Fellow third-genners:

Thanks for all the help during the building of my car. I just had my
final exam today (same day my oldest graduated from high school) ... my ZZ4 IROC passed SMOG. Here are the #'s

1. @ idle (800RPM)

Max allowed Avg. pass Mine

HC ppm 120 29 36
CO % 1.00 0.10 0.53


2. @ 2500 RPM

HC ppm 140 20 1
CO % 1.00 0.10 0.01

Just goes to show, we build the baddest, cleanest machines around. Future items are MSD digital 6, possible nitrous, a new driveshaft and spohn subframes (when the convertible model is
available). I just changed the rear to 3.73:1 - definitely noticable!

Thanks again.

 

You da man.

 

Thanks for the info man! I always wondered if it could be done here in CA. I didn't think the ZZ4 heads had the provisions for EGR. Now I wonder, will the LT4 hot cam still pass in that motor?

 

The ZZ4 doesn't have EGR passages so you tap into the headers and run a special manifold - a lot like the LT1 setup. TPIS, Scroggin-Dickey, Edelbrock have the manifolds.

Don't know about the hot cam, what I've told is that duration over 220 degrees can be problematic with respect to emissions.
Got this info from AFR.