!!!!!!!!detonation!!!!!!

well, my previous best was 11.89 @114.44 1.686 60'internally stock.

Since then i have added a set of home ported ls6 heads, and a tr224/227 .563 .569 114 cam. and had it dyno tuned to make sure everything is good.

first pass was;
1.69 60'
7.52@91.42 1/8
11.82@115.34 1/4

.......I though i would have done much better than that. I checked the car over to make sure nothing was in the intake, no ses lights, not burnt tranny fluid. The only other thought was bad gas maybe?

so i added a gallon of 110 to my 3 gallons of pump 93 i had. I then entered a bracket bracket race they had there but it was only 1/8 mile. car went 7.44 @92.34 1.675 60' So the car definitely picked up some, but from the gas?

after that i got back in the 1/4 and the car spun to a 11.83@116.45 1.75 60'

my tuner showed up and we hooked the laptop to it to find it was detonating and pulling about 4-5 degrees of timing away, we tried to add a little fuel and pull timing but the car only picked up to a 11.800 @116.99 still detonating & spinning 1.75 60'.

the night ended and it looks like we still have some tuning to do.

this was the first time i bought gas from bp, so i'll fill up with mobil 93 and go back to my tuners to see if it is still detonating. I think the car has a 11.5 in it IF it hooks with a 1.6x 60' and we figure out what is causing the detonation.


We had the computer hooked up to it and we were data loggin some passes. we found that the car was detonating and pulling timing off the line, then during the 1-2 shift it would detonate, and during the 2-3 shift it would detonate and pull about 3-4 degrees timing, then it would clear out in the end of third. the car did not do this during the dyno runs a few days earlier, so i'm thinking bad gas? how about plugs? i used the original autolites that came with those ls6 heads, so will switching to a cooler ngk tr55 or tr6 help?

Hard to say without being there. As far as the plugs go, it depends on which autolites you are using. I run the APP103's,,,,these run cooler than the NGK tr55's and 6's,,,,,so if you have these autolite plugs then switching to the NGK won't do anything for you as far as cylinder temps go,,,,been down that road on the dyno already.

If you are running the APP104's then step down a heat range to the plugs I mentioned.

But most of what you mentioned sounds like it will have to be tackled in the tune.

Do you have any idea how much timing the tuner is trying to run with???? I have found with mine that about 24 degrees total is about the limit in the high load areas,,,and on a hot day it will still pull 1-2 degrees on the shift points (high load). The factory tune on mine only allowed 19 degrees,,,,so I wasn't able to deviate much from the stock timing tables as you can see.
These cylinder heads on the LS motors have very efficient combustion chambers and don't require alot of ignition lead. Now your camshaft with more overlap will change things a bit, but that is still a very tame camshaft you are running. Also changing the cylinder heads to the LS6 will bump the compression about 1/2 point,,,thats if they haven't been milled. If they have been shaved your compression could be even higher. There are alot of unknowns here to give a good answer.

Without knowing what else you've done to the car it's hard to say...gears??? converter??? etc...

Problem with the dyno tune and then driving on the street are 2 very different things. The dyno can't simulate real world conditions. Driving day in and day out in 90 degree heat with 70 degree dew points with different elevations and the DA changing constantly.
I have always found that even after I dyno an engine and have it tuned to what appears to be razor sharp on the dyno ,,,after it's on the street in real world conditions I have always had to tweak it here and there. Especially at the track... I'm sure if you post up the tune there are a few here that can have a look see.....maybe give you some ideas.

OK, well my tuner has all the info in his computer. He did want to ride around on the street and do some more tuning. i have a 2800 stall, 3.73 gears, car weights 350 with me. the ls6 heads we not milled, just minor porting. i think he was runnin 27 degrees full advance but maybe only 22-24 during the lower rpm's. I don't know for sure. I'll go back when i get the time and well see if he can straighten it out. He seems pretty good, i goes all around the country to tune vipers. His car is a viper that runs low 9's.

Maybe a week or two i'll set up an appointment with him and let you know what we figure out.

Subscribing

Well, i may be onto something. I checked the oil and saw i overfilled it a little. about 1/4 quart. I also noticed that a little oil was dripping from my pcv hose at the front of the intake, so some more oil than normal was definitely entering the engine. I'm going to change the oil and fill it to the proper level this weekend and then go to my tuners to see if it has cleared up. from what i have been reading oil can cause detonation if too much is in the combustion chamber. I still do think that the tuning still need to refined more, but this is a start. I have also been reading up on the ls6 pcv conversion, which can help keep oil from entering the intake. I may even look into just open venting the crankcase and keep all the oil and crankcase fumes from entering the intake. But I don't want to much oil leaking from the vents. I have a 78 440 big block in my truck and the crankcase is open vented, no problems with leaks so i may try it on my LS.

http://www.ls1howto.com/index.php?article=18

good wright up!!

how much timing are you seeing at wot and what's your afr like?

A/F was 13.2 all across the board. I think max timing was 27. I will know more when my tuner gets back in town June 2.

that af is lean, just richening it up some would help you out.

Quote:

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Originally Posted by 0rion

that af is lean, just richening it up some would help you out.

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which ratio? 12.9? 13.0?

I have been reading that a lot of people are running 19 or 20 degrees with the ls6 heads, does this sound right? Also what about false knock? How would you determine that or get ride of it?

I would shoot for 12.8ish if I were you. I don't think the extra couple of HP you might gain is worth running it that close to the edge.
You can run some 100 octane and watch knock and if it goes away then it's real knock but if it's still there it's false. This is the only real way I know of checking for false knock and I'm sure there are better ways out there than this....it's just the only way I know of.

Maybe Frost will chime in since he's forgotten more than I know. :D

Quote:

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Originally Posted by silverz28camaro

Well, i may be onto something. I checked the oil and saw i overfilled it a little. about 1/4 quart. I also noticed that a little oil was dripping from my pcv hose at the front of the intake, so some more oil than normal was definitely entering the engine. I'm going to change the oil and fill it to the proper level this weekend and then go to my tuners to see if it has cleared up. from what i have been reading oil can cause detonation if too much is in the combustion chamber. I still do think that the tuning still need to refined more, but this is a start. I have also been reading up on the ls6 pcv conversion, which can help keep oil from entering the intake. I may even look into just open venting the crankcase and keep all the oil and crankcase fumes from entering the intake. But I don't want to much oil leaking from the vents. I have a 78 440 big block in my truck and the crankcase is open vented, no problems with leaks so i may try it on my LS.

http://www.ls1howto.com/index.php?article=18

good wright up!!

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I think you are experiencing what most LSx owners have complained about for years. These things are known for having terrible crank case ventalation.
Mine has had leaks all over the place. When I bought the car the rear main seal was leaking as well as the rear plate it rests in. I have since fixed that since it was leaving a trail everywhere I went.
But the engine still seeps oil out of both valve covers and the front timing cover looks a little gungy as well. I have to degrees the motor every couple of months. It seems the oil tries to push out every orifice the engine has :think:
I was having a small amount in the PCV valve as you mentioned. I switched to the updated PCV valve and that has seemed to stop almost completely though...I also installed an open vent in one of the valve covers in an attempt to relieve some of the pressure,,,so far it seems the seeping has slowed down a bit.
I may eventually install an oil catch can as that is what most LSx owners do to keep the intake charge clean. Just another extra precaution thats probably not a bad idea.

Quite an interesting thread here. So glad my 2002 has many of the LS6 perks. Surely I don't have the oiling issues that FirebirdJones mentions! I have considered a catch can though, just to ensure that the intake isn't taking on needless amounts of crankcase oil.

I'm guessing the OP's issue is in his tune being too lean and perhaps timed too high. Back into the 26-27* max timing area and drop into the upper 12's for AFR and your car will come back to life! :)

-Eagle

If it was left at 13.1 after tuning on an unloaded DJ, particularly the 224, I bet the car ends up around 13.5 on the street. You can run more timing on an unloaded dyno than on the street too, and you aren't going WOT through shifts on a DJ either, so street/track tuning is always critical. Some cars make quite a bit more power at 13.1-2 than 12.8, and some don't make anymore at all higher than 12.4; it depends on the combination.