Can you here any detonation in this sound file recorded from the knock sensor?

Engine Sound

For as second I thought you were talking about detonators as in dynamite and bombs!

What engine is it? Sounds like a Playstation to me...

I just repaired a Pinto with a similar problem. Should have run it on unleaded high octane but was running on a cheap supermarket mix.


Nice article on detonation can be found here

http://www.zhome.com/ZCMnL/PICS/detonation/detonation.html

To answer the question - No
HTH

Try putting in a high gear and pulling up a long hill from low RPM, if you get "Pinking" the fuel grade or ignition timing aren't right.

Only slightly connected to the thread but of interest
In cylinder video

http://video.google.com/videoplay?docid=-5815350492893860613&hl=en

I'm certainly no expert but I found this a while back.
There is a sample wav file on there that the author claims is knocking and I can't hear that in your wav file.

When I ran the spectrum analyser software you did have a peak just after you changed gear at about 3750 hz but I've no idea if thats knock or something else.

Let us know how you get on with your ignition because thats the part I'm most unsure about.

Paul.

[Edited on 6/11/07 by Doofus]

Its a 2.3 Duratec with 11.6/1 pistons & Cosworth cam.

It has damaged the pistons previously due to detonation and I'm wary of damaging the new set.

It's running on a mixture of 97 & 99 octane fuel.

Discussions with others with a similar setup indicate that this engine seems particularly sensitive to ignition timing when the compression ratio is raised.

The exhaust and induction noise tend to hide the engine noise when running which is why I have recorded it. I am very interested in others opinions who have had experience of detonation. I am familiar with the pinging at high load and don't hear it, but aware of a more subtle form that leads to piston damage.

The sound clip is at 98kpa+ MAP pressure up to about 5.6kRPM, so pretty much at full load.

Another trick is to listen to the sound in Winamp or similar that allows you to use the equaliser to focus around the 5khz region.

Here is a spectral analysis of the sound. There does appear to be a strong signal around the 5khz but I'm not sure of the significance.

http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=Rec200711041453%20Clipped.jpg

One of the anti detonation techniques is discussed here

britishtrident - nice video, but I don't intend going that far in monitoring the engine .

Doofus - I think I have seen the site you refer to - if I keep listening to my sound I can convince myself that I hear something similar.

11.6:1 with a bumpy cam and mixed 97 octane petrol!!!

Errrm, you should really be running that on 99 octane fuel, no less. My M3 which is 10.8:1 will pull the timing as it pinks on 95 and feels flat on 97.

Not an expert by any stretch but that all sounds like mechanical to me, no nasty burn related noises that I could hear, sounds very clean