Working on an article for DIY knock detection. Anyone else interested in this sort of thing?

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Here's a breakdown of the whisper2000 and how to make your own detonation detection device.



The mic is removed from whisper2000, rewired to 5-10 feet of ext wire, and then it's glued onto a alligator style clip.





The clip is then placed somewhere on the engine to best detect knock. On the KA the clip should be placed as close as possible to the factory knock sensor. You're then able to listen for knock via headphones.



This method looks and sounds crude, but I have read nothing but rave reviews of how well it actually works. Guys with data logging software are able hear knock before the factory knock sensor registers any. Of course for those of you that don't want to use headphones, you could always connect the whisper2000 to an alarm and LED.

Now after some browsing and brainstorming I found this.



For $30 bucks plus a headphone extension cable, we get a unit with a self contained mic which removes all the BS involved with the above whisper2000. If I can avoid soldering, I'm going to.



With this unit I believe we can attach it right under the intake manifold with the mic right over the knock sensor. This should give us a good signal, remove the need to rewire anything and the price is a hell of a lot better then the other knock monitors on the market that range from $200 to $600 and don't do much besides turn on a light and make noise.

Also, if you want to datalog the "knock" you can get a headphone splitter and connect another 3.5mm cable directly to your Line In slot on your sound card, it's usually marked in blue with the line out marked in green.



Then simply select "start", type the word 'sound' in the search box and Sound Recorder should be one of the choices. Select Sound Recorder and then click record when your ready to start.

Thoughts?

WD

wouldn't something like this pick up general motor noise? how would it tell the difference between regular noise and knock? I guess you would have to note a base noise level and then note differences during tuning? Cool idea but it seems a little iffy.

Pretty awesome idea.
It'd be cool to wire it up to turn on one of the unused warning lights on the gauge cluster.

If you have an AUX input you can run it directly to your car stereo and avoid the headphone while driving. You'll pick up motor noise yes, but you'll be able to tell knock from injector or valvetrain noise real easy. Really loud rice crispies from my worst memories.

Cool, I'm no expert so trying to diagnose things by how they sound is sometimes really hard. Makes you run around in circles sometimes. If it's a distinct noise as you say this should be pretty cool. I was going to get a knock light but may do something like this instead.

WDRacing wrote:If you have an AUX input you can run it directly to your car stereo and avoid the headphone while driving.

That's an awesome idea.

SiDwAyZ240 wrote:Cool, I'm no expert so trying to diagnose things by how they sound is sometimes really hard. Makes you run around in circles sometimes. If it's a distinct noise as you say this should be pretty cool. I was going to get a knock light but may do something like this instead.

The sound is definitely unique. The mic will be sitting right against the block, so any knock will transmit right into the mic. You can induce mild knock by advancing your ignition timing and revving the motor. Mild knock can be heard by the naked ear with the hood open. Severe knock can be heard inside the car...ask me how I know

The problem with knock lights is that most don't have a sensitivity adjustment, so you don't know for sure what the sensor is picking up.

There is also some really cool, free, software for your PC that graphs sound so you can watch spikes as you listen etc, or just datalog. It's like having the formula for any type of equation, once you know what you're looking for, the rest is easy.

post up some free software wd

anywho you guys got me thinking(that and leaning out a hair at 14psi today(from 11.8-12.2:1 prime time for knock)) so I did some digging on my own found this
xxxx can I post an outside link wd?
I may need to get the proper hardware to finish it up, but as it sits its reading the sensor(played through stereo jack just really high pitched right now. update tomorrow.

Post it up, I'm in the process of writing an article on this so I can use some additional references. Is the link to a forum? I've read through a couple places that use the stereo mini jacks (3.5mm). If they wanted to, anyone can tap the factory knock sensor and listen to it with any basic sound amplifier.

As far as being lean goes, I don't consider an AFR lean until it goes past 12.5. But that's just me. There is a pretty big difference in power and mileage when you compare a tune in the low 11.s and one at 12.5 or so. If I can't run 12.5:1 AFR's then I'm running to much timing or I'm octane deficient/limited. Again, that's just how I do things and it's another huge reason that I have always used some sort of alcohol/water injection.

ok, thought I was gonna get shot posting hybridka back on line..

http://home.netcom.com/~bsundahl/knock/ ... listen.htm
very simple, take the boy to school then I'll hit radio shack..

http://audacity.sourceforge.net/ seems to be pretty decent freeware available for for every OS.

neverlift wrote:ok, thought I was gonna get shot posting hybridka back on line..

http://home.netcom.com/~bsundahl/knock/ ... listen.htm
very simple, take the boy to school then I'll hit radio shack..

Funny, I've read that a few times. I have the capaciters listed on there saved on my parts list.

Audacity is pretty good and easy to use, I've used it in the past.

audacity didnt work for me IDK

anyways no luck so far, unless I just cannot hear engine sound over the whine. Currently using 2 100k ohm resistors and 1 .1 uf capacitor. NO love

it is odd wd last night while working over a new evo it would not lean out and it was substantially cooler(should make leaner burn due to more air). 12.5:1 is scary to me lost too many motors near that afr, sure timing may have been a factor(oem ecu at 13* base timing,10psi)

Yeah, you can't run those AFR's unless you're monitoring for knock and using subinjection bro. I also made sure that my tune was capable of retarding timing on boost, that way my base timing could stay at the factory specs, maybe even advanced a touch depending. I was using the MSD BTM, the MSD Knock Alert, the LM1 and Alcohol injection. The MSD BTM is an awesome piece of equipment because you can adjust your timing retard value, per psi of boost simply turning the knob. For me it made tuning way easier. I'd just pull out 2 degree's of timing per psi, tune for .85 lambda and then add timing back and watch the knock alert. Then I'd drive it like I stole it, heatsoak everything that could be and either add alcohol or pull timing until no knock was shown.

It should be noted for the record that I destroyed 3 RB20's by short cutting and generally not knowing what I was doing back in the day. I had a boost controller before I had boost gauge

If I were just running pump I'd stay in the 11/s as well.

The only way to "hear" knock is to induce it unfortunately. I can usually make a motor ping just by messing with the dizzy, for trial and error purposes only of course. Might want to advance your base timing like 8-9 degree's and run the throttle up by hand while listening for ping.

I can add as much as I want at idle via nissan data scan
yeah just pump gas atm, gonna make a better water injection setup than last time.

Yeah, that dude was a bit low budget. But it worked.

hey I was pleased with a 10$ 45psi water injection setup. Gonna focus on high pressure this time. Possibly pre turbo, no IC

I'm not a fan of pre-turbo injection. Just to much evidence of compressor wheel damage. That and you can get just as much atomization with a high pressure pump and a quality nozzle. Never get rid of the FMIC or any sort of intercooler. There's just no justifiable reason to remove a free heat sink from the system.

My .02

good point, but I would have to at least got to a small core(currently running a 3x31x12 iirc) and at this point I dont see no IC working, less boost maybe no IC but a bar or more needs it with my tiny t3.

Anyway back to the subject at hand. No updates for today, gonna try some stuff tomorrow if I get around to it.
Any one else?

quick update on this:

best sound so far is with only a single capacitor wired inline

This thread got my wheels turning, so I started doing some research on an actual knock gauge. Something like this:


So it turns out these are designed for GM cars, and mainly the Grand Nationals. During my research I found an article about a guy making this work on his Supra:
http://oldschool.supracentral.com/htm/ks_mon.htm#kmpart

I sourced all the parts to make this work including the gauge, esc module, and a gm knock sensor and I'm looking at $90. Do you guys think this could work on a 4 cylinder, or does it only work on the Supra because it's a 6. I just don't know how the gm knock sensor is setup to monitor knock, obviously the noise a V6 makes is going to be considerably higher than a 4Cyl. What I'm concerned about is that everything appears to be working than when you get a moderate knock reading on the V6 sensor and gauge, the 4cyl is actually screaming for help. Does this make any sense? WD, you seem to know your fair share about American muscle, what do you think?

Knock occurs at pretty close to the same frequency on all motors, like 7400 hertz iirc. So a knock sensor will pick up the freq no matter what motor it's installed on. In fact there isn't even much difference between alum and iron blocks.

I think you'll be good2go.

Great, this is going to be one of those gauges I was talking to you about. Trying to put together the most useful set I can. Think there is any chance I can get the ESC (electronic spark control) module to read my OEM Nissan knock sensor? I was thinking maybe tap the knock pin on the ecu. Since you say the knock sensors read pretty close to the same, it would be nice to not have to figure out were to mount a GM knock sensor on my motor and save me $30

You can tap the factory sensor.

Woot, Woot, Woot, can't wait to get this up and running.

just came across this in case anybody is interested:
http://zilvia.net/f/sale-items/455753-m ... gh-hp.html