Apparently the "later" JDM B16A offered in the 92-95 Civic got a power bump to 170hp with a slight bump up to 116tq. This engine had higher compression (10.4 vs. 10.2) and revised camshafts. No idea what, specifically, was revised with them.
Sounds like it's already compliant to the regs to me. I'm betting that all the bits n pieces are the same general bits as the USDM one, so grind off the "B16A" off the block and ensure all the parts meets the US-specs and the STL limits (e.g. 11:1 compression, .425 lift valves).
Remember, STx has the "alternate parts source language just like IT. So if the parts are the same, we don't care about the source. The only time this becomes an issue is if the JDM version has something special like crankshaft/weights/etc.
There was also the B16B offered in Japan for the even yet later Civic Type R. This was a high zoot engine and, if I'm honest, I don't think that STL would benefit by including it into the ruleset.
I concur. I was looking into the history of that engine some time back and was VERY impressed with it, all while being really pissed we never got something like that here in the States. I've often given thought to replicating one of those cars, just for fun...white with ITR wheels, please.
What about the tranny legality?
Either the original transmission or an alternate transmission must be used; the alternate transmission must be from the same manufacturer as the vehicle (i.e., an Acura transmission may be installed in a Honda car). Alternate transmissions must be used in their entirety; any OEM gear sets that fit w/o any modifications to gears, shafts, and/or case are permitted.
Nothing in the regs limiting transaxles to US-market...
- GA
Edit: As I understand it, and very generally speaking, JDM engines were classified as B16A, without the number. US market engines got the number, such as B16A1/B16A2. If all the important bit are all the same (such as the intake manifold, throttle body, crankshaft and case, head casting, etc) then there's no need to request JDM/EDM approval. The parts are, functionally, all the same. The only time you need to be concerned is when the engine may have some desired equipment that was not delivered on the US engine and does not comply to the STL regs (e.g., bigger intake, larger throttle body, different-weighted crank, etc).