How to Increase MPG

off the top of my head,there are three alterations which would help a lot

first and foremost, combustion efficiency needs to be raised, remember that the exhaust should theoretically contain water and carbon dioxide only? that's right. do steam and CO2 smell? of course not. does exhaust smell? got my drift?

www.himacresearch.com...

lightweight construction, especially for drivetrain and engine

generous use of electric transmission and capacitors to regain some energy upon decelerating, a neat side effect would of course be better acceleration per prime-mover HP (capacitors supply juice for a limited amount of time)

Mod Edit: Fixed Link.

[edit on 7/7/2006 by Mirthful Me]

posted by Long Lance

Off the top of my head, there are three alterations which would help a lot

First and foremost, combustion efficiency needs to be raised, Remember the exhaust should theoretically contain water and carbon dioxide only? [Edited by Don W]

Well, Long, with computer technology running MPI systems, and with catalytic converters, we are getting close to the “perfect” exhaust. I have no idea who many pounds per 10,000 miles a 2006 Honda Civic would put out compared to say, a 1972 8.2 liter Cadillac Eldorado, for example. I’ll bet the difference is significant.

Will any fossil fuel internal combustion engine ever reach exhaust gas Nirvana? I doubt it. Do you have any idea how efficient a gasoline engine is today? When I was young, the number offered was 25%, the remaining heat going out the exhaust pipe, through the radiator and radiated into the air.

“ . . lightweight construction, especially for drive train and engine . . “

Yup. But I fear the law of diminishing return is about to limit further advancements. Crashworthiness will be a limiting factor.

“ . . generous use of electric transmission and capacitors to regain some energy upon decelerating,

If I had to choose between spending a limited sum on capacitors or batteries, I think I’d vote for trying to improve batteries. It’s a matter of amps. Batteries hold more amps.
Amps are power. Not volts, where capacitors excel.

I used to work at a flight school, and we had a lot of people come in and buy 2-3 gallons of avgas. It's 100 octane, and they'd mix it 10-1. 10 gallons gas to 1 gallon avgas. According to them the engine just ran a lot better when they did it, and they got a little bit better gas mileage. Especially with older cars.

Originally posted by donwhite


If I had to choose between spending a limited sum on capacitors or batteries, I think I’d vote for trying to improve batteries. It’s a matter of amps. Batteries hold more amps.
Amps are power. Not volts, where capacitors excel.

understandable, you may even be right IF battery weight can be brought down to reasonable levels. i currently favor capacitors because they are light weight, comparably cheap and don't use as toxic materials as most batteries do, AND (big plus) their peak current is very high, so you'd need less of them for the same amount of (short term only, though) power.

as for crashworthiness, the chassis is not the problem, the heavy engine and gearbox are.

posted by Zaphod58

I worked at a flight school. A lot of people come in and buy 2-3 gallons of avgas. It's 100 octane. They'd mix it 10-1. 10 gallons [87 octane] gas to 1 gallon avgas. According to them the engine ran better and they got a bit better gas mileage. Especially with older cars. [Edited by Don W]

There used to be hucksters at the annual State Fair who’d demonstrate some kind of fuel or oil additive and then sell it to dutifully impressed motorists. Some people believed it helped. As a young “pump jockey” I used to sell such items as Marvel Mystery Oil, Wynn’s Friction Proofing Oil Additive, Liqui-Moly and finally Andy Granitelli’s STP. I was alive and well when Shell introduced their X-100 brand of motor oil. Top of the line, then, and an extra cost item.

Roger Huntington OTOH, an ME who wrote a monthly article in Road and Track, never had much regard for those additives. He explained that Pennsylvania crude was especially well suited for lubricating engines. That was why Quaker State and Pennzoil and Valvoline were so popular. SOCal - Chevron - developed special refining processes and chemical additives for motor oil to counter the almost total domination of the lubricating oil field by small Pennsylvania companies. Anathema to Standard Oil types.

Sun Oil Company of Philadelphia, later Sunoco, was a small competitor in my neighborhood. Their claim to fame was the single octane grade they sold as Blue Sunoco. Dyed blue. Where most gasolines were regular at 76 octane, and premium at 80 octane, Blue Sunoco was right between. 78 octane. They knew many cars that called for premium would work ok on the lower octane. They priced their gas 1 penny over the other companies regular but a penny or 2 under the other's premiums.

A lot of people believed the higher octane made their car run better. Roger Huntington explained why that was not so. Gasoline is truly fungible. Unless you dye it blue. It all has appx. 35,000 btu per gallon. Octane rating relates to knock resistance. Knock was a popular name for pre-ignition. That is, the mixed air and gas charge fires before you intend for it to fire. Ping! That noise you hear is the connecting rod slamming against the crankshaft bearing. Or sometimes you just burn a hole in the piston. Knock or ping is very destructive. And to be avoided.

During the mid 1960s, Sunoco offered its “260" brand and it was the highest octane available at the pump. Cars were sold with 10 to 1 and even as high as 12 to 1 compression ratios. It takes a lot of octane to resist knock at those high comp ratios. OTOH, if you’re running 7 to 1 or even 8 to 1, regular grade gasoline at 87 octane won’t knock. So will it run better on 89 or 93 octane? They all tell me “No.”

Regardless of its octane rating, all gas has 35,000 btu per gallon. An internal combustion engine is a heat conversion device. It takes the latent heat in gasoline and convents it into motion at the crankshaft, ready to be harnessed to do work. Q. How much octane do you need? A. Just enough to prevent knock which is sometimes called “spark knock.” That is because another way to reduce knock is to retard the spark, that is, to slow the timing. Or alternatively, you can enrich the mixture by “choking” the air flow, but now, all chocking is done automatically.

GM and Dupont learned adding lead to gasoline also retarded spark knock or ping. They created the Ethyl Corporation which marketed tetraethyl lead for 75 years. before we discovered the hazards of lead. Octane is now mainly determined by the refining process. I believe Standard Oil of Indiana's American Oil Co - Amoco - was the lone holdout to lead as an octane booster.


[edit on 7/8/2006 by donwhite]

Avgas isn't just automobile gasonlie with higher octane though. It has several additives that Mogas doesn't have. One of them is TEL, which is no longer used in Mogas.

Originally posted by donwhite


C/T, was the Geo Metro a 3 cylinder, 4 cycle engine? An abomination only GM could devise. As in Corvair and Vegas. And that half of a V8 in the first LeMans. Or the small block 350 diesels offered in 1970s Oldsmobiles? At least the Saab 93 was 2 cycles. 6 firing impulses every 720 degrees of crankshaft rotation. A bit peaky on torque, however.


[edit on 7/7/2006 by donwhite]

The Metro was a re-badged Suzuki Swift. You can blame the Japanese for that car.

Originally posted by apc
. A leaky exhaust manifold will murder your mileage. The oxygen sensor in the exhaust line will be getting fresh air from the leak, confusing it into thinking there is more oxygen in the exhaust than there should be, meaning it tells the computer to add more fuel. Wasted fuel. It's amazing how many cars drive around with exhaust leaks. After the catalytic is no big deal other than the noise. But O2 sensors are usually right before the cat or at the manifolds. If there's a leak near them, they'll get mad.

Seems to me the exhaust manifold is underpressure & not gonna be sucking air in, though an honest to goodness mechanic might be able to convince me otherwise. I expect, being the bonehead I am it would take paper & pencil & a good bit of splainin to make me believe it.


An unobstructed air cleaner is important. On Ford pickups a Torque cam will give better performance & better mileage. Why they don't roll off the line so equiped is a mystery. Low end performance is what a p/u is sposed to be doing anyway.

I more than doubled my mileage, but I did spend $5,000.00 to do it. It can be done for less, tho. I got a motorcycle! It's fun . Maintenance, (tires & oil) cost more, & special riding gear is an expense to consider & depending on climate that varies some. If you are just needing to go to work & an occasional trip to the grocery store for a few items it is something to consider. Used bikes are around & if ya change your own oil & adjust the valves it's not too costly on maintenance. Fewer pistons is fewer valves & easier access. Single cylinder bikes are fun, 2 cylinders is a bit MORE! I have a Suzuki 650 Boulevard & it gets about 50 mpg unless I ride it more sedately & it will get 55 plus if riden gently & below 60 mph.Very dependable machine & have seen one with 85,000 miles, Suzuki LS650 Savage, pre Boulevard incarnation, same driveline, engine. They can be had for under $2,000.

There are various driving techniques that can improve your mpg, for instance try to keep your vehicle at a constant speed and throtle pedal in a constant position (stop/starting murders mpg) if driving in town when aproaching stop lights aproach them slightly slower and try to keep the vehicle moving so that when the lights change it isn't at a standstill this will also save fuel.

make sure your tyres are at the right presure as well, when tyre are at a lower pressure than optimal it causes drag and uses more fuel, open windows and roof racks also cause more drag and use more fuel. also clean your car out and don't carry any unnecessary junk this will only add weight and use more fuel to drag along.

also most of the devices you see advertised as fuel catalyst's of devices that bleed air into the fuel system are a scam and have been proven not to work

[edit on 23-9-2006 by solidshot]

Between the high pressure exhaust pulses is a low pressure zone... a relative vacuum. Properly designed headers will use these low pressure pulses to assist in drawing exhaust out of other cylinders. If you have a large enough exhaust leak, the LP will also draw fresh air in through the leak.

And I agree, the air filter is an often overlooked component unless the owner takes it to a shop or quick-lube place. An upgrade to a high flow filter such as K&N is strongly advised.

$2K on a scooter here.. tops out around 45MPH with 70-80MPG depending on how much time I spend at WOT.

>

There are various driving techniques that can improve your mpg, for instance try to keep your vehicle at a constant speed and throtle pedal in a constant position (stop/starting murders mpg) if driving in town when aproaching stop lights aproach them slightly slower and try to keep the vehicle moving so that when the lights change it isn't at a standstill this will also save fuel.

Wellll stopping doesn't murder MPG, just the starting again part
But you're right... when I'm wanting to save gas I drive like my brakes are going to give out any moment. Only use throttle when it's needed to accelerate or maintain speed.


[edit on 23-9-2006 by apc]

posted by Desert Dawg

I would argue the point:

“ . . [today’s] vehicles get worse fuel economy than vehicles of the past. Auto manufacturers are putting larger engines in bigger vehicles, which results in unsatisfactory fuel economy. [Edited by Don W]

My immediate family was “lucky” to have bought a new Chevrolet and a new Studebaker in mid-1941, so we entered WW2 with new cars. The 2 door Studebaker Champion got in the high 20s mpg and the Chevrolet Master Deluxe sedan got in the low 20s mpg. However, it must be kept in mind there was a well respected and enforced 35 mph national speed limit.

I owned a new 1961 Falcon with the “optional” 170 cid engine (2.8 liters) which delivered in the mid-20s mpg. In the 1980s, the US did in fact move to smaller engines overall. The mid-size Buick Century came standard with a 4 cylinder engine of 2.4 liters. Probably about 80 hp in real terms. 0-60 in 20 secs. Top speed about 78-80 mph. But, about high 20s in mpg.

Today’s cars have much more efficient and more powerful engines than ever. If the Federal government would raise the CAFÉ - corporate average fuel economy - from the 26 or so of today, to say, 30 by 2010, and 40 by 2020, and include all vehicles, we could see a very substantial reduction in our dependance on foreign oil. Never to eliminate it, but at best to reduce it. Unless we do this, then all the talk is just that, talk. About which an old time sage said, “talk is cheap.”

With more and more things being controlled by computer in engines and in engine systems, I had an idea the other night driving home from class...

While on the interstate, I noticed that while driving my manual transmission, when I depressed the clutch the RPMs when down from approx. 3400 to 1100 while in 5th gear, then back up again. Expected of the engine.

Taken into consideration, I was driving on level ground, nearly level, would it be possible to have the engine do that for me automatically?

Also, how about attaching gyroscopes like the devices used in the Segway (and NO, not to create another silly scooter) to tell the engine how level it is so it could determine when and if to allow the car to coast. If you really wanted to get fancy, you could integrate a GPS system that allowed the system to determine where it was and anticipate the contours of the road.

All of this would be to maximize the efficiency of your route, allowing the engine to run not only at greatest efficiency, but also taking advantage of things like momentum and gravity.

Anyone? Thoughts?

In order to make my previous post work, the whole design of the IC would have to be rethought to allow for an intermittent power distribution, rather than a constant-on design (i.e., start the car, it idles, push the gas pedal, it revvs.)

I know there are designs out there, have to be, but its about what the Overlords can sell. I always thought the triangular piston and elliptical direction of force produced by the Wankel was pretty cool. Must be just me.

Maybe you could explain that a little better... because so far it sounds like you're describing an automatic transmission with cruise control.

An automatic with cruise control is not adaptive regarding the power output of the engine.

It only sets the speed and maintains that speed until you disengage the system.

What I am describing is something that monitors RPMS...actual output of force to push the car forward. If the car doesn't need to "push" constantly going downhill, the engine lowers its RPMs to an idle or lower rate of torque.

Another picture in your mind might be, and this is assuming the car is traveling in a straight line, a kid on a Razor scooter. They kick then they glide, kick then they glide. To keep kicking the whole time would defeat the point of having low-friction ball bearings on smooth wheels. Besides, the kid would likely eventually not want to scoot for much longer and find another toy.

I'm just not sure today's engines are taking full advantage of every thing that could be used to make them more efficient.

On a different topic, what about flywheels. They were a while back considered to be paired with electric motors as kinetic/potential energy devices with rare earth magnets attached to their spindles that created current. The current charged batteries and then powered the electric motor.

Why not use the energy within flywheel assemblies (which, if I'm not mistaken, was researched by Chrysler) to make IC engines more efficient?

Not sure how to do it, just pondering....

I bought a hybrid a couple of years ago. It has a little gauge that tells you your instintanious milage. Over a relatively short period of time this little guage taught me to drive with a very light foot.

I do this in my other cars as well and was pleasantly surprised that my milage in my other cars has improved about 10-20%. When you accelerate after a stop, accelerate slowely. When you are approaching a stop sign, let you foot off the gas and allow the car to slow down. Don't keep your foot on the gas until you need to use the brakes.

When you are driving on the freeway try to use the your auto pilot. When you allow the car to keep the speed, instead of your foot on the accelerator, you improve your mileage by about 10%. So, when possible, use the cruise.

Also, go speed limit. It will save you money. Yesterday, I was driving into town in my little hybrid. Speed limit is 55 on that road. I got passed by a teenage girl in a huge pickup doing at least 75. I bet her gas is still being bought by her parents.

Originally posted by justin_o_guy
Seems to me the exhaust manifold is under pressure & not gonna be sucking air in, though an honest to goodness mechanic might be able to convince me otherwise. I expect, being the bonehead I am it would take paper & pencil & a good bit of splainin to make me believe it.

Exhaust leaks DO suck in air and DO screw up your o2 sensor readings. It will ruin your mileage and make your car run like crap.

I'm an ASE certified mechanic if that helps you believe me

Plus apc did a good bit of explaining a few posts up on how it works if you are still having trouble.

May I recount the methods of raising an existing motor vehicles MPG anytime.
1) Replace wide tires with narrow tires. For example, if your car now has 225/50 tires, then go for 195/75 tires. 80 profile if available.
2) Overinflate your tires, 45 psi in front, 40 psi in the rear. Natch, pump up your spare to 45 psi and let out the air if used on the rear.
3) Open your windows and turn the AC to “OFF.”
4) If your car runs a 195 deg thermostat, replace it with a 205 deg. If already at 205, then maybe the bold will go to a 215 if available.
5) Refuel daily. Calculate - unless your car has an electronic calculator - how much fuel you use daily, add 2 gallons reserve, and keep that amount in your car, saving perhaps 10-12 gallons of fuel being hauled around unnecessarily. 75 pounds more or less.
6) Use your cruise control every time you can. Set it for 5 mph UNDER the posted limit.
7) Start up slowly, stop even more slowly.
8) Keep your car clean and waxed. It will lower air resistance and save gasoline.
9) Empty all unnecessary contents from your car - keep it light!
10) Use 100% synthetic oil and
11) change your air filter often.

[edit on 5/4/2007 by donwhite]

#1 get a Yamaha BW50
85MPG city
90MPG highway

www.trader.ca...

or a Yamaha Vino125, 86mpg

www.powersportsnetwork.com...

#2 build a water car

www.abovetopsecret.com...

[edit on 4-5-2007 by junglelord]

You're right, Mr junglelord. But I have a distinct aversion to sub-zero weather and driving rains!

I have a friend who is selling Chinese and Korean 2 wheelers. The 49 cc machines have surprised me how strong they pull!

He sells a Korean ‘bike that looks like a 3/4th scale HD Classic, and at $5,900 is 2X easier on the pocketbook to own. Both Chinese and Korean machines are top quality! Say goodby to the American and Japanese bike makers.

Globalization has triumphed. Workers displaced, buyers rejoice. Capitalism prevails, values fall.

[edit on 5/4/2007 by donwhite]