iRV2 Forums

iRV2 Forums (
-   Class A Motorhome Discussions (
-   -   cat diesel (

PL KIDS 04-18-2008 01:43 PM

We have a 34 Beaver with the 400hp cat engine. We tow a Jeep wrangler for a toad and our mileage is running 6.2 mpg I run 65mph. Is there away to improve mileage? Thanks

PL KIDS 04-18-2008 01:43 PM

We have a 34 Beaver with the 400hp cat engine. We tow a Jeep wrangler for a toad and our mileage is running 6.2 mpg I run 65mph. Is there away to improve mileage? Thanks

RV Wizard 04-19-2008 01:17 AM

How many miles do you have on the coach? Is the generator a diesel? Are you running it too? What RPMs are you doing at 65 mph? One thing I do and see an improvment in fuel milage is use acetone in the fuel in a ratio of 2 oz. per 10 gallons of fuel at fill up. I also use it in my pickup and not only get better milage but it stops the pinging under heavy loads and burns cleaner.
You should get better milage when the engine is broken in but it will probably take 50k - 60k miles.

PL KIDS 04-19-2008 04:44 AM

The coach has 25K and yes the generator is diesel but wasn't used. RPM's are about 1650 at 65mph. I'll try the acetone treatment. Thanks for the hint....

cannon man 04-19-2008 01:20 PM

loose the jeep n slow down.
acetone???????? what are you guys thinking????????? better hope cat doesen't see this.

SargeW 04-19-2008 03:18 PM

What exactly is acetone susposed to do to the fuel? Acetone is a solvent, won't that break down the diesel and cause a loss of lubricity?


historyljc 04-19-2008 08:38 PM

How much weight are you carrying? Have you weighed the rig and balanced the air pressure in the tires to weight? Slow your speed down to just what is needed to kick the transmission into sixth gear or whatever speed just above that which you find through experience to be your engines "sweet spot" for best mileage. I find my best mileage right around 60 mph. Let the cars pass, you're traveling to see the sights.

J Walker 04-20-2008 06:47 AM

Check the peak power RPM range for your engine and stay within it. That plus making sure your engine is running properly is about all you can do. You do seem to have a lot of HP for a 34' MH. I bet it really moves quickly.

Hillbilly2 04-20-2008 05:42 PM

Boy, that really does suck, I'm getting 7.7 MPG with a 460 ford gas burner at 65 mph in a 36' Southwind pulling a four door tin top Suzuki Sidekick, I get 8 MPG without it.

Chief 04-21-2008 05:26 AM

According to my Freightliner display window I get 7.5mpg. I usually run about 62 mph while always trying to keep the rpm at or above 1750.

While attending "Camp Freightliner" Mike Cody said that that portion of the program did not work properly and Cat refused to fix the problem. Has anyone else heard this?? Guess it would have something to do with the ECM or some sort of metering device.

At any rate, it has not been a big issue with me as I intend to use the coach anyway. Guess if it dropped dramatically I would be more interested.

historyljc 04-21-2008 07:23 AM


You, like I, must have one of the older display units. Freightliner started installing the new type displays about mid-year in 2006. The old style units, like mine, give the average milage from day one and cannot be reset. That's why Mike said the info was worthless, it includes all run time whether on the road or sitting still. My display shows 7.2. That includes fuel used on the road, while idling, and generator runtime. My "instant mileage" generally shows about 8.5 while traveling on what I think is flat and level road. The only way to check it for sure is the old fashion way of dividing the mileage between fuelings by the gallons pumped into the tank. I believe Freightliner will up-date the info center -- for about $2000.00

Richard and Babs and a Bob Tail Cat 04-22-2008 04:12 AM

What is your engine a C 9? Pre 07 emission or after? Mileage as mentioned above? What is your GCVW? Our total weight is about 34,000 and we drive 65 or a bit more and our Silverleaf shows 7.4 mpg in 100,000 plus miles. It was 7.5 until we went with the larger toad 4 years ago.

Some report mileage gains by using the Allison economey mode and driving at 62 mph and accelerating like a little old lady. We also have noticed better fuel economy if we use the cruise a lot.

PL KIDS 04-22-2008 04:23 AM

Yes, pre 07 emission. I have tried the economey mode and drove at 65, used cruise control, tried 5th gear at 60 mph which is about the same rpm's and nothing different. We have a Aladden system that tells us each trip, total, instant. Towing the Jeep made about 1 mph different. Thanks for your imput. Eddie & Krissy

CaptBill 04-22-2008 04:52 AM

Our mileage improved noticeably when the engine had somewhere around 18 to 20,000 miles on. We just recently came back from a winter in Florida, and I did an experiment.

On the trip down from Delaware, I drove with traffic at 66 to 71 mph. We were towing a Jeep Cherokee, and averaged 8.1 mpg.

One the return trip, I drove no faster then 62, and in areas where speed limit was 55, that's what I did, even if traffic was going 65 (as was often the case). My return trip averaged 9.3 mpg, calculated the old fashioned way of dividing miles by gallons, and the result matched the trip computer on the Sliverleaf.

In 5 years of ownership, this is the first time I actually tried this, and I was pleased with the results.

Now if I can only keep my foot out of the accelerator...

All times are GMT -6. The time now is 09:18 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.