DIY knock ears

Make your own cheap and easy electronic system to listen to what the engine is doing.

[@Kj16V]

I "upgraded" mine by swapping the microphone with a piezo transponder. It's a lot more robust than the microphone and you can clip it to hot parts of the engine. Whenever I listen for knock while tuning, I always end up having to clip the sensor to an exhaust manifold bolt. Piezo transponders can withstand the heat much longer.

[@maxthemadtuner]

I am knew to understanding of piezo transponder. Doesn’t this sensor need to be sandwiched against a flat surface to work? I have some and want to try your method.

[@RulgertGhostalker]

i would think, listening for knock, the best place to clip it would be the spark plug ? .. oh wait, this is about cars ... i am a motorcycle guy, who would go for the spark plug.

[@G.J.G.P.]

Thx for the tip and instructions in how to make one. Just purchased some

[@woodzy575]

This is perfect thanks. I have a knock sensor but what is knock and what is engine noise? That's what this will help with.

[@ukulelebatz]

Indeed interessting. Hard to find advice for a good, cheap tool. Thank you!

[@JulianEdgar]

Glad it was helpful!

[@brownco_customs]

Thanks, legend!

[@Anderson_Motorsport]

Bloody awesome. Very descriptive. I'll be making a pair. Thankyou for your tips!

[@JulianEdgar]

Thanks - they work very well.

[@maxthemadtuner]

I am going to try your DIY. Thanks

[@CentreWheel]

Thanks Julian for producing this informative video. I purchased a Listen Up device on Ebay and modified it as described. I glued the microphone onto a battery clip and extended "speaker wire" to the amplifier. Sadly, I am getting significant noise from the ignition system. I do have resistor wires to the spark plugs. Did you use a shielded cable? If so, what type and did you ground the shield to the battery clip?

[@JulianEdgar]

Yes you can use shielded cable (eg 2-core microphone cable) and ground the braid at the negative terminal of the battery.

[@CentreWheel]

@@JulianEdgar Thanks for the tip regarding shielded cable. Found some in my wire collection and wired it in. Less ignition noise now. The Listen Up mike and amplifier is very sensitive to small mechanical noises. 😀

[@alundrasrt]

Hi, 2 wires for the mic, how do you solder the wire to the clamp, please?

[@chillycheeese]

You don't. You just glue it to the clamp.

[@A-TeamRacingZA]

is it possible to connect knock sensor directly to microphone audio jack . and record then put recoreded audio data in a spectogram to find the frequency of the knock.

[@JulianEdgar]

A knock sensor is normally tuned to a specific frequency - that of knock on the engine to which it is fitted. Therefore, if used on another engine, it's not a good way of sensing what the knock frequency of that other engine is. Instead you could use a normal microphone and then do an FFT frequency analysis to find the knock frequency - but of course the engine has to be knocking. Alternatively, the likely knock frequency can be calculated from the cylinder dimensions.

[@rickjames3034]

Have you tried connecting it directly to the engines knock sensor?

[@JulianEdgar]

No, I always want the engine knock sensor working with the engine management.

[@RulgertGhostalker]

if the book explains how to figure out at what rpm the exhaust valves start opening before the charge finishes burning, i will buy it... ( thank you for observing the factory rev limit ) it would be nice to know where you can set your rev limit when you are done. ( if it is lower than ring fpm max ) and with today's metallurgy, it usually is lower. *I Just Thought Of The Answer, the power curve flat lines, when the valves start opening before the charge has finished burning* so write a book on how to stop people from running their engines past that point... because to do that, they are using extra fuel just to blow the flames off, and quench, their exhaust valves with that flammable substance .... *MAYBE SOMEONE SHOULD CALL THE EPA, AND EXPLAIN TO THEM THAT EMISSION DO NOT JUST OCCUR AT IDLE !!!!!!!!!!*

[@steveo3002]

intresting thanks