G4X Knock Logging 350Z PnP

[Oldmanz350]

Hi,

2003 Nissan 350Z VQ350DE CP Pistons 11-1, Carrillo Rods, Head Work, Alloy Valves, 272's Kelford Cams, Vortech V7 YSi-Trim

This Log is on 93 Octane, Blower Pulleys are set for Low Boost. ( Blower Speed about 64,000 @ 7500rpm )

Drag Race Tune will be on C16 or Q16 on High Boost ( Blower Speed about 76,000 @ 8000rpm )

 

I'm just in the process of setting up Knock Control. I have watched HP Academy's 049 (setting up knock control) 6 times.

I do not yet (but will soon) have audio knock. So, I'm, Learning to interpret the Data.

I have beed in the process of Tuning in Vac/with 5psi & 4000rpm max, but, most below "0" psi area.

My knock log (Top pic) shows: 2000-3500rpm & 18 in vac-2.6psi with 30-34% throttle, in 5th gear. Driving it very easy. All thru this area Cyl 3 has many spikes, Cyl 5 two small ones.  Is this what False Knock looks like? Or? Motor sounded fine.

Also, in another area (Bottom pic) where there were peaks above the other Cyl's, but no where near the Threshold, the ECU pulled Timing, or at least that's what the Log showed. What is going on here?

Just some backround, Please forgive me as I'm a very Old School, X-Automotive Mechanical Design Engineer. My Dad taught me how to Tune Race-Car Motors in the 60's & the biggest lesson was about Detonation & how it Kills Motors. He taught me how to listen & I've have not lost a motor from detonation yet. But, I also want to grow too, it's just new for me.

Thanks,

Tim

 

 

[Adamw]

Cyl 3 looks quite noisy so you may need to turn the gain down further on that cyl to balance it up.

Boosted on 11:1 comp with pump gas I suspect will be very susceptible to knock so you will really need audio gear on there to verify if you are displaying knock or just noise.

 

5 hours ago, Oldmanz350 said:

Also, in another area (Bottom pic) where there were peaks above the other Cyl's, but no where near the Threshold, the ECU pulled Timing, or at least that's what the Log showed. What is going on here?

When the ecu has detected knock it will retard the knocking cylinder/s until the knock stops, it records the amount of retard it needed to apply to that operating area in the relevant knock i-trim table.  So next time the engine passes through that same cell that had knock previously it will get the same amount of retard so it doesnt knock again.  If you continue to drive in that cell for a while (advance delay) and the ecu doesnt detect knock, then it will slowly advance back to zero trim (advance rate).   Those trim tables are usually set to clear on power up.  

[Oldmanz350]

Yes, Mine is set to clear on power up.

Helpful info......

Thank You,

Tim Hampton

[koracing]

I would free rev with the datalog running and see if cyl 3 is still a bit higher at no load at that rpm as well.  That could certainly indicate a need to reduce the gain on that cylinder.  
 

If it’s false knock retarding the timing and adding enrichment in that area typically won’t have much affect.  So you can treat it like actual knock and turn on individual cylinder fuel and timing trim tables for that cylinder and add fuel and take out timing in that load and rpm range and see if the knock level improves.  If adding 3-4% fuel and subtracting 2-3 deg advance doesn’t improve it then possibly try going the other way on timing a couple degrees and see if it gets worse.  Short pulls at low load (or partial dyno pulls if possible) since it is built.  I wouldn’t necessarily try that on stock pistons.  If adding fuel by itself resolved the higher knock levels then you can surmise there was an airflow imbalance leaning that cylinder out.
 

Keep in mind adding advance on pump gas is potentially very dangerous to the motor, while taking a bit of timing away usually is safe enough as a first try.  I wouldn’t necessarily go much more than 2-3 deg either way on an individual cylinder before making a global timing adjustment.  Making a global timing change on a dyno would be allow you to see if reducing timing loses power.  It should lose power or you had too much to begin with.

[Oldmanz350]

This is such helpful information, thanks so much Koracing.......