A&Q about 350Z
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[quote=curtis73]Good gosh. I wasn't going to say anything until now. There is no oil company conspiracy. The Pogue carburetor and its vaporization carb cousins are hoaxes. Just because it has a patent and someone said they drove a car 200 miles on one gallon of gas doesn't mean anything other than an ill-concieved publicity stunt to draw attention to a business.
Uhh...I think I just said that.
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So how come this technology is used in airplanes to keep the fuel from freezing?
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As a single engine pilot and mechanic, I can answer that one. They don't. They use carb heat to prevent freezing, but it has nothing to do with those vaporizer carb designs. Airplane carbs don't have the advantage of underhood heat to prevent icing, nor do they have hot intake manifolds. They also venture into altitudes where the ambient air is often 30 below. Carb heat is simply sourcing intake air from behind the cylinders where its warmer. It is intended to be used at high altitudes, or where humidity and barometric pressure dictate. Its no different than a manual version of a preheater shield on the manifold of an 80s car with the vacuum assisted thermac door.
It has nothing to do with the vaporization of the fuel, its designed to prevent the carb from freezing into one big snowball causing a dangerous condition where you can't alter throttle position. That would be bad.
Trust me, at 6000 feet in the winter where the ambient air is 10 below, the best intake air temperature you can muster with the carb heat wide open is about 100 degrees at a very slow cruise; no more than a Qjet in a buick in the summer. The older (1973) Piper Archer II that I fly I won't even take up if ambient temps are below about -10; primarily because the cabin heat sucks, but also because if I want to cruise above 100kts, I can't get enough carb heat to safely prevent freezing.
In answer to your question, they are not there to prevent fuel from freezing, or to extend fuel consumption, they are there to prevent the EXTERIOR of the carb from turning into a snowball.
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You did. I just couldn't keep my mouth shut
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works for me
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Well the ideal fuel for a car is propane and not gas. You can also run a car off of natural gas. This is the same concept, turning thje liquid fuel into vapor. I asked my auto teacher who's been teaching 30 years and he said it's possible and the thing I'd have to worry about the most of pre-ignition.
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On what principle do you determine that propane is the ideal fuel for a car? Just because a hydrocarbon exists as a gas at room temperature doesn't make it any better. The word Carburate means to turn a liquid into a gas. A carburetor uses pressure and heat to turn gasoline into a liquid. When metering liquid propane into atmospheric pressure, you are using.... heat and pressure. The ONLY difference is the temperature at which they evaporate.
A carburetor doesn't just put little droplets of gasoline in the air, it evaporates it. Surrounding heat, venturi, and the screaming hot walls of the intake and head port make sure that almost all of it is entirely evaporated by the time it reaches the chamber. Its not perfect; there are still a few droplets, but its not like just squirting gas from a spray bottle.
That very principle is demonstrated in the fact that Propane (although it has slightly fewer BTUs than gasoline) makes less power than an identical gasoline engine. Propane only has 86% the BTUs as gasoline, and takes much more to be stoichiometric. So, all that extra fuel you're using to make less power doesn't seem to make sense except environmentally.
And don't get me started on the "ideal" fuel. There is no such thing. Each one has their own set of benefits and trade offs. But everyone here who wishes to keep their status as a member agrees with me... Diesel is the best fuel
Just kidding.
Seriously, you keep quoting your teacher. We're all very knowledgeable folks here. He's given you a basis, but its partly his opinion. Open up your mind a bit to the possibilty that we know what we're talking about, too.
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Yes I understand you guys know what you are talking about and that's a main reason I joined here. I just could see this working. I don't know why. I know fuel is vaporized essentially when it hits the intake manifold. What I'm thinking is if the fuel is vaporized beforehand that heat that was supposed to vaporize the fuel could be used to expand the gas molecules a bit more (and my reasoning behind no real loss in power). I also reasoned that there are already engines that run on "dry" gas. They seem to work fine. That got me to thinking if gas were in a gas state before it could work and use less gas overall.
I'm not going to attempt making this thing until the semster is over and I have a good firm base on mechanics. Also I bought a chemistry and physics book (I work at a public library and these books were surplus and cheap
).
About the whole oil conspiracy thing I think there's some of it going on. Come one Exxon just posted record profits for any corporation. What would be worse than something that would reduce the use of their product and cause profit loss? They knew that fuel saving devices were a threat to theri industry just as the robber barrons knew competition was a threat to their business. Don't think the oil industry is so innocent of everything. I heard the found of google is making a documentary about the oil industry.
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if i understand what you're trying to say, you want to get the fuel into a gaseous state before it enters the cylender. i don't understand this thing you were saying about no lost energy, there's very little energy lost in pumping the fuel, the only energy lost is to the alternator.
the boiling point of octane is 125 degrees celsius so you might have to preheat the gasoline to 150 degrees. the problem that comes with this is that you'll have some very high pressure gas trying to force its way out of the injectors and it'll be hard to controll the ammount that flows. another thing is that in the event of a colision the car could very easily burst into flames. if you can control the gas and control the flow, then you might have some improvements in fuel efficiency and power, becuase there will be more surface area and the gas will react faster.
I think your biggest problem will be getting the gasoline into a controlled gaseous state. after that it'll be getting the right fuel/air mixture.
BTW curtis, you weren't kidding, the diesel engine is the best engine that's widely available today. you know the reasons, most of which you probably told me at some point or another.
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And that's why my teacher said it would have to worry about pre-ignition and getting it too hot especially in the summer than it would have to be. Plus I'd be able to generate this heat from the exhaust manifold. I mean 30% of the gas in there is used for turning the crank the other 70% is lost to heat in the combustion process. You can "recycle" that heat. Most likely I'll probably try this on a small engine first before I get to something that will cost a lot of money if I blow it up.
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The evaporation of gasoline in the intake and carb forces evaporation adiabatically which cools down the mixture considerably. Adding heat first means that you have hot fuel vapor without the benefit of that adiabatic cooling and detonation and power loss may be more of a destructive roadblock instead of just something to watch for. The downsides seem to outweigh the benefits currently.
The best way (with current technology) to recover heat is with a turbo, but there again without the detonation-reduction of the cooling evaporation, it might be a reliability issue.
I often thought about a hypersonic method of evaporation. You've probably seen the foggy fountains in stores. They have a little hypersonic speaker that adds enough energy to the water to evaporate it instead of heat. Its the same technology used in cool-mist humidifiers. I wonder if that might be adapted to gasoline technology. You wouldn't have the advantage of adiabatic cooling, but at least you wouldn't be adding temperature to the mix either.
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Of course you all realise that Direct injectin Gasoline engines make all of this redundant?
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From what I read it's better to have a warm mixture because it ignites better.
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A warmer mixture ignites better, but detonation is when it ignites too well. The mixture that exists in a plain old carbureted engine is pretty good, and the spark energy is definitely enough. Getting it to burn doesn't seem to be the problem. Keeping it from burning on its own (detonation) is. I don't think its limiting factor in efficiency is the temperature of the incoming mix.
In fact, much more power (at the expense of greater HC emissions) can be found by cooling down the intake mixture. It can be pretty cool and still vaporize the intake charge effectively. Cooler, denser air means more molecules of oxygen per volume, which means we can add more fuel. Some guys ice down their intakes between races, use special ice canisters with coils for the fuel lines, and go to great lengths to source air from outside the engine compartment. Of course, that is just for power, not MPG. It stands to reason that the denser air racers crave supports more fuel being ingested, and therefore less MPG.
On the other end of the spectrum, the auto manufacturers in the 80s went to great lengths to source hot air from under the hood. This made less dense intake charges which supported stoichiometric mixtures with less fuel. The downside is higher NOx emissions, but EGR counteracts that pretty nicely.
I think the key here would be to find a way (since the spark energy does more than enough to ignite the mixture) to completely vaporize the gasoline without heating it. Then you would have the benefits of both the cool charge and the complete burn.
Do an internet search for HFI. I haven't been able to find it again, but a few years ago, an engine builder came up with a pretty good idea. He designed a passive direct injection fuel idea. He drilled a passage all the way through a head front to back, removed the intake valve seats, and drilled a small passage to intersect with that passage. Then he re-installed valve seats and drilled little fuel jets in them. He then pressurized that whole passage with fuel. When the valve was closed, the engine received no fuel. As the intake valve opened, it drew in air and fuel. Since the valve seat was hot (at temperature) the gas easily and instantly evaporated. His design had no throttle, instead he varied RPM with a variable lift system he designed. He had a 4.3L V6 chevy that was a running prototype.
I'll see if I can find any pages on it. If I do I'll post them here.
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Yes I refered to this as "pre-ignition." I may have put the wrong term on it but that's what I meant. That is what I can see being my biggest obstacle.
I know it makes the fuel more "rich." This is one of the factors why when it's really cold outside (below 0) you see a big change in gas mileage. I want to make this system for fuel economy, not performance. This is for the everyday driving in which takes most of my gas at least.
I'll definatly check that out. What's wrong with heating the gas? You can easily get the heat lost in combustion. I knwo it's also mechanically possible and I'll look into it.
I'll have to start with a small mechanical 4 stroke engine. This won't work with a 2 stroke because if you vaporize the gas before it hits the chambers then there's nothing to lube the rings and your pistons will seize up. Plus if something does got wrong it makes less of a mess with a small engine and is cheaper to fix.
Also another problem I'm going to be with fuel injection. I'll have to make sure I start with a carbeurted engine. No comptuers or anything emtering the fuel. I could see this getting very complicated with fuel injection.
Curtis now do you see where I'm coming from? Do you think this is possible now? I mean you mentioned about mechanically vaporizing the fuel.