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Supercharger Knock / Rattle

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The Whipple supercharger upgrade has been popular for the SGT's, so I wanted to post my experience here to hopefully save another member a lot of frustration. I installed a Whipple 400hp kit on my GT vert five months ago and I have been trying to resolve a knock / rattle issue in the motor ever since. It has been VERY frustrating, but I finally figured it out tonight! :happy feet: My vert has been to the install shop numerous times, I spoke with Ford Racing and Whipple several times. Whipple even rebuilt the supercharger and my vert sat undriveable for a five weeks while I waited on the rebuild. The problem persisted and no one could figure it out. :banghead:


In the end, it turned out to be a simple fix. My throttle body rattles. I swapped the throttle body from my GT-H with my vert and the rattle/knock is gone! It was very unnerving because the noise sounded exactly like engine knock to everyone that heard it, so I was worried I was going to blow the motor.


The issue I had was a noise that sounds just like engine knock that is constant between 2000 – 2500 RPMs under WOT with at least 4psi of boost in any gear. All three conditions (RPMs, WOT, 4+ psi) must be there or it will not make the noise. Also, if you let off the gas in that RPM range, the noise gets louder for a second and then stops. If you have this problem after a Whipple install, check your throttle body!! Also, prior to the Whipple install, I never heard this noise.


I hope this saves someone a huge headache in the future. If anyone has a GT throttle body they want to get rid of cheap, I could use one!

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Good info for sure!


I know the E-force was having a simliar issue, but the symptom was a surging in the rpms..

My experience has only been the alternator.. I knew a bunch of racers, they have always said, the higher the horsepower, the more frequent the repairs..



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