Turbo Performance Bug in Beam Exporter

I’ve been absolutely loving the Beam exporter so far, but I have also discovered an issue with turbo engines.

While testing 2 variants of a 1.3L light sports car, I noticed that the faster, turbo version was quite the opposite in Beam. After messing around a bit, I brought up the engine dyno app in Beam and did some pulls using each car. I found that while the N/A engine mimicked Automation’s model pretty much exactly

Figure 1a

the turbo engine appeard to have its entire power/torque curves scaled down by a third.

Figure 1b

For thoroughness, I also exported another car that had a properly set up N/A and turbo version (this one a 4.6L V8) and got similarly skewed results. Again, the N/A lined up perfectly.

Figure 2a

But this time the turbo version was 25% more powerful than it should have been.

Figure 2b

Does BeamNG do its own different calculations for turbo performance, or is this an issue with the way the exporter is saving the engine data?


I had the same issue and posted a thread on it. It’s based on boost, so high boost cars for me have about 30% loss, and medium boost about 10% loss.

I think it’s a Beam calculation issue. I’m not certain if it’s proportional to boost or simply a difference in the “torque coefficient” method. The issue is known to the devs though I’m not sure exactly how they resolve to fix it.