super efficiency! (OT)

[41/53dodges]

hi everybody! wondering if anybody would mind if i used this as kinda a "sounding board" for some ideas. recently, i re-joined a club in school called supermileage. in it, we are to build a kind of go-kart that gets in the vicinity of 150+ MPG. this is our first true year in operation, so i was looking for ideas to make a small (3-9 HP) engine efficient (strong is not necessary). if you guys dont mind, any ideas are helpful. nothing is off the table in this competition!

[tysouthwick]

are there any rules on what kind of fuel? Because Propane seems pretty efficient

[41/53dodges]

well here,

there are total 5 classes of this competition. we are going with one of the last 2, i am the engine mechanic of the group. 1-4 requires fossil fuels

1: ELECTRATHON: electric car, 75 LBS batteries, go 1 hr, most laps wins

2: BRIGGS & SCRAP IRON: take a 5.5HP briggs out of the box, drop it in car, drive.

3: OPEN STOCK: any stock engine, 5.5 HP or less

4: MODIFIED: engine can be modified, no fuel injection, must use original crank, block, ETC.

5: UNLIMITED: nothing is off-limits

[Dave72dt]

Aluminum tube chassis, rock hard tall, skinny tires, some type of lighweight fairing to reduce wind resistance, should also have no sharp angles on any exposed material, set engine up with a compression release so it's not using gas except when pulling, run it up to speed and let coast

[41/53dodges]

all of this is a little out of my category, everything else is not my decision. my department is engine. i was debating making some kind of hit & miss type system.

[KJ's Dodge]

I don't know if you have seen some of the discussions around using and recovering some of the hydraulics brake energy to increase mpg but that could be a thought for you. If you are trying to just increase mpg over a sustained speed this will not help you out much but if you are in the stop and go that is common to city driving than a brake to energy transferred to hydraulics system maybe your ticket.

KJ

[41/53dodges]

our task is to do 2 laps at road america, about 4 miles each. the track is on pretty good terrain. could only look it up to tell.

[Don Coatney]

What most folks fail to realise is that everytime you press your brake pedal you have lost part of your fuel economy mileage average. When you press your gas pedal it increases your gas consumption. When you press your brake pedal prematurely you have lost efficiency. In order to take advantage of this potential lost efficiency it is best to let the vehicle you are driving coast to a stop. I do this when driving. And I always find some a$$ right on my rear bumper when I do this. Most drivers keep there foot on the gas pedal until the last moment before they must stop and then slam on the brakes. A lot of folks switch lanes behind me as they dont like the slow speed I am driving. Funny thing is at the next stoplight I am ahead of them in the other lane.

[TodFitch]

What most folks fail to realise is that everytime you press your brake pedal you have lost part of your fuel economy mileage average. When you press your gas pedal it increases your gas consumption. When you press your brake pedal prematurely you have lost efficiency. In order to take advantage of this potential lost efficiency it is best to let the vehicle you are driving coast to a stop. I do this when driving. And I always find some a$$ right on my rear bumper when I do this. Most drivers keep there foot on the gas pedal until the last moment before they must stop and then slam on the brakes. A lot of folks switch lanes behind me as they dont like the slow speed I am driving. Funny thing is at the next stoplight I am ahead of them in the other lane.

You suffer the same curse as all of us that try to "time the signals": Tail gaters who don't understand physics.

On the other hand I get a lot more miles out of my brake shoes/pads than the average driver as well as better MPG. Sound like you might also.

[greg g]

High compression, advanced timing and lean as possible (16 to 1) mixture at as high an operating temp as the engine will stand. Probably need premium gas.

Is the drive train open to interpretation??? If so a centrifugal clutch (or a viscous coupling) attached to a big flywheel (think John Deere) with a manually controlled cvt between the fly wheel and the drive. This is kind of like the hit and miss but probably more efficient.

The trick here is to have the engine run at a set rpm say 3600 or what ever the HP peak is, almost like an electric motor and have the vehicle speed addressed through the transmission.

The biggest thing with Road America is probably the elevation changes so a system that can take advantage of the down grades and use the momentum to deal witht he up grades. The front straight raises 100 feet from turn 14 to turn 1

For a viscous coupling look at some of the foreign car all wheel drive system or some of the awd drive atvs. they use an electrically energized fluid that works like super fluid drive. Or for something real simple the clutch out of a automatic washing machine, or maybe a blade clutch from a riding mower.

[41/53dodges]

i have been doing research and experiments with CVT's, and they have much higher resistance than a chain or gear drive. we were thinking of using a bicycle shifting system rather than a CVT or transmission. i was thinking of creating a system using the pressure fuel & vapor generator like a coleman lantern or stove, set it to a specific setting, and construct a hit & miss system.

[Don Coatney]

You suffer the same curse as all of us that try to "time the signals": Tail gaters who don't understand physics.

On the other hand I get a lot more miles out of my brake shoes/pads than the average driver as well as better MPG. Sound like you might also.

Tod;

You are correct on the increased lifetime of brake parts. Another thing I do is pay attention to the small speed limit signs when exiting a freeway. I take my foot off the gas as soon as I exit. In this area most exit speeds are 40 MPH. Freeyway exit ramps are sometimes very long. As soon as my vehicle speed slows to 40 MPH on the exit ramp I maintain that posted speed to the end of the ramp. Once again the tailgaiters think I should still be going 70 MPH on the ramp.

[Big50Dodge]

As long as you stick with a motor from a generator or something else that is small, you should be able to get 100+ MPG from a go-cart with a diesel right out of the box. If you really want to show how GREEN the diesel can be, then make a separate tank with a coil of copper tubing going through it to heat the contents. Put a temp gauge plug somewhere on the tank, then strain in some vegetable oil. If you have a burger joint nearby, they might give you a few gallons of used veggie oil. Start on regular diesel fuel, then when the oil is up to 140 or more degrees, switch to the veggie oil. Just remember to switch back before you shut off you motor.

Wow - around 13 previous responses and no one else said this.

[41/53dodges]

if we could use diesel with a true advantage, we would. the thing about this competition is we have to go through all the math to compare in BTU's and all that crap, so it would come out with no advantage in the end! that, and an out-of-the-box engine would put me out of a job! we also dont want to put our whole funding towards an engine!

[Don Coatney]

we have to go through all the math to compare in BTU's and all that crap,

Not to be offensive but I would think the point of this challange is to make the winner go through all the math and all that crap. If you dont do it how can you win?

[41/53dodges]

not quite what i meant, it means if we use a different fuel, we do equations to find its equivelent in gasoline. in other words, if i used diesel, i would have pretty much chop down the results to be the same as gasoline.

btw: I HATE DOING MATH.

[Merle Coggins]

I thought you said any fossil fuel was allowed. Now you say that you have to mathimatically equalize your fuel's BTU capibility to equal gasoline? If diesel is twice as efficient you have to double the number of miles you get out of a gallon? Why not just have a rule that you have to run pump gas?

[John Mathias]

Try looking at these sites for some ideas. I built a version of the Pogue carb 20yrs ago for school on a lawn mower engine and it ran for 4 days on less than 12oz of fuel. It was 20yrs ago, I dont remember the exact amount. Granted, it was not loaded down, just idle the whole time, but you get the idea.

http://blog.hasslberger.com/2007/04/pogue_carburetor_gasoline_vapo.html#more , http://freeenergynews.com/Directory/VapSter/index.html , http://peswiki.com/index.php/Directory:Bourke_Engine You can also look at the US patent office website to search for high milage carbs.

[John Mathias]

BTW: vapor carbs dont work as well as they used to due to the long chain molecular stucture of the additives they put in todays fuels. And, for some reason, winter fuel works better for low altitude milage tests than it does up here in Denver. I will be building another Pogue style carb for the kid's 54' that has a 55' Windsor 301 poly in it. If you can find a way to break the chain down closer to its basic (origanal) form, you'll find your milage increase as well. I've had good luck with the Fitch(?) catalist system.

[41/53dodges]

I thought you said any fossil fuel was allowed. Now you say that you have to mathimatically equalize your fuel's BTU capibility to equal gasoline? If diesel is twice as efficient you have to double the number of miles you get out of a gallon? Why not just have a rule that you have to run pump gas?

its kinda stupid, i know. yes, we can use any fossil fuel. for all they care, we use coal to run a steam engine! but yeah, if we use a fuel that is 2x as efficient, we have to chop our mileage in half to match!

[TodFitch]

its kinda stupid, i know. yes, we can use any fossil fuel. for all they care, we use coal to run a steam engine! but yeah, if we use a fuel that is 2x as efficient, we have to chop our mileage in half to match!

I am having difficulty in understanding the concept of "a fuel that is 2x as efficient" (or any x for that matter). Would it be accurate to say that the goal is the best miles per BTU (or kilometer per joule)?

[greg g]

how about water injection?

[41/53dodges]

basically, tod's explanation is about right. its BTU's per mile. the issue with water injection is that we would have to carry that water with us, so thats weight. that, and it would be a pain in the *** to rig up with the hit & miss system!

[Don Coatney]

I am having difficulty in understanding the concept of "a fuel that is 2x as efficient" (or any x for that matter). Would it be accurate to say that the goal is the best miles per BTU (or kilometer per joule)?

Dang Tod;

Why is it you always reduce the best answer to the lowest Common Denominator?

basically, tod's explanation is about right. its BTU's per mile. the issue with water injection is that we would have to carry that water with us, so thats weight. that, and it would be a pain in the *** to rig up with the hit & miss system!

What are your plans?

[41/53dodges]

nothing is set in stone yet, but we are attempting to get a 6 HP kohler engine that will be equipped with a hit & miss type system, coupled with a 7 speed bicycle type shifting setup & manual clutch, all on a car roughly 6 ft long and body 2 ft wide, with wheels going out about 1 ft on each side, and one centered wheel in the back.