Bombguy99z28

I'm tuning the car right now, but w/ 93 octane I seem to only be able to run 21* of timing without seeing KR. I thought this seemed low, although the car pulls like a ****. I had to pull a TON of timing at part throttle too. Does this seem right?

redtail2426

iTrader: (10)

if you have ls6 style heads then its right but if you have regular chambered heads then its not right.Because of the more efficient design of the ls6 combustion chambers less timing is required.

Bombguy99z28

I have 5.3l heads milled. Its not a matter of how much timing I want to run, its a matter of how much I can run ~93/94 octane, I'm trying to tune out most of the KR.

Bad30th

iTrader: (13)

Heya Ben,

I ran about 22 degrees with those heads on 91 pump gas. FWIW I don't think it knocked at all with that timing but Mark@AAP did the dyno tune. I don't think I ever scanned it for knock at WOT with AutoTap after the dyno tune, but I never 'felt' it knock and it pulled pretty strong (410rwhp/415rwtq).

Glad to hear the car is up and running.

Cheers,
Rob (Bad30th)

silverTA2002

iTrader: (1)

I'm running 5.3 heads with about 11.3 to 1 compression (unmilled, .040 cometic gasket). I'm at 25* of timing, compared to about 27-28 before the heads.

From what TEA told me, that's the nice thing about higher compression is that you can make a bit more power without having to run as much timing.

As long as the car is running great, why not stick with 21*? Then again, that is a little low. What's your A/F ration, you could be a little lean. That would keep you from running as much timing.

Bombguy99z28

Well, I've been street tuning and running outta injector. My narrow bands didn't seem lean, so who knows. I'm flat broke so I'm getting some 98 injectors tomorrow to help a tad, I need 30 or 36 but I ain't got any money, so 28.8s it is.

I feel better now that I know other people had to pull a bit of timing too, I think once I get the injectors sorted out everything will fall into place.

I'm commanding 12.7 at WOT, how close that is I don't know (narrowband says .890-.910), I need to dyno tune it, hopefully next week, just to verify my AFR and get some numbers.

CAT3

iTrader: (9)

I never heard of the LS6 having a more efficient chamber thus not needing more timing? I have heard and know the LS6 has a smaller chamber, in turn increasing the compression, which uses less timing to control knock. A more efficient chamber should be able to handle more timing, same timing but make substantially more power, or use less timing and make same power.
FWIW, KR isn't always due to timing issues either. Mess with the fueling unless its dialed in via SD, VE, MAF Calibrations.

Bink

The greater the efficiency of the head the less timing neccessary. LS6 head is far more efficient than LS1.

HumpinSS

iTrader: (1)

More efficient chamber and d-port exhaust make for a better flowing more efficient head

Bombguy99z28

My VE and MAF are dialed in. I'm putting slightly larger injectors on today, I'll see if that gives me anymore leeway.