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Discussion Starter #1
I'm trying to find a good spot to mount a knock sensor on my Alfetta 2L, but I'm having trouble finding a location that doesn't require major block modifications yet will still give a decent reading from the sensor.

the sensor I'm using is a Bosch style broadband unit, which is 20mm thick and needs an 8mm stud to sit on.
Ideally it would mount towards the rear of the engine, near the top of the block (but not on the head).
About the best idea I've come up with so far is to weld a stud onto the coolant drain plug, the location isn't perfect but at least that would save having to drill and tap the block.

Has anyone got a better suggestion?
 

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Hi Festy,
I just saw this post. The answer is simple: on the 1.8T, the sensor is mounted on one of the inner lower head/manifold studs, which is longer for this purpose. No other special arrangements are needed. Just put a longer stud in and you're done! hope this helps.
Jim K.
 

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Discussion Starter #3
Thanks Jim, I'd forgotten that the 1.8T used a knock sensor.
I'd been avoiding the head because of valve noise, but if it was good enough for Alfa then the extra noise can't be too bad.

I'm running an L-Jet Spider inlet mainfold on an Alfetta head, so one of the manifold studs is already about 20mm too long - the sensor should fit straight on there.
 

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If you want to delve deeper into the workings of the 1.8T, I could send you the ignition ecu -the 1.8T has two ecu's, one analog for fuel and one digital for ignition (this one being almost the same with one used in the 164 2liter V6 Turbo).
Jim K.
 

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"Just put in a longer stud" is one of the most difficult things you can do to a Nord engine. You have to heat the block in a large oven to get any head stud out without breaking it or the block!

Robert
 

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...Ahhh, you're married to an old Alfa???? Live with it!:D You know you wouldn't have it any other way!;)
Jim K.
 

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In engines with open deck block design or with wet liners the transmission of the combustion noise/vibration to the external of the block is not direct, in these cases the one of the best option is to install the sensor near the base of the cylinder head, preferably in the middle (shorter path for external cylinders)
 

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In engines with open deck block design or with wet liners the transmission of the combustion noise/vibration to the external of the block is not direct, in these cases the one of the best option is to install the sensor near the base of the cylinder head, preferably in the middle (shorter path for external cylinders)
The open deck V6 24 valve engine used 2 knock sensors mounted in the valley between the 2 banks.
Aluminium is a good conductor of noise, so the block will transfer most of the mechanical racket throughout the aluminium structure.

Ages ago I did read about piezo electric knock sensor microphones that were installed under the spark plugs. These would probably be the best for an open deck design and you wouldn't be able to mount a sensor any closer to the combustion chamber.
 

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2 different studs?

"Just put in a longer stud" is one of the most difficult things you can do to a Nord engine. You have to heat the block in a large oven to get any head stud out without breaking it or the block!

Robert
Didn't JIM K indicate to mount it to a replaced lower inner head manifold stud .....not a head block stud which indeed are difficult to remove?
 

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Good God! :eek: Not the block/head 12mm studs! I mean the intake manifold mounting studs on the head; one of the lower studs, which are closer to the block. ...I just saw what 60's racer wrote, it didn't register back then...:oops:
Jim K.
 

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Maybe not so obvious was the notion to mount the sensor on a cooler part of the engine such as the intake manifold as opposed to an exhaust manifold stud, seems heat would be problematic and to be avoided.
 

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Discussion Starter #15
I installed the sensor on the top of my inlet manifold (L-Jet Spider).
I think the mounting hole was originally for securing the fuel rail - whatever it's for, it's not in a very good spot.
I only tested it quickly, but looks very promising.
When I induced knock at about 1200rpm, I could clearly hear it over the (unmuffled) exhaust and my knock filter appeared to respond properly - but then I had what I think was a ground loop problem between the USB port of the knock filter and the USB port of my ECU, and my laptop blue-screened :(
I'm hoping to get back to this in the next couple of days (a friend is rather keen on installing one of my filters for some dyno runs) and I'm pretty sure I know where the problem is so will report back soon ;)

But as far as Nords' valve gear being too noisy for a knock sensor - I reckon I could accurately detect heavy knock with a microphone from inside the car!

To mount the sensor in a better spot, before I mess about replacing studs I'm going to make up a long nut to screw onto the end of a stud, then install the sensor with a short bolt in the other end of the extended nut and see how the readings compare to it's current location.
 

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Discussion Starter #16
Well the problem wasn't strictly a ground loop issue, let's just call it "user error" and move on, shall we? :eek:

So once the previous problem was sorted, I hooked up a LED to the knock filter output, and with the engine off I tapped various spots on the engine with a spanner but got absolutely no response.
Resisting the urge to whack it harder, I re-checked my wiring and noticed I hadn't plugged the knock sensor back in :eek:
Once that was done, sure enough the LED flashed differently depending on where (and not how hard) I tapped.

I started up the engine, and the LED went mad so I backed the knock filter settings right off until it stopped.
With the engine idling, I increased the timing by 10* and immediately the LED started flickering away. When I set it back, the LED stayed off.

I think I'll get a cleaner signal when I move the sensor away from the injector/valve, but it looks quite usable as it is now.
 

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Nothing stopping you from tee-ing into the knock sensor signal with a small microphone and listening to it.
Adaptronic have a headphone jack and small amplifier built into their computers now for that very reason.
 

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Festy...where did you end up with this? Were you able to get a usable location and set-up for your knock sensor?
What knock sensor are you suing? Do you have a P/N for it and a opic where you mounted it?
Thanks,
Don
 
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