The Bosch EFEP 5C

The ORIGINAL Bosch Test Bench
For Mechanical Fuel Injection

The Bosch EFEP 5C was one of the first commercial Bosch test benches created to calibrate diesel fuel injection pumps for Mechanical Fuel Injection (MFI) with up to 8 inline cylinders. It featured a two-stage gear transmission which had selections for low speed (up to 1500 RPM) and high speed (up to 5000 RPM) and a neutral position which would disengage the transmission.

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A shift lever on the right is used for starting, stopping and reversing the gearbox as well as speed control, while a hand wheel to the left of the lever is used for minute adjustments to reach the desired speed.

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The test nozzle set can be swung out as seen in the illustration below for easier access to make adjustments on the left side of the pump. This was eventually modified in later benches so that the measuring glasses were more easily viewable during testing and so that the bench could be adjusted to be used in a variety of configurations.

The overall set up of Bosch test benches has remained similar throughout the decades, only making minor adjustments and upgrades for ease of use and accessibility. Check out our other test bench pages to see the adjustments and development over the years, plus more great vintage illustrations of german engineering!