swap research, please help

[civicpadawan]

I recently purchased a 1990 Civic HB, (ed6, standard model?). It has the stock d16a6 with five speed manual transmission. After some research, I think according to my budget and what I want from the car, the dohc zc 130hp seems perfect. What confuses me however is that everytime I think I come across a solid "how to" help guide, there are so many variances. The engine will bolt right on, yes. I already have the dohc zc ecu and transmission, (another reason I chose the zc. I already have a good start!), but that is where there seems to be alot of different opinions. What changes need to be made to the stock car for the transmission and ecu to work? I can't find a clear answer on this. Thanks for any and all help!

 

[CAFROG]

There may be a few different ways to deal with a ZC swap but I know you should use the engine harness for the DOHC ZC

If I'm right and the D16A6 is the Si motor then you may be able to use that harness but I'm not sure.

Make sure you get all the ZC motor mounts. You may be able to use some of the D16A6 mounts but I'm pretty sure you will need at least a few ZC mounts. I would get the ZC ones for less headache.

I know there are others on here who know the EF chassis and ZC swaps better than I do.

The ZC is the easiest swap for your chassis so you should be fine after a few more guys chime in.

 

[cjvictoria]

The D16A6 is the Si motor. You were right CAFROG. IDK about the harness though.

 

[jlicrx]

if the DOHC ZC is the 88-91 OBD0 model from the JDM CRX/Civic Si, it will bolt right in without any modifications - ZC and Si mounts are the same - use the Si engine harness on the ZC - you will need to make a minor wiring change at the distributor (see attached) - everything else on the harness plugs right in - to use the ZC transmission, you must have the JDM ZC intermediate axle shaft and you need to use 90-93 Integra axles

 

[civicpadawan]

you are exactly right jlicrx, just heard back from the seller. All I need is that shaft and I'm ready to drop. Just curious though...if I were to only put the zc engine and ecu only and use the stock transmission, (in case the shaft is difficult to find), are there any differences power wise?

 

[jlicrx]

you are exactly right jlicrx, just heard back from the seller. All I need is that shaft and I'm ready to drop. Just curious though...if I were to only put the zc engine and ecu only and use the stock transmission, (in case the shaft is difficult to find), are there any differences power wise?

if you have the Si transmission, it will be a little quicker on acceleration in 1st thru 3rd gears due to the lower final drive gearing of the Si (4.25 Si vs. 3.88 ZC) - the ZC transmission has lower individual 2nd thru 5th gears than the Si, which results in less rpm drop between shifts and this somewhat makes up for the difference in 2nd and 3rd - 4th and 5th in the ZC, even with the higher final drive gearing, is lower than the 4th and 5th in the Si which results in higher rpms when cruising in 4th or 5th with the ZC - we have run both the stock Si and the stock ZC and there isn't a whole lot of difference in the overall performance - the best option is to swap the Si final drive gears into the ZC transmission which results in all of the 2nd thru 5th gears being a lot lower