944S2 16V Turbo Build

[Thom]

Are you talking about the very faint, slightly off-rythmic rattle/tapping sound? If so then I'm not sure its related to your variocam tensioner as I've heard the same sound from both of my 8V engines. Sounds pretty normal to me

Agreed. This subtle off beat metallic tapping sound is caused by lifters and can occur on a warm engine. Definitely not caused by the chain tensioner.

[Bergerac]

Are you talking about the very faint, slightly off-rythmic rattle/tapping sound? If so then I'm not sure its related to your variocam tensioner as I've heard the same sound from both of my 8V engines. Sounds pretty normal to me

Agreed. This subtle off beat metallic tapping sound is caused by lifters and can occur on a warm engine. Definitely not caused by the chain tensioner.

Well I have been wondering if the stiffer springs were causing some lifter noise, I think someone here dismissed that early on though. It does get louder than that.

[Thom]

Any chance to hear a video that captures the louder sound then?

[Bergerac]

We went for a drive today and I had the knock headphones on for the first time, I really couldnt hear anything unusual with those and you can hear the valve train really clearly. Might try to record that through the laptop one day but I need to keep an eye on it until I get the Knock control property setup.

We tuned in the base Waste Duty cycle for 0.8bar but we started to get some light rain just as we got it dialed in, wheel spin started to become an issue so we had to stop.

80-100 in spot on 2s with 4 to 5% slip between the driven/non driven wheels Road was slightly uphill too

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[ealoken]

On my 951 engine, i had 3 bar oil pressure on hot engine.
With a ported oil pump ( intake side )

5.8 bar on 6800 rpm.

[Bergerac]

Yeah Im hitting 5.1bar just over 6000rpm.

Went upto 1.2bar today, holy cow, you can see my brown moment on the TPS graph Full boost at 4000, I keep backing off before it hits 6000rpm, I need to find a quieter straight road to really wind it out.

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[ealoken]

Yeah Im hitting 5.1bar just over 6000rpm.

Went upto 1.2bar today, holy cow, you can see my brown moment on the TPS graph Full boost at 4000, I keep backing off before it hits 6000rpm, I need to find a quieter straight road to really wind it out.

Screenshot 2026-06-20 163712.png

I think you can fiddle some more on WG duty to spool earlier.
But full beams at 4000 is reasonable

[Tom]

Great logs. Thanks for posting! I'm curious about the 13.8 btdc timing in the second run. Over the years I've dialed my full throttle timing back to almost exactly that (14 if I recall) --to keep the 8v head from blowing off -- and always thought that was below the norm in light of my higher static compression. How did you settle on 13.8?

[Bergerac]

I think you can fiddle some more on WG duty to spool earlier.
But full beams at 4000 is reasonable

There is a tiny bit in it, that was just the first pass to get the base DC right with the closed loop PID zerod out, the boost ratio is pretty much 1:1 right up until the wastegate opens then it drops to just under one for a bit until the turbo catches up again. The boost is super stable so far without much tuning but I might be able to get it down a couple hundred rpm without overshooting. From memory the turbo was originallly built for a 3.2 so it might be slightly on the large size for my engine.

Screenshot 2026-06-21 133303.png (44.22 KiB) Viewed 80 times

Great logs. Thanks for posting! I'm curious about the 13.8 btdc timing in the second run. Over the years I've dialed my full throttle timing back to almost exactly that (14 if I recall) --to keep the 8v head from blowing off -- and always thought that was below the norm in light of my higher static compression. How did you settle on 13.8?

We started out pretty conservative because were road turning (Im also running 9:1 comp ratio), the plan was to tweak the timing when we had a better idea if there was going to be knock issues but thats proving very hard to do in the higher boost range on the road with the laptop bouncing around all over the place, Im going to have to find a someone to fine tune the timing on a dyno. The other strategy now that I have the knock amplier setup on a spare knock sensor is to confirm the knock detection is working and tune the ignition of the long term knock timing trim tables, the ECU will be much better at detecting it than me.

Bas did share his ignition map for his 968 at one point as well, we had similar numbers but I was running a bit more timing in the cruising cells.