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Raize · Joined: 18 Sep 2013 Posts: 445 Location: Scotland

I finally got a cheap used KnockLink.

The 924 2.0 block doesn't seem to have many good locations though.

Options:

1. Sharing the bolt for the forward mount of the coolant transfer tube,
Quite low on the block away from the combustion and very hard to get my hand in there, not sure I can physically install it - can just get my fingers on the bolt at an awkward angle, would have to remove the k-Jet unit or at least the expansion tank to get better access to this.

2. Sharing one of the two upper alternator mount bolts.
[i]Fairly easy to access, but knock waves will have to transmit through aluminium of the alternator mount. Nice and high up on the block. Very close to exhaust manifold. Very difficult to route wiring (over valve cover is hideous and putting it in the alternator loom might have EM interference and is also a huge job)

3. Intake manifold lower bolts.
Not even bolted to the block, but super easy access

4. Upper engine mount bolt under the intake manifold.
Could get to this with my hand if I take the ignition coil out and maybe the breather hose. Not particularly high on the block. M10 bolt is wrong size for the sensor so I would have to replace the bolt with an M10-M8 adapter stud and use a stack of M10 nut, spacer washer, knock sensor, M8 nut

I can't see any other accessible mounting locations. Any suggestions/recommendations on which option to go with?

Raize · Joined: 18 Sep 2013 Posts: 445 Location: Scotland

Actually don't think I can use the engine mount bolt as the engine mount is a sort of stamped steel hollow part and probably won't transmit sound waves well.

Think the boss to the left of the engine mount top bolt gets covered by the engine mount when installed as well.

924RACR · Posted: Tue Feb 25, 2025 10:18 pm Post subject:

My inclination was to go to the head for mounting; I think I recall seeing that this was used for one of the 944s, the 951 or S2?

Is there any detailed instructions from the supplier on where to try to mount?
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Cedric · Joined: 27 Aug 2004 Posts: 2801 Location: Sweden

Mine sits on the unused boss under the intake, the na bracket looks a bit different though if i remember correctly. I even have two knock sensors in there nowdays, its long story

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safe · Joined: 18 Mar 2017 Posts: 698 Location: Sweden

On the dyno my tuner screwed in one on one of the unused M8 holes quite low in the middle of the block.
It worked perfectly fine for him to hear the knock or "preknock".
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

I also used one of those mounts for listening to knock when doing the tuning on my prototype cars.
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Raize · Joined: 18 Sep 2013 Posts: 445 Location: Scotland

I have installed the knock sensor on the unused mount below the intake, had to take some tubes off to get to it but it wasn't too bad. Sounds like the location is good enough.

I also added a banjo bolt on top of it with a 4mm hose coming out, which could be attached to "det cans" in the future if I wanted to explore that option without having to go back in there and add more fittings.

I am pretty sure I have audible knock going up steep hills on full throttle but this will confirm. Sounds like gently frying bacon in the exhaust note.

Raize · Joined: 18 Sep 2013 Posts: 445 Location: Scotland

I got knock at just 3 psi with 8 degrees base timing…

On the one hand probably good to know, on the other hand kinda sad because I was having fun driving it and it’ll make it slower to pull timing.

Any rough guesses how much timing I have to pull to get a knock-free 1 bar?

safe · Joined: 18 Mar 2017 Posts: 698 Location: Sweden

If I can find my 98 map ill share it.
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

Cedric · Joined: 27 Aug 2004 Posts: 2801 Location: Sweden

Raize · Joined: 18 Sep 2013 Posts: 445 Location: Scotland

safe · Joined: 18 Mar 2017 Posts: 698 Location: Sweden

Raize · Joined: 18 Sep 2013 Posts: 445 Location: Scotland

It’s 8 degrees of base timing so add on the 26 degrees of centrifugal timing for 32 degrees. I still need to check that it’s actually 26 degrees, just following the manual for now.

Considering you are running 22-25 degrees in the peak torque danger zone at my boost level, I am probably a bit too optimistic thinking I can run 32 without det.

Need to get one of those vacuum canisters that can pull timing on boost.

Cedric · Joined: 27 Aug 2004 Posts: 2801 Location: Sweden

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

I run a similar ignition map for low and mid RPM on my SC tunes like Magnus does on his 98RON turbo tune, just a lot more conservative on high RPM due to being non intercooled and i dont get knock.

The cars running just my SC kit, the base advance is 6deg BTDC like Cedric mentioned, with a properly running kjet, that does not knock with up to 0.3bar which is the max boost on the standard setup.
So if yours is knocking, you can go to 6deg base advance and see how it behaves, but most likely your fueling is bad.
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