ORIGINAL:
I remember a few years ago the hot engine for War Bird racing down here in AZ was the 120SC on 30-40-50% nitro and it was making huge power in the Top Flight 60 size war birds like the P-51 and P-47.
Recently, the hot engine for Warbird racing in AZ has been a YS 1.20 bored out to take a 1.40 sleeve making it a 1.34. It also has some mods to improve breathing. Running on 80% nitro, it is an awesome engine.
Only problem is that after about 30 heats, a minor problem occurs: