I'm getting some detonation in my LE2 setup, but only when my temps start to rise on hot days. I have logged the car fairly extensively and done some tweaking to my tune, but don't really see any way around pulling timing one way or another when the temps rise to get around the detonation. I had some false knock going on, but have zero'd out the knock tables and that made it run 10 times better since I'm now able to run more timing....but still have detonation issues when the temp creeps up. Granted, I'm in S.C. and we've had about 14 consecutive days of 100+ temps here so I may be just facing a fact of life, but figured I'd see if others were successfully running my kind of setup in extreme heat with no detonation.

Basically I'm trying to decide if I should move to a colder plug to see if that helps. I'm running Autolite 104 Platinum tips now. I've been told that the platinum tips may run a little hotter than the standard 104's, so maybe I should try some regular 104's. Just thought I'd see what kind of thoughts you guys had.

Thanks in advance!

Robert

 

Whats the intake air temp and coolant temp when you have probs? I've had my car at 205 and IAT of 100 without issue running the XP104 plugs. Thats on Sunoco 94.

 

96flame,

here's a screenshot of my datamaster log when i was on the way home from work in traffic and my temp was at it's highest of the run (209.8*).

LOG

and here's the .uni file

 

Do you actually hear it pinging? What fuel do you use?

 

yes, distinctly hear it "pinging" when the temps creep up. i use 93 octane hess fuel. i have just filled up tonight with BP (Amoco) as a test, but i will be surprised if brand makes that much difference. oh, i have also been running octane booster with every tank.

 

Is it possible that its running lean also? I've yet to hear my LT1 ping even when I use 91.

 

Its "pinging" because he had the knock retard zeroed out. That's the risk you run when you eliminate the knock retard.
Appears that at least in Cell 5 there are seriously split BLM's. Colder plugs might help..... hard to tell with no info about the CR, cam profile or spark advance. Tried your .uni file and got:

 

Injuneer,

The interesting thing is it doesn't detonate any worse with the knock tables zero'd out than it did when the base tune for my setup, and not at all with either until my temps rise....but certainly understand and agree with your statement.

If you right-click and "save as" my .uni, I think you'll be able to pull it down to your PC. It's just a direct link to the .uni and not an html page.

I'm definitely going to try a colder plug and also putting new O2 sensors on just for piece of mind. Mine are stock with 12 years and 155K miles on them. What plug would you go with if I'm running Platinum Autolite 104's now?

Robert

 

As an update....

Just got off the phone with NGK tech support and they tell me that:

NGK TR6 is one heat range colder than Autolite 104's
NGK BR7-EF is two heat ranges colder than Autolite 104's

Wonder how cold I could go without fouling out?

 

You're saying you had audible detonation with the base tune, and with the knock sensor/retard system still functioning? Sort of hard to follow the story.

Detonation increases with higher temps... doesn't matter why the temps are higher. Higher coolant, higher inlet air, higher combustion chamber temps....all increase the risk of detonation.

What is your static and dynamic CR?

"save as...." does nothing. Get an error message the IE can not open the site.

 

I am running the standard LE2 cam for a 383. I think I am at around 12.0 static and 8.5 dynamic. These are rough numbers but should be pretty close.

I'm sorry if I was confusing, but yes, when temps got up on 100+ days, I heard some audible detonation with my initial tunes. I then pulled 5* of timing across the board and was still able to hear some detonation on those very hot days when the temps creeped up. Maybe it was indeed less than I hear now with it zero'd out, but the reason I tried the zero'd out knock tables was that the amount of knock retard was virtually the same between the initial tune and the tune with 5* of timing pulled. That made me suspect that there was false knock going on. When I ran the tune with the zero'd out knock tables, it ran a LOT better with no detonation as long at it wasn't above 90 or so outside. So maybe it's fair to say that I did have false knock that was retarding my timing, but that if I continue to run the zero'd knock tables, I'm going to have more of a challenge with detonation when the temps creep up?

Do you think my best bet from here would be to try colder plugs and maybe adjust the timing for specific TPS settings?

 

How much timing are you running?

 

37* at WOT