When driving our Project FR-S on the track, we noticed that the engine has a pretty noticeable vibration at 6500 rpm. This was especially noticeable in the higher gears where the engine would spend a lot of time in this RPM range. The vibration was bad enough that we would short shift to try to keep the engine from spending too much time at this rpm. We were thinking that the crank had torsional vibration that the supercharger was amplifying making the vibration more noticeable. After speaking to several other FR-S/FT86/BRZ owners of track-driven cars, they all noticed this vibration as well. Because our car seemed to vibrate the worse we decided to see if we could do something about it. We called the tech guys at Fluidampr to discuss the problem.
When they did a vibrational analysis of the FA20 engine using a frequency sweep, they found that the amount of torsional vibration of the first order, second-order, and, third orders were reaching a peak from 5000-6500 rpm
Here are 3D vibrational plots showing the harmonic peaks of the vibration.
Here are some 2D plots that might be easier to understand! as you can see in this plot, the amount of torsional vibration in the 3rd order was cut in half by the Fuidampr,
Here in the second order, the torsional twist was greatly reduced from 3500 to 5500 rpm.