Resources for Building a Detonation Detector

[Indycars]

Hmmm...maybe an aftermarket knock sensor would be a good thing to have. I'll look into that.

I've never considered a knock sensor. How would one hook that up?

I was interested in building a detector at one time and was looking into the how for building one. I've since fixed my problem by retarding the cam timing 4°.

Another Electronic Det Can Example - Miata Turbo Forum - Boost cars, acquire cats.
DIY electronic det can build - Honda-Tech - Honda Forum Discussion
EFI Express
Engine knock detection and indication for all vehicles

The software linked to below is mentioned in the PDF file that is attached.
Engine knock detection and indication for all vehicles
.

 

[PotvinGuy]

Most interesting, Indy. I've found 3 aftermarket units, including the one you referenced. They are around $300 and details are skimpy. Apparently the unit has to be tuned to match your engine. One of them says it is "self-tuning," but no details. New cars all have knock sensors but they report to the ECU.
The sensor itself is just a dumb transducer that makes voltage. But decoding that voltage is the hard part.
I suppose one could attach a sensor, hook it to a 'scope and then advance timing until knocking starts and see how the output changes. Then design a circuit that would detect such a change. From what I've been able to snag off the 'net, it is related to the resonant frequency of the motor.
Just read your PDF and it doesn't look so hard after all. I might try it.

 

[Indycars]

Yes I believe you are right, it's going to specific to each engine. You might get away with
each engine type such as SBC or BBC, but I'm afraid with different, cranks, camshafts, and
heads that we tend to use this would not work. In your design would a user be able to tune
the selective filter so it could be tuned to each specific engine?

It would also be nice to have the ability to listen yourself with headphones to confirm what
the your circuit is telling you. Since our car are usually loud, the headphones would be most
helpful to block the outside noises. If a user is going to tune his/her detonation detector, this
would be critical to getting it right.

 

[Indycars]

Amazon has lots of microphones, some that even work with the Arduino.

Amazon.com: Electret Condenser Microphone: Industrial & Scientific
I tried to post the link to the Arduino, but it just leaves a big white space. Use the link above and
page down until you see the pic below.


.

 

[PotvinGuy]

Yeah, I think a generic GM sensor would be OK. Then do the headphones like in the PDF and add a 'scope to see and hear what the knocking looks like. Maybe a simple tunable op-amp bandpass filter could then sharpen the sensitivity. Damn, sounds like a fun project now. And I must ask: why isn't some SEMA company doing these things? Aw, I feel a rant coming on. The OEM world has had electronic ignitions (no points, no springs, no bushings, no distributors period) for decades, but our aftermarket weenies are still selling antique distributors ( and no vacuum advance! That's disgraceful) and coils like it was 1980. It's all about the $$$; if you do no R&D, just keep selling the same old crap, you maximize profits. For one shining moment years ago Mallory did a totally modern distributor, the MaxFire. It is completely electronic, selectable curves, vacuum advance, boost retard, RPM limit. You can even hook a laptop to it and make your own curves. I have one. When MSD bought Mallory they dropped it. More Tech Support than they wanted to deal with. And it was expensive and not a big seller. OK, end of rant...for now.

 

[Indycars]

Are you thru now, can we get back to the DD??? hehehe!

On the electronics side, I certainly can only thru out possible options. You would know
if they are viable.

Maybe a simple tunable op-amp bandpass filter could then sharpen the sensitivity.

Would this bandpass filter be adjustable?

 

[PotvinGuy]

Well, now that I've had a few minutes to ruminate I have several hundred things I want to get off my chest. But I will spare you...for the moment.
Yes, a filter with adjustable center frequency and bandwidth would be easy. Doing a spectral analysis of the knock waveform would yield ballpark numbers and one could incorporate pots to fine tune the response. I'm an old analog guy; I know microprocessors can do magic, but I like op-amps and other ICs. You know, real circuits, not coding.

Some light reading: https://www.electronics-tutorials.ws/filter/filter_7.html

 

[old round fart]

I plan on using Fitech injection and they offer knock detection and timing control with a 2 wire distributer. All it takes is money! Lol

 

[Indycars]

I know you are made of many things, including bull shit, but I didn't know money was one of them !!!

 

[fletcherson]

It would be a cool addition to a timing computer. Wonder if or why msd has or hasn’t marketed one... I battled it in a stroker build years back, I would have welcomed such an enhancement if affordable.

 

[T-Test]

It all boils down to common sense in the Hot Rod world that is tried and proven. Anything that is new will have its own problems being sorted out and cost money to get it right for EACH engine that is out there or which ever they choose to do it for. R&D aint cheap.

If you hear a knock then you need to track it down and fix the source of the knock which could be timing or pistons or rods. If you can't hear a knock, get hearing aids or it will show its' self when it goes boom.