Detecting detonation

[hottscennessey]

I just thought I'd post my newest way of detecting detonation, also the way I'll be building my timing map.

I had a chat with a local tuner about how he detects knock (detonation) when he's tuning for ignition.. he told me about his device "det cans" where he takes a coper tube, crushes one end, drills a hole in that end and proceeds to bolt it to the block. On the other end he attached a hose which tee'd and went into two hollowed out ear mufflers (attached via JB Weld). This allowed him to listen for detonation (he claims it sounds like rice hitting tin-foil).

I intended on making my own "det can" as he described, until I ran across an electronic stethoscope...

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95653

What I did was I took a bolt, and welded the SS probe to the bolt.. I then bolted the bold into my bock. The hardest part was finding a place for the bolt which would allow room for the "mic" piece of the digital stethoscope.

The headphones even reach into the car! The best part (I think) is that I can hook up a camcorder (mic in) so I can record the sound with the tach, and maybe even a WB02 display to easily re-call exactly where I need to adjust my timing.

Now, I havn't taken it for a test drive yet, but I can already tell you it's working as I can hear EVERYTHING. I'll update once the rain stops and I can actually drive my car/play with the timing.

I wish I took pics of my progress.. but I just like to get it over with. Sorry! I hope some of you find this interesting and maybe you could even elaborate on this idea..

PS- I know this isn't anything new, I just thought I'd share because some of you might not have heard of this.

 

[tissimo]

sweet


I've heard det cans can pic up even the slightest detonation that wont show on knock logs or dyno graphs or anything.. Never tried them out though..

 

[IJ.]

It's really interesting to use electric ears on the Dyno you'll be amazed at how much mechanical noise an engine produces!

 

[jmcboost]

So, do the stock knock sensors like ones on a 7M pick up much? I thought that one could use these for sensors somehow. I like the idea of listining yourself, but it would be nice to have an electrical sensor that would sense detonation and automatically adjust settings for you. Scott, it would be cool to hear the audio of that.

 

[OneJoeZee]

"bang bang"

 

[hottscennessey]

Scott, it would be cool to hear the audio of that.

Oh, you know I'll be posting some sound clips in the future :naughty:

 

[JimR]

I'm bumping this thread because I REALLY want to hear those sound clips!

Please post them if you have any.

Cheers

 

[suprahero]

If I were you, I wouldn't be bumping threads this old. You can always pm the guy that started the thread and find out if it worked or not. Just thought I'd let you know.

 

[JimR]

Since this thread is already at the top, I might as well say Good Point. It is a judgement call in each case... In this particular one my judgement is questionable because I just lost my newly rebuilt engine to detonation yesterday. I will have to pull and disassemble it yet again.

But that's just background info, it's irrelevant to bumping/not bumping.

 

[suprahero]

good point, and I'm glad you did bump it because I'm giong to order those, but I'm also not a moderator and sometimes they don't like the old threads brought back to life.......cheers.

 

[hottscennessey]

Hey guys, I'm no mod either but I don't mind you bumping my old threads. I'm not going anywhere.

Unfortunately I never did make anything of my plans. Before I even made any clean pulls the stethoscope had awful feedback, could be because of the electronics in the engine bay, could be because of the vibrations causing some of the internals on the stethoscope to come loose. I'll give it another try soon.

 

[IJ.]

I'm a Mod and I don't care

 

[annoyingrob]

http://www.hksusa.com/products/more.asp?id=3473

Wideband, and electronic ears in one. I run the previous model.

 

[TheNewRed]

does anyone use these? i was thinking of getting one.

http://www.turboxs.com/more_info.php?ID=212

 

[TheNewRed]

I guess ill give it one more bump.:biglaugh: I really want to know what and what dosent work as far as this subject goes.

 

[annoyingrob]

The absolute best solution is something you can listen to yourself. Computers are only so good at recognizing knock above all the background noise of your motor. Don't bother with little lights or anything. EVERY motor sounds different based on a vast array of variables.

-Knock sensor placement
-Cylinder bore/stroke
-Bearing clearances
-Timing belt/chain tightness
-etc

It's very hard for anything electronic to compensate for all of this. The best judge of knock is going to be your own ears. I know a lot of pro tuners that use a simple mechanically tuned antenna for knock detection.

 

[TheNewRed]

The absolute best solution is something you can listen to yourself. Computers are only so good at recognizing knock above all the background noise of your motor. Don't bother with little lights or anything. EVERY motor sounds different based on a vast array of variables.

-Knock sensor placement
-Cylinder bore/stroke
-Bearing clearances
-Timing belt/chain tightness
-etc

It's very hard for anything electronic to compensate for all of this. The best judge of knock is going to be your own ears. I know a lot of pro tuners that use a simple mechanically tuned antenna for knock detection.

Well thanks, do you think a stethoscope would work?

 

[annoyingrob]

not unless you can figure out some way to attach the cup to the block to properly transmit the sounds.

 

[TheNewRed]

not unless you can figure out some way to attach the cup to the block to properly transmit the sounds.

No... sorry, i should have explained, my father is a mechanic, and when ever he needs too, he uses this "automotive stethiscope. Instead of having the cup on the end it has a long wire like rod. its pretty cool. have you ever seen one?

 

[JimR]

Hehehe.... I can assure you he has. But this begs the question... how on earth do you use a mechanical stethoscope while driving? ))