Build a Knock Detector

Indycars

Indycars

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Staff member
mathd said:
Rick
About the detonation can, i use the MSD knock alert, i think its discontinued.(i can design a electrical circuit for that if that's necessary, i can also have PCB made for us from the factory and do the assembly too. We can also add a micro controller( and some lcd or bluetooth app to run on your phone too ;))
Click to expand...

What kind of circuit would we need, when you say Design a electrical circuit? Would this be the amplifier?

What kind of microphone will we need, will it have to be like the link below?

https://www.summitracing.com/parts/cei-102010

PCB from the factory??? You mean a copy of the MSD Knock Alert?

What function would the micro controller perform?

Interesting, again what would we control with the phone, ignition timing?

Will it have a filter so we can tune each one according to the needs of each engine?

I'll pay for the parts since you are doing the majority of the work, except the microphone if it's
going to be $80 some dollars.

mathd said:
You should try to avoid that 14.7:1 air fuel ratio since this is a carb equipped RACE engine, you should move away from "good" gas mileage a little bit.
Lean plenum charge will cause detonation off the line(i had that problem when i tuned my engine, it did show on the knock alert even before boost kicked in and could not be tuned out with the accl. pump.) Probably because the blower cause a BIG plenum charge vs a NA motor but just saying.
Click to expand...

I did back off some with the bigger main jets, but I'm not that low at 14.7 AFR if I remember
correctly. Maybe the carburetor can be tuned better to richen up on light throttle application.
 
The Problem with building your own knock sensor detecting circuit is that there is no way to easily discriminate Exhaust Primary Header tube noise.

On the The C4 Corvettes the Knock Sensor circuit has to be shut down Tuned Out once Headers are installed.
Otherwise the Engine goes into Knock Retard all the time. Pulls ignition timing back 30 degrees and stays there.
Its in the Corvette Forum Archives 2001-2009.

On my 87 Corvette with the Hood Open and engine running I can make the engine Hiccup pull back timing by just tapping the Upper TPI Plenum or Runner tubes with a plastic screwdriver handle.
The knock sensor is mounted down next to the starter motor passenger side in the block.
Gives you an idea how sensitive they are .
 
Knock sensors are shut off on modern EFI Cars Modded for High HP too.
I worked in a Race shop with an AWD Mustang Chassis Dyno.
3 guys doing EFI tuning.
I built the Race engines.
 
The Engineers that built the factory Knock sensor detection system must have Oscilloscope analyzed all unusual & and unusual engine noises.
Snap Shotted.
Designed the Noise discrimination circuits & Logic controls.
 
Roller Rockers installed on a C4 Corvette makes it go into Knock retard also.
An EFI Tuning Master I used to hang with on Corvette Forum Taught me that.
You actually lose 50-100 HP instant.

Dave & Me were the only to use Stock Rockers.
We both knew.
 
You will Find Grumpy in the Corvette Forum archives.
Me too.
Grumpy was always talking about Racing back then.
 
Indycars said:
What kind of circuit would we need, when you say Design a electrical circuit? Would this be the amplifier?

What kind of microphone will we need, will it have to be like the link below?

https://www.summitracing.com/parts/cei-102010

PCB from the factory??? You mean a copy of the MSD Knock Alert?

What function would the micro controller perform?

Interesting, again what would we control with the phone, ignition timing?

Will it have a filter so we can tune each one according to the needs of each engine?

I'll pay for the parts since you are doing the majority of the work, except the microphone if it's
going to be $80 some dollars.



I did back off some with the bigger main jets, but I'm not that low at 14.7 AFR if I remember
correctly. Maybe the carburetor can be tuned better to richen up on light throttle application.
Click to expand...

Well, i can design a complete circuit on my own from zero or do a plain copy of the MSD unit(easier option).
I was thinking of a knock sensor like that:
https://www.summitracing.com/int/parts/smp-ks7/overview/make/chevrolet

PCB from factory. By that i mean i can design a working electrical circuit(schematic) and draw the PCB(printed circuit board) with my computer and send the CAD files to have my own PCB made from the factory vs homemade(better quality/repeatability of course)

I can add a microcontroller to add any function that we find usefull(kinda like the megasqirt DIY efi controller)
I did not study the MSD circuit yet but yes am pretty sure we can tune to a specific frequency(probably using the microncontroller and save that into memory and make it programmable over USB i can make a C# windows app for that, or make it programmable over phone/bluetooth). I can do just everything the only limit is how much time i spend into it.
Well all this is not necessary, but i think it's great since you are not adding more screen/buttons/wiring to the dash this way(and it has the cool factor).
 
mathd said:
Well, i can design a complete circuit on my own from zero or do a plain copy of the MSD unit(easier option).
I was thinking of a knock sensor like that:
https://www.summitracing.com/int/parts/smp-ks7/overview/make/chevrolet

PCB from factory. By that i mean i can design a working electrical circuit(schematic) and draw the PCB(printed circuit board) with my computer and send the CAD files to have my own PCB made from the factory vs homemade(better quality/repeatability of course)

I can add a microcontroller to add any function that we find usefull(kinda like the megasqirt DIY efi controller)
I did not study the MSD circuit yet but yes am pretty sure we can tune to a specific frequency(probably using the microncontroller and save that into memory and make it programmable over USB i can make a C# windows app for that, or make it programmable over phone/bluetooth). I can do just everything the only limit is how much time i spend into it.
Well all this is not necessary, but i think it's great since you are not adding more screen/buttons/wiring to the dash this way(and it has the cool factor).
Click to expand...
You Have to Make Rick's T-Bucket Engine Knock intentional.
Light knock to Severe.
Screen Oscilloscope Snap Shot. Save the Data.

Not sure how much more Abuse The Dart SHP 400 Brodix 200 cc intake runner engine can take.
 
Maniacmechanic1 said:
You Have to Make Rick's T-Bucket Engine Knock intentional.
Light knock to Severe.
Screen Oscilloscope Snap Shot. Save the Data.

Not sure how much more Abuse The Dart SHP 400 Brodix 200 cc intake runner engine can take.
Click to expand...
We could use a spectrum analyzer then program a microcontroller to use FFT(Fourier Transform) then select that pacticular tone/note the engine make.
Then we need to intentionally make the engine knock to learn/read the tone from the sensor using the (hopefully build-in)spectrum analyzer.(or make it adjustable over dash control/phone/usb and "tune" it around the "right" tone.)
This take alot of time of course, there must be other alternatives?(if not then its a good reason to make our own, am in no hurry:p)
 
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mathd said:
We could use a spectrum analyzer then program a microcontroller using FFT(Fourier Transform)to select that pacticular tone/note the engine make.
Then we need to intentionally make the engine knock to take a readin from the sensor using ths spectrum analyzer.
This is time consuming of course, there must be other alternatives to the MSD knock alert?(if not then its a good reason to make one :p)
Click to expand...
The J& S knock detection safeguard unit I put up on my little website & Mike & others know about posted same similar is likely the Best.
They are mentioned being used in Vintage Car Craft & Hotrod magazine tests from the late 1990's.
Guys like Kenny Dutwiller & His Boosted Engines Tuned to the Max for Pump Gasoline Performance.

Need $. Age old problem as you know also.
If I recall right the J&S is around $800.00.

It would be easier & cost less to start off Tuning on Pure untainted 110 Race Gasoline.
Buy 10 gallons.
Then Mix with Pump gas in different ratio blends.
Keep Tuning till your able to run on 91- 93 octane with no detonation.

A Big Key is stable Coolant temps .
'The water temp gauge does not detect internal Hot spots or steam pockets inside of an engine.
The Olds 425 V8 I have been playing with the last few years is a Bitch to keep Cool, very good for trapped hidden steam pockets in the cylinder heads like a SBC.
The New Griffin Pro Series Radiator Solved.
Able to drive on 87 octane now here.
So far tested 28-50 F outside air temps.
 
Stable cooling and stable conditions make tuning easier. I believe all cylinders spark need to be mapped using timing light at differ rpm other wise you are just relying on info in packet with your timing. Other thing is you change fuel or timing you need to match the other as it changes burn speed in the cylinder. Lean mix burns quick hence if you did not change your curve yo might be detonating. Good fuel elliminates knock due to compression. Allows you to elliminate one source. Like this guy I who' forum I frequent says. You need to do a thought out method of trouble shooting. Rely on facts only change one thing at a time.
 
mathd said:
We could use a spectrum analyzer then program a microcontroller to use FFT(Fourier Transform) then select that pacticular tone/note the engine make.
Then we need to intentionally make the engine knock to learn/read the tone from the sensor using the (hopefully build-in)spectrum analyzer.(or make it adjustable over dash control/phone/usb and "tune" it around the "right" tone.)
This take alot of time of course, there must be other alternatives?(if not then its a good reason to make our own, am in no hurry:p)
Click to expand...

Any idea where a estimate in your head might end up? If it's going to be north of several hundred
dollars just for the major parts, then it might make sense to buy one.
 
mathd said:
Well, i can design a complete circuit on my own from zero or do a plain copy of the MSD unit(easier option).
I was thinking of a knock sensor like that:
https://www.summitracing.com/int/parts/smp-ks7/overview/make/chevrolet
Click to expand...
Seems we should save time where we can, this is already looking like a major project. Are you
sure about tackling this, are you going to have time. Maybe down the road you could sell some.

What kind of thread (pipe, English or Metric) is that on the Summit sensor, where will it attach
to the block?

mathd said:
PCB from factory. By that i mean i can design a working electrical circuit(schematic) and draw the PCB(printed circuit board) with my computer and send the CAD files to have my own PCB made from the factory vs homemade(better quality/repeatability of course)
Click to expand...
Could you bread board the first one or too complex for that?

mathd said:
I can add a microcontroller to add any function that we find usefull(kinda like the megasqirt DIY efi controller)
Click to expand...
Would it be able to control the timing while retaining the MSD distributor I have now?

mathd said:
I did not study the MSD circuit yet but yes am pretty sure we can tune to a specific frequency(probably using the microncontroller and save that into memory and make it programmable over USB i can make a C# windows app for that, or make it programmable over phone/bluetooth).
Click to expand...
I like the idea of using a smart phone to make adjustments. But it still needs an idiot light so one
can confirm at any time if there is a problem.

mathd said:
Well all this is not necessary, but i think it's great since you are not adding more screen/buttons/wiring to the dash this way(and it has the cool factor).
Click to expand...
Yes space is at a premium for me to add more wiring. It would also be much easier for the average
person to add to their car with less wiring.

But I think we are getting ahead of ourselves. First thing would be to get a working model without
all the bells and whistles. At first could it have a headphone jack, then improve it from there.

Again it all depends on you and if you have time. I would be happy with just the basic function and
a headphone jack.

What do you think, take your time before answering. Or maybe you need time for some research
before answering.
 
Too much Liabilty at stake.
Wrong car and engine to experiment on.

A junkyard 350 Chevy would make a perfect test mule.

The money spent couild be used to buy an Electromotive Crank Trigger.

Johns EFI System.

Or a Vertex Mag I prefer and Love to use with a Carburator.
 
Those sensor attach to the lower coolant drain plug on the side of the block.
When i get 2 minute ill see if i can make/simulate a small circuit with as little component as possible(to bread board).
This should be under 5$ of parts.
About the ignition, on my MSD box, i can ground the white/point wire to kill the ignition, i guess it could be an option to prevent engine damage?

It will monitor a single frequency (and make it adjustable between 2 and 12khz according to this article posted above: http://www.autospeed.com/cms/article.html?&A=0348).

This seem like a good option too(but not permanent(also from the link above)):
http://www.autospeed.com/cms/article.html?&A=0353
 
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