Originally Posted by
trapper7
The PDP letters are black for the standard PDP engine and the PDP blitz will have red PDP letters I believe. You can tell which version you have if you look at the piston ring on the piston through the exhaust port. The standard engine will have a Dykes ring which will be at the very top of the piston. The Blitz engine has a chromed steel liner (harder to tell the difference) and the piston has a very narrow standard compression ring down a couple millimeters from the crown. The pic below is a PDP Blitz piston/liner as well as the HB .61 Dykes. The Blitz is a little more powerful than the standard PDP with dykes ring, but generally dykes rings are better for higher rpm duty.
The breaking in routine is the same for both, but how you prop the engines will be different. The Blitz you'll want to prop a tiny bit lighter than the standard PDP. I'd suggest a 10x5 or on the high side a 10x6.