Auto Tap RPM vs Timing Advance
Auto Tap RPM vs Timing Advance Should not (in theory) the timing advance continue increasing along with the RPM's????
I have a WOT run where the ITA drops slightly a few times even though the RPM's keep increasing.
I even think my table from the LS1 Edit, reading my cars computer, shows it doing that. Should not the table be set up to increase the ITA as RPM's go up???
I have a WOT run where the ITA drops slightly a few times even though the RPM's keep increasing.
I even think my table from the LS1 Edit, reading my cars computer, shows it doing that. Should not the table be set up to increase the ITA as RPM's go up???
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From: Live Oak, FL - in the woods where the creatures lurk.
Re: Auto Tap RPM vs Timing Advance I've got a plot of 6 or so WOT/2nd gear/A4 timing vs RPM. The lines look like a lazy sine wave and don't really increase to/level out to max timing (27.5* - 28*) until around 5400-5500 rpm.
This data was taken over a 1 year spread so I feel it's pretty "normal",at least for a stock pcm.
This data was taken over a 1 year spread so I feel it's pretty "normal",at least for a stock pcm.
Re: Auto Tap RPM vs Timing Advance No, timing should not increase with RPM.
Timing, as far we are concerned, is how much we can get away with without running into KR.
How much timing we can get away with is closely related to cylinder pressure.
Cylinder Pressure is closly related to Torque (see where I'm going <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> )
The more torque you are making, the more cylinder pressure, the less timing you can run.
If you look at a dyno graph you will notice that peak torque, for most LS1's, occurs around the 4500 mark. This is the point in the load up scheme that you have to run the least amount of timing. Once past peak torque you may increase timing to the moon (or whatever your engine will take). Many people make the mistake of thinking the higher the RPM, the higher the timing. The truth is that you have to wait till after peak torque until you take your timing to the moon. If you don't wait till after peak cylinder pressure to apply the brunt of your timing you will run into KR for the remainder of your WOT run.
GWJ: Your timing looks like a lazy sin curve (nomral) because it starts high, coming in from part-throttle timing at ~30 deg, goes to WOT timing, drops for peak torque, then rises again to the proper WOT setting.
Good Luck,
Kevin
Timing, as far we are concerned, is how much we can get away with without running into KR.
How much timing we can get away with is closely related to cylinder pressure.
Cylinder Pressure is closly related to Torque (see where I'm going <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> )
The more torque you are making, the more cylinder pressure, the less timing you can run.
If you look at a dyno graph you will notice that peak torque, for most LS1's, occurs around the 4500 mark. This is the point in the load up scheme that you have to run the least amount of timing. Once past peak torque you may increase timing to the moon (or whatever your engine will take). Many people make the mistake of thinking the higher the RPM, the higher the timing. The truth is that you have to wait till after peak torque until you take your timing to the moon. If you don't wait till after peak cylinder pressure to apply the brunt of your timing you will run into KR for the remainder of your WOT run.
GWJ: Your timing looks like a lazy sin curve (nomral) because it starts high, coming in from part-throttle timing at ~30 deg, goes to WOT timing, drops for peak torque, then rises again to the proper WOT setting.
Good Luck,
Kevin
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Joined: Nov 2001
Posts: 9,246
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From: Troy, AL
Re: Auto Tap RPM vs Timing Advance If everything is working ideally the timing should continue to rise with RPM at WOT. If it doesn't then most likely you are at some point getting some knock retard. Very common.
<small>[ November 18, 2002, 11:07 AM: Message edited by: Colonel ]</small>
<small>[ November 18, 2002, 11:07 AM: Message edited by: Colonel ]</small>
