Yes, you have to manage it. There are no limiters. For a while I was surprised, but Woochoo pointed that out, and he was correct. Now I don't remember from when did rev limiters begun, but I know Porsche 917 still didn't have them. Woochoo has placed graphics on tachometers, which are marking healthy rpm limits. Once you drive over these rpm limits you are damaging your engine, the higher above you go, the quicker you are loosing life of it. There are some cars that are ok to cheat slightly, for example car that takes place of GT40 MK2, normally you can overrev 1st and maybe 2nd for better acceleration, as long as you are overreving for a a second or two, but not more if you would like to finish 24h of race.
****rant time****
I have that pdf manual that points out a lot of stuff too, which I never shared, I'd like to share it with an update. I also keep on working on them cars, but I am beginning to doubt if I should share it, maybe will just keep to myself. It seems like sharing so far didn't bring as much joy as I expected, sometimes it is opposite. I don't think people are discovering it as much as it is worth it. I spend loads of time on it. Of course, as I get the cars better, they get more chances to get some more love, but otherwise it will just also make me more sad if they'll go under radar or unloved, not meeting expectations which in some cases are wrong, historic simracing community becomes less united, smaller and more chaotic and fragmented as time goes by, it is sad, and I probably shouldn't expect to be welcomed to it as most of my "haters" are also historic race cars simracers, it is a sign to stay alone. I'd like to share videos of me driving them, but it takes time to capture, process and upload them, and who has time and interest to watch me