Gas Mileage

Yes, the Volvo engine is a great engine. I am curious to see how the mileage improves as you get more miles on it.
We all try to get the best mileage and I am always looking for those little increments that add up.
Bill

chuckftboy wrote:
A mechanic told me, DEF allows Cummins to tune for better mileage. Non DEF motors were more tuned to satisfy the EPA and less for mileage. Diesels built in the 80's and 90's were pretty fuel efficient though. I have owned both and won't say what I get because the naysayers wouldn't believe it. Although I bet your mileage will get better after break in.

Mileage doesn't get better after break in of any new internal combustion engine. Vehicle mileage will never be better than when new.

Bill, I was told that the Volvo engine is more efficient than the Detroit Diesel that it replaced. It is quieter also. With 230 gallons of fuel, I will run up to about 1,000 miles before refueling which is between 1/4 and 1/2 a tank. We have a 16 gallon DEF tank that I fill every other tank full.

Mark

Brett is right. But once again we are back to comparing apples and oranges. Unless you are comparing the exact same setup with the same load under the same conditions, it is just what that coach got at that time on that stretch of road. Someone driving the same coach over the same route may have different results.
On the same theme I think Mr.Mark is getting better mileage than I am because he is moving nearly twice the weight for only slightly less mileage.
Bill

Mine has 3000 miles on it as it had to make its way home to the West Coast. I know this is the wrong way to ask another question but when using your engine brake what is your Max RPMs. I like to keep it 25 or under.

Enjoy that new Discovery! We have the 8.9L ISL and 44' tag with Wrangler 4 dr and DEF and get 7.5 pretty consistently driving the speed limit (except WY maybe - can't do that 80 :))

rgatijnet1 wrote:
The Allison transmission control module can be programmed to regulate the shift points. If you want it to shift in to high gear sooner, just ask the shop to program the TCM to do it.

True, but changing the shift point (actually minimum RPM in next higher gear is what is changed) changes ALL gear's shift points.

SO, first question, is how far above your engine's PEAK TORQUE RPM are you when it shifts into each gear. Make a note of this next time you drive when at light throttle. You may be able to drop it, may not.

The Allison transmission control module can be programmed to regulate the shift points. If you want it to shift in to high gear sooner, just ask the shop to program the TCM to do it.

You're getting better than I , but all my trips so far are under 1.20 hours. So combined with urban traffic. Just over 6 mpg with ours ( same rig as you). Not broken in yet. Under 800 miles on it. I travel around 65-68 mph. I suspect it'll go up. Yours too probably.

How many miles on yours?

WILDEBILL308 wrote:
I get better mileage going faster. I can't get it to shift into 6th gear till 65+. Tried the slow speed once. Drove the length of California at the posted 55 for towing. Got an average of 1-1 1/2 mpg less than average. Bill

Something is wrong with your setup as you should be able to get it into 6th at 55 if on a level road. Even in 5th at 55 you will get better mpg than at 65 in 6th...the square of the speed.