Stand-alone knock sensor?

[Matt@RFR]

I need to put a knock sensor on a motor that has no computer. All it will do is activate a light on the dashboard. Anybody know what sensor would be best? Is there a universal unit, or do I have to order one for some random car and adapt it? Are there different (adjustable?) sensitivity specs?

The engine dyno I used to work with had what I'm talking about...just a porcelin looking thing that bolted basically anywhere on the motor, and it activated a 12V light in the booth. We usually bolted it to the manifold using a manifold bolt.

[Hammered]

MSD sells one.

[Matt@RFR]

This thing? (http://www.msdignition.com/tool_8.htm)

There's no way in hell that ugly box is going on this dash.

I just want to activate a small red light. No buzzers, no timing control, just a light.

[MrForce]

Try J & S electronics. A lot of Dyno cells use these.


http://www.jandssafeguard.com/

[Fuelie Fan]

That seems like a solid product, but probably a little overkill for Matt's needs? I'm assuming this is for a small black chevy? If so, I would pull a knock sensor and module (they're usually paired) from a donor vehicle (87-95 ish), and get a buddy who is sharp with electronics to rig up a 555 timer or somethin like that to take the module output and control an LED. I don't think you can use the module's output directly to drive a bulb (too much current) or to drive an LED (I'm guessing it would flicker on and off so fast you may not notice it), which is why the timer would be used to extend the duration. Never tried it myself, but it was something i pondered a while back.

To answer your more general questions, different engines have different natural frequencies. At first, manufacturers were installing knock sensors whose sensing frequencies were matched to the engine, which is why I stipulated the small block chevy, with matching sensor and module. Nowadays, most uses what's called a flat response sensor. These sensors respond basically the same over a very wide range of frequency inputs (mV/g level is nearly constant), and the manufacturers rely instead on the processing power of the ECU to sort out the knock from the noise. Usually, it requires some sort engine phasing input, so that the ecu only samples the knock sensor when the cylinder is near TDC, which makes the burden a little more managable.

[Matt@RFR]

Thanks guys. This is for a blown early hemi.

Well, unless somebody wants to sponsor their time to do this for me, It's not gonna happen. I don't know anybody who knows electronics, and I dont have the time to learn. No biggie...it's not worth the trouble on this car.

[paul67]

What about fitting it into the glove box , then buying some fiber optic cable , drill some small holes in a plate cover over the front of the panel then run the cables to were you want them drill small holes and fit , if you cannot find cable by itself try buying a light and dismantle the cables, just thought , they did something like this on the early vettes to show if the rear bulbs had gone