DodgeTalk Forum banner
Not open for further replies.
1 - 20 of 45 Posts

13 Posts
Discussion Starter · #1 ·
Hey yall Yes I searched before i posted up but didnt come up with much. Wanted to get answers to my situation. I have a 01 5.9 gas 4x4 offroad. 4.10 r/p. 275/70/17 badyears. I drive like a grandpa and dont romp on it unless I have to. I was getting 11 mpg cruising at 70-75. I put on a flow 40 and pipe/tips. This got me up to 12mpg. Im thinking about some 295s or 315s to even out the 4.10s. Also definately adding a KN FIPK soon. I put new plugs on and help startup but not gas. What do yall think about this?? thanks clayton

The Green Machine
1,722 Posts
Clayton, that seems like decent mileage - especially with the 4.10s. I'm getting around 11.5 mpg with 3.55s (98 1500 QuadCab 360 4x4). Not sure you can do a whole lot better with a full size truck with a pushrod engine ;)

65 Posts
the average speed for all cars at which you get the best gas mileage is 40 mph. going 70-75, 11 mpg is amazing. i have a '96 with several performance mods and if i go 70-75 i'd be lucky to get 9 mpg. but driving normal on our 55mph highways, i can get about 12mpg with my 3.55 gears and 315 tires.

Chicks dig bench seats.
1,901 Posts
The only time I got better gas milage is when my rear diff went out adn it was replaced. I think it has less friction than the stock one so i get about 13-14 mpg now. But i have 3.92 gears. Larger tires may help on the highway.

13 Posts
Discussion Starter · #6 ·
thanks yall yeah getting better gas in a dodge is like kicking a dead horse. you aint going nowhere. went and tryed on some new shoes yesterday. 315/70/17 bfg ats fit on stock wheels. no rubbing!!! 315s oughta even me out and hopefully the KN kit will help
later clayton

115 Posts
If you're looking for numbers check this...

Before throttle body spacer was 240-290 miles per tank.
After throttle body spacer was 319-339 miles per tank.
The truck also maintains speeds better, especially climbing hills on the highway.

The laws of physics don't seem to fit here, because they're smaller diameter holes (2) than the throttle body, and the fuel isn't being atomized in the intake plenum.

Adding bigger tires won't get you better mileage. That is.. unless you "live" on the highway. As soon as you hit the ramp and head for home all that highway help turns into a hefty- off highway purchase offsetting the gains.

1,733 Posts
This was written for second gen Rams and has been partially modified but needs
to be re-written for 3rd gen Rams
{please point out broken links}
but the basic principles apply

old post:

Ram Pickup MPG improvement discussion :
{last modified 12-21-04}

Switching to synthetic lubricants - - engine oil, diff, Amsoil C+ Mopar-spec
transmission fluid, and syn greases in wheel bearings is good for 2-5% MPG
improvement. That is only about 0.5 mpg but every little bit helps.

Larry Shepard writes in the 'Magnum Engines' book published by Mopar Perf that
running engine oil and transmission ATF levels 1-0.5 quarts below the 'add'
marks on the dipsticks can increase MPG slightly due to less oil drag. If you
do this, you must check levels very frequently to see that you don't drop oil
levels even lower into the 'danger zone.'

Another 'non-sexy' but effective way to increase mpg is to keep an electric
block heater on while the truck is parked. The Dodge PCM computer richens the
mixture until the coolant temperature gets to 147 degrees F. By keeping the
block warm the engine goes into the more fuel efficient 'closed loop' control
sooner. This MPG improvement works best on trucks that do short trips. At 8
cents per kw-hr electric rates, running a 700 watt block heater for 8 hrs
costs 45 cents.

As others have said, a hard tonneau can lower the aerodynamic drag. I
installed a ARE hard tonneau and found it was good for about 1 mpg
improvement. Ford says that a soft tonneau is good for +1 mpg on the F150 and
tried to get the EPA to allow them to add this to their highway MPG result by
re-classifying the tonneau 'standard equipment.'

This Fibernetics hard tonneau has a 'Roofline Extention Spoiler' on the back
that might help MPG a bit more than a conventional design. Here's a view of
the rear spoiler, but on a F150:

There is an interesting student project on a aero improvements tried on a
Dodge Ram model truck several posts down at this link:

or go directly to the stored old pages here: ffner/did.htm
and onneau.htm

Note that the students found that camper tops and removed tailgates hurt, but
tonneaus and lowered tailgates helped slightly.

It is possible that a 2inch front/4 inch rear drop on a Ram suspension could
improve the aerodynamic drag. There is some evidence that on a 1996 Indy Ram
this improved the Cd by a few hundreds.

The 3rd gen body on the SRT10 Ram uses a 4/6 inch lowered stance, a rear wing,
tonneau, and perhaps partially block off of the 'too big' radiator grille to
lower its aerodynamic Cd from the 0.50 of the stock 2500 Ram to the SRT10's
value of 0.45

Bug shields at the front of Rams nearly always hurt MPG.

The Dodge Ram Diesel that set the Bonneville speed record had 'Mooneye' wheel
cover discs. These are supposed to reduce aero drag by 1-2% but hurt brake
cooling. I also notice this Ram had mirrors and wipers removed.

I have recently had some aerodynamic success with home-made little aluminum
tabs called 'Wheeler Vortex Generators'. I mounted 5 just behind the side cab
windows, and another 5 just in front of the rear brake lights. These improved
my coasting speed down a 6% grade hill by 2 mph, and also improved MPG at a
steady 70 mph by 1 mpg.

I had previously tried this product on the roof of the truck, but it did not

The vortex generators I made were cut from 5 inch by 7 inch aluminum
'flashing' from Home Depot. You cut the flashing into 3 and 9/16th inch
circles, and then bend the sides up to form the 'wings'. A circle of course
has 360 degrees. The front of the wings take up 107 degrees of the circle,
and the back takes up 22 degrees. The finished product looks like this:

but without the magnet backing. I used 3M 'Super Strong' outdoor mounting
tape from Target to stick the vortex generators to the truck's sheet metal.

I am still testing with the Wheeler Vortex generators. I have tried bending
dimes into tiny ones for the mirrors - but no measureable change. I have also
tried little 1.5 inch ones on the bottom of the Ram airdam - felt more stable
but no measureable change.

Sparkplug and ignition advance changes. I did a careful test run of 311 miles
after indexing sparkplugs in a 5.9V8 and
got a 4% improvement. That could be random variation but I suspect not. To
index the plugs, buy 16 instead of the usual 8 and choose plugs that tighten
down so that the gap points toward the V of the engine and the ground
electrode is on the fender side. Return the 8 plugs you don't use to the store
or give them to another Ram owner. This puts the metal post of the ground
electrode over against the metal wall of the cylinder head where it does not
block the growth of the flame. See this webpage for a view of the combustion
chamber. In the picture the top is toward the fender and the bottom is toward
the center V of the V8 engine:

There is an article with several good illustrations at this Phord site:

On a 5.7Hemi, it is very probable that by re-arranging the stock 16 plugs to
their best position you could achieve indexing without buying more than 4-6
additional plugs at most, perhaps none at all.

Tests of the Bosch+4 sparkplugs at 60 and 70 mph highway speeds with 87 octane
gasoline found no improvement - actually a slight loss - on a 1500 1995 SB CC
Ram with 5.9V8 AT. A further test of the Bosch+4 sparkplugs with one of the
electrodes closest to the exhaust valve cut off (making a Bosch+3) also showed
no MPG gain.

There is controversy about MPG and thermostat temperatures. Pure theory says
that cooler air intake temperatures give improved MPG because cooler air takes
slightly less hp to compress, but hotter oil on cylinder walls gives less
friction to
the piston rings which can also mean better MPG. Theory also predicts that
hotter block walls and cylinder heads will absorb less heat from combustion
and permit a greater 'push' on the piston.

Some Dakota owners who switched to 180 degree thermostats have reported less
ping, peppier acceleration and about +1 mpg. Other Dakota owners reported no
mpg change or a loss. Four Wheeler magazine reported +0.8 mpg gain with a 192
to 180
deg thermo swap in a 454 Suburban. Marlan Davis has reported that all things
considered, fuel economy is better with coolant at 210 degrees F.

My own experiments with failed thermostat that cracked and stayed open at
around 140 degrees, 180, 195 (stock) and 205 thermostats showed no measureable
improvement in MPG at steady 60 mph highway cruise on a 1995 5.9V8 Ram CC
shortbed. The 180 degree thermostat also did not reducing pinging, nor did
the 205 thermostat increase pinging. The cracked thermostat that stayed open
at about 140 did reduce pinging.

Note that on 4.7 and 5.7Hemi engines the thermostat position and function has
been totally
redesigned to control the coolant in, rather than the coolant out
temperature. The 5.7V8 also has a closing bypass feature.

The Fuel Economy Calculator from Performance Trends software predicts that a
change from a 195 degree thermostat to a 175 worsens MPG by about 0.20 at a
steady 70 mph.

Undersized crank pulleys can increase MPG slightly and are relatively cheap.
Some report an additional undersized alternator pulley is too much for the
street truck that may have to idle a long time without enough rpm to charge
the battery. I haven't tried one yet - but did much the same thing with a diff
gear change.

I changed out my original 3.55 differential gears to some $75 new-in-box but
20 years old Mopar ones of 3.21 ratio in hopes of better mpg. I got about a
0.5 to 1 mpg improvement at 70 mph. I had hoped for more. Quarter mile times
got worse by 0.75 second. My 5.9V8 now accelerates about like a 5.2, but has
about a 5 mph increase in top speed in 3rd gear as the gear ratio is more
matched to peak hp.

Note that on the 5.7Hemi with the new auto trans the overdrive gear ratio was
made "taller"
to 0.67 from the old 0.69 at the same time that the 17 or 20 inch wheels &
tires were made larger in diameter. This has an effect like changing from 3.55
to 3.21 in the experiment above.

A less restrictive muffler can help on a Ram. I switched to Walker's
'QuietFlow' type and gained about +1 mpg and dropped 0.2 seconds from the
Q'mile. The QuietFlow is as quiet as the stock muffler. Walker also owns
DynoMax, and the tech on the telephone told me the DynoMax is about 10% less
restrictive than the QuietFlow but much louder. But after 15,000 miles, my
QuietFlow began to rattle and I had to squeeze a dent in it with a large
C-clamp to stop the noise. So far it is still quiet.

I later replaced the QuietFlow with a 30 inch long 'straight through' DynoMax
UltraFlo Stainless Steel 2.5 inch in, 2.5 inch out.

part number 17298 that cut the wide open throttle exhaust backpressure from 7
psi to 5 psi. This reduction in backpressure only yielded a gain of about 0.2
MPG. The Ultraflo 17298 was a little louder than both the stock muffler and
the QuietFlow, but just barely. I later had to add an additional 16 inch long
UltraFlo as a tip to eliminate a 1700-2000 rpm resonance when cruising in

I also moved my exhaust outlet to face rearward and installed a megaphone tip.
A rear facing exhaust oulet has a very very small 'jet engine' push to
it - notice most cars exhaust backwards - but trucks that pull trailers need a

side exhaust to safety exhaust carbon monoxide away from where it could cause
a deadly build up inside a camper.

On the 5.7 Hemi Rams, the exhaust pipe sizes, muffler and resonator are
already fairly low restriction.

Headers are heavily advertised as helping MPG - a psychologically trick that
helps create sales - but in most cases headers don't do much because the
primary pipes on them are too short. Many headers are put on at the same time
as new less restrictive exhausts - and the header gets the credit for what the
bigger muffler actually did.

Increasing the air pressure in your tires, and picking a narrow 'rib tread'
commercial delivery truck type tire that has low rolling resistance
definitely helps MPG. Raising the air pressure by 15 psi to the max 70 psi in
Goodyear Wrangler HT 235/85R16E tires increased my mpg by +1 in a 311 mile
test run - but the ride was bone jarring. A narrow, highway rib tire like the
HT gives the lowest rolling resistance. Wide, aggressive tread tires can be
three times harder to roll. It might pay to have a 4 tire set for the weekday
and a weekend mudder wide tire set.

Consumers Reports is the only organization I know of that tests for rolling
resistance of tires, but you have to have an internet subscription to read
their results. Consumers Reports did mention in one test of 15 inch SUV tires
that the Michelin LTX MS had the lowest rolling resistance of any of the tires
tested. When I tested these LTX MS tires against Bridgestone Dueler HL tires
the MPG on a 100 mile loop was exactly the same.
{The California Air Resources board is pressing the tire companies to make
rolling resistance measurements on tires freely available to the public, one
of the few worthwhiles things CARB has ever done in my opinion}

The lower profile 17 and 20 inch tire designs used on the 5.7Hemi Rams have a
'sticker' tire tread and higher rolling resistance than earlier year Rams. It
is probable that if a manufacturer makes available a 235 85 R17 tire in Load
Range E it would be lower rolling resistance than the stock tires and might
improve MPG by 1-2 at 70 mph.

A carefull MPG test of a 1995 1500 SB CC Ram with the 5.9V8 AT (3.21 diff)
with and without the radiator fan showed a 0.8 MPG improvement without the
fan. No overheating occured in this steady 70 MPH test run over 212 miles.
There was also no sign of overheating at stoplight stops or city driving in
mild winter temperatures. Several Diesel Ram owners have posted that they can
run without a fan in winter and gain 0.5 to 1 MPG.

With the electric fan & clutch fan combo on the 5.7 Hemi Rams it is probable
that the clutch fan
could be removed for all but the hottest weather or towing service.

Another MPG test over the same stretch of highway at a steady 70 mph showed
0.7 MPG worse without the Ram's stock front bumper air dam, than with the
stock air dam in place. Other 2500/3500 Diesel Ram owners have reported
better MPG after taking off their air dam on the TDR website - but those tests
did not seem to be carefully done.

Weight reduction is supposed to improve MPG - the rule of thumb is " a 10%
reduction in weight yields a 6% improvement in MPG." So 540 lbs off a 5400 lb
Ram might increase 14 MPG to 14.8 mpg.

The US Army is giving some of your tax dollars to Ford as a Research grant to
try out ways to cut the weight of a pickup truck by 25%.

Aluminum wheels save 40 lbs total. New Aluminum Magnum heads save 46 lbs.
Aluminum diff and rear axles saves 150 lbs. Fiberglass leaf springs save 75
lbs or monoleaf steel springs save 40 lbs.

Do Google searches for 'monoleaf spring' or 'fiberglass spring' to find
{direct specific webpages have changed from}

Do you really need that rear bumper - are damaged bumpers less expensive to
replace than damaged sheet metal?

Mopar Perf has a $3000 aluminum 'R' engine block with 9.56 deck height that is
a direct swap for the cast iron Magnum block. If you start looking at the
prices of all these lightweight parts the cost adds up sky high - the mpg
saving would never pay for them.

It is possible that 'Rhoads' style variable hydraulic lifters installed on a
Magnum engine would increase MPG by opening the exhaust valve later and nearer
bottom dead center and closing the intake valve sooner. A 'RV' grind camshaft
does this too. This gets the last little bit of energy out of the combustion
pressure, but it also hurts higher rpm horsepower.

Higher compression ratio pistons are a reliable way to get better MPG.
Usually this means you have to purchase more expensive higher octane gasoline.
Raising the compression ratio from 9 to 9.5 is estimated to give 1% better
MPG. On a Magnum 5.9V8, changing the stock head gasket thickness of 0.047
inches to a Cometic 0.025 gasket will raise the compression ratio from 8.9 to
9.3. Replacing the stock 5.9V8 pistons (with their -13 cc depressions in the
crowns) with flat top pistons of compression height 1.626 inches will raise
the compression ratio from 8.9 to 10.2 Using flat top 1.67 inch compression
height pistons will raise the compression ratio from 8.9 to 11.3

There are combustion chamber designs that claim to allow compression ratios of

10-14 on 87 octane gasoline. You can read about them at:

The last MPG technique is the simplest, but the one few of us want to hear. I
have done several 300-400 mile test runs at steady 60 or 70 mph on I95.
Slowing down from 70 to 60 mph saved 3-4 mpg each time. I also did a 80 mph
test run once driving with the crazy flow of traffic from north of West Palm
Beach to Ft Lauderdale. This lowered MPG by 4 compared to going 70 mph.

Notice that I don't claim this slowing down is 'cheap' because of the
'How much is your time worth ?'

If you want to read more about MPG improvements that work, the US government
has put a book online at:

In the Appendix of this book is an interesting table where the Dept of Energy
sent a questionaire to all the auto makers and asked them what various mods
were worth to improving MPG.

Kevin Gertgen's Fuel Economy Calculator software is very impressive and can be
read about at:

There is an online Java based webpage calculator at:

115 Posts
All bow to the man who spent a week typing up usefull information...



Very insightful!

65 Posts
wow that's a whole lot of info. 1 mpg doesn't sound like much but if you think about it i have a 35 gallon tank so for every mpg i gain, i get 35 more miles on each tank. say i get 11-12 mpg that's about 3 gallons everytime i fill up. at $2.50/gal that's $7.50 each time. say i fill up once a week, that's $390 every year. that's some serious savings. would a Rhoads type lifter really help even though the magnum engines already come with hydraulic roller lifters?

47 Posts
I get 16-20 mpg. Are 360's that piggish on gas?

The Green Machine
1,722 Posts
rufnredi said:
I get 16-20 mpg. Are 360's that piggish on gas?
Rowing your own gears can help out in that department too, but 16-20 is AWESOME for a pushrod engine in a full size truck. Best I ever got was around 14mpg when doing long highway trips - but that didn't last long :D

217 Posts
my 318 jeep that is full time 4 wheel drive that has 3.73 gears gets 18-22 miles to the gallon the highway and around 14-16 miles to the gallon in the city depending on how hard i press on the gas. Heck I towed a 92 awd tallon from peoria, Ill to Lafayette, IN and got just under 13mpg. Thats not that bad with about 4000lbs behind the jeep. Every mod that I have done helped my gas milage except for the T-stat.

1,733 Posts
That FAQ has been written a little at a time over about 5 years.

Rhoads lifters would be an interesting experiment on a Ram 5.2/5.9 V8. A Rhoads lifter is nothing more than a normal lifter than had been taken apart and a flat ground onto one side of the normally cylindrical internal lifter piston. This flat causes a 'leak' that allows the lifter to partially 'go flat' at lower rpms.

I have read US Patents where a guy who had made an improvement to the original Rhoads design claimed that his modified Ford F150 got 10% better MPG with the variable hydraulic lifters.

See more supposed advantages at this link:

and the original Rhoads patent at:,524,731.WKU.&OS=PN/4,524,731&RS=PN/4,524,731

2,138 Posts
One would hope so. . . I have a 99 1500 4x4 5.2 5sp and I'm LUCKY AS HELL to get 13 on the highway with a tailwind and little gremlins pushing from the bumper. I also drive it very conservatively. 16-20 with an 2001 is hard to believe, especially since all the posts I've seen say the 318 is in the 13 range and maybe some mods might get another 1-2mph but not up to 20?!? The sticker when it was new said 13-17 which is a load of hooey also. rufnredi--you should go buy a powerball ticket cause you are one lucky farmer.

47 Posts
I do seem to see a wide swing with 5.2/5.9 engines, anything from under 10 to over 20 mpg. I will say the mods have helped my milage, I used to get 14-18 mpg. Also most of my driving is at or over 60mph. My milage when I'm off road drops down to maybe 6 mpg. And this time of year I do more off road then on road drivin. I think in New York it's called Mega Millions.

1,733 Posts
At wide open throttle acceleration on a flat road my 5.9V8 Ram drops to 6 MPG.

At a steady 55 mph on a level windless concrete road it tops out at 24 MPG.

That is a wide range.

37 Posts
I bought a ram this last december and was very disappointed in the gas mileage.
Its a 99 1500 5.9 ext cab 4x4, I was only getting about 11 on average driving 30 miles each way to work at 65mph. I now get avg of 18+ on work drive and best I've got was 22 mpg with 2 mx bikes in the back over a 250 mile trip all highway.

Heres the upgrade steps I took and what they did for the gas mileage. It was a week between each mod, and I drove same route at same speed back and forth to work to test it.
1. Air Filter - nothing
2. Headers - nothing
3. Ported throttle body - nothing
4. Changed plenum plate with hughes one. - nothing for gas, but doesnt eat oil now
5. Used Hypertech programmer 3 - BOOM , instant from 11 to 20's mpg.

I couldnt figure out why this would have caused my problem, so just to test it the next week I programmed it back to stock. Mileage went right back to normal 11mpg.

I then opened up exhaust more hoping for even better mileage, nope killed my torque and I found my self laying into throttle more. When I say opened up I removed cat and ran straight pipes. I guess these engines need that backpressure. I put cat back in and the torque came back.

Next thing Im going to try is going back to stock size tires. I have 285/75's on there now which are approx 33". So im guessing that the engine will work easier allowing more torque to be put to the ground..

BTW a good tip for getting that extra mileage. If you notice that your mileage is lower than normal, speed up a little bit then quickly let off throttle and ease it back on until it settles back at your speed. The TPS must be a little sensitive..

217 Posts
Just checked my gas milage last night for 3 days of driving highway and city and it was 16.59 miles to the gallon. When I drive to work I see no point in raping the jeep. I will keep her under 2.5 grand and she keeps up with a lot of the traffic.

Have you guys tried replacing your O2 sensors?
1 - 20 of 45 Posts
Not open for further replies.