Gas Mileage: 454

Winnebago Warrior 94 · April 04, 2017, 08:49 AM

Thanks for yalls help ..I hope my winnebago warrior gets as good of gas mileage or or a little better being as mine is a 22ft ..my hubby didn't open the top on what he said looked like a carburetor . .he just noticed it when he was changing the air filter..I don't know alot of proper mechanical terminology . .but I don't mind getting my hands dirty and I like to know and find out info about things ..I did change out the wiper blades ..lol

Elandan2 · April 05, 2017, 07:33 AM

That's probably the most important. It doesn't matter how well it runs if you can't see where yer goin'

Winnebago Warrior 94 · April 05, 2017, 11:48 AM

Quote from: Elandan2 on April 05, 2017, 07:33 AM
That's probably the most important. It doesn't matter how well it runs if you can't see where yer goin'

good one

and true story ...lol.I also called Chevrolet and they said it is fuel injected I'm ready to check out the gas mileage . .I need to get insurance and get it inspected

tmsnyder · April 05, 2017, 12:43 PM

A lot of lessons learned here, summed up nicely regarding mpg's:

https://rv-roadtrips.thefuntimesguide.com/rv-gas-mileage/

1990HR · January 02, 2018, 12:47 AM

We went on a 1600 mile trip and averaged 7.23 MPG. I don't think that's too bad as there was 4 of us and we were loaded up pretty good.

tmsnyder · January 02, 2018, 09:14 AM

That seems about right, but I don't put much faith in anyone's numbers unless I can see all the data. Mine are here: http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843

Set up an account and every time you fill up, send a text to fuelly with the odometer reading and the # gallons. It's very easy, and free. And then we can all see what fantastic mpg's everyone is getting LOL Otherwise I'm a skeptic. Mid 7's is realistic. But double digits? Show me the data.

It's very common for someone to calculate their mileage based on one fill-up after driving only a few hundred miles, gently, downhill, with a tail wind and all the tires fully inflated. Then claim that that's their mileage while they hammer down the road at 75mph, into a headwind, with tires they haven't checked in months still claiming 'Oh yeah, I get 13mpg!'

RickNC · January 03, 2018, 12:08 PM

We took our first long road trip just before Christmas in our 1995 warrior 23. 1367 miles RT. Used 140 gallons of fuel which works out to about 9.7 MPG. ~Flat roads and 90% interstate. Cruise set mostly on 65mph. 15-20 gallons fresh water. Two people and a 20lb dog. Prior to the trip all plugs/wires cap/rotor were replaced. TBI system cleaned and serviced. Tires ~77 psi.

legomybago · January 03, 2018, 05:54 PM

Quote from: RickNC on January 03, 2018, 12:08 PM
We took our first long road trip just before Christmas in our 1995 warrior 23. 1367 miles RT. Used 140 gallons of fuel which works out to about 9.7 MPG. ~Flat roads and 90% interstate. Cruise set mostly on 65mph. 15-20 gallons fresh water. Two people and a 20lb dog. Prior to the trip all plugs/wires cap/rotor were replaced. TBI system cleaned and serviced. Tires ~77 psi.

At 23' your weighing in around 10k?? I would say your at the "optimal" mpg for a P30 chassis rig, due in part to not weighing a lot and having TBI and you probably have overdrive?
But on 14,000lbs +/- a 1,000, a carburetor, and a TH400, your back to 5-6.5 mpg depending on how/where you drive and what you are towing. That's been my experience anyway, out in the wild west.

WrigleysBraveWin · January 10, 2018, 10:09 AM

1994 23â€™ Brave with 454 Chevy and Banks Power Kit and going from Vegas to Chicago I was able to get 11.6 MPG and when I ran the foothills in Missouri I was at 10.2 MPG ..... For sure my best mileage came when I traveled about 55 MPH

legomybago · January 10, 2018, 12:10 PM

Quote from: legomybago on January 03, 2018, 05:54 PM
At 23' your weighing in around 10k?? I would say your at the "optimal" mpg for a P30 chassis rig, due in part to not weighing a lot and having TBI and you probably have overdrive?
But on 14,000lbs +/- a 1,000, a carburetor, and a TH400, your back to 5-6.5 mpg depending on how/where you drive and what you are towing. That's been my experience anyway, out in the wild west.

I'm still curious what the gross weights are, and if these rigs have overdrive with fuel injection. At least overdrive?....

Rickf1985 · January 10, 2018, 03:04 PM

Overdrive can be a double edged sword. It can give better mileage on flat ground with no headwind but it is generally dropping the engine down pretty low in the power band so you will be lugging the engine on hills and into the wind and therefore using more gas there.

Winnebago Warrior 94 · February 09, 2018, 10:12 PM

My 94 Winnebago warrior is fuel,injected and not sure about the overdrive ..not sure about the gas mileage but I will be finding out soon ..I got my belts changed today and I got my new awning installed and transmission fluid and filter changed ..I drove it. Around 65 miles and used less than a 1/4of a tank ..

..I do need to get me some new tires especially on the front ..mine are 2007 ..so time for new ..next will be,my paint job ..ylpee

Rickf1985 · February 10, 2018, 09:41 AM

hat is only 260 miles per tank roughly according to the gauge so don't get your hopes up to high. That said you cannot base your mileage on the gauge, you have to go by fill ups and true mileage ideally from a GPS. And you have to do it over several fill ups. On a 94 you probably do have overdrive.

tmsnyder · February 12, 2018, 07:48 AM

And you may have to correct for your odometer. Easy to do, just note the odometer reading as you pass a mile marker. Then after 100 miles or more, see how far off you are . Then correct your odometer reading. Especially if you changed tire sizes (diameter) it can be off.

Biggest factor though is you have to drive some significant miles, not just a couple hundred.

tmsnyder · April 07, 2018, 08:58 PM

We just did a trip to Florida and back to Buffalo, over 2500 miles and got the following on all my fill-ups.

6.76 mpg
7.32
7.79
7.73
7.76
7.43
7.80
7.38
7.53

This is a 454 chevy, edelbrock carb, recurved distributor, towing nothing, 40 gallons of water in the tank, and I drive between 60-65 mph. All except the first one was highway, pretty hilly along some sections of the route.

All the data are here: http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843

Average over the 13,458 miles for which I've logged every drop of gas is 7.3 mpg.

tmsnyder · April 15, 2018, 02:14 PM

Just as a sanity check to put my mpg numbers in perspective, I was wondering what is the Maximum possible mpg I could ever expect from my motorhome. It's actually a fairly simple calculation. I assumed:

Air at stp
No other hp losses, just air resistance.
8' wide by 9' tall front area
Flat road

Different shapes experience different resistance to air flow, and this is quantified as a drag coefficient. I considered worst case though best case. Worst case = a brick shape, Cd=1, this is pretty much what I have. Modern cars can get down to 0.3 or so, my RV is nowhere near that, it does have a little bit of a sloped nose. Best case, I only took it down to 0.6. I can't imagine an RV having a better Cd than 0.6.

For engine efficiency, there are published values for how many lb/hour of fuel are burned per hp made by the engine. For gas, they vary from 0.45 to 0.50. This would be for an engine that is in tune and well maintained. If not, all bets are off obviously.

By my best SWAG (scientific wild a$$ guess), I'm thinking my Cd~0.8, and engine is about 0.47 lb/hr/hp, I could only ever see 8.5mpg at 60mph. That's the max mpg I could ever get from the rv just considering air resistance, no other frictional losses. I'm getting 7.5mpg now, so even if I spent a bunch of money on engine mods, I'd be running up against this hard limit to fuel economy. I was thinking about installing a wideband oxygen meter to check on my carburetor tune, but now I'm reconsidering it. $200 to try to eek out a few tenths of an mpg doesn't seem worth it.

It resulted in an interesting plot that came out of the analysis, I'll try to post it. It verifies as mentioned many times in this thread that if I'm willing to drive slower, the mileage can increase.

One way to change the Cd of the motorhome might be to change the shape of the air flow around the back end of the coach using airtabs. They are about $200 for a set. Without them, the whole back end of the coach is a large low pressure area, pulling back on the coach. Airtabs are supposed to disrupt this and create a shape behind the coach similar to the trailing edge of an airfoil. Kind of like the fold-out shapes on the back ends of tractor trailers that you find on the interstates these days. Might be worth trying them out, there are some threads on this website that claim that they do actually work.

Rickf1985 · April 15, 2018, 07:29 PM

They do work but make SURE you put them on in the right direction!! They do NOT go the way you would think they do.

And that drag coefficient is figured at sea level and 75 degrees and 45% relative humidity and no wind so transfer all of that to real world figures where you will very seldom, if ever, see those conditions your figures are probably pretty close to the mileage that you are getting right now. I am impressed with the consistency of your mileage, it is very close on every tank.
I have to start from scratch on my distributor and timing settings again this year. I also need to buy a new advance timing light. I like the quadrajet but I think I am going to go with a Performer manifold and carb, That carb is just so much more adjustable. And that way I also get rid of the EGR and all of the associated passages and crossover heat.

tmsnyder · April 23, 2018, 02:20 PM

That sounds like a fun project!

I want to play with my edelbrock too, with an O2 sensor to try to milk some more mpg's out but based on my fluids calculations there's not a lot to gain there just based purely on wind drag.

Maybe a Duramax swap, or that 7.3L you have ....

WrigleysBraveWin · May 18, 2018, 09:41 AM

Fuel Injection... 94 Brave, 23â€™ ..... 464 with Banks Kit ..... Best mileage at 60mph 11.6 ..... Average in Mountains of Missouri 10.2

tmsnyder · May 29, 2018, 02:01 PM

Kept it 60 mph or less and drove another 660 miles this weekend. Usually I ran it at right around 58 mph. From Buffalo to Syracuse (flat), down through the Pocono mountains with some pretty good hills, and back.

8.6 mpg
8.2 mpg (some of this was running the generator about an hour)

udidwht · August 09, 2018, 03:53 AM

Fleetwood Southwind Storm 28ft 454 TBI w/4L80E trans

Renton Highlands, WA. to Blaine, WA. I netted 8.75 mpg with an average speed of 58mph. Overdrive in these rigs is a bit of an oxymoron. I usually just keep it in D due to the hills here. It does just fine MPG wise. No towing.

The best I netted was from Renton Highlands to Medford, Or. with a 10.04mpg. A lot of flats. Speed again at 58mph. No towing.

BrandonMc · August 09, 2018, 11:36 AM

I have to say I've enjoyed reading this thread, and can't wait to reveal my MPG when the fuel system is back together.

Something not many of you have mentioned is what Octane rating are you all running? In Colorado, we have 85-87-89 available at most pumps. Now check this out, the label of a lot of P30 Chevys strictly say, FUEL REQUIREMENTS - USE 89 OCTANE OR HIGHER" This from the P30 Chassis manual page 7-92. My 89 454, and many others I'd assume says to run 89 octane!

What say you? I've always put 85 in to save a few bucks but this could be relatively important right? I suppose it depends on your locale.

tmsnyder · August 09, 2018, 12:32 PM

The cheapest stuff available! Yes I ran a bunch of 85 octane last summer on our 8000 mile loop out west and back.

87Itasca · August 09, 2018, 01:47 PM

You mean 87 Octane?

There's no way I would run E85 in one of these. I couldn't imagine it would run at all well, and if it somehow did, you would ruin the fuel system in short order. These were not designed for ethanol fuels. 10% ethanol is pushing it already, any more and you're just asking for trouble.

tmsnyder · August 09, 2018, 02:37 PM

Oh yeah, 85 octane all day long. Cheapest stuff they had. Makes no difference in MPG, only problem would be preignition and I never heard any of that. These are low compression engines, it doesn't need high octane.

I do worry about the ethanol attacking fuel system components, so when I get home I arrive as empty as possible and fill up with ethanol-free, drive it around a bit, run the generator, and park it.

Ethanol actually _increases_ the octane of gasoline, it's 113 octane on its own. So if they are selling 85 octane with 10% ethanol, it would actually be lower without the ethanol, about 83 octane.