Motor Home Mileage

[ALANSD]

My only mods are the tornado ar manager over the carb. The carb is stock but kept clean as i can keep it... I run mid-grade gas mostly, I put in Marvel Mystery Oil once in a few tanks...(a favorite of my dad who was a car man for years)

My exhaust is stock, except neweroem type mufflers added by Merlin Muffler. Dual exhaust with manifolds.
Tuned and new spark plug wires. I like Brett get 7-9 towing my Saturn running the generator for summer a/c.

I would like to get MSD ignition parts, and maybe a freer flow exhaust down the road...like Hedman or something.
Meanwhile I'm happy...the rig runs well and has been quite dependable.

[PeterH-350LE]

Originally posted by 87MH
.....I know that PeterH is out there waiting to jump in with an advertisement for Jacobs Ignitions, but I think that I will go the MSD route with an adjustable timing kit...

Did I ever mention the jacobs ignition system????
On our big trip last summer, I averaged 8 mpg. I noticed a considerable increase in fuel consumption with speeds over 65mph.

[wb13798]

i get about 8 when im not getting my foot in the tank and when i do mpg dropps to six . which is not bad, i pull a trail blazer LTZ that weighs more than i had planned to pull. but it pulls it with no problems. i dont think 7mpg is a bad figure for a gas mh pulling a toad or anything. the new fuel injected engines seem to get a bit better, if you stay under 65mph .

[joepospisil]

We just returned from a 4100 mile round trip to arizona and back with a cummins powered 82 310. 13.5 mpg overall and used no oil. Joe

[joepospisil]

The trip was done from Minnesota and averaged 62-65 mph Joe

[ALANSD]

yes that diesel does have its advantages.
I guess we gassers make up a bit in lower maintenace costs. Then again your diesel will probably do more overall miles. Oh well, either way you gotta be happy to have what you have

[zduke4x]

I like it cold inside in warm weather, so I run all the air I can and when parked obviously get no mileage per gallon....the dog needs air, too.

I have run test hiway mileage and with no accessories running I seem to get close to double figures but under my normal running of the back roads and genset all together 7 seems to be the norm...jem

[87MH]

I only plan one more trip prior to the Texas heat making weekend trips unbearable.

I hope to add some ignition upgrades along with the new dash -

[ALANSD]

about $2500 in gas at the current prices or .27 a mile. So 6.6 miles = 27 cents. Not bad if you look at it that way

[JanP]

Dennis, That steel exhaust manifold that you have is made by "RING" the slip ring amidships is supposed to releave the heat expansion cracking of the factory exhaust manifolds.

Ernie and Jan

[GlenCoombe]

The last mileage test was 9.53 MPG without the genset running.
Headman headers without the "H" crossover yet.
High performance wires on stock distributor ...so far.
New rear tires and very serviceable front tires, inflated and checked often.
I'm adding a free flow air breather box today with a four inch inlet ducted from the grill with a cone filter inlet.

[cooperhawk]

Someone said they were interested in the Izusu diesel mileage. I have gotten 16 mpg driving sensibly. I usually get about 12 mpg driving over 60 and towing a full sized car. I don't know what extra maintainence you all are talking about. I believe the diesel requires less maintainence. Mine is later version with increased power.

[swebster]

Jim,
Those numbers make me want to find an old Fedex truck for parts and start a conversion!

[cooperhawk]

A few years ago my neighbor was doing maintainence on a fleet of Isuzu delivery vans. He quoted a price for a rebuilt engine and it wasn't bad. It is cheaper to buy the complete engine than to buy parts to rebuild one because of tarrifs.
I also could buy a rebuilt Allison 4 speed for around $1100.00 at Catco.

[wanderingeye]

We are considering replacing the existing three speed auto transmission with a remanufactured 700R4 overdrive transmission. We anticipate that the mileage will go up by 20%. There will be a separate switch to put the trany in overdrive and out again. We know that the trany bolts to the 454 engine. We need help with an adapter between the end of trany and the parking brake. The parking brake is on a yoke bolted to the frame so it is easy to move and reconfigure the drive shaft. Can anyone among the supperior mechanics who frequent AS forums help us find this part? Has anyone made this modification? Cheers Tom

[87MH]

Originally Posted by wanderingeye

....Can anyone among the supperior mechanics who frequent AS forums help us find this part? Has anyone made this modification? ...

Tom:

Most any area that cater to "Big Rigs" - East Houston, Memphis, Atlanta - any place where the larger truck terminals are located and a lot of service work on the 18 wheelers goes on - will have machine shops that are able to modify just about any drive shaft (torque tube). I would pay a few extra bucks and get it done at the one with the best reputation.

Having said that - the 3-speed R475 tranny (Heavy Duty version of the R400) is more than adequate behind the 454....I do not think the 454 in my 345 generates enough torque to be happy under 2800 rpm - just my observation - I drive a lot by the vacuum gauge, and I have trouble keeping the vacuum gauge in the "sweet spot" on the Texas Level Four Lanes that I frequent on my trips around Houston.

In my instance (345 weighing in at 16,000 lbs consistently) a Gear Vendor or other type of final ratio splitter would not be a wise investment, since the engine/final ratio seems to be optimum right now - 45 mph at 3,000 rpm in second and about 60 mph at 3,000 rpm in third. I find I have to apply full throttle on even minor grades, and shift to second quite frequently. Since I drive a lot at 55 mph (2700 to 2800 rpm) I notice a definite decline in torque from the 3,000 rpm mentioned above. Granted, the 454 is probably a bit tired at 80,000 miles, but I doubt if ANY 345 (even with a new engine) would be happy with the final drive ratio geared to 2500 rpm at 60 mph.

My thoughts only with out ever having put the chassis on a dyno-test - hope someone chimes in with actual (and honest) results of a regear from the original chassis build specs.

[slow-canoe]

As far as putting a 700r or a 4L60 ,same transmission . Yea it will bolt up but it is a far cry from a turbo 400. In short it is not up to the challange, A 700 is a light duty transmission with over drive. If you would see inside of one you would change your mind , too many light and small parts. They also have a low presure problem and sprage clutch problems. GM makes a 4L80E which is a basicly a Turbo 400 with overdrive, problem is it is a electric controled unit for computer controled trucks 1992 and up. My two cents, Gear Vendors overdrive the only way to go.

[wanderingeye]

Thank you Slow-canoe for the help. One of the reasons that htis forum is so valuable is the wide and deep knowledge pool. We had already reached the conclusion that the gear vendors trany was the way to go based on other opinions. however your experience and wiilingness to post are appreciated. In Jan. we purchased an '84 MH 27' Classic in wonderful original condition. We got 10 to the gallon on the 1390 mile drive home used one quart of oil. The former owner took care of it but was of the fixit mindset...I am of the restore mindset. Over the next year we we renew every system. The gear vendors transmissiom is at the top of the list. Cheers Tom

[andymills77@]

This is a little embarrassing, but I'm a newbie. Will someone please tell me what a genset is ?

[guy99]

Motorhome usually have gas powered stand alone generators so that you can run them to power your 110V appliances (Air conditioner, Microwave, etc) and recharge your batteries without running the motorhome engine. Many people also run the generator while driving so that they can run their roof airconditioners to keep the cabin cool.