Stock '99 Spark Tables... Why the dip?
11-15-2010, 03:05 PM
#1
Stock '99 Spark Tables... Why the dip? I was looking at my stock '99 Trans Am spark tables and noticed something pretty odd I bet most of you have already noticed.
There is a pretty significant drop in timing from 0.52g/cyl x 4000rpm to 1.20g/cyl x 5200 RPM. It seems like they dialed back the timing that that area for some reason. Especially in the 4800 RPM column, the higher cyl airmass cells are only getting 23* while at 5600 and 3600 RPM are getting a full 28*.
I smoothed it out so that area is flat now but I'm just wondering why they put that dip in there?
There is a pretty significant drop in timing from 0.52g/cyl x 4000rpm to 1.20g/cyl x 5200 RPM. It seems like they dialed back the timing that that area for some reason. Especially in the 4800 RPM column, the higher cyl airmass cells are only getting 23* while at 5600 and 3600 RPM are getting a full 28*.
I smoothed it out so that area is flat now but I'm just wondering why they put that dip in there?
11-15-2010, 03:35 PM
#2
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Thats a stock table? My stock 01 table didn't have near that much timing pulled. For whatever reason the dip in that rpm range is, the stock PE table is richer in that area too.
11-15-2010, 03:47 PM
#4
It's a stock table. My old 2000 file didn't have that much timing pulled either, but it still had a dip.
My EQ Ratio vs. RPM under PE is a flat 1.250 across the board, must be a difference in the years.
I was thinking about there being peak torque around that area as well, but still pulling 5* of timing seems a bit extreme. I guess the GM was was thinking "better safe than sorry" back in '99
My EQ Ratio vs. RPM under PE is a flat 1.250 across the board, must be a difference in the years.
I was thinking about there being peak torque around that area as well, but still pulling 5* of timing seems a bit extreme. I guess the GM was was thinking "better safe than sorry" back in '99
11-16-2010, 06:06 PM
#5
It is supposed to come in and go like a wave. Just as Joecar said. I have seen timing tables that were like static grids. The car ran horrible. That is where most of the load is on the engine. Notice, again like joecar said, that HP/TQ cross at 5252? There does seem to be a correlation there.....
Usually the stick cars will have a little more aggressive timing than the auto cars as well. I have seen PE numbers go all the way from static to jagged. Also the PE enable TPS on stock cars I have seen go from 89% to about 20 so its really hard to compare one car to the other.
Usually the stick cars will have a little more aggressive timing than the auto cars as well. I have seen PE numbers go all the way from static to jagged. Also the PE enable TPS on stock cars I have seen go from 89% to about 20 so its really hard to compare one car to the other.
