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WILDEBILL308 · 12-06-2012, 06:40 PM

Well got back from Fredericksberg Texas Yesterday. Short trip only 469 miles round trip. Went down the back roads going and coming back picked up I35 at Belton. I filled up and checked my mileage today 8.496 mpg. I learned that I wasn’t driving fast enough. I ran about 55 going down and on the way back on I35 I was running 60 –65. I was watching the tack and noticed that I was running lower rpm at 60 than at 55. Apparently I wasn’t going fast enough to get it to shift into 6th at 55. I was running in economy mode all the way. I am wondering if anyone else has noticed this happening on their coach. This is a 2003 Bounder 38N 300HP Cummins with Allison 6spd. The more I drive this coach the more I am learning, I almost have a 1000 miles on it since I bought it. By the way I like my Kroger fuel points my price for diesel was $3.296 lots better than it has been.
Bill

jlfbatonrg · 12-06-2012, 07:48 PM

Bill,

I have a similar set up to you but in the Expedition model. My best average mileage 9.5 mpg pulling a Saturn Vue at 63 mph tach 1650 rpm. As you stated, running 55 mph tach 1750 rpm fuel mileage drops to 8.7 mpg.

WILDEBILL308 · 12-07-2012, 07:27 PM

Quote:

Originally Posted by jlfbatonrg

Bill,

I have a similar set up to you but in the Expedition model. My best average mileage 9.5 mpg pulling a Saturn Vue at 63 mph tach 1650 rpm. As you stated, running 55 mph tach 1750 rpm fuel mileage drops to 8.7 mpg.

I was towing my 2012 Civic. I just wish I had known what gear I was in I might have bumped the speed up a little. Not bad milage for runing the Texas hill countrey.
Bill

jlfbatonrg · 12-08-2012, 06:43 PM

Bill,

Our average mileage includes driving in the Eastern Mountains, and the Western Mountains. We just finished a trip to a rally at Sandy Creek State Park close to Jasper,TX. What I have found, and it seemed true in those hills, is if you run 6th gear at 61-63 mph, the transmission continues to search between 5th and 6th gear. For our set up I increase the speed to ~65 mph. This increases the rpms to around 1750 rpm and the tranny doesn't search much if any. On the Jasper trip we covered 495 miles to and from, and avereged 9.1 mpg.

When in the mountains I manually keep the rpms at 1900-2000 rpms, by manually shifting the tranny as necessary. This seems to work for us.