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knock sensor on an N42 block


rossman

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My turbo engine uses an N42 block. I want to install a J&S Vampire Knock Control but this block doesn't have a sensor boss like the F54. I am trying to figure out where to locate the sensor. It's a Bosch sensor with an M8 thru hole. The sensor came with a stud that has an M10 x 1.25 on one end and an M8 x 1.0 on the other. The M10 part of the stud is about .63" long. I would like to us the stud but I don't think it's necessary. I emailed J&S a while back but they are unresponsive. So what I would like to know if anybody here has drilled a knock sensor hole on a not turbo L6 block and where they located it. Right now I see two options. The first option and probably the safest is to drill out one of the heater hose mounting boss' to M8 and install the knock sensor on that. This is where I plan to mount a Ron Tyler LS1 coil bracket. I suppose I could just get a stud long enough and mount both to the same hole. I don't know if this would have a negative impact on the sensor. The second option is to locate the senor on the serial number boss right were L28 is written. I have no idea how much material there is behind that boss. Drilling out an M10 hole with full threads .63" deep might punch into the water jacket or something else. Here is a picture of the side of the engine. The red circle is the first option the green dot is the second option. Right now I'm leaning towards the first option but I'd like to hear some options either way.

 

knock_sensor.jpg

 

Cheers,

Ross

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I had my sensor in exactly the same position as Big Phil. It was even the same (factory) sensor. :D

 

The only potential problem I see with this position is its proximity to the head. There's a lot of 'noise' up there, it could create some problems with actual knock detection. The factory positions its sensor much lower. Valve train noise would be dampened down there, the software able to filter out these 'other' noises much more effectively.

 

Having said that, the upper position worked well enough for my aftermarket 'Link' knock sensor. All I had to do was turn down the sensitivity so that the knock lights didn't flash up all the time (and I knew the engine wasn't knocking). Therefore, was it able to detect light engine knocking??......probably not.

 

The advantage of using a stock sensor in a stock (or stockish) position.....they're calibrated and 'designed' to work there. Anywhere else is a compromise IMO.

 

Cheers.

factory knock sensor_thumb.jpg

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I think ozconnection is right about valve train noise. The head gasket should provide some damping. In my case I am running a MLS gasket so the damping may be minimal. I'm thinking I may mount the senor down low on the upper part of the block's skirt or near the transmission mount. Regardless I'm going to try it out on a junk block to veryify that I don't drill into anything important on my rebuilt engine.:-P

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