Im looking onto buying a 91 civic si with a stock zc non vtec sohc motor swap in it. I asked the guy for a copy of the smog papers which are shown below. The question I have is the car barely passed the 15mph test but on the 25mph test the car did extremely well. What could be the cause of it?

 

It looks normal for the 1.6l. The cat takes a while to warm up and it was still warming up @ the 15mph..

Just so you know, the test has what is called fast pass. What the system does is it set's the max allowed numbers and when the numbers drop below the max allowed number for 5 seconds the test fast passes to the 25mph.

The tests are not showing you the final numbers. Just that the numbers are lower than allowed.

Now what I have to ask is does the car have a BAR label for the ZC motor. Because the ZC is not a USDM motor. It should be illegal to smog unless you have a BAR label. If no BAR label then you might have a hard time smogging it. Also some referee's will BAR label it some will not. This is a gray area and has been discussed before if you want to search this site you will find more on this topic.

 

You don't need to bar a sohc zc. The sohc zc is a jdm replacement motor for the d16a6

If you're going to bar an engine let it be a b18 or b16.

IF they see it's a jdm motor and won't pass you for that. You just have to swap your intake manifold for the usdm one.