Ls3 (24x), PRC heads, close to stock compression pump gas.
Just got back from tuning it at the track (road coarse).

This is what I ended up with to get rid of knock!?
Is this normal? AF is 12.4-12.6 steady...
WOT
3500-4800 20*
4800-6500 21*
Seems really low...

 

I have stock L92 heads milled .020", and what you arrived at is pretty close to what my tuner ended up with on my LS3 longblock on a Mustang dyno... 19-20* 3600-4800, then 23* the rest of the way. We tried adding more timing but it didn't gain anything. My AFR is roughly 12.2-12.3. Max spark advance before detonation is not necessarily ideal for mean best torque, though.

 

I have PRC 250cc heads and heads/cam/intake LS3. On the dyno, 21 degrees on 93, 27 degrees on E85 at 6500. See my thread All Motor LS3 Dyno Results.

 

With my hci (and chamber redesign on the heads) I'm only running between 19-22 timing on 93 also. Have been told different chambers (especially more efficient ones) don't need as much timing.

 

I am going to type up a whole thread anyway but I'll give you a very significant piece of info.

I wanted to see how much i was getting out of my flex fuel setup. So i put the car on the rollers with E85, and logged the alcohol % at 68%. (E85 can have min 70% ethanol on winter blend and that's what I had).

Car made best of 505 rwhp SAE on E85 (68% alcohol). On 27 degrees timing.

Drained the tank and filled up with Costco 93.

Car made best of 515 rwhp SAE on 93 (12% alcohol). On 21 degrees timing.

My car has estimated 11.5:1 static compression.

So our hypothesis is that I do not have enough compression to benefit from E85. Furthermore, my engine makes MBT (i had to look up that term) at lower timing.

I have HPTuners logs of all runs. Hit me up if you want to get into the nitty gritty.

Dan

 

Cynic can you post your timing map. That's pretty interesting that 6 more degrees of timing did not help at all and in fact hurt your power output.

 

Did you do the entire tune between the two fuels or just the timing?

 

Thank you for moving this into the correct section.
Yeah I started with 23* and now even at 20* there is still the occasional knock (.5 - 1) every now and then.
So this is not ideal for max TQ? I'll take some more out and log another run

 

Interesting thanks! I thought there was something wrong... Next time I'll try 19* at peak TQ..

 

I just read your thread, fast times for heavy car!
I would love to take a look at your timing tables if you don't mind. Please post or PM me the hp tuner file. Thanks a lot.

 

I have a feeling my timing tables needs a lot of work... Started with the LS6 base tables and 23 WOT and basically just pulling timing untill all the knock was gone.
Probably not the best way to tune timing...

Was wondering, can I get Ideas from a LS3 ECU main spark table or would they be different from my LS6 ECU tables? Are there any other tables in the LS3 ECU that effects timing that I don't have?