21 foot '77 -- mpg guess?

[Phil47234]

Anyone care to hazard a guess as to what mileage a 21 foot '77 with a 440 motor gets on the highway and going up and down steep windy roads?

Part two of question: If you lightened a 21 footer and installed a Dodge 318 (1970's), what gas milage might you get?



We have a gasoline 1980 Mercedes Hymer in Europe, 17.4 feet long and nearly 9 feet high and 2.2 meters wide. We consistently get 15mpg, no matter how steep or windy the road. Although we rarely drive over 62 mph. It's not geared for much more. It's a 2.8 liter four cylinder motor, and the construction of the camper is of lighter material than in the States. Man, I'm having a hell of a time figuring out with what I could consistently get over 11 mpg in the Americas. By the way, in some countries, they consider these gasoline Mercedes obsolete, because they use too much fuel. They only take the diesel Mercedes. At $333 per thousand miles at European prices, I wish we had a diesel over there and the gasoline one over here.

[caninecaravan]

I have a 78 in the same size with the same engine and we are getting 7.5mpg when we keep it at 55 on the hwy. That seems to be the average for the Clippers. CanineCaravan

[clockwork]

I've experienced mileage as high as middle 8's on flatlands @ 52-55 mph, and low 6's on the same roads @ 65-68mph. Wind direction and speed can have a significant impact as well.
Considering the aerodynamics, I suspect the 318 would have a hard time producing much better results w/o major mods. Perhaps some of the 360 AC owners will  chime in with their power vs. mpg observations.
dave   

[JerryT]

We have a 78 with the 440 and we also get 7.5 avg.  I kissed 8 once but don't think I've ever seen the 6's. I added the GearVendors overdrive, I really like it, it adds so much to the drivability of the coach, it seems to drive like the newer stuff. I can now drive at 70- 80 and still get my 7.5. I slowed down and checked my mpg at 55 with the OD and guess what? yup, 7.5, fast, slow, it don't seem to matter, I even towed a travel trailer with no real change. The only pay back I can see for the OD $ is that the motor will last longer by turning 25% slower and by the reduced heat/wear factor. The 440 engine/4.10 rear gear ratio/OD trans is a nice combo, I don't know if I would put one on a 360.
JerryT