KR at 5200 even with timing dropped way down

[jon6.0]

I keep getting KR even though I dropped timing 4* in the 5200 cell from where it was. E85 and 15gph meth nozzle. AFR at .73-.75 lambda this morning. Knock sensors at stock sensitivity, but attack and decay rate changed. Burst knock also turned off. I can hear my headers or something else rattle/vibrate, but when I hear that isn't associated in the rpm range of the knock. Will having a cam and centri blower make the LS3 knock sensors too sensitive?

[jon6.0]

Here's my dyno run from a couple of days ago. 18* up top and the 5200 cell had 14* in it.

[jon6.0]

Added timing back in and the KR was worse. Real or false? Uggh...

[realcanuk]

I am not an expert but I would think its real knock if timing is effecting like that. Kind of weird its only there though. Did this just start happening on its own, or did you change anything on the car ?

[jon6.0]

I am not an expert but I would think its real knock if timing is effecting like that. Kind of weird its only there though. Did this just start happening on its own, or did you change anything on the car ?

I just bought HPT Pro and started logging. We also just did a McLeod RXT a couple weeks or so ago and had to take the headers off for that. Now my exhaust is rattling against something. It could have always been messing with me, but I'm not sure. The things I changed from when the tuner tuned it was the lower rpm timing. He had it at 29 for 6th gear cruising. I basically went back to stock LS3 timing at lower airflow.

What I don't understand is that people are telling me they are running their pump gas+meth LS3's at 18*-19* of timing and I'm on E85+meth and having issues. I'm not enough of a cam guru to know if maybe my cam is making the cylinder pressure too high? I wouldn't be as concerned with a degree or two of KR if I had a forged bottom end, but I don't. I would like it to last at least until tax refund time, lol.

[realcanuk]

I just bought HPT Pro and started logging. We also just did a McLeod RXT a couple weeks or so ago and had to take the headers off for that. Now my exhaust is rattling against something. It could have always been messing with me, but I'm not sure. The things I changed from when the tuner tuned it was the lower rpm timing. He had it at 29 for 6th gear cruising. I basically went back to stock LS3 timing at lower airflow.

What I don't understand is that people are telling me they are running their pump gas+meth LS3's at 18*-19* of timing and I'm on E85+meth and having issues. I'm not enough of a cam guru to know if maybe my cam is making the cylinder pressure too high? I wouldn't be as concerned with a degree or two of KR if I had a forged bottom end, but I don't. I would like it to last at least until tax refund time, lol.

You should definitely fix the exhaust rattle to be sure its not messing with the knock sensors, but if it was that I don't see why timing would effect it. I run 20 degrees on pump gas with no knock, but I don't know enough about E85 to know the differences there. 2 degrees of knock is no big deal, but I also like to see 0. It makes me feel better.

[jon6.0]

Talking with a buddy and we are thinking maybe my cams dynamic compression is too high for how much boost I'm trying to run and creating too much cylinder pressure around that area. Martin at Tick Performance recommended I try a 223/243 .617"/.627" 115+5 cam over what I have now. His suggested cam opens the exhaust valve 8.5* earlier than my current cam. The rest of the valve events are within .5* of each other.

He also said this:

I can retard the IVC event to a later close which will decrease cylinder pressure and allow you more of a window for tuning and ignition timing. Right now you're probably creating too much pressure too soon before TDC which is causing detonation. This can easily be remedied by a later closing event to decrease pressure at this piston position