This ever so popular 1.6 DOHC engine was introduced in late 1983, when Honda of Japan debuted the E-AT civic & E-AS crx. This motor was tagged “ZC” and was found in the higher end AT/AS models. Why Japan dubbed this engine the “ZC” still haunts me (and others) to this day. The US wouldn’t see this same 1.6 DOHC engine until 1986, when Acura first opened their doors with the debut of the ‘Integra’ line up. This first generation US Integra would contain this 1.6 DOHC engine, and become known as the “D16A1“. Of course, the US is wack in many aspects when it comes to the auto industry and we never received any 84-87 civic/crx’s that came equipped with this same engine, hence the reason for hybriding!!! In Europe, their version of the ZC/D16A1 engine was known as the D16A8 or D16A9 engine, and came in the same AT civic/AS crx models (lucky them!). To add to the chaos, there was also a JDM SOHC ZC engine that came about in 1987, known to the US as the D16A6 engine (but that’s another story). 

All U.S. 86-89 integra’s (RS, LS, GS) all have the same initial D16A1 engine design. Only slight engine changes were made between the 86-87 and 88-89 Integra models. The biggest difference between the two is wiring/ecu/& ignition. Remember I mentioned Vacuum Advance Ignition earlier? Well among Integra’s, only the 86-87 Integra’s use this Vacuum Advance Ignition system (just like the the 86-87 Civic/CRX Si models do). This is a big reason why 86-87 D16A1’s electronics & wiring are compatible (plug n play) with 86-87 Si’s. Whereas 88-89 D16A1’s electronics are not — you cannot carry over & use (plug n play) the OBD-0 ecu/wiring/ignition system that 88-89 Integra’s have into an 86-87 Si. It’s just not compatible. But, you technically can convert an Si to OBD-0, but it’s an enormous pain in the ass and I don’t suggest doing it unless you’re the adventurous type and love playing with wiring. 

Normally, the browtop ZC & D16A1 engines are a dead ringer for having Vacuum Advance Igntion (VAI) systems, which were pre OBD-0 engines; blacktop’s being OBD-0. So, when purchasing a motor for your 84-87 civ/crx (especially for an Si model), a rule of thumb would be to look for a browntop ZC/ D16A1 engine if you don’t want to run into ignition & wiring incompatibilities. Of course, it is possible to convert an OBD-0 blacktop ZC/D16A1 to a VAI system by simply removing the OBD-0 components and replacing them with VAI components. Doing this will allow you to take advantage of an updated and slightly more powerful ZC/D16A1 engine.

There are 3 continental versions of this 1.6 DOHC engine:

I’m not too keen on the history of the Euro D16A8/9 engine (I’m learning!), I assume it ran along the same timeline as the JDM ZC. On a side note, in the U.K., there’s an automotive company known as Rover which had a line of coupes that went by the name of 416GTI, which used Honda’s D16A8/9 engine. Visually, it looks identical to a ZC engine, but what makes it different from the Honda version is the unique valve cover it has seen here:
 Rover Coupe 416 GTI engine (pics stolen from an ebay ad)
Pretty weird eh? Kinda reminiscent of a an 84-87 Si’s SOHC valve cover! I’m not sure how long the Rover coupe lifespan series lasted.  

Rover had other coupe models that shared Honda SOHC D-series engines as well. A fella by the screen name of Ben_K on the D-series.org forum has kind enough to share some detailed info on the Rover SOHC & DOHC coupes. Here’s what he told me:

The first generation of this 1.6L DOHC engine (JDM/US/EDM) all had a 4-bolt brown colored valve cover, which overtime has been nicknamed “browntop” by Honda enthusiasts. The browntop ran for about 3 years in Japan and 2 years in the US and ?? in Europe. 
 Browntop valve cover(s) ZC & D16A8/9
 Browntop valve cover U.S. D16A1

Browntop ZC/D16A1 engine specs:

Then, sometime in 1987-88, Honda made a few updates to the browntop engine… 

Changes made to the US D16A1 engine in 1988-89:

Changes made to the JDM ZC engine in 1988-91 and 92-95 ZC: