Can I improve my gas mileage?

THe 8.1 is a thirsty engine. There's really nothing you can do as far as add-on gadgetry to improve mpg.

THe MPG you are getting is pretty much what I hear everyone else getting.

I used to have a 6.0L. It would get about 8.5 mpg towing.

The 8.1 is very different from prior BBC. The block is different, the pistons are much different and the heads are not interchangeable. We have had two with a diesel in between, they each have their pluses and minuses.

The 8.1 is a very good, well designed engine from the factory, as good a towing engine as ever produced. It takes a lot of money to really improve its performance. There is a company called Ralar that has speed equipment for the 8.1, bring big money, and frankly all the speed parts in the world will not improve mileage on this engine, spend the money on a diesel.

Mileage, At 65 mph we get just about 8 mpg pulling a 8,000# car hauler with the camper loaded to about 4,000#. With just the camper at 65 mph, we will get somewhere around 11-12 mpg. Slow down is what I have found works the best, if you can keep it at 55 you will see 12 mpg+ maybe even with the Jeep. If you remember the 454, we had several of them, I saw down to 4-5 mpg in the "old" days with a strong 454, which was not nearly as good as the 8.1 performance wise.

Maybe time for some BG44K, to keep the valves and injectors clean. I use it at least once a year, more like twice, it really works. Use synthetic oil, there are a lot of big parts in this engine and the synthetic oil helps. Check the plugs, you can try AC Delco 41-932 plugs which are (for the most part) no longer available, you may find them on ebay. There may be a newer plug that is slightly warmer that may help. A 180 degree thermostat may help. There really is not a lot you can do, it does not need a more open exhaust, it has plenty of exhaust capacity and the heads flow great. Get a tune at a good tune shop, their are plenty in Denver, I and many of my friends have used Lou's cars. Lou has not worked on the 8.1.

I have a 45 gallon Transfer Flow replacement tank that really helps. I generally have a 350-400 mile safe range, depending on load, with about 50+ reserve. With a 26 gallon tank we were always stopping for fuel, our range is now about double. Transfer flow no longer makes the gas version of their replacement tank. You may be able to find one on the salvage market.

With a gas engine your are paying for gas. With a diesel you are paying for the engine and the potential repairs, and more maintenance then a gas motor.

I have come to the conclusion that for us gas is better, it does not have the power, it does not have the fuel economy, but it does have a different type of economy and its very quiet and smooth. Either way it takes $$$$ to go down the road. Make your choice and pay your money!

Good Luck.

trail-explorer wrote:
Educated Jeep guys never run K&N air filters because they allow dust to pass through.

OPs not talking about a Jeep driving in dirt or a Turbo diesel either. :) If he had, I wouldn't be suggesting a K&N.

I had an 89 Chevy 3500 crewcab dually with 454 throttle body injected turbo hydro 400 A/T and 4.56 diffs. I joked about 15 mpg which is 8 mpg hiway and 7 mpg city that equals 15 doesn't it?? Realistically it averaged 8 mpg empty or loaded. K&N filter and flowmaster exhaust made no difference. 70 mph in drive and 3600 rpms. Could pull a brick outhouse anywhere but past a gas station. I put 83k miles on it in 21 yrs due to gas cost. I now pull a 13.5 k 5ver with a Ram 3500 4x4 megacab cummins with 4.10s and get 10-12 mpg towing. 56k miles in 5 years and lovin it.

SDcampowneroperator wrote:
Sometimes its as simple as lightening your right foot, looking ahead at traffic and lights to lessen use of the left foot.

Two footed driving is bad too.

jimh425 wrote:
... K&N...

THose things are evil.

THe reason they flow so much more air is because there's holes in the filter media. I've taken a number of them out of the package and held them up to the light in the store.



Educated Jeep guys never run K&N air filters because they allow dust to pass through.

Hi,

What octane gas are you running? While 85 octane is 'regular' in the high altitude mountains, it is not really all that great for fuel mileage. 89 or 91 octane, and the engine will not ping, not pick up pinging with the anti-pink sensor. With higher octane fuel, it can lean out the mixture, advance the spark timing, and overall improve the fuel mileage.

And remember that many states are using 10% alcohol. This is mandated by the environmentalists who think we should be using more 60,000 Btu's per gallon alcohol instead of 125,000 Btu's per gallon normal gasoline. For some reason (yet to be discovered by them) 60,000 Btu fuel will not take you as far as 125,000 Btu per gallon fuel, but they still mandate it.

And forget what "Congress" says, higher octane fuel will give better mileage in a fuel injected car or truck. Check it out for yourself. . . Or keep believing what 'congress' has to say about fuel economy.

I get 8 MPG with a 17,000 pound motorhome towing a car! My engine is the 1997 460" V8 in a Bounder 30' long, so much more wind area that you have. I get 8 MPG with Chevron or Mobil 91 octane gas. Other brands do not get as high of MPG.

Good luck,

Fred.

Get someone with a lot heavy driving experience to ride with you a few miles, see how you drive. Minor changes in driving habits can make big changes in economy. Sometimes its as simple as lightening your right foot, looking ahead at traffic and lights to lessen use of the left foot.
Getting good mileage out of a heavy high profile vehicle takes a different approach.
edit.
another thought. while the many worthwhile mods proposed could likely improve power or fuel economy, do they justify the cost? That is the reason for your post isn't it, about cost /mile? If so, then mods to engine breathing & fuel system would be more benefit costly than fuel savings?

Bigger exhaust, K&N, and a tuner or slow down.

I have heard these will improve mpg. Haven't tried them so can't
recommend. http://voloperformance.com/fs3fuelsaver.html