Went to the track and logged one run

[walterd]

So I reviewed the log I am confused why I got some knock at the end of 4th. Anyone willing to offer a suggestion on how to narrow this down? The knock sensors are still stock values and I do have some mods such as 100 shot, headers, exhaust, 1-piece driveshaft, ls1, m6.

Thanks for any opinions on the log!!!!

[PurplePiss]

Your running 13-14 AFR and spraying? :boom:

After the first 2 gears, the next run up through 3rd the cylinders are getting hot, that's why you see knock, combined with a dangerously lean AFR IMO.

Looks like you short shifted second, then lugged 3rd.

Nice flat torque curve though. LS1?

[Tim05GTO]

The LC-1 A/F looks fine. Purple, I think you might be looking at the commanded A/F ratio.

It looks like a little bit of timing might need to be pulled.

Tim

[edgZ06]

He didn't short shift second, he actually had the highest rpms (6196) of the run in 2nd.

A/F looks good to me.

Fourth gear has a higher load and you will get KR easier in it than the other gears.

I would try and drop a degree or 2 at 5600 just to be safe and log future runs.

Ed

[EC_Tune]

It's also dipping into the low 11's & 10's at the top of 4th. May be too rich causing the KR with the cylinder temp climbing???
I agree though, pull out 1 degree or so at the top end.

EC

[walterd]

Thanks guys, appreciate the advice, I am surprised I was getting this knock at the timing I had 22.98 - IAT correction = 17 and getting knock. I was hoping it was false knock but I will try pulling two degrees at 5600 + to see if it makes a difference. I think I was running a fuel jet that was too big for the n20 jet, trying to get 11.5-12.2 when spraying so I am thinking about changing my PE to be a constant 1.130 vs 1.180 starting at 5200, sound like a plan?

[walterd]

can being too rich(~11.0) really cause knock?

[Russ K]

I would install one heat range colder spark plugs. Once you get the AFR closer, you can multiply the Knock Retard Attack > Base Retard by .75 and double the Knock Retard Decay Rate table. Make sure that there is no audible spark knock.

Russ Kemp

[EC_Tune]

Yep, too rich can cause knock. Had it happen on a supercharged LM7 5.3L motor and it was "only" in the low 10's AFR wise. Leaned it out to ~11.5-12.2 and the rich knock went away and I was actually able to add a bit of timing.

Different case than yours but it "could" happen with the N20. I don't have much N20 experience so thus my caveat of "could".

EC