experimenting with a carb..

[gliscameria]

Hi all,

Just as an introduction, I have a degree in physics and am doing my Ph.D, work in electrical engineering.

Now that I have two bikes, and my 750E is now my backup, I'm thinking about playing with the carb. I've done some reading about possible performance improvements by heating the bowl to help vaporize the gas.

I'm thinking about mechanically altering the bowl to add in an electrical heater that will function to both increase the surface area of exposed gas and act as a heater to bring it up to 200-300F as it's being pulled into the carb.

This may sound like a totally crackpot idea, considering I am not a mechanic, but the science of it sounds good to me. It's far enough below the flashpoint as to not burn the gas, but hot enough to help it vaporize. Also, I was thinking of adding a heater into the fuel line right before the carb instead to save some trouble. Or adding a preheated reservoir.

I understand that re-jetting the carb would increase performance more, but this is an idea I'd like to tinker with. Is there something I'm missing to make this a completely futile idea?

Feel free to tell me I'm a moron. =)

//Glis

[tkent02]

A little more research might be in order....

"It's far enough below the flashpoint as to not burn the gas, but hot enough to help it vaporize. "


Where did you get your flashpoint of gas numbers?
Gasoline used to flash at -45 f
I think it would be impossible to start a cold engine if it weren't so.

But go for it, the worse thing that could happen is a large black melted spot in the road where your bike used to be.

[gliscameria]

Terms

Sorry, I mean the autoignition temperature.

[wolfie]

Sounds like a vapor-phase carb. Supposedly it will increase fuel economy as well. Keep us posted. I'm interested.

[gliscameria]

More info

I just found this...

http://www.himacresearch.com/books/secret.html

It's a nifty read, a little too conspiracy theory for me though. =)

[Mysuzyq]

How much load will all this heating put on the electrical system.....assuming you will be using an electrical heater, and not some kind of heat sink to use the engine heat ( which might actually be a good idea!). I have a windshield-washer fluid heater on my car that heats the fluid to 60C in 1 minute...it draws a fair bit of juice to do this...u would be drawing even more to maintain the kind of temps u are planning, I imagine?


Tony.

[gliscameria]

Electrical

I've been thinking about this a good bit.

The electrical load mayh be entirely too much for the battery to keep up with. I'll have to look into the specific heat of gasoline and the amount of fuel flux during running conditions. I was thinking about possibly funneling some exhaust gas through a spiral tube to do the heating, or possibly running the engine oil through the same element for heating. I'd need to do some reserach on how much heat can be extracted that way.

Currently this is the layout I am thinking of...

A small fuel pump will provide fuel to the 'heater'. This heater will basically be a 'hot fuel' reservoir. Inside of the heater there will be a float plunger that will determine the 'on' of 'off' state of the pump. I've been doing some reading on a possible post-carb blower fan, or exhaust powered turbine, that will aid in vaporizing the fuel.

The reason for the pump is that I'm afraid that the additional resistance of the heater may starve the carb. However, including a blower fan may help create enough of a vacuum to help pull the fuel through.

I'm beginning to think I may want to try this on a smaller scale at first, such as on a weedwacker or lawn mower engine, but what's the fun in that?


Also, does it seem reasonable to think that the oil flow is porportional to engine RPM which should be porportional to fuel consumption to possibly use the oil to power a turbine to work as a fuel pump?

[gliscameria]

Okay...

It seems so far that most efficient way to do things for the first run is to make a heat exchanger that uses the engine oil as a heat source.

I'm doing a rough estimate of the engine oil being about 300F. I'm having trouble with the thermodynamics though. I need to find out how long it will take a 300F surface... estimate a very large surface area, to heat about 1/30th of a gallon of gasoline to sayy...200 to 250F.

I need to know this to find out how to design the heat exhanger... any help would be greatly appreciated.

I have all the needed constants.. specific heat capacities and what not.

[fifer]

Thermodynamics problem you are having

Hey gliscameria,
Excellent work you are doing here. I can see that you are getting very close to coming up with a design and shortly after that a prototype. Don't you have equations and such to use to figure out the thermodynamics problem since you have a degree in physics? Anyway, it seems to me that you are in need of acquiring the proper partial differential equation in order to figure this one out since there will be a temperature gradient in the metal resevoir that you are using and it will be losing most of its heat to the environment due to the larger surface area facing outwards and really only the interior surface will be effective to heating the fuel. Since the outside will be losing heat rapidly by convection the amount of heat available for conduction to the fuel will be lower than you are likely to calculate, unless you find the magic equation. You already know the specific heat of the fuel, the thermal conductivity of the the resevoir and the temperature of the resevoir. Keep in mind that the contact area of the fuel will not be the entire internal surface as the resevoir will not always be entirely full and therefore not the entire internal surface can be considered the effective contact surface to allow for the heat exchange to occur. So in the end I guess what I am saying is that you need to figure out the heat transfer rates between all of your materials since you already know how much heat is required to get your fuel to 200-250 F, so with the heat flux equation you will be able to figure out the rates and the rest will be gravy.

For conductive heat flux I have used a general equation of Q=Ak[(T1-T2)/s]

Where:
Q is the heat in cal/sec
A is the effective surface area in cm^2
k is the thermal conductivity of contact surface (cal x cm^-2 x sec^-1 x degreeC ^-1 x cm) this is .11 for steel and .49 for aluminum
T1 is the temperature at a distance from contact point
T2 is the temperature at the contact point
S is the distance between T1 and T2

S will give an idea of the rate at which the heat is travelling away from the surface like into the environment or can also be the thickness of the material you are using. You could always work it backwards and make the ideal resevoir and through vacuum and such be able to regulate the flow and hence the time required to heat the fuel. Anyway, I use this type of equation for determining the heat flux in animal housing systems and what materials will work best to reduce operating costs. I hope that this might help you on you quest.... Good Luck

Mike

[gsbill]

Hi all,

Just as an introduction, I have a degree in physics and am doing my Ph.D, work in electrical engineering.

Now that I have two bikes, and my 750E is now my backup, I'm thinking about playing with the carb. I've done some reading about possible performance improvements by heating the bowl to help vaporize the gas.

I'm thinking about mechanically altering the bowl to add in an electrical heater that will function to both increase the surface area of exposed gas and act as a heater to bring it up to 200-300F as it's being pulled into the carb.

This may sound like a totally crackpot idea, considering I am not a mechanic, but the science of it sounds good to me. It's far enough below the flashpoint as to not burn the gas, but hot enough to help it vaporize. Also, I was thinking of adding a heater into the fuel line right before the carb instead to save some trouble. Or adding a preheated reservoir.

I understand that re-jetting the carb would increase performance more, but this is an idea I'd like to tinker with. Is there something I'm missing to make this a completely futile idea?

Feel free to tell me I'm a moron. =)

//Glis

A cold intake charge makes power..Not a hot one. Isolating the carbs from the heat of the engine is a popular performance mod. Put the fuel on ice, not a heater.

[KEITH KRAUSE]

Bill beat me to this. I don't know how your proposed set up would effect intake temp, but colder intake/fuel mixture= more oxygen=more power.
I'm a little leary of any "home made" electrical/carburetion connections too.

[tkent02]

He's onto something, cold air makes power, not cold fuel...

Cold air makes power because it's more dense, more air molecules can get through the intake valves in a given time. That's why all the performance mods increase airflow, it's the limiting factor. Cold fuel does nothing, any moron can get more fuel in by changing the jetting. On the contrary, hot fuel burns much better.
Why not put a heating coil in the bottom of each float bowl and heat it to near it's boiling point there? A bigger alternator would be easy to do if it is needed.
Similar to those coffee heaters that you plug in and place in the coffee cup?
Just need a custom floatbowl made with enough space for the heating element.
Maybe a fancy heating element that changes resistance with temp so the temperature is more or less stabilized in the floatbowl? Or even a digital controller similar to the one that keeps a jet airplane's windshield at a constant temp regardless of ambient air temp.

[gsbill]

So wouldnt hot fuel heat up an otherwise cold intake charge? If heating fuel was a secret to making power, nearly every race team on the planet would be heating fuel. How hot is the fuel getting just from engine heat? In my opinion heating or trying to heat the fuel outside the engine is a script for disaster.

[fifer]

The heating of fuel is something that is being looked at by many car manufacturers and aims to increase fuel efficiency by allowing for a more complete combustion. this is already being done by some diesel operators by using exhaust to provide the heat and has been shown to reduce fuel consumption in the area of 20-40%. I am not sure about the efffect it will have on boosting power, but I would bet that with less energy being expended by the motor there is room for an increase in power with this kind of technology.

[gliscameria]

A cold intake charge makes power..Not a hot one. Isolating the carbs from the heat of the engine is a popular performance mod. Put the fuel on ice, not a heater.

Cold air = good. Cold fuel = bad.
The amount of 'hot' fuel compared to the mass of air should heat the final mix minimally. Plus the venturi should do a fine job at cooling back down. The goal is to crack some of the larger molecules in the fuel, and also give it some extra energy to vaporize better. Most of the heat added to the fuel will be lost when it vaporizes, and sadly when it's sitting in the bowl. I may have my mechanic run a sniffer on it before and after to see if there is any change in exhaust gasses, that should be a good indicator on if its helping to get a cleaner burn.