yo87_racing
New member
yes I know, but strictly talking about engine safety, using lower or higher soi....
Is it safe to advance SOI on a PD?
- Thread starter martin33100
- Start date
TDIMeister
Phd of TDIClub Enthusiast, Moderator at Large
You can't tell much from a rolling road dyno session other than to find MBT (minimum advance for best torque). Some people ignore the "minimum" part and just go for absolute best torque lol at their peril.
Cylinder pressure measurement allows pinpointing the 50 percent MFB (mass fraction burned), which has been found in many engines to coincide with MBT at about 7 degrees after TDC. Additional math of the cylinder pressure data allows determination of the dP/d_theta (the rate of pressure rise per degree crank angle). Generally you want to keep this under 10 bar/deg to keep combustion noise reasonable by managing the premixed part of combustion that QuickTD alluded to, in contrast to the diffusion combustion phase that is constrained by the fuel evaporation and mixing rate.
Cylinder pressure measurement allows pinpointing the 50 percent MFB (mass fraction burned), which has been found in many engines to coincide with MBT at about 7 degrees after TDC. Additional math of the cylinder pressure data allows determination of the dP/d_theta (the rate of pressure rise per degree crank angle). Generally you want to keep this under 10 bar/deg to keep combustion noise reasonable by managing the premixed part of combustion that QuickTD alluded to, in contrast to the diffusion combustion phase that is constrained by the fuel evaporation and mixing rate.
