Knock Ampliftiers and Knock headphones
 

I've started using the head phone output of my knock amp during driving after some skepticism that the knock readings in my datalogs were real or not. I now believe they are very minor but real events and have altered my timing to suit.

I have realised unless the knocking is really prenounced I don't really know what I am listening for.

So does anyone have any learning material on rotary engine knock?

page 4B-30 in the turbo supplement for the s4 training manual ( foxed.ca has a scan of my copy )

shows a simple scheme for the amplifier and filter


so from that if you know a sound/ electronics guy you may be able to scale the frequencies it filters out or allows to pass

from the diagram it appears the target pass frequency is 3.5 kHz +/- 0.3 kHz

and some info ( ie.. max 7 degrees retard between 900 - 4000 rpm )
and from the 900- 4000 rpm thing we can assume the knock control is disabled above 4000 rpm , possibly due to the whole engine bell ringing

anndddddd that's the crux of the problem isn't it? Often it's pretty easy to tell when the engine is knocking severely, but not so much when it's borderline. It's basically a judgment call as to how much noise is too much. Even the chosen center frequency is a compromise. That 3.5 kHz was chosen for a stock engine. You start modding and that may not apply.

I'll put it to you this way. If you want to be really methodical about it, you at the very least need time on a loading dyno. Hold the speed steady, raise the load up, try it with different spark timings and see how the knock sensor reacts.

For your situation (adjusting things on the street), you're doing the right thing. Add or subtract a couple degrees of timing and see if you notice a difference when you do pulls.

bought this 2 years ago after corresponding w the Green Bros. it clearly IDs knock onset and Luke at Beyond Redline uses it as a primary tuning tool. fabulous.

sound cancelling, knock amplified. we set it at 3500 for the rotary.

KnockBlock - digital knock interface ? Link Engine Management Systems - plug-in & wire-in aftermarket ECU's


here's another... http://tunertools.com/gizzmo-electro...or-system.html


howard

Thanks for the replies.

I may have to get a 3.5mm microphone cable with a male plug on each end and connect it directly from the knockamp headphone output into my tuning laptops microphone port and make some recordings.

I have the HKS AFK2 setup to set off an audio alarm when the knock threshold exceeds 1%. Of course that depends on the input gain and threshold setting in that device. I believe I have it calibrated reasonably well.

I'm using noise isolating in ear canal phones called Shure SE-215 and they are really good. I chose them over active noise cancelling because I figured I would get annoyed constantly charging or replacing batteries.