on the engine designer, when you go to manual test mode where you can run the engine with the slider
a button on that screen to open the rpm limit to 12000, one of the reasons i use this test screen is to see how fast i can run the engine with the given parts
That… is actually quite a good idea. I’ll see what we can do. Plenty of spare UI space in the testing screen so could be quite workable.
A bit like Alfa Romeo did with the DTM v6 they had. Max rpm in race was 12k, on the testbench they tortured it to 14.5k rpm. 
I support this idea! Save me some tie of finding the perfect RPM limit without breaking down 