Jeep Stroker MPG

i have been told that it gets better gas mileage and the people that say that run premium fuel but the improvement in mileage makes up for the extra cost. i know a few people with xj's that run 4.6 or 4.7 liter strokers with correct gears for their tires and corrected speedo's that say they getter mileage than my 4 liter gets but i get crap for mileage.

I'd bet that the better mileage is from being a fresh, well-built motor. But all things equal, there shouldn't be much difference.

Mine stayed just about the same as when I had the old 4.0. However, I maintain everything that needs to be, so its always got 20+ on the highway.

All else being the same, you can't have a power increase without burning more fuel.

Now if your stroker engine is geared a little higher than stock (numerically lower) say from 3.55 s to 3.07s. Gas mileage would be about the same at cruise conditions.

I get better milage in the city than I did b4. I run a 4.7L with 33's and the wrong gearing(3.55), give me a break i am a poor college kid. With the right gears I would probably get even better milage in the city.

Theoretically this is due to a larger amount of torque at a lower RPM. However, since it is much more fun to drive now and I tend to romp on it a lot more my milage has been decreasing. If I go a full tank without hamering it then I get the same milage I got before, or a few mpg better

I've heard about the same mpg... engine doesnt have to work as hard so it uses less fuel... assuming gearing is well matched to the engine.

smaller engines having to be on the throttle more for loads (hills) would decrease mpg, whereas a larger engine would not have to work as hard to do the same. Of course, there is a limit to this, where the bigger mill is just using a lot of fuel.

I know this thread is old but has anything changed with the 4 years of researching?

The TV show "Top Gear" did a test of a small, fuel efficient toyota vs. a beast of a BMW and found that the BMW got better gas mileage WHEN DRIVEN LIKE THE TOYOTA.

Gas mileage has more to do with how you drive and one of the big problems with power adders is that people use them. If you use the extra displacement simply to go faster or start quicker you should expect your gas mileage to go down. If, on the other hand, you drive conservatively, your gas mileage will be better (the same is true for your current engine).

My "other" project is a replica of a 1965 Shelby Cobra. 310HP at the rear wheels on a 2000lb car is a blast to drive but I can't keep myself from standing on the gas pedal so my mileage in the city sucks (<10mpg). I recently drove it 140+ miles from Houston to Austin and cruising in 5th gear I found I was getting closer to 30mpg (used less than 1/4 tank of gas). On the highway, the increased HP and torque was being used to maintain speed so it actually used less gas because the combo is hyper efficient. Even big hills barely made the engine work so it consumed almost no gas. My wife was following me in her '05 Toyota Highlander and used almost 1/2 a tank (20Gallon tank vs. the 15Gallon tank in the Cobra) simply because her engine had to work a lot harder.

The real question is "how do you intend to use the displacement?".

Wow dredging up an old one... but I will contribute... I gained 1-2 mpg highway going from 4.0 to 4.7, changing nothing else(same trans, gears, tires). I lost city mpg, although I think most of that is due to a change in driving style. It's hard to keep your foot out of the pedal with a stroker.

The cam you choose has an effect on your fuel mileage as well. A change in cam can mean a change in your power curve, which results in different fuel comsumption for city or highway. For instance, if you go with a "hot rod" cam, that moves your power band higher into the rpms, chances are you are going to drive in those higher rpms more frequently around town and thus use more fuel.

If you choose a low end heavy cam, where your power and torque are in the lower rpms, you may find yourself struggling at highway speeds. It's all a give and take, but overall, if you are trying to justify a stroker for mpg reasons, you are in it for all the wrong reasons.