[crystal_Imprezav]

Ok, I have received a lot of questions regarding rescaling and timing of the different OTS Cobb maps. Below you will find comparisons of various OTS Stage2 maps and an excel worksheet that will do the DA and Total Timing comparisons. Keep in mind in these worksheets, I am assuming on DA A is used. In reality unless you have the special Cobb map, the ECU is likely to use an interpolation of A and B depending on sensor feedback and how happy it is with the gas, elevation, and etc. The comparisons included are 91 CAL, 91oct, an older 91oct revision, and 93oct.
Comparisons:


Link to Worksheet:
Click here Worksheet

[STLSTI]

Nice, Thanks Crystal

[crystal_Imprezav]

Here is a new revision to the worksheet. This one uses an average between DA A and B which is more likely what your ecu will use (if you don't have the Cobb modified map). I am leaving the other one just incase anyone does use a map like this or wants to use an 'all the same' DA tables. This new worksheet also has a comparison of the fuel maps, which are identical I think after glancing over them.

Link to Worksheet Rev2:
Click here for Worksheet Rev2

[06stiman]

Originally Posted by crystal_Imprezav

Here is a new revision to the worksheet. This one uses an average between DA A and B which is more likely what your ecu will use (if you don't have the Cobb modified map). I am leaving the other one just incase anyone does use a map like this or wants to use an 'all the same' DA tables. This new worksheet also has a comparison of the fuel maps, which are identical I think after glancing over them.

Link to Worksheet Rev2:
Click here for Worksheet Rev2

Thanks Crystal for putting this together!

I just verified that the Cobb fuel maps are in fact identical, but my question is why? Wouldn't we expect to see a "leaning" trend as the map octane increases? I suppose the explanation could be that Cobb adheres to the "more timing, more fuel" theory as opposed to "less timing, less fuel" theory. So while maintaining the same fuel ratios across the maps, they choose to focus more on using the higher octane to increase timing.

Maybe Christian can chime in here.

[STLSTI]

I guess they say if is not broken dont fix it.

[flatthump]

Originally Posted by 06stiman

Wouldn't we expect to see a "leaning" trend as the map octane increases?

I think it's a saftey thing.....

Thanks Crystal!

[crystal_Imprezav]

Well its not that you necessarily need to lean out the fuel map to lean out your actual fuel targets. You must keep in mind that with that fuel map and the stock intake calibration curve, that you will run pig rich dipping into the 10's at peak torque then leaning out a tiny bit before going rich again. Now by keeping the same fuel map but changing timing, say in the case of the 93 map adding a degree or two of timing throughout the upper load range, it will infact lean out fuel as well. More timing will equate to leaner fuel b/c the burn rate will be more complete therefore combusting more fuel. Get where I am going with that? For example, on my racegas map, I can keep the exact same fuel map as my pump map (which w/o extensive tuning of the intake cal was in the 12's to hit an 11:1 afr) but adding 4*+ of timing leaned out from an 10.9-11:1 afr to almost the target of 12:1.