If you want to see what detonation will do go to the advanced engineering tech section C5R Kaboom thread and look at the pics. Melted pistons and one blown C5R.

 

I thought that 27* was good in my car until logging showed 3* knock reduction from 4200 & up. Now she runs 24* without issue. Engine spec's. in sig..

 

24.5 degrees. Adding more timing does absolutely nothing for my horsepower numbers.

 

It seems that most of you understand that every engine is a little different. But when you are comparing LS1 LS6 LS2 L92 heads different cams and compression ratios one persons timing won't even be close to the next. With these fuel injected engines we run a small LSA of like 114 or 116 this closes the valves sooner and doesn't have alot over lap for emmisions. This makes our cranking compression higher than some more radicle cams on old school engines. In old school engines you had what was called a fast burn combustion chamber compared to the normal combustion chamber. I would have locked 36* in an old big block Chevy but put Olds heads on it you could only run 22*. This is the same in princible for the different heads we have available to us. We also have different fuel in different regions it all my say 93 octane but different blends for different areas at different times of year all reacts differently to how much timing you can run. My big block example was with 118 octane NOS blend VP brand. We also have the different blocks I have an iron block can't run as much timing as an aluminum block. If you have an after market set of pistons in a motor and they were installed out of the box without someone filing down the sharp edges on the valve reliefs or domes too bad for you because this will cause early detonation and rob HP to. This is only considering N/A applications if you have a power adder of any sort detonation is an engine killer under full load by the time you hear it or see it on a guage it is usually too late. You can also have your pistons and combustion chambers coated by some companies with a ceramic material. This wont' stop detonation but will dermaticly reduce your chance of melting a piston. In the old school discription above if you lost mile an hour in a run then move the timing back. I know it has nothing to do with us or our engines but Top fuel nitro motors run 70* of timing just to give an example of how much cylinder heads and type of fuel changes things

 

~ 26* WOT,and 91 Octane NA for me.

 

I should also mention that my tune starts @ 24* during WOT & is down to 16.5* @ 6,400. Anymore & she pulls timing. 10.8 SCR, 8.4 DCR; airflow is 400 g/s @ 100 KPa during WOT.

 

UPDATE:
Turns out that the knock sensor software from my 98 PCM was not correct for my current set-up. For this reason, the PCM was pulling timing when it should not have been doing so (too sensitive). I re-flashed the PCM w/ 99-04knock sensor software settings & am able to run from 26* down to 23* @ WOT. Again, this is related to the 98 PCM knock sensor software settings only. Has nothing to do with other knock sensor sensitivity settings. Wanted to archive the issue. It's doubtful that others will be using a 98 PCM to control more modern set ups in the future, but you never know.

 

im runing stock timing and seeing 2-3 KR..... WTF..........

 

I'm running 30* but am thinking about knocking it down to 26-28*. I'm not showing knock but it doesn't hurt to be conservative.

 

25 degrees here

 

I run 26 degrees and zero knock at WOT.

 

27*, zero knock anywhere, 10.8:1 cr, 91-93 octane. I tried up to 29* and I would get an occasional small amount every now and then so I went back to 27 and called it good.

 

I had my car Tuned for a long time by a sponsor that had me at 30 deg wot. I bought efi live and started playing with it after hearing that backing the timing down and adding a little more fuel may not make the best dyno number but will be quicker at the track. i went down to 26 deg wot and from 13.2 af to 12.8 and picked up 1.5 mph at the track after 3 passes at 30 . the next 4 passes were at 26 and went from 120.8 as the best with 30 deg. to 122.4 as the best with the change to 26 deg.

That was my old set up with 10.7/1 and f13 cam.
I am now running the same heads with a lq4 and an f14 cam with 10.3 /1 compression and have not changed the timing as I have not raced the car or dynoed the car yet . IT feels great on street tuning though.
I am hoping for track times soon , just did not want to chance breaking anything with Cruising the Coast comeing up on the Mississippi gulf coast.

 

31 on motor, 17 on the jug. sig says it all, stock 853 heads.

 

24.5, picked up no power going to 26 or 28

 

Started off with 28*, then tried 29*, picked up some HP and torque, went to 30*, once again picked up some HP and Torque (even less though), pulled the plugs, timing mark was nice, not pushing it to hard, tried for 31 degrees, picked up 4rwtq, HP stayed the same, so I left it at that. TEA Stage II LS6 heads, coated forged pistons, CR 11.5:1, BP 93 octane fuel, AFR 13.0:1. Pulls were done on our loaded Mustang MD-1100SE dyno, scans never showed any KR.

 

Did you try different AFR's too? Curious to see difference in numbers if you richen it up a tad to 12.7~12.8:1. Picked up 5~7hp by doing that on one of my previous applications...not to mention the slightly safer mixture.

 

I tried AFR's ranging from 12.8:1-13.2:1. 12.9:1-13.0:-1 seemed to be the sweet spot. I kept it at 13.0:1 becuase the car seemed to sound "cleaner" at that AFR, although there was no difference in rwhp or rwtq between the two.

 

Cool....

 

My cam is ground in a 110+4 lsa. I'm running 28 grees at WOT now, How does cam advance affect what you timing should be set at?