SEMA 2017
- Thread starter Cobrar
- Start date
fjpikul
GT Owner
BlackICE
GT Owner
Fubar
Totally ****** Up
It’s not the belt, it the sound coming from the supercharger discharge port... when the blow-off valves are open (computer is commanding no boost) there is a pretty much a straight shot thru the blow-off valve to the discharge port. Every supercharger makes that sound, it’s just that none of them have a down stream blow-off valve, so you can’t hear it.
BlackICE
GT Owner
I think the stock FGT discharges the air between the MAF and throttle body so that the MAF readings are still correct. I guess that muffles the noise.
Fubar
Totally ****** Up
The stock blower setup doesn’t really need to discharge boost because when you let off the throttle, the throttle closes and the supercharger is immediately operating in a vacuum. It has a small boost dump for quick gear shifts but the amount of air that needs to be handled is inconsequential. That bypass should only be open for a second or two, plus it’s pretty small.
The 4 blow-off valves on my GT have 2” discharge pipes... it’s a big gapping hole that could swallow a small animal or unsuspecting import car. To put it in perspective, I put a decibel reader inside the tip of my engine exhaust at idle and got 118db, under higher rpm conditions it would register 127db. The blow-off valve ports would register 128db at idle and were beyond the limits of my machine at higher rpm. (The display said “FU, I Quit!). I argued with Fischer because I that the sound was coming from the intake side of the supercharger but that runs at slightly less volume than the motor.
I wish I had made a video of Shawn explaining the system because you need the visual too understand the amount of air that is being managed. That’s the reason it can be such an effective cooling mechanism when we don’t need boost.
The 4 blow-off valves on my GT have 2” discharge pipes... it’s a big gapping hole that could swallow a small animal or unsuspecting import car. To put it in perspective, I put a decibel reader inside the tip of my engine exhaust at idle and got 118db, under higher rpm conditions it would register 127db. The blow-off valve ports would register 128db at idle and were beyond the limits of my machine at higher rpm. (The display said “FU, I Quit!). I argued with Fischer because I that the sound was coming from the intake side of the supercharger but that runs at slightly less volume than the motor.
I wish I had made a video of Shawn explaining the system because you need the visual too understand the amount of air that is being managed. That’s the reason it can be such an effective cooling mechanism when we don’t need boost.