actually the hard part is usually not to make the number on a dyno, the hard part is to make it useable everyday with acceptable amount of smoke and lag. that's where the hours seep in.. making a tune for high dyno number is the easiest thing ever. boost limit/durationmap. done. takes estimated under 2 minutes of calibration work on a PD/2260 to make 230hp, if the only thing what counts is a number on some dyno.
Agreed, and re: AFR, a lot of time is spent on the dyno properly calibrating the duration maps to give the right amount of fuel for higher quantities than are available on the stock duration maps.
It's one thing to just set the 60mg row to 60 degree duration (and completely decalibrate the file/trick the ECU), it's a different thing to get some good fuel scaling on the axis and extrapolate the stock durations to higher fuel quantities, and its a third thing to actually then calibrate exactly how much duration is required at different SOI points to get for example, 100mg, by measuring AFR, boost level, MAF and therefore calculate the actual fuel delivery vs what you requested it to do, adjust the file, upload over OBD, go again, rince repeat... Without calibration my extrapolated fuel quantities have at times been 3-5mg/stroke off!
I've seen countless "professional" tunes where the tuner claims the file will do 270bhp and the file looks like this:
I'm sure the file does do 270bhp but I'm not willing to use it! Looks disgusting.
I like the car to know exactly what is going on, make the tune like the OEM would with correct fuel quantities. I actually find getting a straight AFR line accross the rev range challenging on a PD. When you start trying to do this you have many more things to take into account:
- Diagnostic limits over 70mg to allow block 4 logging to tell you how much mg/st the ECU thinks it's putting in
- Diagnostic limits for MAP sensor and MAF sensor to read above 3 bar or 1250mg/st air
- Block 4 logging to tell you exactly what SOI and duration the ECU has decided to use once it has interpolated between different duration maps and IQs etc
- Calibrating the duration maps to give correct fuel quantities at different SOI points - bearing in mind the varying fuel injection pressure depending on when you start injection
- Fixing the boost/N75 after you have increased/decreased fuel where required to maintain steady boost levels
- Changing axis on N75 maps to give you additional "resolution" where needed - for example stock maps often jump from 2500 to 3500 on the axis - giving you no control over the important areas of a GTB2260 spool
- Playing with different SOI levels to find the most effecient way to deliver the fuel
- Playing with different static cam timing (measured as sync angle on block 4) to find the optimal timing between cam and crank
Doing these things can take up hours and hours of dyno development time, especially when you are flashing over OBD every time. However, once you have done it and the "backend" of the file (duration calibration stuff) is done... you have so much more flexibility in that you can start playing with torque limits, boost levels, AFR/smoke limiters, SOI points, and build a really good tune that is smooth, responsive, smoke free, low EGT, etc etc
Anyway, almost finished preparing a spare ECU with immo off and header pins instead of an EPROM chip which I can hook up to OLS300 and really speed up the calibration process. Just waiting for the header pins to arrive, they were difficult to source!
