1. From another car using similar recording technique (no I'm not making my car det so I can record it for you )
http://www.johnbanks.dsl.pipex.com/1...steep hill.wav
2. From my car through the gears. Smooth but fairly dramatic increase in background noise (this lights up the first green at high revs and the occasional flicker of the second green at the very top).
http://www.johnbanks.dsl.pipex.com/3.wav

Detonation sounds similar to the first one to the ears. These recordings are made using a knocklink sensor connected to the mic input of a laptop. Don't try the OEM knock sensor - you get horrible ground loop interference. The Knocklink sensor is not grounded to the car so escapes all this

 

http://www.johnbanks.dsl.pipex.com/knock.wav

This is an old recording from the OEM knock sensor on my car (when it was too lean with a TMIC running rather a lot of boost on a hot day whilst mapping). It is detting as it heatsoaks but the background noise, static interference and ground loop effect make it difficult to hear. Not a very good example, but you could hear this detting occasionally in the cabin.

I tried making det cans by trying to couple a stethoscope to the block with copper pipe and rubber hose, but could never hear much decent, the knocklink sensor into the mic input on the laptop works best for me and you can hear loads of stuff going on. Note that when you do this if you leave the knocklink plugged in it reponds less well.

On my car on maximum sensitivity, any sudden flick into the first orange or higher makes a nasty sound in the headphones, usually if it hits the big red you can hear it in the cabin. Whatever, this gives me confidence in the Knocklink's abilities despite some criticising it. I have the sensor mounted under where the TMIC used to live just behind the OEM sensor.

Hope this is useful/interesting/geeky/educational - delete as appropriate. If I'd thought would have made the .wavs into MP3s.


[Edited by john banks - 11/24/2002 9:07:11 PM]

 

third link doesn't work, should be

http://www.johnbanks.dsl.pipex.com/knock.wav

Iain

 

Thanks Iain, edited the original too.

 

John did you ever get anywhere with the DIY knock sensor thing? Great job on the DIY AFR (which I'm about to build myself), can't see how the knock link justifies £130ish for a microphone and some signal processing electronics. Either that or I'm just a cheapskate .

Don't think I've ever heard knock from my engine (thankfully) but it's one of those things that gets you paranoid unless you can monitor for it.

Cheers
Paul.

 

I've downloaded you wav files but I'm not convinced that I'll recognise it still

When you were pointing it out to me around Knockhill I couldn't hear a thing. It may be because I was in the back and concentrating on the 'warp drive' type scenery at the time

Thanks for sharing it anyway.

F

 

Never made the DIY knock sensor project. The Knocklink is good because although simple at least it is fairly standardised, and the time it would take to build one you may as well just buy one, they are not that expensive.