Twin_Turbo's knock sensor box

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Apr 18, 2006 | 09:47 AM

mdj21

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Racer

Joined: Mar 2005

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From: Jacksonville FL

Twin_Turbo's knock sensor box

does anybody know where i can find the components to build this knock sensor that Twin_Turbo describes here:

http://forums.corvetteforum.com/show...t=knock+sensor

i was leaning towards the first one because it sounds like it would be easier to do.

i checked NAPA for sensors for 82 corvette and came up blank.

is there some other name that these parts go by other than "knock"?

thanks,

Mike.

Apr 18, 2006 | 10:05 AM

mdj21

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Racer

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From: Jacksonville FL

stupid eyes.....

picked chevette in stead of corvette.....

wow, $100 for a detonation sensor. maybe i should get one from the junk yards. is a detonation sensor something that is likely to be bad on a junker vette?

what about the ESC module? still can't find one of those.

Apr 18, 2006 | 10:06 AM

comp

Team Owner

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From: eville in

Hmmmmmm

Apr 18, 2006 | 10:23 AM

Twin_Turbo

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ESC module: yours for only 7.99$!!!!
http://cgi.ebay.com/ebaymotors/85-92...QQcmdZViewItem

These are the nicest ones to use as you can just use the female plug and cut the wires you don't need or just use some amp connectors, the earlier ones have edge card connectors requiring the use of the edge card connector or soldering.

these are also from a roller motor which means they have an ignore circuit for those kinds of noises, stick a roller or a gear drive in an engine equipped w/ the early ESC and it may go berserk.

Apr 18, 2006 | 10:30 AM

Twin_Turbo

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oh, the knock sensor..100$ wow!
Get the one w/ this type of connector, not the earlier w/ a little metal pin/tube that sticks out and uses a rubber block connector w/ metal retainer clip.

http://cgi.ebay.com/ebaymotors/TBI-T...QQcmdZViewItem

and use this type of sensor:

http://cgi.ebay.com/ebaymotors/85-89...QQcmdZViewItem

Apr 18, 2006 | 10:40 AM

mdj21

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Racer

Joined: Mar 2005

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From: Jacksonville FL

aahhhhhh.... ebay.... i should have thought of that.....

so it's also called a spark module?

is that the detonation sensor mounted low on the block between the 2nd and 3rd main bearings?

is that typically where they are mounted?

is getting this sensor from a junk yard a good idea? not too thrilled with paying NAPA $100 for one. or is ebay a better choice than junk yard...

Last edited by mdj21; Apr 18, 2006 at 12:03 PM.

Apr 18, 2006 | 10:46 AM

Twin_Turbo

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yea it's the same but be aware that the module in the hei distributor is not the same deal

Yea the sensor is usually mounted in one of the block drain holes, they don't go bad very often so one you get from the junkyard should be fine

Apr 18, 2006 | 10:56 AM

JoeRags

Melting Slicks

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From: Meriden CT

interesting....

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Apr 18, 2006 | 11:20 AM

stickboy

Safety Car

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From: York PA

I bought a sensor/harness from Accel. Looks like I overpaid

and on top of that I had to cut of the plug that was supposed to connect to Accel's DFI harness because they had two different style connectors

Apr 18, 2006 | 11:22 AM

#10

mdj21

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Racer

Joined: Mar 2005

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From: Jacksonville FL

Thanks, Twin Turbo.

i've got side pipes and the glass packs are pretty shot so she is plenty loud

i want to set up my timing as Lars describes in his paper, but got nervious about being able to hear the detonation over my pipes when i read that other thread about being able to hear it or not.

is that firebird ESC module going to have the same pin-out you described previously or am i going to have to hunt down that information elsewhere?

this is starting to look more like a project i can afford. call it cheap insurance.

thanks again,

Mike.

Last edited by mdj21; Apr 18, 2006 at 11:50 AM.

Apr 18, 2006 | 01:24 PM

#11

mdj21

Thread Starter

Racer

Joined: Mar 2005

Posts: 487

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From: Jacksonville FL

last question....

are any of these sensors going to work or should i just try to pull one from an early 80's vette?

http://cgi.ebay.com/ebaymotors/85-89...56238002QQrdZ1

http://cgi.ebay.com/ebaymotors/96-Co...56455623QQrdZ1

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

thanks,

Mike.

Apr 18, 2006 | 01:50 PM

#12

Twin_Turbo

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The difference is the sensing frequency, much like a tuning fork. They have a little piëzo-electric crystal that produces a tiny voltage (<1 V) when in "tune" with the sensing frequency. It's nothing more than a microphone. So, get a sensor from an engine that is as close to what you're using as possible. The detonation may travel through a V6 casting in a different frequency than in a V8, so an L98 or LT1 should work. I wouldn't use the V6 one.

Last edited by Twin_Turbo; Apr 18, 2006 at 04:23 PM.

Apr 18, 2006 | 02:05 PM

#13

mdj21

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Racer

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From: Jacksonville FL

thanks again....

Apr 18, 2006 | 04:17 PM

#14

69427

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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.

Quote:

Originally Posted by Twin_Turbo

these are also from a roller motor which means they have an ignore circuit for those kinds of noises, stick a roller or a gear drive in an engine equipped w/ the early ESC and it may go berserk.

The plastic housing (Half Function ESC) modules like pictured above are the way to go if you want to do some spark curve/knock intensity monitoring. Please be advised that they come in many calibrations and center frequencies. I don't know the calibration details of the module above, but if you're on your own in a junk yard try to find one off an early to mid 80's SBC, as they are more likely to be calibrated (filter/freq response) for an engine similar to yours. You also ought to be able to find a sensor off a junk vehicle if you look around. The lower frequency sensors had a light blue (anodizing?) color around the connector plastic end. Also measure the resistance from the connector to the threads. It should be around 100kOhms. Later sensors generally have a 4kOhm resistor inside it. You don't really want to have to use those sensors with the older modules. The lower resistance will kill most of the signal, and you'll possibly need some reasonably heavy knock to trigger the filtering in the module.
Good luck, and keep asking questions if you run into problems.

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