Speed

g1g · 03-27-2011, 04:26 AM

On my 95 Coachman I generally averaged between 15-16 MPG. I usually try to drive between 55-60. My lowest that I ever got was 14 mpg on old gas and 17 mpg both highway drriving. On my last trip I wasn't able to drive due to my medication so we took a friend to do some of the driving. During this trip we only averaged about 11mpg. I am thinking that it is because the other person drove a lot faster. I really can't say how fast as I was sleeping part of the time and just not able to see the speedometer but I believe they were going between 70 - 80 and maybe a little over. We did have an extra person and their luggage, that may count for a small amount but I think the speed was the biggest factor. I am looking forward to see whay I get on my next trip.
Has anyone else actually documented speed and MPG on their B?

Mike · 03-28-2011, 02:25 PM

I've been able to get 20 miles per Imperial gallon (4.5L) on a short (300 kms), flat, almost
entirely highway trip, at 100KPH on cruise control in the Spring or Fall.
I have done this with full fuel, propane, and fresh tanks, and empty holding tanks.
So that would read as ideal conditions, pretty much.
If the snow allows, I may try to see what numbers I can come up with now, and may compare
to what the Scangauge is telling me, should I ever get a chance to plug it in. It's bloody cold here!

Mike · 03-28-2011, 02:28 PM

I've been able to get 20 miles per Imperial gallon (4.5L), and sometimes a bit more, on a short (300 kms),
flat, almost entirely highway trip, at 100KPH on cruise control in temps well above freezing.
I have done this with full fuel, propane, and fresh tanks, and empty holding tanks.
So that would read as ideal conditions, pretty much.
If the snow allows, I may try to see what numbers I can come up with now, and may compare
to what the Scangauge is telling me, should I ever get a chance to plug it in. It's bloody cold here!

Johnny R · 06-17-2011, 03:47 AM

I changed the air filter on my unit and the mileage improved by 5 mpg. The tailpipe was very clean, no indication of running rich. But it's still lazy when merging or climbing a grade. Dodge 250 with a 318 (5.2L) engine.

Mike · 06-17-2011, 02:49 PM

WOW!! 5 mpg from a $20(?) part.
Excellent investment.

Johnny R · 06-17-2011, 08:08 PM

Well, maybe I drove a bit slower too. The air filter was not that dirty. Nevertheless, I was pleased.

Photog · 06-20-2011, 06:27 PM

We get an extra 2 MPG when we drop from 65 MPH on cruise control, to 55-60 MPH off cruise control. No trouble getting 15-16 MPG on the interstate, and 14-15 MPG on the 2-lane highways.

arrveedogz · 07-28-2011, 04:48 AM

Just got back from a 3000+ mile trip through New Mexico and Colorado (mountains!) where we averaged better than 17.5 mpg. I rarely exceeded 65 mph, despite the 75 speed limits. Kept a close eye on engine temp (Scan Gauge 2) throughout. Very fast temperature response to going uphill or downhill - about a 15 degree range.

Dan F.
Back in hot humid Houston

Mike · 08-08-2011, 05:59 PM

We tried one or two steeper grades last summer in Lake Placid, and farther east, and saw similar rapid rises in
water/engine temperature. We only have the gas 350 V8, and it struggles, when presented with a 6% grade or higher
in hot weather. Not enough torque, I guess. I often slow down going up steeper hills in cooler weather, just because
I'm (I think) under powered when loaded up.
I actually had to pull over and turn around on one road in Lake Placid, where we wanted to try to get up a ski area
hill for the view. The temp gauge jumped up after about 30 seconds of climbing. Glad I didn't damage a head gasket,
or the weak intake manifold gasket, which I eventually replaced later anyway, due to the (Dexcool related?) leak.

VernM · 08-08-2011, 08:22 PM

So many factors enter in to mileage, Mike. Speed is one. Style of driving another important one (smoothly and with anticipation ahead of throttle changes), grade, altitude, wind, tire pressure, engine condition and tuneup, brake useage. Acetone as an additive to fuel (that from a high school-mate of mine who is playing with it and finds no measurable change, but he's an educated tinkerer who also is working on fairings to clean up aerodynamics).

My solution is work off the top half of the tank and don't largely worry about it other than to keep an eye on big changes that might signal something important. If you can afford it and can't get it to run on peanut oil (your Pratt and Whitney jet engine :drinkers: s will) or something like that, just go and enjoy.

arrveedogz · 08-09-2011, 04:16 AM

I guess the key is to not be in that much of a hurry, which was fine with me.

I did have a lot of fun at a campground with a pretty steep hill. We were near the top and got to watch the jumbo 5th wheels burn several gallons of fuel on their way up. Good times!

Dan F.

Mike · 08-21-2011, 07:15 PM

Quote:

Originally Posted by arrveedogz

Just got back from a 3000+ mile trip through New Mexico and Colorado (mountains!) where we averaged better than 17.5 mpg. I rarely exceeded 65 mph, despite the 75 speed limits. Kept a close eye on engine temp (Scan Gauge 2) throughout. Very fast temperature response to going uphill or downhill - about a 15 degree range.

Dan F.
Back in hot humid Houston

We just got back from a week away. Saw similar temp fluctuations when hill climbing out in Gaspe QC.
I still haven't gotten around to adding the transmission temperature codes (assuming I find them and figure
out how to build my own optional readout), but water temps ran between 188F with no load on the engine downhill
no throttle, and a high of 207F when struggling up a hill with the 4-ways flashing. I'm not sure how useful watching
my transmission boil would be anyway.

Cubey · 09-15-2012, 04:51 AM

I haven't driven my van yet enough to know the mpg but I am hoping for 12mpg. I have told to expect 14-15 but I'm not sure about that. But then again, my van doesn't have as high of a top as many vans do so it has less wind drag for sure. Also, mine lacks the emissions system that some vans have (as far as the air pump). But still, a 70's 5.9L V8 engine with a carburetor? Not so sure it's going to get 15 even at 55mph. If it does, I'll be tickled pink. But I am keeping things realistic.. expecting 10-12 hwy.

I will be keeping the rear tires maxed out for air pressure (80psi as I recall, tire capacity) due to the large amount of weight in the rear. Front I will keep around 50psi which I think is the factory spec. I might try 60 and see if it helps and doesn't make it ride too rough.

I had a 1997 Ford E150 conversion van (without a high top) with a 4.6L V8 engine. It got about 14-15 at 70mph and about 16-17 at 60mph. But it had a fuel injection and a smaller engine.

poncho62 · 09-15-2012, 01:10 PM

Speed does make a big difference in mileage....I can see that driving at 80mph plus would drop the mileage that much
The air filter being clean helps too.....I have never seen a 5mpg difference, but you never know.

Cubey · 09-15-2012, 04:45 PM

Quote:

Originally Posted by poncho62

Speed does make a big difference in mileage....I can see that driving at 80mph plus would drop the mileage that much
The air filter being clean helps too.....I have never seen a 5mpg difference, but you never know.

Sometimes an air filter can be clogged and not look like it. I took my air compressor to my mower's air filter and you should have seen the dirt coming out of it. It didn't look as dirty as it was. It's a $25 filter so I try to extend it's life as much as possible.

mlts22 · 01-13-2013, 07:54 AM

I definitely would say that speed greatly impacts MPG. Air resistance increases by the cube of the speed, so a doubling in how fast someone is going means that eight times as much force is needed to deal with the resistance.

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