Homemade Inline Electric Supercharger

Electric superchargers, inline or otherwise, have a dubious reputation at best. Though electric supercharging has been around for decades, it has only been fairly recently that automotive applications have met with any measure of success. However, current off-the-shelf parts can make for a unique experiment for those with small displacement engines.

Blower CFM

  • Bad news first: no electric inline supercharger currently available with off-the-shelf parts is going to feed an engine with more than 1.5L of displacement and make any power. At 6,400 RPM, even a 1-liter engine needs about 125 CFM (cubic Feet Per Minute) of airflow. At 2 pounds of boost pressure, that number shoots up to about 180 to 200 CFM, which is right on the borderline of what a large 4-inch diameter Turbo 4000 marine blower will push while delivering 2 psi of pressure.

    On the positive side, 1 psi of boost is usually worth about 8 percent increase in power, meaning that the aforementioned 60 horsepower, 1.0L engine might stand to gain as much as 10 horsepower; not an insignificant increase for a 2000 lb car. So, go with the Turbo 4000 marine blower ($35 as of 2010) for any hope of making power.

Mounting

  • You could use 4-inch aluminum tubing with rubber or silicone connectors for your intake tract, or you could go the cheaper route, and use aluminum drier ducting of the same diameter. Begin by removing the rubber air intake tube that connects your throttle body (main engine air valve) to the air filter box. Fabricate an adapter to fit the 4-inch diameter tubing to the throttle body, and measure out between 12 and 18 inches of tubing. Attach the output side of your Turbo 4000 blower to this tube with large hose clamps.

    At this point, you could either connect the input side of the blower to the stock airbox (which some cars will require to retain the airflow-sensors), or you could simply mount a cone-style aftermarket air filter to the blower. Cars that use a mass-air flow sensor (you'll see a wiring harness connected to this sensor, which is attached to the air-box) must retain this sensor. You can install the sensor up-stream from the blower input with a 3-inch length of tubing, and secure the air filter to the sensor itself.

Wiring

  • Extend from the blower's black wire to your battery's ground terminal. Run an extension from the red wire to a switched power source in the cab or engine bay. Some people run a jumper wire from the power-on side of their fuel pump relay, which is often conveniently located in the black fuse box right next to the ersatz air filter. Doing so will ensure that your electric blower is running whenever the engine is on.