So I've stumbled into the ownership of a 1992 Civic CX Hatch. I was really surprised to open the hood and find a D15B2 in it - the head is stamped PM3-16 (year stamp of 1990). [editing to add - manual transmission, 5-spd]

​​​I've found loads of debate over whether that head uses the same cam or a different one, if that head is stock for that engine, etc etc. I can't actually find... any concrete information. I'm not even sure if this belongs here or in the previous generation's forums. But I figured I'd start by asking the experts - what should I expect from this engine? Is there enough overlap between it and any other D-series that I can buy parts without concern?

I have no idea who swapped it, or the history on it at all. Obviously, I'll be tearing into it soon (as the clutch is shot and the gears don't exist) - will other D-series guides be relevant for this engine as well?

I apologize for the possibly dumb questions, but it seems to be an unpopular motor and I don't know what at all I'm getting myself into. I thought I'd prepared myself by reading up on the stock motor, lol. Thanks in advance

 

D15B2 and the D15B7 from a DX is pretty much the same motor. The difference was OBD so injectors and distributor.

If I recall the block, crank and pistons are the same and I am pretty sure the head is the same. As such, there shouldn't be much if any difference in camshaft as the combustion chambers are the same. Same water pump, timing belt, tensioner, crank pulley etc.

However, in your case, since it's swapped in, they would have kept the the OBD2 injectors and dizzy from the CX.

This of course opens up other questions. USDM CX or CDM?

 

It's definitely USDM, it's very... lacking. I'm glad most of the workings will be the same, it makes scrounging for parts much easier. The dizzy is very square, but that's about all I've noticed - my accomplishment for today was getting it to start, I haven't torn into it too far.
[editing to ask - how would I identify if it's using b8 mpfi or b2 dpfi? and how would I know if they kept the old distributor? it seems like a fairly sound swap but i have no idea what they did or didn't alter]

 

I ran a D15B2 in place of a D15B7 in a 94 DX for a long time. As TomCat said, those two non-VTEC 16 valve engines are virtually identical. I don't know what if any control differences there are iwith the D15B8 originally in the CX. Very likely you have CX manifolds, dizzy, etc. and only the block and head are D15B2. Is the catalytic converter attached to the manifold in front of the engine or is it underneath the car? The DX and EX had converters underneath, a system that flows better.

All USDM from 1992 on was MPFI. This is readily identified by there being four individual fuel injectors instead of a vertical throttle body injection system with a big round cover that says "Dual Point".

 

Since it's a USDM CX, the injectors will be a lower flow than what the B2/B7 requires.

Also check your ECU, if it's not a P06, then it's likely trying to run a 16 valve motor as an 8 valve. (Thanks for catching that @Chrisfrom1986 )

Those are the two areas you will have to swap out to make the car right for that motor as far as I am aware. Oh yeah, good catch by mk378, the cat in manifold instead of under the car.... That will be the other thing to swap out if you want it to run like a true DX.

 

Just thought I'd update yall - whomever put this engine in is an absolute moron, but it's been fixable thus far. Transmission is nearly out to replace the clutch, every bushing & boot needs to be replaced, and the spark plug holes were more oil than spark plug. Radiator overflow looks like it has oil in it, and the radiator fan is wired to a dash switch. I haven't gotten to checking the computer yet, but I'm willing to bet it's the wrong one so I'll have to hunt down a new one.

It doesn't have a catalytic converter at all, so I can't testify to whether it has the better airflow or not, but the exhaust system is its own headache. I wouldn't have gotten this far without your help, so thank you a ton.

 

The lack of cat is understandable. The CX had the cat on the exhaust manifold right up front where the B2/B7 motor it's under the car so better flow. They would have kept the manifold of the B2 and just hooked it to the existing under pipe of the CX.

Very much like I have done with putting a Z6 in my VX chassis.

No cat will work better on that motor than the cat on the manifold will.