mazda compression question

my buddy just put a 2.2 out of a 626 he had laying around in his backyard in his truck. he just used the shortblock. the head he used was a 2.0 head. he reported to me that this thing screams like a wild banshee and is faster than any mazda hes ever driven or rode in. what could have happened here? did the smaller head chambers cause some kinda weird performance gain?

The shortblock out of the 12 valve 626, MX6, and Ford Probe is exactly the same as in the B2200. The cylinder heads on the B2200, B2000, and the old 8 valve 626 are almost exactly the same, there is no difference in combustion chamber size or the valves.

Even if the compression ratio was increased the horsepower gains from compression maxes out at about 2% per point of compression. Since the stock compression is 8:6:1 even if it was raised to 12.6:1 your only looking at about a 7 hp gain and there is no way your getting the compression that high without machine work or aftermarket parts.

It was probably just a strong shortblock.