Damn, I love the internet I came about this site that shows you how to build a device to actually "listen" to your engine, using headphones..Its cheap to build, and it works GREAT. Basically, this is what it is:

You use a "amplified listener", and modify it. Radio Shack has 2 of these models available, one with a 3 band EQ and is stereo with 2 electret mics, and one is mono, no EQ. I got the one with the EQ, since it has a 6khz slider on it, which is great for our motor's knock frequency..Cost on that was around 35 bucks. You then need to get some length of audio mic wire, either 1 or 2 conductor, and internally braided(less noise pickup, esp in an engine bay). You take apart the listener device, and remove the small electret mics, and de-solder the wire connections that attach to the board. Now take your wire, and solder the leads to your board. Since this unit has two mics, i just used the negative lead to the board for both mics, then used each of the positves.(there is a L/R balance control on this model, so you technically could use 2 clamps, and put one clamp on cyl 1, and the other by cyl 4, and use your L/R ear to see which is sounding louder for the knock) My wire i bought has a braided wire in it, used that as the ground for both mics. Then the two conductors in the wire were each hooked to each of the mic's positive leads. Drilled holes where the mics used to sit on the front cover, for the wires to exit the unit. Now, you need to get a small metal clamp. I then taped each mic(front of the mic agaisnt the metal clamp arm) to the clamp, one on the backside of each clamp arm. Now you have a VERY sensitive device that can hear any kind of vibration or what we want to do, listen for "knock". Here are some pics of the setup. I already had the headphones(closed ear phones are best), so that kept the cost down also. Total cost was around 45 bucks.







I was getting this sound in the car, that i thought was knock..a strange rattling sound. So i built this, and put the clamp on the passenger side of the block, on the engine pull bracket, and took the car out for a drive on the highway. Man, this is super sensitive, even with the volume control on the unit all the way down! Listening to the motor is strange, yet fukin cool! Did the normal 5th to 4th WOT drop, where that rattle was heard in the car at the 2 psi boost spike, just to be sure it was there..Heard it..Then put the headphones on, and did the same thing...NO audible knock whatso ever..Motor sounded smooth as silk under boost..So this pretty much sums up that i'm not getting knock..now i want to use this thing to find that damn rattle! Here is the link to where i found about this device:

http://www.autospeed.com/cms/article.html?&A=0353

Needless to say, this would be an excellent thing to use on the dyno...supposedly, this will let you hear the faintest of knock, well before a typical knock sensor will even hear it..

Whoa! Farkin cool! :-o

damn matt you are the freaking masta haha.

yea i know that sound your hearing... if its not knock or a little detonation i dont know what it is :\

Originally posted by soulcontroller
damn matt you are the freaking masta haha. yea i know that sound your hearing... if its not knock or a little detonation i dont know what it is :\

haha yeah i know..i've heard the same sound in a few other boosted clipses..I'm going to find it dammit!

Pretty nifty. It seems to be more versatile than a mechanic's stethoscope to diagnose for unusual sounds under the hood.

Yeah man, thats pretty cool.


95 Eclipse RS : 5 speed
15.7 @ 87.9mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

Damn Matt...when am I gonna see on T.V.? LOL

I may bulid one of those...or just come over and see if I can barrow yours ;)

Originally posted by micyek
Damn Matt...when am I gonna see on T.V.? LOL I may bulid one of those...or just come over and see if I can barrow yours ;)

Haha yeah man anytime..I'll prob bring this thing to the shootout too :) Whats even more cool about this, is I can hook this up to my laptop, and actually record the sound during a pull..That way I can go back and scrutinize the pull over and over again hehe..

dude that's real neat! i might do this as well...here's the new Corbin ladies and gentlemen! j/k! but that's awesome, i'm going to construct one as well before i dyno. thanks for taking your time on that idea!