Austarion

I love the word "Transducer" ahhh.

Anyway, i was in a friends ae85 the other day, listening to his engine (quite modified) on a set of headphones. A mate of a mate (gets flakey here, i know) works for LinkElectro, and has developed a cool filtering software to let you listen to the engine noises on the headphones really clearly. They used it for road-tuning purposes, apparently it was very helpful. I dont know what the delay would be in the filtering software, but i dont imagine its noticeable at all.

I have heard mention of the 'headphone' method before.
I would suggest that putting an amplifier between the existing knock sensor and a set of headphones may be an acceptable way of listening for knock. After all, the knock sensors are normally tuned to the engine in the factory, so some amount of filtering is done mechanically already. Secondly, as far as filters go, the audio processing capabilities of the human ear and brain are second to none. We can pick slight differences in sound that aren't detectable by most electronic analysis equipment...
Assuming that tappets are adjusted correctly and the engine is reasonably healthy, it should be easy to hear. This method is the way that holden adjusts the timing curves for its engines whilst on an engine dyno, so it must be OK.
The main thing is to get a 'baseline' reading, that is, tune the engine to knock at low revs (EG, around 1500-2000 RPM) in a higher gear (to stop the speed and boost coming up). This is to give you a reference for what the knock should sound like, while the low revs will prevent engine damage (lots of time for the metal to cool down between knocks). Once you know what you're listening for, set the timing back to a safe value, then do your tuning.

i have been using a microphone (dynamic type) and simple amlpifier driving a set oh headphones, and its quite a worthwile tool.
this setup deliberately does not have a lot of tuned audio filters, the idea being to "learn" what the engine sounds like, and i mean all of its myriad repertoire.
with the dash engine, you can easily identify the inlet solenoid, 2nd inlet valves etc, bov, turbo and knock.
i had to modify the timing map to get it ot knock though, just to be sure.
but easily and safely done at low revs and moderate load.

And make sure you have a bucket.

I used to repair helical scanning DAT recorders for the australian army a few years back. I asked the guy who dropped them in for repair what they were used for. What he told me shocked me. They used them to record the sound from diesel generators (BIG diesel generators , not garden variety) , and after anylyzing the sound on a pc , they could determine if big end bearing on cylinder 3 was starting to wear , or virtually any part of the engine (bearings , crankshaft , valves) was starting to fail. The cost savings on early detection of failure far outweighed the cost of the DAT recorder & software.

This is a really interesting thread, informing and constructive :beer

my engine went tattattattatatatatata bang! and it was all over lol that was a while ago now though.

Cheers Guys
Ben

Microphones? DAT tapes? What a bunch of pansies.
See, as Camotec has discovered, you don't need all this special equipment to work out when your engine is knocking.

Camotec wrote:This is a really interesting thread, informing and constructive :beer

my engine went tattattattatatatatata bang! and it was all over lol that was a while ago now though.

Cheers Guys
Ben

That's what the bucket is for to collect the pieces if you get it wrong

mrb1 wrote:And make sure you have a bucket.

I find it hard to tune engines whilst stoned..

Hahahahahahahahahahaha