D16Z6 installation and OBD0 (88-91) to OBD1 (92-95) wiring conversion. By Kurt_W This conversion to an 89 CRX Si. List of the parts used/modified: 1. One slightly used 89 CRX Si 2. 93 D16Z6 (further known as Z6) 1.6L SOHC VTEC 3. Partial engine harness from the 93 D16Z6 and harness parts from a 92 Civic DX auto 4. 95 Civic EX P28 ECU (manual) 5. 92 Civic Si distributor 6. #4107 fuel injectors years unknown (will remark more on this later) Remarks on installing the D16Z6 itself. Installing a Z6 itself is pretty close to dropping a D16A6 (a.k.a.A6) engine in. Alterations that need to be made include: 1. Replacement of the Z6 driver side engine mount with the one from the A6. The A6 mount has an “extra” piece  that wraps around from the front of the engine, it is shaped like an “L”. This “L” piece is not needed and for that matter, doesn’t quite fit on the Z6 (wrong angle). In order to get the timing belt covers to fit over the A6 mount, some cutting of the bottom cover is required. 2. The crankshaft pulley that should be used on the Z6 is the one for the Z6. The reason for this is that pulley is balanced for the Z6. The A6 pulley will fit but there is the potential for premature crankshaft bearing wear due to it not being balanced for the Z6. The belts on the Z6 pulley are of a different groove number then the AC and alternator belts off the A6, but it doesn’t seem to matter so long as the belts are tensioned properly. As for accessory over/under turning, no problems have been experienced in the almost 10000 miles put on the car since the swap. 3. Both the intake and exhaust manifolds used were from the Z6. The intake is ported specifically for the engine therefore logically it is best that it is used for the engine (as opposed to the A6 intake manifold). Slight modifications had to be made to the engine harness by transplanting some of the plugs off the 93 engine harness onto the 89 harness so that the intake sensors could be plugged in. Since the MAP sensor on the Z6 (93-95) is on top of the throttle body, it is necessary to extend the wires for the MAP sensor plug from the 88-91 location on the firewall to the top of the throttle body. The Z6 exhaust manifold is a 2-piece 4-2-1 design as opposed to the 2-piece 4-1 A6 manifold. The A6 4-1 fits the Z6, but there is no reason to use it as opposed to the Z6 4-2-1. 4. Clutch, pressure plate and flywheel…The 90+ setups have a wider surface area then the 88-89 therefore offering more contact area and thus more effective power transfer. The Z6 with stock clutch, pressure plate and flywheel will bolt directly onto 89+ year transmissions. It will not bolt directly onto an 88 transmission unless the proper 88 clutch, pressure plate and flywheel are used (due to the 88s having a different spline count on the input shaft). 92+ transmissions can’t be used due to them being hydraulically activated, and the mount positions on the 92+ transmission being different then the ones on the 88-91 transmissions. 5. The A6 alternator and AC compressor mounts bolt right onto the Z6 thus allowing the use of the A6 alternator and AC compressors. 6. The location of the coolant temperature sensor is on the back of the block for the 88-92 engines (88-91 A6 and 92 Z6) thus if a 92 Z6 is used, no relocation of the wiring for it is required. On the 93-95 Z6, the temperature sensor is on the thermostat cover thus the wiring for it will need to be relocated. These steps will get the Z6 into the car. If it is decided at this point to use stock CRX Si (A6) electronics, these steps will have to be followed: 1. Modification of the distributor mounts is necessary. Only the top and front mount legs on the A6 distributor will be used, as the rear mount does not match up to the bolt-in location on the Z6 head. Both of the legs on the distributor will need to be modified (cut or enlarged) so as to get the timing correct. Large washers will most likely be needed to make sure positive contact with the head is made. Make sure to put a new o-ring on the distributor where it goes into the head to prevent oil leakage. It is also necessary to use Z6 sparkplug wires. 2. As for fuel injectors, you must use the A6 fuel injectors with the A6 computer (PM6). To do this, simply replace the Z6 injectors with the A6 injectors. Here is another place new o-rings are necessary. The green o-rings on the fuel injectors should be replaced in order to avoid gasoline being forced out around the tops of the injectors, thus creating a fire hazard. 3. In order to use the VTEC, it is necessary to wire some kind of activation switch for it. Various methods can be used. For example an RPM activation switch or an adjustable shift light.  Use of a Zdyne One-Wire VTEC conversion ECU is highly recommended to ease this process. It will give enriched fuel curves for proper VTEC operation as well as allowing a user defined VTEC activation point and other features. At this point, the engine will run like an A6 but will be VTEC capable assuming an activation switch has been wired up. Back Next