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What would happen....

Discussion in 'The Garage' started by smalltruckbigcid, Apr 4, 2005.

  1. smalltruckbigcid

    smalltruckbigcid 1/2 ton status

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    On diesels you can add propane injection to the airstream and get more power. Could you do this to a gasser with the same results. This should/would be done at WOT , maybe a cheapskates version of nitrous. Or, would this just make the fuel mixture to rich and hurt power. Anybody got any info or wild guesses
    George
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I think it'd just go rich as you're displacing O2 with propane. Less O2 = less fire.

    Rene
     
  3. loafer

    loafer 1/2 ton status

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    You can't do this with a diesel because of the high compression ratio and the injection timing. A diesel compresses only air on the compression stroke and injects the fuel at high pressure toward the top of the comrpession stroke. When the fuel is added the heat from the high compression ratio ignites the mixture. If you have propane mixed with air the engine will detonate early, before the diesel is even added.

    You may be able to do this with a standard gas engine, similar to NOS system, but I don't think there would be much point. There is less energy/lb in propane than in gasoline.
     
  4. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    Actually, you CAN do this with diesel... but probably not with gas... I have nothing to add really, only that correction.
     
  5. adamforsythe

    adamforsythe 1/2 ton status

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    Hello,
    What kind of pot are you smoking? propane is one of the best things you could do with a diesel. More power and better MPG.
    I know I don't know that much about gas engine. I am just getting started in the gas world. But I know A to Z about diesels.
    Thanks
    Adam

     
  6. smalltruckbigcid

    smalltruckbigcid 1/2 ton status

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    Loafer, you are correct that propane has less energy/lb than gas but it does have a higher octane rating than gas IIRC its about 96 for vapor and 112 for liquid. Thats why you can do it on a diesel, the octane resists detonation.
    After thinking about this overnight I think Rene has it right, adding more fuel to the airstream will richen the mixture to much and decrease power.
    Carbs have a tendency to go lean at WOT for a time until the air flow stabilizes across the venturis. I got to see this first hand yesterday when I dyno'd an engine I built, at 4100rpm the a/f ratio was 14.7, perfect, but once the engine started accelerating the mixture went lean until the power nosed over at 5800rpm. So my wild idea was, could you use propane to help stabilize the mixture during the lean periods. So maybe you could but it would be a tuning nightmare at best.
    George
     
  7. ntsqd

    ntsqd 1/2 ton status

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    What you need is a device that can sense the A/F ratio 'on the fly' and correct it with a PWM circuit controling the propane valve. ;)

    BTW, Lambda 1 is perfect, but not ideal. What Lambda depends on the goal for the engine, power or emissions or economy.
     
  8. loafer

    loafer 1/2 ton status

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    You can run a diesel on propane, as this is common, but not by adding the propane to the air stream. It has to be injected.

    You can also convert a gas engine to run on propane. You used to be able to buy conversion kits to do this on the old carburated stuff. The propane conversion burned cleaner, made the engine last longer, but at the expense of a slight power loss over unleaded.

    I believe the origional question was weather you could add propane to the air stream in a diesel and/or gas as a supliment to boost power. In which case, you can not do this with a diesel, but you can with a gas engine. However, I'm pretty sure you can inject nitrous into a diesel, because nitrous won't burn by itself.
     
  9. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    I'm pretty certain that injecting Nitrous into a Diesel would cause severe detonation, hence the use of Propane in Diesel instead.

    Nitrous is to Gas as Propane is to Diesel.
     
  10. k20

    k20 3/4 ton status

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  11. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    Indeed... I was wrong... That's very interesting stuff, though I'd probably still go with the propane as it's safer.
     

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