L&M Low Vacuum Bypass Install

If you are installing one of our high lift or NSR cams on a supercharged engine, you will need to install one of our low vacuum bypasses. We currently stock the bypasses needed for Eaton or Whipple superchargers; if you have a Kenne Bell supercharger you will need to contact them for the correct bypass.

L&M Low Vacuum Bypass Install Notes

Note: This guide assumes you have already finished the installation of the camshaft and you are ready to install the low vacuum bypass. It also assumes the intake tube, throttle body, and inlet are removed from the supercharger. You may also be able to install the vacuum bypass without removing the blower; we usually remove the blower due to the tight clearances.

1. Disconnect the factory lines leading to the factory vacuum bypass. Remove the factory vacuum bypass from the blower.

2. Install the modified L&M low vacuum bypass. The bypass may appear to be damaged, but we have cut off the unused connection to avoid improper installation. See below:


3. Remove and cap now unused line (located next to the EGR lines). See engine passenger side and passenger side detail photos for exact location. Save the heat shielding wire loom for the new line.

4. Cap the nipple on the intake tube that previously had a line running to the factory vacuum bypass.

5. Disconnect the line leading from the fuel rail pressure sensor to the manifold pressure nipple on the front passenger side of the engine. See photos for details.

6. Install a barbed T directly after the fuel rail pressure sensor. Reconnect it to the manifold pressure nipple. See photos for details.

7. On the remaining barb run a line from the fuel rail pressure sensor to the “V” side of the low vacuum bypass. See photos for details. Note: Bypass is not pictured.