Community Forums

Davel · 08-05-2009, 10:49 PM

After not using the gen set and house a/c going down the road we started using it on our trip out West 3 years ago and really got used to the added comfort of having the entire coach cool. It was in the 100-105 degree range and we needed all the power we could get going over the Rockies so I chose to run the gen set over the dash air. Now we use it a lot. I have read estimates of .6 to .8 gal/hour but have found only one person that ran the generator on a seperate fuel line to check usage for an hour. If my memory serves me correctly, always a risky move, his results were .8 gal/hr.

Ron and Dee,
Have you checked with Winnebago about fixing your leak? They fixed mine well after it was out of warranty. It might be worth a call.

Dave

Daysu47 · 08-06-2009, 08:57 AM

Well all, we just returned to San Diego from a 4200 mile trip to the Midwest, Forest City was one stop, and once home did the calculations on mileage. Of course there was NO cheating!

Before I give you the numbers, I did a "seat of the pants" test of using the dash air and not, relying on the Scan Gauge II for change in rpm in similar conditions; flat interstate, rolling hills, and similar grade climbing and could only notice about a 15-20 rpm change. Of course on cruise control constantly. So, my conclusion is that the compressor does not take that much away from the motor horsepower. Max. engine temp. was 235 degrees, with A/C on, climbing grade outside Las Vegas, 107 degrees. Once away from Vegas weather was great, 80-95's.

OK, with no toad, using Mobil I oil, checking tire pressures every 3rd stop, relying on computer and cruise control for the shifts, the average for the overall trip was 7.6 mpg, using the gen. for A/C about 9 hours during the trip, cruising on cruise control whenever possible at 68mph. Used 2 quarts of oil and, 120 miles from home, coming back, turned over 70,000 miles on the odometer. The mountains, I-70, that's another story!! Also noted when traveling TO the midwest we had a fairly good tail wind most of the time which helped BUT coming back, noticed numerous times an increase of 75-150 rpm due to head winds on I-80, sooooooo,

the calculations are in and the tests concluded, we had a great time and the Workhorse and the 8.1 didn't miss a beat!!!!!

Preparing for next years trip NOW!!!

David

Ron & Dee · 08-06-2009, 09:21 AM

Quote:

Have you checked with Winnebago about fixing your leak? They fixed mine well after it was out of warranty. It might be worth a call

Thanks Dave,

I'll give them a call

The two main things I monitored with my newly purchase Scangauge II was the average fuel consumption and the engine temp.

The max temp I reached was 224, and it looked like the mileage dropped almost 1 mpg with the dash air on.

I don't know how much the big fan cost to run but I believe with both the big fan running more and the dash air, it would reduce the average mpg considerably.

Total miles 6278, a little over two quarts of the new Castrol Edge, a lot of HOT, hard driving, mountain driving that is.

Ron

blacktie.shooter · 08-06-2009, 10:09 AM

Quote:

Originally Posted by DriVer

I only run the generator when the gash A/C can't keep up. So far we haven't needed to run the gen a lot. I do turn the gen on before getting off the Interstate if I am going to make a Roxy stop.

Quote:

Originally Posted by oemtech

Me... the dash air on max is usually all we need. But, in the heat of the summer I crank up the genny about 10 to 20 miles before we get to the camp ground. That way the rest of the coach is cool while we setup.

Quote:

Originally Posted by j griff

My philosophy is exactly opposite of Driver's. I only use the dash air when the basement air being operated by generator power can't keep us comfortable, which rarely happens. I do exercise the dash air regularly to insure it will operate when needed. My rationale: I think the engine is working hard enough without the added strain AND I hate the sound of the extra cooling fans. My guess is that the two options use about the same amount of extra fuel. To each his own.

I agree with griff, for a couple of reasons:

Dash air does put an additional load on an engine, that is already working far harder than a car engine. I don't want to put the additional strain on it for absolutely no reason.
Starting then stopping the genset after a few minutes is not a good way to operate either the engine or the generator, or, for that matter, any engine.
A generator needs to be exercised under load periodically, even when the coach is not in use, to keep moisture from doing long term damage.
Many people, particularly when new to MHs, tend to believe that too many hours on the meter is "wearing it out, will affect the resale value," etc. That is akin to putting seat covers on your new car, so that the person who eventually buys it can take them off and enjoy the new upholstery, while you sat for years on the plastic.
A recent article in MH magazine recounted the tale of a coach used by a wildlife authority for extensive field work. The generator required only normal servicing, i.e., oil, filter, etc. To the tech's surprise, the unit had over 22,000 hours on it, the equivalent of 24 hours per day for two and half years.
Running a genset is not hard on it; not running it is.

JC2 · 08-06-2009, 10:52 AM

When our MH is going down the road, 9 out of 10 times our gennie is running and both roof air(s) are being used depending on how hot it is outside. We also run the (2) 12v front window fans in the coach to help circulate the air.

Ron & Dee · 08-07-2009, 08:08 AM

We found that using a small fan placed in the middle of the MH and blowing towards the cockpit works best, especially when the sun is in the front or side. Also keeping the bedroom vents closed and all other outlets pointing toward the front.

And don't look at the outside thermometer

Ron

DriVer · 08-07-2009, 08:23 AM

I have to agree, folks need to run their generators more often and running them for 8 hours a day when you are going down the road isn't at all a bad idea.

I'm wondering exactly how many people here don't even run their generators for at least 1 hour every month. I'm sure the number is high. Even at that rate, that's no where near enough.

The 8.1L Vortec was designed with operate with an air conditioning compressor so I don't see any downside in using the dash air. That 496 isn't going to die because we're running our air conditioners.

Oemtech · 08-07-2009, 06:47 PM

OBTW - When it is 105 degrees here in Texas and I am on the road you can bet the A/C is on max for both the dash and roof units.

Photog · 08-08-2009, 09:30 AM

When I drive here in the SW its usually hot and I run the generator and basement a/c most of the time. I don't bother with the dash unit.

I subtract off .6 gal per hour when I compute actual MPG.

two2go · 08-08-2009, 09:53 AM

On 2200 mile trip to MN and WI towing HHR, we averaged low 8's without AC or generator and mid to upper 7's with. Didn't run basement AC while driving this trip, but I did run the heat pump on the generator once. Strange weather.
Ultrapower, 993 plugs, Taylor wires, Mobil 1, new NAPA air filter.
And no brake issues!

hamguy · 08-08-2009, 11:03 AM

We recently returned from a 5400 mile trip to the east coast (April-June). We hit a few warm days (85°) and hot days (>85°). We were always able to use dash air to keep the cab area bearable (35' Class A). If we were to be in 95° temps, I would run the gene and basement air units.

BTW, which method is easier on gas mileage?

Ron & Dee · 08-08-2009, 11:31 AM

Quote:

Originally Posted by hamguy

BTW, which method is easier on gas mileage?

This has been debated many times and I was always led to believe that it was cheaper to run the gen.

IMHO I think it cost more to run the dash air. On this Summer trip everytime I would use the dash air my scangauge showed almost 1 mpg decrease.

Probably not a very scientific way to determin mpg but oveall I did use more gas this time, and I did have to use the dash air in combination with the house air.

Ron

blacktie.shooter · 08-09-2009, 09:56 AM

FWIW, my Onan manual says my 7KW genset will use .4 gph no load, .7 gph half load, and 1.1 gph full load. Going down the road with both roof units running, I'm guessing that pretty much qualifies as "full load."

Ron & Dee · 08-09-2009, 12:29 PM

My 5.5 generator draws 47 amps fully loaded, going down the highway with just the basement air I'm pulling about 23 amps.

This last trip at 60945 miles divided by 845.2 gals gives me 7.2 mpg, if I subtract the 92 gals used by the generator that gives me 8.1 mpg

Looks like I'm about .6 mpg less compared to what I got on my long trip in 2007.

It was a GREAT trip even though my AC went out in Monument Valley when the daily temperature was in the hundreds

Ron