Dyno tuned with dual widebands yesterday First I want to say Thanks to John Sealock at Woodbridge Dynotech in Manassas, VA for helping so much yesterday. I can't recommend John high enough. John is a great to work with and a great mechanic. Tom, Bergie, Ernest, Alex, everyone -great to see you guys up there. Looking forward to next time. Okay, now onto the experiements and details. John set up dual Wideband O2's in the original O2 locations (I relocated my relocated rearward 6" in my MAC headers, so I have dual sampling bungs.) What my intent was for the day: 1. verify AFR at idle with altered cylinder balance tables 2. verify AFR at cruise to very split BLMS (3-5 BLM split) 3. verify AFR at WOT and tune to 12.5:1 - 13.1:1 and determine torque/horsepower change using the dynotuner spreadsheet. 4. Determine AFR variation between the two cylinder banks. John showed me data proving 0.5 AFR variation around between the two banks (which is why I went with the dual WB setup) Note: timing was left alone as that would skew results. My car is 11.4:1 Hotcam running 35-33 degrees advance at peak RPMs' Please remember every car is different and results on my car do not mean they will cause the same changes on other cars. Results/testing: 1. My idle cylinder balance tables have been altered to give me a BLM balance, whereas the factory table causes a BLM split of 4-6 BLM. The dual Wb's confirmed that O2s were reporting correctly both in open loop and closed loop with a balanced r/l BLM. This is good, I was happy. 2. My BLMs have been reporting 130/126 or similar for a while. I thought this was crap, but sure enough the AFR's verified that the right side was in fact about 0.5 richer than the left side. This also showed up on WOT runs, more on this in next results. 3. I rolled in with the coolant table set to: http://www.carprogrammer.com/index.44.gif - the coolant tables were set to 16 percent at testing temperature, nearby cells were all set to 16 in case of temperature variances, but the car was warmed up to 170 degrees at all testing. - The AFR(post graphs later) at WOT for my dyno run averaged 13.5:1 (14.0:1 left and 13.0:1 right) with these settings. No detonation occured, but I freaked. I FREAKED OUT (sorry to yell) I'm not a bright man, but I know beyond 13:1 AFR is lean at WOT. Lean is mean, but I don't want to make power with cracked pistons (going out in flames of glory). This confirmed two things 1. the left bank was leaner than my right, and 2. that I was lean as hell. I had built a spreadsheet yesterday morning using the WOT dynotuner excel file that I made with John Lamb's help. Using a PEvsCool constant of 16 I had original PEvsRPM, Dyno AFR and the corrected PEvsRPM value needed to get a desired 12.5:1 or 13.1:1 (wanted to test both) Changes: Cylinder Balance: I changed the off-idle cylinder balance table to richen the left side by .01 - Results: nothing, the AFRs were still split by 0.5 AFR, I later tried to richen the left side by .02 and lean the right by .02, this still did nothing, so I can say the following: 1. either the off-idle cylinder balance table is not used in WOT mode, or the changes have to be larger to get the two banks in synch. I even set the tables to all 1's like the 1994 flashes, this gave me exactly the same split between the two, so I have to wonder if these tables are used, or if other ones are. More experimenting later. I will richen the left bank to get my BLM's to match up, and share how much change that takes. I did the calculation on each cell in the PEvsRPM using the dyntuner and it took a major change of 7 percent to lower from 13.5:1 to 12.5:1 - I could have just changed the PE vs. Cool table, but I made that a constant in my experiement. So some of my values went from 0 to 7, or 7 to 14, etc. I was suprised so much a change in percent was needed but then the results surprised me even more: Enrichening the tables by a value of 8 across the board corrected the net AFR from 13.5:1 to 13.0:1, so in fact the real world change takes twice the value change that my spreadsheet had given, but it was exact. I changed the values up by 14. The R/L cylinder balance split remained of course. so I shot for an average of right and left of 12.5:1 The whole time I expected to get major changes on my Torque/ horsepoewr readings, but as the AFR lowered to the desired 12.5:1 my torque/ horsepower lowered 2-3 hp/lb-ft as well. Hence the term "lean is mean" but I prefer not to race 13.5:1 in a 11.4:1 compression 3800 lb car. I ended up averaging 12.5:1 between the two banks, which I feel will lean me slightly on the street, since the dyno drum is like 500 lbs less than my car. I was not able to richen the left side to match the right, but I will try more major changes in the future, too rich is always the safer way to go. In summation, I have a bunch of graphs and charts to share, but it will take a little time to analyize it, I will share more later if people find this interesting. -Christian (I ended up just over 300 ft-lb torque and right under 300 rwhp with a 11.4:1 HotCam, so needless to say, I'm not bragging, stock heads are killing me, more experiments to follow.)