Hi Centaurus,
QRH speeds depend on density altitude and actual weight, plus runway slope and wind corrections. I don't get the point of your question. Maybe you are talking about QRH speeds and Runway tables speeds, that only depend on actual or assumed OAT. If you consider a very light B733 such as a ferry flight or a test flight you will get very low QRH speeds, probably V1mcg, a small Vr and a small V2. If you check your runway tables for you actual OAT (full takeoff thrust let's say) you will get much higher values. But you will also see that these speeds are calculated for the performance limited weight taken into account, that can be a field limit, obstacle, etc.. this weight will be obviously much higher than you actual TOW. So why using speeds that are calculated for a much higher weight and that do not consider density altitude ?