Spark Plugs and knock sensors all in one!!!

[98spydert]

Here's a long shot... Has anyone come across spark plugs that have intgrated in-cylinder pressure transducers to detect the steep pressure spikes of actual detonation? I've never actually seen them for sale but I'm most likely been looking in the wrong places.

 

[autronicDSM]

There is but they cost over $1000. They're mostly used by OEM for R&D.

 

[98spydert]

I know "there is", I was asking where to find them if they're even available to the regular jo schmo.

 

[autronicDSM]

I know "there is", I was asking where to find them

No you didn't. You asked if anybody came across these.

 

[98spydert]

Ok then, what manufacture's web site did you come across?

I didn't just make up a part and ask if anyones ever heard of one smartass.

 

[98spydert]

Forget I posted that, just don't reply. Thank you anyways.

 

[kpt4321]

Keep in mind that these are NOT "knock sensors." They are pressure sensors, and you could design a system which would act as a knock sensor based on the signal of these. However, the design of a system like that would be VERY difficult, not something you'd do in your spare time.

 

[98spydert]

Keep in mind that these are NOT "knock sensors." They are pressure sensors, and you could design a system which would act as a knock sensor based on the signal of these. However, the design of a system like that would be VERY difficult, not something you'd do in your spare time.

The word "duh" comes to mind But thanks Kyle

 

[kpt4321]

Well, you were calling them knock sensors, even though they are not. The fact that you used improper terminology made me feel like you might not know what you are getting yourself into.

What are you going to use them for?

 

[LightningGSX]

Since "knock" is a pressure wave, and pressure transducers sense "pressure", how couldn't they be called "knock sensors"? They fit the definition better than the piezo microphones everyone calls "Knock sensors". Using them is actually quite simple, if your peak cylinder pressure comes before TDC, chances are you are knocking or you could just monitor the pressure slope, a steep slope vs a smooth slope would indicate knock.

 

[98spydert]

Well, you were calling them knock sensors, even though they are not. The fact that you used improper terminology made me feel like you might not know what you are getting yourself into.

Since "knock" is a pressure wave, and pressure transducers sense "pressure", how couldn't they be called "knock sensors"? They fit the definition better than the piezo microphones everyone calls "Knock sensors".

Sorry, I couldn't go into in an in depth definetion for a title.

Using them is actually quite simple, if your peak cylinder pressure comes before TDC, chances are you are knocking or you could just monitor the pressure slope, a steep slope vs a smooth slope would indicate knock.

Correction, knock causes huge pressure spikes and that is what they are used to detect. ex, if normal in cyclinder pressure is 900 psi, look for a spike of something like 2200psi.

I just wanted to read more about them and see them first hand. So far they're way too pricey for a Joe Schmo enthusiest anyways.

 

[LightningGSX]

Correction, knock causes huge pressure spikes and that is what they are used to detect. ex, if normal in cyclinder pressure is 900 psi, look for a spike of something like 2200psi.

Actually most, if not all, fuel management systems capable of using in-cylinder pressure sensors, monitor the pressure slope.Typically 8-10 Bars per CA Degree pressure increase, indicates knock.

 

[talont3t4]

The cost of the sensors is minnor in comparison to the price of high speed data system needed to monitor the signal!

 

[LightningGSX]

The cost of the sensors is minnor in comparison to the price of high speed data system needed to monitor the signal!

High speed ADCs are very common and very cheap these days, name brand processors with ADC peripherals capable of greater than a half million samples per second, are around $15.The supposed high price, is just hype from automotive electronics companies to justify their extreme profit margins.