Does anyone know what the stock horsepower output of a B20B that is factory equipped with a P8R head is as well as the compression ratio? What vehicles did these come out of and what years? From what I understand the P8R head was only available on some of the 96-98 JDM B20Bs and I am assuming the superior B20B head makes more power than the P75 head equipped 96-98 JDM B20Bs that are rated at 126hp. Looking to get some definitive answers here. Thanks.

b20Z is 145hp and 133 tq

There is no such thing as a JDM B20Z and all USDM B20Zs are equipped with a P75 head. Does anyone know what the hp/tq output and CR of a JDM B20B factory equipped with a P8R head is and what models they came out of?

The P8R came on some 96-97 JDM, and apparently some Russian Honda models. Which, I can't remember, but they are very rare.

The compression ratio would have been around 8.6:1, since it came with the P3F pistons (I cannot confirm, this is what I have read and researched, since my I bought my P8R separated from the block) and its 47cc combustion chamber.

Anyway, you should read the FAQ...

I can also confirm that the PHK pistons do NOT have large enough valve reliefs for the 33 mm intake valve on the P8R head. I would assume the same for the P3F, although with the dish, it shouldn't be an issue.

I still have plenty of room for cam movement despite this fact with the head shaved 0.030" and running Crower 403s. (+/- 10 degrees on both intake and exhaust cam).

I also forgot to mention that you will run into valve float if you order the Crower valve springs for this motor (part number 68181) since the intake valves are 4 grams heavier than the B18A/B counterparts. (My valves started to float around 7500 rpm!) I bought the springs used, so its possible that they were fatigued, but their measured specs were only VERY slightly below Crower's listed specs.

I would recommend using the 68182 spring kit from Crower, which has similar spring rates and pressures to the Skunk2 Tuner springs, and a few other manufacturers.