Knock sensor locations for a 3.2

[kamaro]

I have decided to play/experiment with adding a knock sensor circuit to my turbo'ed 3.2 using the Megasquirt ECU, I can't seem to find a good location for the sensors, for the guys who did that, where did you put the sensors? .. I know Clewett Engineering has a nice 993 style knock sensor bar, but a) its expensive. b) it needs to have the heads drilled/tapped in a very tough to reach location and using a small angle drill! .. How about having them installed underside the engine? near the return tubes? .. let me hear what the experts would do.

[flightlead404]

There are two options that I'm aware of. In the later cars I think there's a sort of a bridge between each cylinder head in a bank. There's also a boss on the upper front of the engine case towards the RHS if I recall that is used by a lot of folks (myself included).

There are a few other locations people have tried, I would do a search here or using google site:forums.pelicanparts.com

[KSira]

Mine are mounted on the intake manifold. My engine have a 3.2 Intake manifold and should be similar to yours. I'll snap a picture if yor're interested.

[kamaro]

Originally Posted by flightlead404

There are two options that I'm aware of. In the later cars I think there's a sort of a bridge between each cylinder head in a bank. There's also a boss on the upper front of the engine case towards the RHS if I recall that is used by a lot of folks (myself included).

There are a few other locations people have tried, I would do a search here or using google site:forums.pelicanparts.com

If I ever get my engine apart for a future rebuild I would certainly drill my heads to accept the 993 style knock sensors mounts, I think this is the best location for them but it needs to take all of the upper engine components apart.

[kamaro]

Originally Posted by KSira

Mine are mounted on the intake manifold. My engine have a 3.2 Intake manifold and should be similar to yours. I'll snap a picture if yor're interested.

That looks like a very good location for my situation, please post some pictures for it. thanks!

[dannobee]

The later cars have a bridge that bolts to the BASE of the cylinders, NOT at the heads. Just because everyone puts them on the cylinder heads does not make it right. The sensor(s) will pick up a lot of valve train noise.

Mounting it off of the stud that supports the throttle bracket is probably the best way to mount it, but even that needs the boss trimmed flush, otherwise the sensor won't sit flush on the case.

[stownsen914]

There've been a few threads on this with varying opinions on the best location. Here's one thread:

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/803651-knock-sensor-location-ideas.html

[kamaro]

Thanks guys for all the info .. I spent all the last night taking off the intake and I have put the sensor on the engine block using the throttle bracket stud. Hopefully it will be able to catch any detonation once it happens. Has anyone tried to weld on a bung on the engine case to accept the knock sensor? like putting a bung on each side of the engine block? .. that would be great.

[KSira]

Her's a picture of where my knock sensors are mounted. Picture is from left side. Right side is similar.

[kamaro]

I never thought of that location, have you been able to detect any knock successfully?, isnt that too close to the valve train noise?

Originally Posted by KSira

Her's a picture of where my knock sensors are mounted. Picture is from left side. Right side is similar.

[Dr J]

When mounting a knock sensor, it is best to avoid connecting to parts that are separated from the case or cylinder by gaskets. For our cars, the knock frequency is in the 6kHz range and intervening gaskets act as mechanical low-pass filters that diminish these higher frequency vibrations. So, even if you mount on something connected to the case, avoid parts that have gaskets in the connection path.

[KSira]

Originally Posted by kamaro

I never thought of that location, have you been able to detect any knock successfully?, isnt that too close to the valve train noise?

It works very well according to my tuner. The location is not ideal, but I use a life racing ecu that has very advanced knock detection. If I end up pulling my engine at some point I'd probably install the oem Porsche knock bridge, but this will do for now.

[philip j]

Here is the reading we recorded on the dyno of the Bosch knock sensor during my tuning session...

[kamaro]

That looks like a well working knock sensor/s , where did you put them?

Originally Posted by philip j

Here is the reading we recorded on the dyno of the Bosch knock sensor during my tuning session...

[philip j]

Originally Posted by kamaro

That looks like a well working knock sensor/s , where did you put them?

On the block to the right of the oil vent chimney... in the factory taping.
just 1 sensor...

[KSira]

There is not much information out there on how the different brands implements knock control. For those of you who want to geek out a little, Pectel has made a document on how their knock control is (was?) working. Quite complex stuff

https://manualzz.com/doc/11660996/a-pdf-on-pectel-knock-control-strategy

[matthepcat]

My engine builder is using LS knock sensors. See if I can find a picture.

[Ken911]

I got the 993 knock sensor bars and tapped the heads.

[Dr J]

Here is how I did it in situ. It was not trivial.

http://forums.pelicanparts.com/9687362-post18.html