Is this knock ?
#21
So I installed a new aftermarket TPS sensor, removed the old exhaust wrap and and stainless wire / cable ties and installed new heat sleeves and ties. Then after a bit of autotune ran these tests again with 98 euro octane fuel. I *think* I'm starting to see what actual knock looks like in the logs.
Also showed the pics of the plugs to Jan from SPS and he told me he can't see anything concerning or issues / signs of knock. vOv
So with the 98octane fuel on 26degrees spark table and a leaner top end I think those cylinder 2 spikes at lower rpm are clear knock spikes during the slightly downhill 2nd gear.
Maybe the 20-30% variation of knockin between cylinders at the topend is just general noise ? Wouldn't make much sense that 24 to 28 degree timing runs have same levels of knockin now with 98+EU/93 US fuel ?
Here's the logs for another 24/26/28 degree downhill run in 2nd gear(2gang) and 24/26 degree runs in 3to5th gear(5gang).
Also showed the pics of the plugs to Jan from SPS and he told me he can't see anything concerning or issues / signs of knock. vOv
So with the 98octane fuel on 26degrees spark table and a leaner top end I think those cylinder 2 spikes at lower rpm are clear knock spikes during the slightly downhill 2nd gear.
Maybe the 20-30% variation of knockin between cylinders at the topend is just general noise ? Wouldn't make much sense that 24 to 28 degree timing runs have same levels of knockin now with 98+EU/93 US fuel ?
Here's the logs for another 24/26/28 degree downhill run in 2nd gear(2gang) and 24/26 degree runs in 3to5th gear(5gang).
Last edited by Stoffl; 04-21-2023 at 02:24 AM.
#22
followup~
Had another short session on the dyno this weekend to confirm my suspicions. Running plain 98 euro-octane/93 freedom-octane fuel, stock intake and air filter box. Made a couple 5th gear pulls with my current 26° spark table and the 28° spark table from previous dyno session. Both with and without knocksense/-control enabled.
Once again no signs of knock / detonation on the power curves. 3hp difference between 26° vs 28° spark tables. Didn't trigger knock retard this time with my new knock sense values. After going through the logs from the 28° pulls lowered my knock sense settings again and will most likely just run the 26° spark table unless at a trackday.
tl;dr:
There was no actual proof of knock / detonation. There were weird knock sense spikes caused by steel wire and cable ties from the header wrap directly touching the exhaust manifold runners. Even audible and reproduceable at certain rpms. When I pulled the disintegrated old header wrap off again and reinstalled the DEI sleeves these shifted to cylinder 4...once again a steel cable tie close was touching the underside of the runner right next to the engine. Showed up as random spikes at certain rpm at cylinder #4 knockin.
So don't be lazy when wraping your heads and don't have stuff resonating off the engine or exhaust basically.
Had another short session on the dyno this weekend to confirm my suspicions. Running plain 98 euro-octane/93 freedom-octane fuel, stock intake and air filter box. Made a couple 5th gear pulls with my current 26° spark table and the 28° spark table from previous dyno session. Both with and without knocksense/-control enabled.
Once again no signs of knock / detonation on the power curves. 3hp difference between 26° vs 28° spark tables. Didn't trigger knock retard this time with my new knock sense values. After going through the logs from the 28° pulls lowered my knock sense settings again and will most likely just run the 26° spark table unless at a trackday.
tl;dr:
There was no actual proof of knock / detonation. There were weird knock sense spikes caused by steel wire and cable ties from the header wrap directly touching the exhaust manifold runners. Even audible and reproduceable at certain rpms. When I pulled the disintegrated old header wrap off again and reinstalled the DEI sleeves these shifted to cylinder 4...once again a steel cable tie close was touching the underside of the runner right next to the engine. Showed up as random spikes at certain rpm at cylinder #4 knockin.
So don't be lazy when wraping your heads and don't have stuff resonating off the engine or exhaust basically.
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