100 MPG

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ASMART":12i4gv33 said:
I have no idea. Just thought if you could get it you wouldn't have to worry about clogging due to corrosion. Is heat the concern with nylon?
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the problem with nylon is that it won't transfer heat very well. the only things that conduct heat are those that conduct electricity, which means almost only metals.

thanks y'all for advice where to find stainless.
right now i have brass in there, i'll keep you posted on how it performs. right now, its great, but i dont have numbers yet.
 
well, Asmart, you were right - driving home yesterday that brass screen clogged up on me. i wish i would've taken it off dirty so i could see how bad it got, but the weather sucked, so i just shot carb cleaner down it - hope i get another chance in a couple of days :)
 
I thought that the main idea was to cause turbulance to aid fuel atomization. I had not thought about the heat transfer.
 
i was kinda thinking about those too, the problem is that they have even smaller holes in the screen, and i think that slightly larger holes might help me. but for those, i would go to some little second-hand joint and pick one up for a quarter - i wouldnt spend $ i dont have (trust me, if i had money, my girl would be wearing a promise ring) :) but anyway, yeah, i might try one of those and see how she does after this brass clogs again (probably after another tank of gas)
the other problem i have with them is that i keep tearing a hole in them with the throttle plate. i tried bending the screen down to shape, and the first one lasted about 2 tanks, then i felt it tear, and 2 miles later, it clogged up. got home and replaced it with what i hope is a deeper screen, so i'll see how that goes.
 
dcook":3gp86kg0 said:
Using engine coolant as a source of heat is insufficient. The endpoint of gasoline is around 430 degrees, so your source of heat must be substantially higher, or you end up with a lot of unvaporized gasoline.
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ok, change of plans here: the new plan, after discussing with my people, is to use an electric heating element (similar to a stove burner) instead of engine heat. that should simplify the plumbing end of things quite a bit, as well as producing enough heat. the heating element as well as the coil of tubing(with fuel in it) would be immersed in a liquid in a closed container. now we have to find a good liquid with a high enough boiling point to not be a problem. the need for a liquid (as opposed to air) is simple: if you put a lukewarm can of coke into a cooler with a block of ice next to it and come back in half an hour, your coke is still lukewarm. but if you add water to that same cooler, your coke is cold within 5 minutes. same idea here.
i'll keep y'all posted--josh
 
A few thoughts.

1. How big of an altenator are you going to have to run to power the heating elementa and will it use up as much energy as you are saving?
2. Your example of the coke in ice and water is improved upon by adding salt to the water. I was an experiment on the Myth Busters show where they experimented cooling a 6 Pack with ice, ice/water, and ice/water & salt. The salt won by far.
3. You could use the electric element at startup and coolant or exhaust heat afterthe engine is warmed up. Definately use the hottest thermastat you can on your engine.
 
thanks for the tip, Asmart! but as for straight water, or saltwater, they boil at too low of a temp for me. heck, i cant find anything that boils over 500 (im trying to get it to 450-475 so the heaviest HC's are vaporized, otherwise it makes sludge in the heating coil). since we cant find anything, my old man is thinking maybe just leave air in there, with insulation around it and it should work alright. maybe.

and the primary reason for using electric as opposed to engine heat is control. it doesnt cost much for an electric thermostat to control my temp, but trying to find a valve (to control exhaust flow) that was thermostatically controlled would be difficult and expensive.
as for power consumption, the heating elements we found (free) take 3.75 amps at 120v (use an inverter). thats not too bad. or maybe it is - that woule equal 37.5 amps at 12v plus losses in the inverter. good point! to answer your question, its a 70A alternator.
thats all for now--josh
 
Bear with me, I'm working from memory...

The 88-91 Honda CRX HF got 65+ MPG out of its 67HP 1.5 liter.

The 93-95 Civic VX got nearly 50MPG from its 105HP(?) 1.5 liter. It was a lean-burn (17+:1), but took an expensive catalytic converter & sensors.

The 96-00 Civic HX got 40+MPG from a 115HP 1.6. It ran lean, but not as lean as the VX (stricter emissions standards).

The 2000+ Insight gets nearly 70MPG from a hybrid 1.0 liter with an electric motor acting as the 4th cylinder and torque booster. Combined HP: 70 or so.

I don't doubt carmakers can get 100+ MPG from a gas engine, but would it be powerful enough to survive real-world driving and still pass emissions standards? And how crashworthy would the car be?

PS: Mid-80s Hondas used an electrically heated spacer beneath their 2BBL progressive carburetors. Some may even have had a screen beneath them. It might be worth looking at. Look for a crossflow engine - the older non-crossflows used exhaust heat.
 
My experimenting on this subject came to a halt for numerous reasons, one being that the engine in my truck was on its last leg. I've also come to the realization, as others have told me, that fully vaporizing gasoline with a 430 degree end point is not practical. At least not on demand, and on the vehicle. BUT, I'm thinking about a device to put a small amount of gasoline in (maybe a gallon) and separate the lighter ends out into another container. I'm thinking to start out with a target of 250 degrees and see what volume that yields. I've not found anything to describe the make-up of gasoline, by volume, in terms of end point, but have found several references that imply that the heavier ends make up a relatively small portion. I'm hoping that an end point of 250 -300 degrees will not result in a significant loss in volume. An end point of 250-300 would be much easier to vaporize on the vehicle and would eliminate the fouling problems the heavier ends and the additives cause.
 
i figure you wouldnt lose too much volume. to see how little is actually the heavier HC's, pour a bit of gasoline into an open pan and let it sit out in the sun all day. the little bit thats left when it dries up is all of hte heaviest HC's. it shouldnt be too much, not more than 5 or 10%. but that'll make it a pain in the butt to add gas to your truck - youll have to go home and distill it before you can use it.
i still think that it is possible to get enough heat to vaporize all of the fuel on the vehicle, if youll read some of what ive written here lately (im sure you have, ignore the stuff about the screen under the carby that gains a little bit of mpg) i would love to do an exhaust heater, except that its difficult to have an effective thermostat for it, electric is a lot easier to control with an oven thermostat. right now im working with my dad (when he's not at work) on setting it up in a jeep whose head is going (gotta start somewhere), and we'll see how it works.
good to have you back on the topic, dcook
--josh
 
I think there is something we have all missed here. The temps needed to boil these hydrocarbons are most likely at standard pressure. I think this is sea level atmospheric pressure. Whenyou are driving for econanly there is a "vacuum" in the intake manifold that would lower the boiling point of any liquid. It is the same as the fact that water boils at much less than 212 degrees on a mountain.

Hmmm.
 
good point there, but now that i think about it, at least with my design, i might need more than the number i had been thinking. because my design is a long coil of copper tube taking almost all of an area 8" around and 6"high, with a heat source around it. but what im thinking is we have a pump raising the pressure in the coil, and friction maintains a higher pressure than atmosphereic (i would assume).
well, im not sure, i guess it would be at vacuum pressure above the fluid level (in the part of the coil that contains vapors only).
but i would still hate to not have enough heat, as that would result in residue buildup, so i still like setting my heater to 475*F.
 
ASMART":1pdzxjsm said:
I think there is something we have all missed here. The temps needed to boil these hydrocarbons are most likely at standard pressure. I think this is sea level atmospheric pressure. Whenyou are driving for econanly there is a "vacuum" in the intake manifold that would lower the boiling point of any liquid. It is the same as the fact that water boils at much less than 212 degrees on a mountain.

Hmmm.
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But then it all gets compressed which raises the boiling point back up, so you're back to square one. It may be even higher than atmospheric.
 
Do you want to get vapor in the fuel delivery system prior to the injector or do you want to get the fuel to vaporize immediately upon release into the intake. Adding pressure in itself will add a small amount of heat. The ideal situation in my mind would be if you use a high pressure fuel injector to introduce the fuel to the intake that has a pressure of less than atmospheric. 1. A high pressure injector will help atomiz the liquid fuel and 2 the vacuum and high temp of the fuel would help the atomized fuel vaporize. This would be aided by a heated manifold.

By the way, you probably do not want to vaporize the fuel if you are using a carb.
 
I asked a chemical engineer about vaporizing fuel at atmospheric and at manifold pressure, he said the temperature difference is negligible. But then again he also said it is impossible to get 100 mpg.
 
This is what altitude does to waters boiling point. Unfortunately it is at different altitudes. I can't say what the actual pressures are. What are the average vacuum readings you see at cruise and part throttle?


See Level 212
5,000 ft 202.9
10,000 ft 193.7
15,000 ft 184
 
FYI I saw one of the Renault diesel hybrids, apparently at 70+ mpg combined cycle.

100mpg is doable right now, just not economically feasible. You need to chop weight out of the car - that is by far the biggest contributor. Acclerating and slowing weight takes energy.

Things like carbon fiber roofs, aluminum body structures, careful attention to accessory design, lighter weight seats, lighter insulation, lighter carpet. It all adds up, it's just not cheap.

My SWAG for a 100mpg civic or corolla class car would be 40-45k USD right now.
 
I remember that the VW golf in Europe came out with a special economy car in the 90's. They made it that every time you stopped the engine would shut off to save fuel. Wouldn't be my favorite but it could work if you have a strong batterie and starter motor. I can't remember much about it other then it failed because there were none after the following years with that option. They now have a small "green" TDI 1.3 or 1.4 ltr engines in theyre Polo's (small version of the Golf) in europe en they seem to drive forever but are death traps since theyre so small and light.
Anyway I found this article about better mpg, these people got 76mpg out of a new bug. http://www.green-trust.org/2005/09/vw-b ... ze-76.html
 
Ok, I don't want to be taken seriously here I'm a Junior in HS right now, but here I go.

Your first problem as of late is that you plan on vaporizing the fuel in a vacuum environment, ie the head. When the mixture enters the cylinder the pressure of the compression stroke will still recondense the fuel. You have to find a temperature in which the vaporized gasoline enters the the cylinder and the heat of compression sustains the vapor state. One more thing is that vaporization is just and intense form of atomizing; seperating the fuel into molecules instead of droplets. (Yes temperature increases with an increase in pressure, if everything else remains constant.) PV=nRT

When I started reading this thread it seemed to me that, from my chemistry knowledge, a chemical reaction has an equal amount of reactants and products. If you run lean all the gasoline is being burned and there is leftover O2, if you run rich you have leftover. 15:1 is an average for the difference in lengths of the hydrocarbon chains. So my first plan was to seperate the Hydrocarbons to a more controlable mixture, and then crack what is left over. Of coarse that gets dangerous.

My third Idea would take some serious fabrication, more than anyone would want to attemp, but here it goes. The most heat is lost in the combustion stroke of the engine so use the fuel to cool the cylinder. Maybe with a cylinder sleeve/gasket sort of thing. That will definately generate atleast your 475 degrees F. The way you conrtol the temperature of the fuel is with an electric pump, you can speed or slow the flow of the fuel. Like a constant flow water heater. Then you have a problem with excess or too little fuel. You may have to recirculate the fuel. Take carful consideration when you choose the size and number of coils running around the fuel chamber.

I don't think I can do that calculation yet, that will be next year after Calc and Chem AP.

Well some food for thought. Back to my trig homework.
 
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