I am familar with the HB engine both with and without Perry Directional Porting. However, what or is there a difference between the PDP written in RED and PDP written BLACK?
Also what was the difference in the Blitz and the regular PDP?
I know the Blitz had a black head but never knew what else.

Thanks
Curt

I don't know the answer to your question, but I have one of my own...
I have one of the black head 40 pdp's and several of the standard head versions. I know the black head is a very strong engine, but the standard head engines aren't bad either.
These engines are big and heavy though, compared to today's standard, they are bigger and heavier than most 46's.

The 40 "Black" PDP has a larger crank than the "Red" PDP. It is a later model. As I also understand it, the "Blitz" models had a standard ring in a chromed steel liner, whereas the "normal" non blitz had a dykes ring.

I really like HB engines/ I think this question came up on the RC online site a few years back, and I think the answer was the Red has higher compression then the black.

I used to race the red PDP engines in the Pacific Northwest many years ago. We pylon raced all winter season, the races were at the Boeing Hawks Renton field. They were a class racer and we all ran 15% nitro and a Rev-Up 9-6. I broke the crank in one engine and most others had the same problem until the Black PDP came along.
Great running engine however.
Sparky