Justin Fivella
April 6, 2013

If you grabbed our all-Fox-body special issue, '79-'93 Mustang Performance, then you're already familiar with our emissions-friendly '92 SSP coupe. But for those unfamiliar with the mean and green project car, here's what you missed.

Many projects are built with little or no regard for emissions compliance—we're as guilty as anyone. But for those who are tired of looking over their shoulder for non-emissions-compliant parts and sweating come smog time, we're here to help. It was time to ditch the long-tubes, cat-less mid-pipes, race heads, and big cams. After all, in a smog state those parts are guaranteed to fail tests, and it can cost thousands of dollars in fines if you're busted.

If off-road-use-only parts are the least of your worries, consider yourself lucky. Last we counted, there were over 10 states with emissions testing. California is by far the strictest. The bi-annual test (as of this writing) requires many cars pass both a visual and “sniffer” test. The visual test means all smog-related parts must be intact, like the smog pump, EGR, and so on. Aftermarket parts must have a California Air Resources Board (CARB)-compliant certification. Even though some parts might not increase tailpipe emissions, without a CARB-compliant tag they're deemed illegal. As for the tailpipe emissions, vehicles are strapped to dynos and driven at predetermined speeds, while an exhaust-gas analyzer reads the level of CO2, NOx, and other particles. If it's too high in any category, it fails. Get a Check Engine light and you're done. If you move the cats downstream, delete a pair, or use non-CARB compliant versions, you'll also fail.

Instead of dodging and ducking, we played by the rules. That means running CARB-legal components, which is harder than doing it with non-emissions-friendly combos. We were certain big power and clean emissions was possible, we just had to find the right combo.

The Car And The Plan
Our weathered '92 SSP coupe sports a radio-delete, no A/C, and only power mirrors. It was a stripped-down stick car, just the way we like our Foxes. It featured a Cobra intake, throttle body, and Crane roller rockers, along with a K&N air filter, FRPP shorty headers, BBK catted H-style mid-pipe, aluminum driveshaft, and a few other mods.

Along with baseline dyno and track runs, we first tested the low-compression-boost motor without the blower on the dyno and at the track. Many gearheads have done the same, since laying down money for a motor and blower in one hit can be tough. For those wanting to drive their car before adding the blower, here's a good indication of what you'll see.

The latest addition is a custom SCT chip/tune from Bob Kurgan. We ran the car the old-school way, with the MSD boost-timing module (BTM), the adjustable fuel pressure regulator, and a good ol' timing light. We wanted to see how the car would perform with these parts before wicking it up with a dyno tune.

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