Stratified’s fifth revision to a custom E30 tune is installed and produced the results shown in the following charts. The revision five results are compared to revision four. The dashed lines are Rev 5, the solid lines are Rev 4.
Boost onset is slightly sooner, but this is most likely a result of logging on a cooler day. IAT is about ten degrees lower during Rev 5 logging than with Rev 4.
Interestingly, despite being a cooler day and running the same boost the WGDC is slightly higher from about 5800 RPM on with revision 5.
Air-to-fuel ratio is remaining similar.
Timing is still showing that traction is an issue. Notably I did try lowering the tire pressure to around 28 psi from the normal 38 psi range, a follow-on from the Tire Contact Patch test. That did not resolve the traction issue.
Here’s what is happening to the measured speed, in areas along the line where the value jumps around there is a loss of traction:
The wheel spin is apparently causing the timing inconsistencies.
Here are a few Rev 5 acceleration times shown with the green bars. With traction problems seeming to cause timing drop it is no surprise that the overall acceleration time is getting worse as the tune is further refined.
The pull data was combined and then used with the Virtual Dyno program to generate the next chart.
Looking into the slightly higher WGDC, one hardware change made between the Rev 4 and Rev 5 was to swap intercoolers between an IE v1 paired with Majesty FMIC (Bicooler), to an APR IC.
Comparing the compressor outlet pressure and manifold pressure for these two configurations in the next charts:
The APR IC is producing about 3 psi of pressure drop at the point that I let up, where the combination of the IE+Majesty is producing about 1.25 psi of pressure drop at let up. This difference in pressure drop seems to be the likely source for the difference in WGDC.