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jeepgcoman 05-06-2011 03:11 PM

Hemi Fuel Economy Comparison After Mods.
In January we took an 817 mile trip with the Hemi WK, and then again, took a similar 949 mile route last week. The only real differences were a couple side trips, where we stayed and where we bought fuel. In January the Jeep had all the mods. listed in my signature below, EXCEPT the tubular headers and the SRT bumpers. The weather in January was wet and cold (~15-35 degrees) with little wind, and last week's trip was not as wet and cold (~20-45 degrees), but was quite windy (~10-30 mph) from all directions on all legs. All driving was at altitudes of ~3000-7200 feet, with some in winding mountain roads and some in long, slow inclines. Here are the fuel economy (or lack of) stats. for both trips, with descriptions of driving conditions.

--Fuel used in the January trip was ethanol blend 87 for the first leg, 85 for leg two and three and a mix of 85/87 on the forth leg.
--Fuel used in the April/May trip was non ethanol 87 for the first leg, and ethanol blend 85 for legs 2A, 2B, 2C, and 3, and a mix of 85/57 ethanol blend on the forth leg.
--As stated above, the only differences (aside from weather) is that the WK had tubular headers and SRT bumpers for the April/May trip. For both trips I used a modified Diablosport 93 octane tune. I never experienced any knock retard, and I can get away with this only because of the altitude.
--All legs, except for the beginning of the first leg and the end of the last leg, were at altitudes above 4500 feet, with most of it over 5000 feet.
--Slight differences in distance were mostly due to locations of gas stations and where we stayed.
--Speeds driven were (most of the time) between 55-65 mph, slower in the mountains.
--Total highway miles/gallons used for the January trip was, 800 miles/42.1 gallons (19 mpg) and another 17 miles/1.9 gallons (8.94 mpg) for in town driving, for a grand total of 817 miles/44.0 gallons/18.56 mpg. Total highway miles/gallons used for the April/May trip was, 858 miles/39.2 gallons (21.88 mpg), and another 91 miles/5.88 gallons (15.47 mpg) for in town and side trips, for a grand total of 949 miles/45.08 gallons/21.05 mpg .
--Miles are rounded off, gallons are not.
--I think I got most of the math right, but let me know if I goofed anywhere.

January Trip...............................April/May Trip
Leg 1
254 miles/14.3 gallons/17.76 mpg....259 miles/12.8 gallons/20.23 mpg

Leg 2A
235 miles/12.5 gallons/18.8 mpg......129 miles/4.9 gallons/26.32 mpg
.................................................3/4 ~20-30 mph tail wind.
Leg 2B
*17 miles/1.9 gallons/8.94 mpg........**91 miles/5.88 gallons/15.47 mpg
*This was short, all in town driving with little or no warm up.
**This was ~70 miles of mountain driving (up to 7200 ft.) and ~20 miles city.

Leg 2C
.................................................1 59 miles/6.6 gallons/24.09 mpg

Leg 3
130 miles/6.3 gallons/20.63 mpg.......126 miles/5.9 gallons/21.35 mpg

Leg 4
181 miles/9.0 gallons/20.11 mpg........185 miles/9.0 gallons/20.55 mpg

I am still hoping to get a "good" mileage check, without wind, but I think I'll have to wait until late spring, early summer when the winds calm down a little. By then I hope to have either a new cam installed or advance the stock cam 4 degrees. I am hoping the mileage will change a little more for the better after that.

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