Timing?
05-23-2010, 11:49 AM
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Timing? Just curious but wondering how much timing people are running at WOT. I know mine stock was 32 degrees and my tuner just bumped it to 33 after wide band tuning it. Just seeing how much you guys are running before you start getting knock.
05-23-2010, 12:31 PM
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Temperature might have something to do with it too. I lose maybe 8* from the IAT modifier table when the intake tract heat soaks in town during rush hour. Normally doesn't get warm enough for that table to come into play on the freeway...
05-24-2010, 12:52 AM
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More timing isn't everything. I think the stock tables are too aggressive in the first place. I'm not sure why GM did it but the LS4 runs more WOT timing than any other LS engine I've seen. Most LS engines only need between 25-29* total. I can't imagine them needing much different timing requirements. I have not confirmed what an LS4 likes on a dyno so take it for what it's worth.
05-24-2010, 12:58 AM
#7
More timing isn't everything. I think the stock tables are too aggressive in the first place. I'm not sure why GM did it but the LS4 runs more WOT timing than any other LS engine I've seen. Most LS engines only need between 25-29* total. I can't imagine them needing much different timing requirements. I have not confirmed what an LS4 likes on a dyno so take it for what it's worth.
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05-24-2010, 01:08 AM
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damn, only 18? I've never seen that. I guess it all depends on where you live. BTW, LS engines like a a/f mixture about 12.5-13.0, again not sure what they run so damn lean from the factory.
05-24-2010, 01:39 AM
#9
My tune was extremely lean from the factory. Not sure what it was, the car just wouldn't take any timing before the headers but afterward it took a ton more.
05-24-2010, 07:26 AM
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Odd. Mine was very rich >5,000 rpm. ECM was commanding something like 10.9 in PE mode. Now ~12.8 +/- at WOT. it would be leaner at lower RPM because of the goofy stock PE enable settings - wouldn't go into PE until after 3,500.
05-24-2010, 07:53 AM
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More timing isn't everything. I think the stock tables are too aggressive in the first place. I'm not sure why GM did it but the LS4 runs more WOT timing than any other LS engine I've seen. Most LS engines only need between 25-29* total. I can't imagine them needing much different timing requirements. I have not confirmed what an LS4 likes on a dyno so take it for what it's worth.
While I do have more timing than stock at high rpm, In some areas of my timing map, primarily between 1200 and 2000 I had to pull up to 5* because of KR. It was most evident when climbing a hill on the highway.
05-25-2010, 12:23 AM
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For the most part, I agree with this. In the absence of a dyno, I set timing on the basis of several 3k to 6k WOT runs - whatever timing appeared to minimize the time for the run. Much of my timing table -ares that you can't actually hit while driving - are just "plugged" to make it smother. YMMV.
While I do have more timing than stock at high rpm, In some areas of my timing map, primarily between 1200 and 2000 I had to pull up to 5* because of KR. It was most evident when climbing a hill on the highway.
While I do have more timing than stock at high rpm, In some areas of my timing map, primarily between 1200 and 2000 I had to pull up to 5* because of KR. It was most evident when climbing a hill on the highway.
05-25-2010, 12:39 AM
#14
Only thing I can see a major difference will be the smaller bore shrouding the valves, and the super restrictive intake.
05-25-2010, 02:22 AM
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yeah but the smaller valves help shrouding, in any effect it's not a factor since it will be the same case in all the other 5.3's.
The biggest factors that are going to make a difference aren't much different at all. Chamber design, rod length, stroke, compression are all the same/ similar.
The biggest factors that are going to make a difference aren't much different at all. Chamber design, rod length, stroke, compression are all the same/ similar.