If ur asking what's the fastest engine u could put in the rc8 for fun then u could put in a stock os 28 and that would be just stupid fast. If ur looking for a good all around engine for that car get a ninja 21 it's hands down the easiest engine to tune and is fasst! I have tried alot of engines out n it's my favorite, however not to blowout Maximo's candle but in my experience picco engines can lead u to suicide when a beginner has one and doesn't have much tuning experience. I have not tried maximo's engines tho so maybe he knows how to workout those tuning issues. Look into the new js engines by Eb mods iv heard great things about them.