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Free Boost Bypass Kit installation instructions for:

  • Supercharged Ford Lightning
  • Supercharged Harley Davidson
We have received hundreds of phone call and e-mails asking us if we sold a boost bypass kit. We looked around to find out who was selling boost bypass kits and we were shocked at what we found. There are dealers selling this simple modification for up to $30.00.

While the parts needed for a boost bypass kits can be purchased for less than $5.00, many dealers inflate the price just to provide the instructions necessary to install these kits. While we do not sell the kits, we don’t think you should pay for basic information that should be part of customer service from you performance dealer.

RPM Outlet will provide the instructions for installation at no charge. This allows you to realize all the benefits of these kits without spending money on what amounts to, paying for words.
Disclaimer: This modification is for off-road use only. This modification may violate U.S. laws and regulations and emission standards.
What is a boost bypass valve? The bypass valve is integrated in the supercharging system. When low engine power is required, the bypass allows air to enter the engine without passing through the supercharger. The supercharger bypass valve operates in the following manner:
  • Under normal engine operating condition vacuum is supplied to the bypass valve. The valve opens, diverting excess airflow back into the air plenum. This prevents the supercharger form “cavitating.”

  • Cavitating causes reduced performance, increased temperature, and poor fuel economy.
  • At high engine demands, vacuum is removed from the bypass valve causing it to close. This directs all airflow from the supercharger to the intake manifold.
  • The supercharger boost (SCB) solenoid is used to control intake manifold vacuum to the vacuum bypass actuator. The PCM transmits an output signal to the SCB solenoid, which activates the solenoid to apply stored vacuum from the reservoir to the actuator, when the engine is under maximum boost, reducing the boost pressure by up to 3 PSI.
  • Click wrench image for Supercharger airflow diagram.
Purpose of a boost bypass kit

The purpose of a boost bypass kit is to supply continuous boost from your supercharger when exceeding acceleration limits set by the factory. When acceleration exceeds factory limits, the boost actuator solenoid actuates the boost dump valve, relieving the superchargers pressure until the truck is shut down and restarted. With the boost bypass modification, you will now be able to keep your boost at the maximum level when under WOT usage. The term “boost bypass” is a bit misleading by all those dealers advertising this kit for a price. Its true name should be, WOT bypass eliminator kit . . . This modification does not effect normal engine operation and is designed for modifying boost bypass at WOT only. (WOT= wide open throttle)
boost bybass parts
    Parts needed for the boost bypass:

  • Vacuum T-fitting connecter
  • (1) 3/16-inch diameter
    (not required on Harley Truck)
  • Vacuum elbow fitting
  • (1) 1/8 x 5/32-inch diameter
  • Vacuum boot cap
  • (1) 1/4-inch diameter

Below are the easy to follow instructions detailing how to maximize your boost performance on your Ford supercharged vehicle. Unlike other companies, RPM will provide these detailed instructions at no cost to you. At RPM Outlet, we do not charge you for knowledge.
Step 1. Locate the boost bypass solenoid; it’s on the driver’s side of your supercharger towards the back of the engine. (see image 1 and 1a)

Click-On Wrench image for Supercharger system diagram.  Click-Here system diagram
found at any auto parts store

image 1
Note: The correct solenoid has a double vacuum line (pink top/ black bottom).
coming from the side of the valve and a sensor plug with two wires right above it. (see image 1a)
found at any auto parts store

image 1a
Step 2. Disconnect the pink vacuum line and locate the boost gauge signal line. (see image 3 and image 4)
found at any auto parts store

image 2
This is the factory boost gauge signal line with coupler installed and boost signal line disconnected. Signal coupler will be removed in the next step. (see image 4)
found at any auto parts store

image 3
Step 3. Disconnect the factory coupler from the boost gauge signal line (harley truck has boost signal line plugged off) and replace it with a t-fitting. (see image 4 and 5)
Reinstall the boost signal line to the open end of t-fitting (harley truck use existing union) . (see image 5)
found at any auto parts store
image 4

found at any auto parts store

image 5
Step 4. Locate the pink line that was disconnected in step 2 / image 3, and connect to the Vacuum elbow fitting that we listed at the top of page to the pink line. (see image 6 and 7)
Connect the pink line with the new vacuum elbow installed onto the t-fitting the was installed on the boost signal vacuum tee. (see image 7)
found at any auto parts store
image 6

found at any auto parts store

image 7
Step 5. Finally use the vacuum cap that we listed at the top of page to cap off the vacuum boot that was connected to the pink line.
found at any auto parts store

image 8
Congratulations! You are now able to add up to 3lbs. of boost to your Supercharged vehicle.
Free from RPM Outlet !