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Three-stage boost for 4-cyl engine?

  1. Dec 1, 2011 #1
    I have a 2004 Chevy Cavalier with the 2.2L Ecotec. I already have a supercharger and charge air cooler on it. What I'm contemplating is adding ram air and an "e-turbo". Since the boost is multiplied in each stage of boost, any increase into the throttle body would be multiplied considerably before being forced into the engine. The "e-turbo" would be homemade, utilizing a 12v dc motor I have just taking up space in my garage. I know they work on very small naturally aspirated engines, but I don't know about an engine that's already sucking in the air of a small N/A V8. I have many different 12V DC motors, ranging from tiny actuators up to a starter motor for a large V8 engine, so whatever size I need, I probably have. I have a couple blower motors that pull 16A and 27A with no load, that have the impellers still on them. I would like to use one of those if either, or possibly both, would be powerful enough.

    Facts about the engine:
    2.2L 4-cycle
    14 PSI of boost from the supercharger
    At it's 6,800 RPM redline, I calculate that the supercharger sucks in about 520 CFM.

    How large a motor do I need to build about 1-2 PSI before the supercharger? Keep in mind the "e-turbo" would have minimal boost into it from the ram air. I will build a controller that opens the bypass valve on the supercharger to maintain a maximum of 18 PSI, so I'm not worried about over-boost or the wide range of boost that I'm sure this setup would (probably?) create

    How much would the ram air help? I already have more power than the tires can handle below about 40 MPH. The gear-limited top speed is 148 MPH. I will be taking the car on a road course next summer, where I expect to stay between 70 and 130 MPH. I also drag race and hit about 105 MPH at the 1/4 mile (maybe more depending on how much boost this adds). The left front headlight assembly can be removed easily and I can fabricate a funnel/pipe to go in it's place and feed into a custom air filter housing for track use, on the street I won't have any use for extra boost anyway.

    I should add that the main reason for going this route, for now, is to alleviate some of the heat of compression in the supercharger. I could go with a .1" smaller pulley, but the IAT has gone as high as 170°F and would have gone much higher if I hadn't let off the gas (that's measuring after the water-to-air cooler). I am currently designing a water/methanol injection system that should help a lot, after that is installed I will probably switch to the smaller S/C pulley. Down the road I will either switch to a turbo or twin-charge setup, but I can't add much more power before I need stronger internals.

    Thanks in advance for any help!

  2. jcsd
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