Burst Knock and Launch Timing

[oztracktuning]

I now have a tank of Boost 98 (10% Ethanol fuel) and did some data collecting regarding stalling it up and what happens off the line.

When i stall it up to about 2000rpm simulating "in stage" the log shows about 70 MAP, 2319rpm and 0.41g/cylinder with a desired AFR of about 14.4 measured was similar.
Then when the throttle is stomped it quickly jumps to 0.80g by 3200rpm (stall speed is 3600) i cant load the engine enough in 1st it spins - but i did it locked in uphill in 2nd gear( mine engages only 2nd).
In the stalled situation at about 2200rpm and 0.40g it has 27.1 degrees timing - by 0.80g and 3200rpm it has steadily curved to 24.2 degrees. When i stomped the throttle i noticed in this one trial in this "stalled - stomped" situation the log showed that it pulled timing down as much as 15 degrees plus in the situation i just saw another 1.6 for knock retard. Is this Burst knock? What do i do with this for an only at the track tune??

My minimum timing which matches when the VE table has the highest g/clyinder is 23.1 in the 5200 and 5600rpm rows. It then goes up to 25.0 until the shift point.

Any suggestions/ideas would be appreciated. I am racing next weekend and hoping for a sub1.6 60 footer.

[oztracktuning]

Looking at the log more closely shows a g/cylinder change from 0.58 to 0.78 in a single frame and a drop of 19 degrees of timing - from 25 to 6. Then after that this retard started to fade but as it did it had 1.6 degrees knock retard happen in the next frame.

My Delta Burst table has 0.024902 g in the 3200rpm cell and 3.0 degrees in B6212 corresponding with 3200rpm.

My car has changed air flow by 0.20 which is 8 times the 0.024902 amount.

Why did the timing drop so quickly to 6 - it doesnt make sense?

[Tordne]

As you will no doubt know there are a number of things that can conspire to remove spark advance from the final number. These include IAT, ECT, KR, Burst KR (BKR), Traction Control etc.

To understand why you are getting a final spark value of 6 you may need to log a number of these to see which are contributing.

I personally have found that BKR in my tune (MAFless - Speed Density) is best completely all 0'd out (both the airflow and retard tables). Each time I have tried to introduce these back in they have been the cause of logged KR. In some of the stock tunes I have seen the retard at lower RPM's is quite high, around the 6 degree mark.

Hope that helps a bit.

Cheers,

[oztracktuning]

I have searched all the forums on this for ages. It seems that Burst Knock values can be used to prevent knock retard before it happens. ...i have started setting up spreadsheets so that i can get the numbers right and maybe gain some extra performance preventing knock rather than enduring it.

My car has a 3600 stall - its under lots of load at near 3600 at the strip.

Two situation i face that may conflict at 2000rpm stalled up ready to stomp WOT at the strip and 2000rpm locked on the road and then i stomp. The dragstrip one in 1st gear will be able to cope with more timing than locked on the road - but they are similar - but i will need to account for their differences.

What about using Burst Knock at high revs to prevent real knock???

My engine builder told me a big killer of max power is any knock at all - not because of Knock retard but because of whats happening in the cylinders.