H22 is the 2.2L engine found in the Prelude. The first letter is the engine series and the last numbers are the engine size...for example (I'm not gonna include all of em),

H22 - 2.2L, Prelude
F23 - 2.3L, Accord
F24 - 2.4L, Accord
C30 - 3.0L, NSX
C32 - 3.2L, NSX
K24 - 2.4L, CR-V (i-VTEC)
K20 - 2.0L, RSX (i-VTEC)
B18 - 1.8L, Integra
B16 - 1.6L, Civic and Del sol
J30 - Accord
J32 - CL, TL
J35 - MDX, Odyssey, RL, Pilot

Then they have different variations of the engine like B18C2, which is the GS-R (170 HP) and the B18C5, which is the Type-R (195 HP). We're working on getting an engine chart up on the main page so bear with us. Hope I helped you understand a bit