Forced Air project.

Discussion in '2-Stroke Engines' started by zetti_the_man, Oct 29, 2008.

  1. zetti_the_man

    zetti_the_man Member

    check out my intake.
    the build is still waiting for parts.
    i orderd another 36t chainring, lighter wheels tires n chain. ect.. i got some oldschool aluminum bars off ebay for it too.
    i lost my last frame/fork wheels this year
    an acctual MPH will be available after it's finished for all of you that remember

    my last build did almost 50mph without the blower

    thank you,
    b real

    Attached Files:

  2. Tinker1980

    Tinker1980 Guest

    That looks like a neat idea, but i see a problem. When using forced air on cars with carburetors, you either have to put the blower (roots type) between the carb and cylinder head, or you have to build a box around the carb. (centrifugal type) problem is, if you just cram air down the throat of the carb, you end up with a higher pressure inside than outside... the fuel wont be drawn out of the bowl and into the venturi.

    If you want this setup to function, your best bet is to build a chamber that the entire carburetor can fit in, and force air into that. I want to see this beast when it's running!

  3. HI,

    Looks like you have the cast intake....Something that may also be helpful is to get the chromed steel intake....the inner diameter is larger and so it should help flow more as well....I can't remember the difference in size BUT it is noticeable.

    Good luck on your project....looking forward to hearing more...

  4. fastboy9

    fastboy9 Member

    you gotta have your expansion chamber tuned perfectly to stop the boost pressure from blowing your fuel charge straight over the piston and out the other side! But keep it up, cant wait to see the results, and hopefully a video! It can be done
  5. BSA

    BSA Guest

    And you've got to make sure your fuel pressure is regulated or it will lean out.

  6. bonescrub

    bonescrub New Member

    i didnt think forced air would work on a 2 stroke engine. 4 stroke it should from what i have heard/ read.
  7. fastboy9

    fastboy9 Member

    yeah 4 stroke there would be very little problems at all as the valves ensure that the mixture isnt boosted out the other side, but piston port timed poses loaaads of problems.
    Just have to get that back pressure from your expansion chamber timed perfectly with enough force to keep the charge inside the cylinder as the charger kicks in.
  8. arceeguy

    arceeguy Active Member

    Also remember that if you increase air pressure in the intake, you will lean out the mixture unless you pressurize the fuel bowl equally.
  9. Simonator

    Simonator Guest

    Is that one of those electric turbo's I see on ebay all the time? LOL! I know that don't push enough air to create any boost on car engines, but it just may work on these little motors if it is done right. Cool!
  10. Flapdoodle

    Flapdoodle Member

    I am not sure about gasoline engines, but GM 71 series two strokes have all had blowers, and some models had blowers and turbos since the early 1960's. They went from 3 cylinder to V16.
  11. QuadManiac

    QuadManiac Member

    theres a bit of a difference between the class of blower (nickname for a supercharger) and turbocharger and the FAN that is being sold fraudulently to increase horsepower. The fan can either move air OR generate a small pressure differential, but not both. We need both as the super and turbo chargers DO.

    If u do the math, u will find out that these fans can't raise pressure (which is what's needed to increase the air/fuel mass in the cylinder) more than a miniscule amount while moving the minimum amount of air required.

    A positive pressure pump (supercharger) or extreme high flow velocity (turbocharger) is necessary. This FAN (and it is just a squirrel cage fan) is neither.

    In addition, as mentioned before, if you simply apply pressure to the input throat of the carburetor (a pusher), all bets are off.. instead of vacuum pulling air past the jet which pulls fuel into the airstream, you end up pushing the fuel down the jet into the float bowl. As mentioned, you need to keep the entire carb under the same pressure by putting the whole thing in a box and pressurizing the box as well as the input throat, then it acts as a carb again. Conversely, you can PULL by putting the 'air pump' between the carb and the engine intake. In this case, the pump just increases vacuum at the carb and pressure at the intake manifold and all works well... to some degree, but then you are pulling air/fuel mixture thru your air pump mechanism, so precautions must be taken with a flammable mixture passing thru your mechanicals.

    My knowledge here is decent, not expert... i added a turbo to my vw powered sandrail after significant study re: the different types and their idiosycrancies. I chose a puller.
    Last edited: Nov 19, 2008