Community Forums

RVBlogger · 01-08-2019, 01:55 PM

Hello All,

I own a 2008 Gulf Stream Conquest with Ford V-10 engine, which is a Class C RV, and I get about 8.8 mpg.

My question is can I increase my MPG somehow other than driving 55 mph and making sure my tires are inflated properly?

Russ Silber · 01-08-2019, 01:58 PM

Quote:

Originally Posted by RVBlogger

Hello All,

I own a 2008 Gulf Stream Conquest with Ford V-10 engine, which is a Class C RV, and I get about 8.8 mpg.

My question is can I increase my MPG somehow other than driving 55 mph and making sure my tires are inflated properly?

Count you blessings 8.8 is a miracle for F 53 no matter what the year. I guess 55 is majic. I tow at 65 and average 6-7 depending on which way the wind blows[emoji12]

Russ Silber · 01-08-2019, 02:00 PM

I guess class C is a bit more mileage friendly then an A[emoji613]

Podivin · 01-08-2019, 02:09 PM

I think you've about covered it.
Big boxes just don't get great gas mileage.

Arch Hoagland · 01-08-2019, 02:10 PM

Other than taking routes that are only downhill the entire length, which is hard to do, I'd suggest counting your blessings.

I'm at 7.1 and thought I was doing good.

RoadDogYVR · 01-08-2019, 02:20 PM

Both in my personal life and professional life (Fuel Tanker driver with a GVW of 140,000 lbs), I'm a little obsessed with fuel mileage, even when I'm not paying the fuel bill. "Hypermiling" is achieved by using physics to your advantage. Acceleration and deceleration are the biggest consumers of fuel. Keep a larger following distance from the vehicle in front of you and if you need to slow down for any reason, take your foot off the throttle and use up the space between you until required to brake and then only threshold brake to the point where you are no longer closing on the vehicle in front of you. Roll onto the throttle slowly and accelerate at the lowest safe speed given traffic around you. Most drivers demand more torque and horsepower from their engines in any given scenario than necessary. I approach driving "heavy" much the same way that my pilot buddy explained setting power in an airplane to me - figure out how much power you need and govern yourself accordingly. See grades (up and down) before you get to them and get your power management in-line before you get there. Big uphill grade ahead? Gear down or use the throttle appropriately shortly in advance of the grade to make sure you are in the power band just as you hit the grade. Let off the throttle in advance of a big turn and roll onto the throttle at the apex gently. Not only will you have better fuel economy by not braking willynilly, you'll be more stable on the road as a result.

Also, don't travel in stop-and-go traffic if you are concerned with fuel economy. Starting earlier or waiting an hour or two can greatly affect your fuel consumption.

Ethanol blended gasolines also affect fuel economy. My previous daily driver was a Subaru Forester with a 2.5 litre engine. In that scenario, my fuel economy decreased in direct proportion to the percentage of ethanol in the fuel. We have Chevron Supreme Plus 94 octane available here which contains no ethanol. Our regular 87 octane is 10% ethanol. My fuel economy got 10% better with zero ethanol in that application. But since the fuel was ~15-20% more expensive, "economy" was relative. The Subaru had no turbos and didn't benefit at all from the higher octane; the only improvement was the lack of ethanol.

My current bi-turbo F150 with 2.7 litre ecoboost loves premium for power especially in demanding grades but my fuel economy suffers.

Long winded but I hope a little insight beyond "get a cold air intake and a tuner" helps.

ADDENDUM: my Class 5 driving instructor way back in 1988 was a city bus driver. He told me to imagine there is an egg between your foot and the throttle pedal and when accelerating "don't break the egg". Stays with me even today.

RVBlogger · 01-08-2019, 02:32 PM

LOL!

roscoesdad · 01-08-2019, 02:35 PM

Be sure you are traveling DOWNWIND at all times. That will get you maxium mileage.

RVBlogger · 01-08-2019, 02:36 PM

That was a great answer! Thanks!
I heard getting better spark plugs and a better air intake may be an option too. I'm curious to see if anyone comes up with that as a recommendation too.

Winemaker2 · 01-08-2019, 02:48 PM

Periodic cleaning of the Mass Air Flow Sensor has made a difference for me on previous Workhorse MH.
Apparently any dirt caused a shift in air flow measurement and the computer changed the fuel flow to compensate?
Just a guess but it did make a difference.

FatChance · 01-08-2019, 03:14 PM

You need to install a green power band. The stock red power band is for increased horse power.

Sherpa Vern · 01-08-2019, 03:25 PM

Cummins seems to have put a lot of research into the secret answer to the single largest contributor to better fuel mileage, beyond driving 55 and proper tire inflation. Each of us may recognize the greatest contributor, no matter what kind of vehicle you drive.

https://www.cummins.com/engines/heav...r-fuel-economy

RoadDog seems to have known the "secret".

Gary RVRoamer · 01-08-2019, 04:21 PM

Quote:

I heard getting better spark plugs and a better air intake may be an option too.

You will be hard-pressed to improve on the factory supplied components for all-around good performance and economy. It's possible to fine tune for very specific operating conditions. A Class C coach is built using a standard Van cutaway chassis and the engineers have spent a gazillion hours trying to get max fuel economy from those for the CAFE ratings.

55 mph may or may not be the sweet spot for mpg, but the general rule to use a light foot. Keep speed down as long as the tranny can stay in its most efficient (highest) gear and avoid rapid acceleration and deceleration. Every time you have to use the brakes you are wasting fuel.

RoadDogYVR · 01-08-2019, 04:58 PM

With big diesels (my work truck has a Paccar 12.9 Litre) we run along the (very flat) maximum torque curve and shift gears to stay on the "curve" - in my case 1000 RPM to 1350 RPM - for maximum fuel economy. With my gear set, my shift interval between gears is 220 - 440 rpm (depending on the gear) so when I shift at 1350 to 1400 RPM, I "drop" right back into the maximum torque band.

Gasoline engines work much the same way but with very different power curves.

An oversimplification: Torque keeps the engine turning while Horsepower accelerates the engine. Run out of torque for the given engine load, the engine stalls. Run out of horsepower and the engine stops accelerating.

Pulling (or pushing) weight requires the driver to balance staying in the sweet spot for either performance or fuel economy.

Shift early (or allow the automatic trans to shift at lower RPM based on throttle position and load demands) and you'll get better fuel economy as long as you don't run the engine out of torque for the load the engine is tasked to do. Want better acceleration? You risk leaving the torque band and lowering your fuel economy.

Easiest way to get better fuel economy is maintain a road speed that allows your engine to operate in a sweet spot for torque when "cruising" and anticipate greater engine needs in advance and bring the engine up to power for those demands in advance of needing the power.