well... i got mine off ebay for 300$:D


if its not worth it to you... its not... i guess you can just dial the timing back far enough that you think it will work for all conditions.

yes... there is nothing wrong with geting it right the 1st time! but with this you can set it closer to the threshold(more power)... and if it happens to reach that it will dial it back to right on that threshold..

Another good reason to start w/ a 3.6!

This is what the knock sensor and bridge on my engine look like
http://forums.pelicanparts.com/uploa...1107557018.jpg

It is cylinder selective.

very hot bill! but i wonder where i can put one on a 3L...

I went back and added the smiley I forgot, the joke looses something in the translation without it.

I will say one thing:
if you have a 3 liter 911 engine and you need a knock sensor, something is seriously wrong with either your engine or your timing light.

My 3 liter Carrera engine ran great on regular leaded but pinged like crazy on regular unleaded. Had to run 91 unleaded to stop that.

Bill, you indicate the sensor (s) on the 3.6 is cylinder selective. Is there a sensor at each mounting bolt for that bar? It looks to me like one sensor with a simple bar to allow better transmittal of the noise (i.e. the noise travels better through that bar, than across through the case or heads.

My 930 is a testimony to the effectiveness of the J&S unit.

After years of agressive timing and boost my ringlands, pistons and cylinders were in great shape.

I would keep using it but my new EFI has integrated knock control.

If someone wants to buy it I am willing to sell it for $300 plus shipping to anyone who is looking to avoid the hassle of e-bay.

:D

I don't know if it is cylinder selective but it is certainly possible to know which cylinder is pinging using a shared sensor. The computer/DME "knows" which cylinder is firing and when a cylinder could be expected to knock.
-Chris

"Bill, you indicate the sensor (s) on the 3.6 is cylinder selective." - Souk -

The knock sensor on a 964 is NOT selective. It's thru the use of the Hall sensor
(TDC compression stroke) that the DME knows which cylinder is knocking.
The DME with a distributor ignition never knows which cylinder is firing
without cam position info.

"but it is certainly possible to know which cylinder is pinging using a shared sensor"
- ChrisBennet -

Not true! Basically, all knock sensors will "hear" the pinging but at different levels,
i.e. since they are all mounted on the basic same structure/plane even though
they are mounted at different locations. Multiple sensors are used for better knock sensitivity.

Alright, so with what Loren has posted, I take it that the 3.6 is smart enough to determine which cylinder is pinging, even with one sensor per side using a bridge tying a (left and right) bank of cylinders together to that one sensor. The system uses one sensor per bank/side of the engine, and knowing which cylinder is near TDC the algorithm can then assign the pinging to a cylinder since no two cylinder in each bank is fired or at (near) TDC concurrently.

Loren-speak translate to Souk-speak...is y'all confused yet? :)

But Loren, a 964 does have a crank sensor so it does know which cylinder is firing. That's how it's able to have sequential fuel injection.

Why is it not true/not possible? It's normal for engine management systems with individual cylinder knock control to use shared sensors. (ME 7.1.1 Motronic uses only 3 knock sensors for 8 cylinders on the Audi RS6 for example.)
-Chris

No, there is one sensor/side conected by the bridge to the 3 cylinders. the signal is sent to the DME where it is integrated w/ the signals from the Hall sensor in the distributors(yes 964 has them) which determines which cylinder had the issue, that cyl will be momentarily retarded(selective knock control).

Loren, I am sure that you know your business but the 964 does have the hall sensor component and all the literature I have indictes that it is cylinder selective.

"But Loren, a 964 does have a crank sensor so it does know which cylinder is firing. That's how it's able to have sequential fuel injection." - ChrisBennet -

No, the crank sensor on the 964/993 only determines TDC and NOT which stroke
(exhaust/compression) each of the two cylinders is on. You need cam info
provided by the Hall sensor on the 964/993. When the Hall sensor fails,
the 964/993 DME runs like a 3.2 DME (no SFI or selective retard).

"Loren, I am sure that you know your business but the 964 does have the hall sensor component and all the literature I have indictes that it is cylinder selective."

- Bill Verburg -

I didn't imply that the 964 doesn't have a CMP (Hall sensor). I just said that you
need one, which the 964 does have, to determine which cylinder is firing and
for sequential injection.

"I take it that the 3.6 is smart enough to determine which cylinder is pinging, even with one sensor per side using a bridge tying a (left and right) bank of cylinders together to that one sensor." - Souk -

Yes, and based on this, the 964/993 can individually retard the pinging cylinder by
3 degree increments.

I meant to say cam position sensor not crank sensor but after it's all said and done the 964 uses shared knock sensors and the ability to individually retard ignition on a cylinder by cylinder basis.
Just like I said:
-Chris

Excellent discussin gents! I think we are all on the same page now right?

All any system needs to know is now many cylinders it has to provide cylinder specific retardation.

"All any system needs to know is now many cylinders it has to provide cylinder specific retardation."

?????

I am saying you don't need a crank trigger for a system that listens to knock to determine which cylinder is knocking.

It may not know if its cylinder 1 or 5, but it will know which cylinder in its firing sequence is knocking and can time accordingly.

"i have 6 events to take a look at acording to what a user set.... and shortly after the ignition this time i heard a knock... so im going to wait till i notice the next 5 events then when the sixth event is going to happen i will delay the ignition for X millisecconds and then check for knocking....*knock* oh crap, in 5 events i know i will need to delay it X+1 millisecconds...."

that is all thats going through its little purple brian... it dosent need a halleffect or a cam anyhting....

"I am saying you don't need a crank trigger for a system that listens to knock to determine which cylinder is knocking."

That's correct. But you still need a reference point if selective retarding is
implemented reliably or you have PERFECT system which doesn't lose track
of its' timing position in multiple revolutions, e.g. electrical noise, power supply loss,
or fault/random knock signals. In any case, you still need some type of engine
timing input signal to count/time for the next spark retard. You just can't
wait X milliseconds because of the varying RPMs.

The Hall sensor is used for SFI with a distubutor system and determines for the
DME which knock sensor it should "listen" to in a 964/993 system. A standalone
distributor ignition system doesn't need to know the absolute location of the pinging,
only it's relationship to a reference point in the engine cycle. This is contrary to
distributorless ignition system as used in the 996 with individual coils which does
need a CMP.