still runs like new with oil
pressure at 40-50lbs and no oil usage between changes every 3,000mi or so.
The modifications were done at around 50,000mi or thereabout.
You put on a wider, taller, heavier, tire with a more aggressive tread,
that would cost a couple of mpg with the added rolling resistance and
rotational weight. You also raised the truck higher, that put more air
passing under it. The K&N was waste unless you did a bunch of engine mod's.
Your probably jumping on the gas to hear the exhaust and the woosh from the
You have a couple of options imo. Realize it is a 4x4 truck with a hemi in
it that sounds nice but gets shitty mileage and enjoy it. Or dump it and by
econo car. It is what it is.
But Roy, you gave him a black vs. white answer - the truck or any econo car.
There are a multitude of options, including a truck and an econo car (and/or
a bike, bus service, a skate board, not going anywhere, ask friends for
rides, hitchhiking, etc.). Perhaps Buddism isn't that enlightening. ,:<)
However, I must admit you weren't wrong - something to be said about
Buddism, at least from the Buddist view. <BG>
This is hurting not helping MPG, especailly in town but many never
figure this out. It has to do with letting exhaust blow off too
quickly from cylinders because the engine sets its power for expanding
gases, not explosions. Dual exhaust hurt more than help MPG in urban
driving and it is a toss up if they help at all on highway because
modern engine are well tuned from intake to exhaust and when you start
hacking, MPG can take a dump.
This did not hurt
This hurt because the tires have a bit more rolling resistance and
Hemis can be real gas hogs. Engine with torque peaks above 4000 RPM
are seldom their most efficent at lower RPM's and this engine is one
of them. You have a few more things hurting you. First and foremost,
your truck is ALWAYS dragging the front differentail and drive shaft.
Even when not in 4x4 it is locked to wheels and consuming power.
Figure on at least 1 MPG or more lost because of this drag. (even more
in cold weather) Dodge is the only Detoit truck maker that does not
have a front axle disconnect ( the left it out to save them a few
bucks while potentailly costing you over 1000 bucks or more in extra
fuel over life of truck) so they will always do worse than competion
on MPG in 4x4 models. One thing you can do is use better fuel as 87
octane is a joke in that engine and it compromising power and MPG.
Also run tires at near max pressure and change lubes in Tcase and
axles if you have not already done so but do not expect miracles.
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