Jess,


PDP is a feature of loop-scavenged engines, originally introduced by John Perry on the K&B .61 engines and later on the HB engines (both obviously with baffled pistons).

It consists of two louvers on the exhaust side of the piston-baffle, angled toward the baffle on either side, which introduce a cool, fresh charge into 'hell's kitchen', the piston's hot-spot.
This gives these old-tech, loop-scavenged engines the power of Schneurle engines, and extends their lives as well.

I am not sure if it is possible to have PDP ports, with TST (Travasi Super Tiger), some ST baffle-less engines have.


Can you post any good photos of the inside of those Blueheads?