You can apparently ballpark the frequency by piston diameter, but the actual variables are numerous and require advanced math to resolve. Here's a start:

Resonant knock frequency (kHz)= 900/(pi x cylinder radius)

http://www.phormula.co.uk/KnockCalculator.aspx

subscribed...

and that, really, is the 'secret formula'...

Project 935 Blackbird with knock controller. Claims 900 hp at 1.6bar

I'm pretty sure the engine was done by Turbo Mike in SoCal. He installs the knock controller between a F.A.S.T. EMS and two MSD7's.

Reader's Digest condensed version:
http://www.6speedonline.com/forums/930-turbo/179696-reapers-blackbird-build-chronicle.html

Long thread:
http://forums.pelicanparts.com/showthread.php?t=364751

What is the part number for the bridge you got at Pelican? I couldn't find it.

Here you go: 993 104 391 00

Pelican Parts - Product Information: OEM-99310439100

If you are only going to run 1 sensor, why not place it somewhere on the case?

Did I mention we have a 30 day money back trial?

I will waive the normal 10% restocking fee to the first one that orders.

If my motor were anywhere close to ready, I'd take you up on it! Unfortunately, there is no way I'd come close to making 30 days. :)

Any idea if this will fit a 930? I assume it will.

Wouldn't putting two sensors, one on each cylinder bridge, be more accurate?

Where are people placing them otherwise? I read about the crankcase breather but I'm not sure where that is located. Anyone have a pic of that area?

For starters, yes, you need two, once on each cylinder bank, just like the 993s do.

Second, these will fit any 911/930, as long as you drill and tap the underside of the cooling fins so you can bolt these solidly to the cylinders.

But then wouldn't you need 2 separate controllers?

As an aside, can a single J&S unit run 6 coils on a twin-plug wasted-spark motor controlled by MS-II and parallel EDIS units? I already have a Bosch sensor on the case oil breather cover running a KnockSense module that has already given up the ghost.

Please post or mail me a wiring diagram.

See the two links at the top of my home page for waste spark or coil on plug applications. One of these should be able to do the job.

This is from Mike's build but it is basically the same as mine:

http://forums.pelicanparts.com/uploa...1256762490.jpg

To retain dual plug waste spark, you would need two three channel Vampires.

We have a single box version for dual plug with twin distributors.

That's my diagram above, I dont use MS anymore, but similar setup through my Adaptronic ECU. I use two triple-channel Haltech ignitors. When they work they're great but I've had some QC issues.

JohnJL:

The Adaptronic has three outputs that go to two three channel igniters?

The Interceptor version will work.

Three inputs from the Adaptronic, three outputs to each igniter.

So what about this John? Would I need 2 controllers or can I parallel the knock connections somehow to use 2 sensors on 1 controller.

forwheeler:

You have the same set up as sjf911?

According to the drawing posted, you would need two three channel Vampires.