How much does weight effect mpg?

[middlenamesparkle]

Pretty straightforward, curious if making a lighter weight bus will improve gas mileage.

 

[Twigg-SKO]

Pretty straightforward, curious if making a lighter weight bus will improve gas mileage.

Not by much.

Most of the diesel burned is used pushing air out of the way, and weight is a fairly small factor.

 

[PNW_Steve]

I would agree with Twigg when it comes to highway driving.

If you do a lot of stop and go, in town driving it is a little different story.

At lower speeds wind drag is less of a factor and accelerating mass from a stop repeatedly is more of a factor.

If you are like most of us you will likely be doing more highway driving so I would not stress too much about weight.

 

[joeblack5]

From truckers report.com....rule of thumb 0.1 mpg per 1000lbs.

Less weight will get you up the hill faster and also down the hill safer. Your stopping distance is going to be shorter. All that would mean lighter is better.

Later j

 

[tugboater-SKO]

Not by much.

Most of the diesel burned is used pushing air out of the way, and weight is a fairly small factor.

During my trip home I got stuck behind a wide load making about 55-60mph. There was no passing this guy because my governed speed is 65. I tucked in close figuring he'd take longer to stop than I because of weight & he'd also be a good animal plow. I was amazed at how much less throttle I needed to pace him vs. when I was out on my own. He was definitely doing all the air pushing.

....those NASCAR drivers are onto something when they draft.

 

[Tango-SKO]

Weight reduction will improve MPG's if all else remains the same.

But...unless you get rid of a ton or two, you probably won' notice any difference and even then it will be relatively minor. Where it will show up...is on hills. Just a few degrees incline requires much more energy hauling anything up against gravity and a lighter load will require less energy. On flat land, moving air will be the energy sucker. A combination of losing a little weight (which we all could use) coupled with some improved aerodynamics could actually show up at the pump.

Truckers are all about economy, so you will see some good tricks there. Alloy wheels, wheel disks, aluminum trailers, trailer side skirts, truck side skirts, cab extenders, aero bumpers, aero mirrors, roof caps and even aerodynamic mud flaps.

Why?

Because when you travel a few hundred thousand miles a year...a mile or two per gallon puts money back in your pocket.

Funny thing with truckers though. They will spend a few thousand bucks to save a hundred pounds of weight or reduce drag by a percent or so...

...then add three hundred pounds of chrome and bling back on the same rig!

 

[roach711]

Wind resistance is the big MPG killer and the easiest to do something about. Wind resistance goes up by the square of the speed - in plain english, to double your speed you need to quadruple your power. Driving in the slow lane or drafting pays off best at no cost to you other than increased drive time.

 

[tugboater-SKO]

Weight reduction will improve MPG's if all else remains the same.

But...unless you get rid of a ton or two, you probably won' notice any difference and even then it will be relatively minor. Where it will show up...is on hills. Just a few degrees incline requires much more energy hauling anything up against gravity and a lighter load will require less energy. On flat land, moving air will be the energy sucker. A combination of losing a little weight (which we all could use) coupled with some improved aerodynamics could actually show up at the pump.

Truckers are all about economy, so you will see some good tricks there. Alloy wheels, wheel disks, aluminum trailers, trailer side skirts, truck side skirts, cab extenders, aero bumpers, aero mirrors, roof caps and even aerodynamic mud flaps.

Why?

Because when you travel a few hundred thousand miles a year...a mile or two per gallon puts money back in your pocket.

Funny thing with truckers though. They will spend a few thousand bucks to save a hundred pounds of weight or reduce drag by a percent or so...

...then add three hundred pounds of chrome and bling back on the same rig!

Jump over a dollar to save a dime!

 

[TrailLifeBill]

I agree with most all that was said above - in addition, an extremely important concept is balance. If the vehicle has a large imbalance of weight (maybe because all the holding tanks are mounted on the same side, for example), it can cause poor handling, uneven tire wear, and in extreme cases can be quite dangerous. Weight loading behind the rear axle lightens the weight on the front axle, affecting steering and/or braking. Heavier items generally need to be loaded between the axles if possible. Before build, during, and after completion weight and balance needs to be studied and verified that you're safe.

 

[middlenamesparkle]

Omg. Thank you all for your answers!! I’m not planning to put a whole lot in my bus but didn’t know if it would be a poor choice to use old school lockers for storage.

 

[o1marc]

Omg. Thank you all for your answers!! I’m not planning to put a whole lot in my bus but didn’t know if it would be a poor choice to use old school lockers for storage.

Remember the bus was designed to carry a couple of tons of student weight. After stripping and converting I doubt you're anywhere near worrying about weight and fuel mileage.