Refer to item 7. If you're allowing more air in, you need to be able to exhaust more gas (exhaust) that's why when you do an air intake or low restriction intake, you should do your exhaust also!
Sooo many people will do one or the other, but not both and wonder why they aren't getting the performance/MPG they thought they should, or read about. If you pushing more air in, make sure you're letting as much out.
In both vehicles I did both exhaust and intake. One was k&n one was injen. Both vehicles retained only the factory exhaust manifold everything else was custom freeflowing...
And I saw a decrease in mileage and an increase in performance.
I'm wondering if just the exhaust would have been better for mpg.....
The OEM exhaust manifolds on these things are notoriously restrictive. This is the reason why Doug Thorley headers are so popular. They do increase horsepower quite a bit according to the dyno charts that Rob has posted, but more than a straight-up power gain, the increase in driveability and usable power is pretty substantial. I don't have them yet, but an intake, headers and full exhaust are on the to-do list.
How many miles have you gone, and where is your needle? I'd be hesitant to jump to any conclusions based on a fraction of your first tank of gas. MPG's vary widely based on fuel composition, driving style, and add ons. You certainly can't go wrong ditching the roof rack. I like to punch the V8, and man, that sucks down the gas more than anything. Ditch the roof rack, drive like you had an egg under the skinny pedal, and report back in a few tankfulls. I get anywhere from 8-16 MPG, depending...
12 in city in summer running ac....
15 hwy summer with ac
only gain about 1mpg with ac off....
guessing the 90lb Nitto dont help, the steel bumpers, sliders, hilift, 12k LB winch, roof rack with adapters for canoe.
May go back to Nitto Terra Grapplers when these Trails run out of tread...but 2 years and going strong with another year easily left on them...maybe 2 years.
In both vehicles I did both exhaust and intake. One was k&n one was injen. Both vehicles retained only the factory exhaust manifold everything else was custom freeflowing...
And I saw a decrease in mileage and an increase in performance.
I'm wondering if just the exhaust would have been better for mpg.....
My gauge seems a little finicky. I had a quarter of a tank left when I filled up last night and I put on 17.17 gallons, meaning that there was roughly 8+ gallons left. Non adjusted mpg for the tank was about 10.65.
I removed the rack last night and can tell a difference on my drive to work, acceleration is a little better, but after 35 miles on the trip odometer, I am at a 3/4 of a tank! At least I now know that it is not accurate.
I compared mph on my gps to the speedo and the speedo is about 7.5% under true true speed.
Thanks again for all of the tips and I will monitor this through a few tanks to get an accurate measure before I start messing around.
The injen was on a 1.6L 4age engine And the k&n was on a dodge 318... so hard to tell which was better.... I liked that the injen was metal vs the plastic k&n
And the injen sounded amazing...but that probably had more to do with the 4age's 7500rpm song
I wouldn't count on the needle being half way on your dash gauge as being equal with the tank being half empty/full. I seem to go a lot further on the last quarter of a tank that the first quarter after I top it off, in regards to the needle pointing on the lines on the dash gauge.
I am getting close to having gone through my first tank of gas and am a bit surprised that I am getting under 10 mpg. I have read up on the forums, but wanted to get opinions and current MPG from others' rigs.
I am running 285/75/16 Cooper Discover STT and have an ARB roof rack. I am probably going to remove the roof rack because I will not need it but a couple of times a year.
I am thinking of switching to an AT, probably BFG or Terra Grappler, and am wondering if it will make that big a difference in MPG. I would like to get 12 around town and 15 on the road.
Any guidance would be greatly appreciated. Also, is there any market for a set of 5 Cooper Discover STT (1 is brand new and 4 are about 50% treadlife remaining).
I'm quite surprised no-one has mentioned this yet. If you live in a hilly area, you will lose a bit of fuel economy just on that alone. I know this as I live in a hilly area. Here are my numbers (corrected for my 275/70/18's):
11.5 mpg avg city only
13 mpg 50/50 mix avg city/hwy
15-15.5 mpg avg highway
I have done as well as 18.5 mpg in all flat highway driving averaging 55mph.
And yes, I live in a hilly area, driving up and down every day. Do you do hills everyday?
I didn't see it mentioned yet - I see about 1 or 2 mpg difference when I run with the A/C on. Easy to overlook with the automatic climate control and use it when you don't really need it.
Agreed. I get 14.6-14.7 average on the ScanGauge over the past few months blasting the AC with 305/75R16, ARB front, Luke's on the rear, MT sliders, full BIOR skids. My '00 is loaded. 10 MPG aint right unless you drive with a lead foot or uphill both ways.
The DT headers will go on soon, I'll be doing O2 sensors, TB and MAF cleaning. I'll see if that changes anything. BTW, I run the cheap gas and aside from a little power difference, I don't notice and substantial difference in MPG with premium vs non premium.
Good info frog. Don't have scan gauge but upgrade from stock type tires to km2s seems to work a brutal mpg effect. Also affects acceleration and braking. But I like the tires, and don't need to go that fast, and thus braking is compensated for. Filling up after 250 miles rather than closer to 300. oh well. Not like I had delusions of Prius.
Can increase mileage by 1.5 mpg just by the way you drive. But 12 mpg is the best I can do in town. If I drive without being conservative it's runs about 10 mpg. Highway will always be 14-15 no matter what as long as I don't go over 75. The 33" tires reduce the rpm's at higher speeds to maintain 75 and probably adds .5-1.0 mpg on flat ground. When checking mileage add about 6% for the larger tires.
Only other solution is to coast with the engine off a whole lot but is a bad idea and not recommended to anyone.
Mine is usually high 13s low 14s around town [Greater DC so no hills]. Just did a run to Virginia Beach and back yesterday, cruise average around 70, hotter than hell so AC on 100%, yielded low 18s.
Peeps keep saying to get a scan gauge to monitor instant mpg. I just wanted to add that if you have the nav already in your 100 you can see this by going to info then trip info (or something like that).
