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More of Kevin's ideas

Discussion in 'General Tech and Maintenance' started by K2e2vin, Mar 12, 2006.

  1. K2e2vin

    K2e2vin Senior Member

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    I'm sure some of you guys have heard about the "200mpg carburetor". Well, take that idea, and apply it to PGMFI systems. I think some diesels use this concept, I'm not sure though.

    Wouldn't raising the temperature of the fuel help increase atomization? I remember reading about how atomization helps make more power; ie: Bisi's "theory" or tuning concept, that B16 that gained 16hp by moving the injectors back, and then the 200mpg carburetor theories. When you read those 200mpg theories, they all say the key component is having the fuel atomize better by heating the fuel to the temp it starts evaporating.

    My idea is have the fuel heated by the coolant line, similar to how some of the oil coolers in the Hondas work. The coolant is around ~180degrees F optimal temperature, correct?. I'm not too sure about the evaporation point of gasoline, so can anyone chime in?

    I'm also thinking this allow help allow compensation using the coolant temp compensation table in Crome.
    Also, install a fuel cooler on the return line so the fuel isn't as "gaseous" :).
     
  2. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    gasoline doesnt really have a set boiling point. its a mixture of many things that have different boiling points. google search turned up 100-400F for the boiling point.
     
  3. K2e2vin

    K2e2vin Senior Member

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    Well, would a general higher temperature than ambient help increase atomization?
     
  4. VTECin5th

    VTECin5th Administrator

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    It's a good question and concept.
    From what i've read, 450F is the needed temp to vaporize gasoline, i guess part of the problem is the heat required.
    I read it would take 2 gallons of gasoline (in a gasoline application) to produce the energy needed to produce 450F, and then you would be able to get 40-60miles until it needed to be re-heated.
    I'm sure this can be argued, and I'm stating what i read, not what i think. It kinda seems like a perpetual motion concept they are trying to stress.
    I saw some diagrams and blueprints of different designs for atomizers/vaporizers, and i guess it's true that it does help to heat it up.
    My car runs between 100 and 175F depending on conditions, with that in mind, my gas is often over 100F sitting in the Az sun... and there's no miracle gas mileage going on there.
    I did find out that adding acetone to your gasoline will increase gas mileage up to 30% and can increase power as well.
    The hondas noted were at:
    2ounces of Acetone for 10 gallons of gas in a civic=20% better gas mileage
    1ounce of Acetone for 10 gallons of gas in a pilot went from 20 to 25 mpg and so on...
    I guess too much will decrease power/mileage,but it's not shown to cause any harm.

    How does this relate?
    Apparently, Acetone will help increase the speed ((and)decrease the energy needed) of atomization for gasoline.
    This idea would work well on hondas i think, you could build something small that would bolt onto the fuel rail in between the filter and the rail to vaporize gasoline and return the leftovers to the line that already runs from the rail.
    Other than exploding, i'm not worried about trying some stuff when i get back to phoenix?
     
  5. MikeBergy

    MikeBergy Blah blah blah....

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    There is a lot going on in this thread. Yikes. Okay, having been through hours and hours of class time dealing with thermodynamics and aeropropulsion systems, I can pass on a bit of info that might help you understand a little better.
    1) You don't want to vaporize the fuel in the lines. The system is designed for liquid, not gaseous state fuels. If you wanted to use a gaseous fuel, then their ARE conversion kits out there to run your car on propane. It's not rocket science, you just have to have the right equipment for the job. The injectors that are in the car are designed for liquid, along with most of the other parts. Not only that, you are going to have various mixtures of gas and liquid in a heterogeneous mess not good for consistent flow properties within the system. If you have a system designed to completely change the state of the system, then fine, you are back to getting the right parts to do the job. Just random trivia, but the space shuttle main engines run the fuel through the bell nozzle before injecting it into the combustion chamber, in order to heat up the fuel and to remove heat from the nozzle walls. It is a completely liquid system, btw. I hope this clears up the vaporization issue. But good thoughts.

    2) Heating up the fuel helps, but for different reasons than you are getting at. If you heat the fuel up to a certain temperature, the combustion process has to waste that much less energy within the combustion chamber. A similar tactic is used in industrial turbine generators. Exhaust gases being expelled through the turbine side of the generator are routed through a heat exchanger through which incoming air is heated up before combustion. It's called a 'reheat' breyton cycle, I believe. It just raises the internal energy of the fuel/air before combustion, and puts the mix into the combustion chamber at a higher energy state. You wouldn't want to heat up the air in the engine beyond the normal operating temp, because then you are lowering the density of your oxidizer (air), and getting less into the engine. This, however may help with the gas mileage, depends though. Raising the fuel temperature, however, will give you an advantage to a certain extent, in that you are raising the internal energy of the fuel a good bit without decreasing its density, because it is a liquid, and less susceptible to density change pre-vaporization. Another reason not to want to vaporize your fuel in the lines.

    3)Acetone, as far as I know, is not anything more than an octane booster; same with toluene. If you familiar with gasoline chemistry and how it works, you know that gasoline is a long chain of hydrocarbons. Basically, the lower the octane rating of the gasoline, the longer the H-C chain is. That means that for every mass quantity of gasoline that is available for an oxidizer (air, n2o, etc.) to react with, there are less reactions that are able to take place the lower the octane number. To maybe explain this better, think of the hydrocarbon chain as a long table with chairs around it, and the oxygen molecules have to sit down in these chairs inorder to react. Well, as you shorten the tables (i.e. raising the octane), there are more spots available at the end of the tables as they are broken up for oxygen to sit down at, thus more reactions per mass of fuel. I'm laughing as I write this, thinking of how ridiculous it must be to read this. So, when you add acetone to the gas, depending on how much you put in it, it raises the octane of the mixture, thus allowing for more power per mass quantity of gas. This will cause two things to happen. 1) you'll make the same amount of bang with less fuel, and will probably drive at a slightly lower throttle setting as a result, increasing fuel mileage. 2) Your o2 sensor will most likely see a richening of the fuel/air mix coming out the tailpipe as a result of the more o2 being able to react completely with less amounts of fuel, and so will most likely lean out the fuel while the engine is operating in closed loop, thus getting better gas mileage. Of course, you can only add so much octane booster before its benefits begin to flatten out at a peak.

    I am sure this is the longest post of the night, but this is an informational forum, and genuine questions need answers, some answers not always able to be given in two or three sentences. THis is my take on what you guys are talking about, hope it's bee helpful.
    Mike

    Edit: Oh, and atomization is only really going to be affected by the injector's nozzle fineness, the distance the injector is from the port (needs time to fully mix with the air), and the aerodynamic quality of the flow in the manifold. The temp of the gas may allow the gas droplets to more effectively separate, but that is something I haven't really studied up on yet. If you want a good lesson in combustion, look up a book by a guy named LeFabvre. It's a jet engine combustion text, but it addresses a good bit of what you guys are talking about.
     
  6. K2e2vin

    K2e2vin Senior Member

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    Great information guys. :thumbsup: I'll go look for that LeFabvre text and go to the library(if I find my library card) and see if there are some books on the subject.
     
  7. Citizen_Insane

    Citizen_Insane Senior Member

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    Actually the octane number is a value given for the anti knock properties of a fuel. Fuel is made up of two basic hydrocarbons, octane and heptane (8 and 7 carbon chains respectivly). Octane is less likely to preignite and therefore reduces the likelyhood of knock. The octane number is the percentage of 2,2,4-trimethylpentane (isooctane) to the total isooctane+heptane mixture. Numbers greater than 100 are acheaved through additives such as alcohols that have different combustion properties and have essentially more than 100% anti-knock capabilities.

    This is almost all incorrect (I mean no disrepect Mike, but I want accurate info out there):
    * there are only two main hydrocarbon costituants of gasoline and those are octane (isooctane, 2,2,4-trimethylpentane, all the same thing) and heptane. Octane is an 8 carbon chain that has good anti knock capabilities, heptane is a 7 carbon chain that does not.

    *there is no added "bang" with higher octane fuel. it contains exactly the same ammount of energy per mass (or actually less for fuels with alcohol additives such as ethanol). The reason you see better gas mileage is because you are getting a more complete combustion in the chamber. This could lead to more power, but it isn't because there is more engery stored in higher octane fuel's chemical bonds, its because of engine characteristics only.

    *like above, the O2 sensor will probably show that you run closer to stoicheometric because of more complete combustion in the chamber. Thus, since your lambda is reading close to 1 a more ideal amount of fuel (read less) can be added to the camber to have a more prefect combustion.

    *adding octane will not benifit your car what-so-ever if you are not already experiencing power loss from knock/preignition. Higher octane is needed for high compression ratios and turbo/supercharger setups where the a/f mixture is highly compressed (the cause of preignition).
     
  8. MikeBergy

    MikeBergy Blah blah blah....

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    <----- Not a chemistry major. I'm glad someone who is knowledgeable is speaking up on the subject. I'll have to get more into chemistry. :)


    knew nothing about heptane, thanks for correcting me. I am used to seeing JP-4/5/6/7/8 stuff rather than gasoline. Lefebvre is where it's at for that.

    That is basically what I wanted to say. Let me correct myself by saying more power would be achieveable on the same amount of gas because you are able to advance the ignition more, and trim fuel values to achieve the same power on less gasoline, noting that for most older cars with less sophisticated closed loop efi systems such as our own hondas, combustion efficiency might only be around 90%, when, by seeing a higher octane gas, efficiency of maybe 95% or better could be see. On engines that use closed loop systems, utilizing o2 sensor and egt for error inputs, more power might be seen in the trimming of the fuel and ignition. That is basically what I should have said. The fact that a more complete combustion is happening was my main point, but thank you for clearing me up. It's obvious my knowledge of the subject of otto cycle and chemistry is a bit more limited than I would like. I'll cover my butt by saying I am a turbofan guy, not a positive displacement engine (aka any engine with a cylinder in it :) )guy.

    my point exactly.

    It will benefit your car by giving you a more complete combustion, will it not? You just stated that in the last two sections, in which I whole heartedly agree with you. That is a benefit in the search for better gas mileage if I've ever seen one. While I agree with your view on higher octane gas not being a miracle power adder, just as I do not believe in one component of an engine being responsible for large power addition, I do not necessarily agree with your view on higher octane not having any benefits in lower powered cars. True, most cars today are designed to drive with 87 octane as their primary fuel, but this is not to say that with the advanced fuel systems todays cars are equipped with that a higher octane gas will not have any benefits. Show me documentation of long term studies, and I'll step down off my soap box, You have, however, given me much to think about regarding the chemistry of the system, and thanks for your contributrion to the topic. Not my topic, but one of the few in the last 6 months to peak my interest.
     
  9. VTECin5th

    VTECin5th Administrator

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    When i was going thru new mexico i hit 49.9mpg in my b16 swapped 95 coupe completelyyyy full of stuff...
    It was Chevron 90 Octane with their "techron" ..
    My mom filled up with Techron once in her thunderbird, and it corrected her check engine light for emissions control...
    I'm starting to wonder if maybe they use a small concentration of Acetone?
    Is this Acetone the same Acetone you can buy at hardware stores?
     
  10. MikeBergy

    MikeBergy Blah blah blah....

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    Yes, it's the same stuff you buy at the hardware store. I've read that toluene is better to use, but they probably work the same. You can buy both pretty cheap.
     
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