Pressurized

I'm still fighting the evil battle against "detonation" and I cam across the idea of the knock sensor.....

Can someone explain what it does? Does it help with detonation?

Also, when you buy the sensor, what all comes with it?, do you have to buy the monitor seperate?

maxcooper

It listens for detonation and restards the timing if it hears some. For each individual chamber (there are six total on a 2 rotor), it will retard the timing pregressively more until it goes away.

However, it is still quite possible to blow your motor with one of these installed -- it won't protect you if you have the tuning way wrong. But it will help you identify a problem (bad gas, too hot, etc.) and offers some protection when there is a problem.

To me, the greatest value is that it tells you when something is wrong so you can let off, rather than the timing retard function.

The unit comes with a wiring harness, main control box, and a knock sensor. The display is extra, and the latest ones have a pretty nice O2 sensor display integrated into the same display unit.

-Max

Nathan Kwok

The J&S Knock Sensor is basically a more sophisticated version of the sensor that is already on your car. It consists of a small microphone that screws into your rotor housing. This microphone connects to a computer that can decipher the sounds of detonation and seperate that from normal engine noises. It is extremely sensitive and can pick up even the slightest hint of detonation before damage is done, and way way before you can hear it. Upon hearing detonation, the computer retards (up to 14 degrees) the timing on the leading coil until the detonation goes away. The computer itself has a readout that indicates how much timing is being taken out, although most people also buy the seperate round dual gauge that also reads out A/F ratio. The latest version also has an option to automatically retard timing based on boost pressure, and can be programmed, although this option costs extra. I believe the regular price for the computer and gauge without the programmable boost/retard is around $700. Although expensive even in the group buy, I felt this unit was worth the extra protection it provides, especially considering detonation is the #1 killer of rotary engines. Due to the quiet nature of the rotary, the sensor works especially well, and I had to turn mine up to almost maximum sensitivity before it would retard timing due to regular engine noise. Here is a picture of the gauge on my website: http://www.geocities.com/nathan356/mycargauges.html