Muscle Mustangs & Fast Fords
1992 Ford Mustang SSP Coupe - Project Smog-Legal Killer
Our emissions-friendly, 11-second Fox-body gets an SCT chip tuned by a legendary tuner for serious power gains.
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.
The Right Parts
We started with a call to Coast High Performance (CHP), which offers the only smog-legal stroker short-block on the market, the 347e. Capable of 550 hp (or more with optional internals), it comes spec'd with a healthy cam (0.491/0.509lift, 212/222 duration, 112 LSA), and even has the paperwork to prove its legality.
The 347e sports Probe SRS forged 14.2cc dished pistons, a cast crank, and machined CNC beam rods. The 347e uses 5.315-inch rods instead of the more traditional 5.400 versions, which allows for pistons with a dry-ring design. This dry-ring design helps with seal and keeps oil consumption and emissions down, so legitimately passing smog for tens of thousands of miles won't be a problem.
We admit that an officer or a smog guy would have a hard time detecting a mild non-carb compliant stroker, but the CHP deal insures you'll legitimately pass. If you're already buying a stroker motor, why not get one that's smog-legal?
A stout stroker is nothing without free-flowing cylinder heads, so we opted for the new Air Flow Research (AFR) Renegade 195s. These big dogs feature full factory CNC porting on the intake and exhaust runners, as well as the combustion chambers. Big 2.05/1.60-inch valves with steep 20-degree intake valve angles help them flow 317 cfm at 0.650 lift—more than the outgoing 205 head.
These all-new 195 heads are emissions-legal, and have a 3⁄4-inch-thick head deck that's perfect for forced induction or nitrous. These high-flow casts come in 58cc and 72cc versions with 70cc exhaust ports, and are intended for 331-392ci motors spinning in the 2,000 to 7,000 rpm range. We opted for the 58cc versions; when paired with our Fel-Pro gaskets and the dished pistons, our CHP 347e arrived at a boost-friendly 9.6:1 compression ratio.
A call to Comp Cams helped solved our valvetrain questions with a cam, lifter, and spider valley tray kit. While the supplied CHP smog-legal cam is nice, its specs weren't ideal for our boosted intentions, so a Comp 284HR blower cam was our bumpstick of choice. With specs of 0.533/0.544 lift, 224/230 duration, and 114 LSA, it's better suited to our blown setup. The wider lobe separation, exhaust-heavy numbers, and the fact Comp's blower cams open the exhaust valves earlier than NA cams makes it better for boost.
Trick Flow 1.72 aluminum roller rockers and Comp Cams Hi-Tech pushrods were called to tickle the valves. The roller rockers necessitated tall valve covers and eventually a 1-inch phenolic spacer to solve our clearance problems.
We opted for fasteners from ARP and head gaskets from Fel-Pro. Some of the ARP goods included a 7⁄16-14 Pro Series head stud kit, 7⁄16-20 1.90-inch rocker stud kit, oil pump driveshaft, harmonic balancer bolt, and intake manifold bolts. As for the Fel-Pro lineup, a set of the Fel-Pro 1133 PermaTorque MLS steel head gaskets are beyond strong, as are the Fel-Pro intake manifold, valve cover, and header gaskets.
Other noteworthy additions included BBK 15⁄8-inch ceramic coated shorty headers, 75mm throttle body, 76mm MAF, adjustable fuel-pressure regulator, and catted X-style mid-pipe. Summit Racing Equipment stepped up with a Trick Flow Street Burner intake manifold, 255-lph fuel pump, 42-lb/hr injectors, water pump, and plenty of other bits like the Summit harmonic balancer, FRPP timing cover, Milodon oil pan/pickup, and Meiling oil pump.
We turned to Rankin Performance Machine for the build since an all-star list of parts is easily wasted with a lackluster assembly. Owner John Rankin assembled the new bullet with the utmost care, making it easy to see why they're known for some of the fastest engines on the West Coast.
A Spec Stage 2 clutch was called into action to feed the power to the pavement through a set of sticky Mickey Thompson ET Radial tires. The combo worked well on the street and offered enough bite to snap a stock axle. Of course, the stock hood no longer fit, so an Auto Metal Direct (AMD) aluminum 2-inch cowl hood sealed the deal. AMD sells the only aluminum cowl hood that weighs a scant 17 pounds, less than half the stock piece, and still uses the factory hinges and hardware. It's light as a feather and fits like factory.
Last but not least was a Vortech V-3 Si self-lubricated supercharger kit. This giant snail is capable of 1,150 cfm, 22 psi, and 750 hp. The high-output kit comes pullied for 10 psi and is packed with everything needed to build boost, like a fuel management unit (FMU) and T-Rex external fuel pump.
The installation was easy, save for the tall valve covers that necessitated Rankin Performance fabricate a new throttle linkage. This also meant the supplied intake connectors didn't work, so silicone 90-degree elbows from Turbo Hoses and a little more fab work from Rankin Performance had us sitting pretty.
Since we opted for 42-lb/hr injectors the supplied Vortech FMU was deemed unnecessary, but those running smaller sprayers should stick with it. Instead, the BBK adjustable fuel-pressure regulator (FPR) was boost referenced at a 1:1 ratio, so we kicked up the base pressure and let the FPR take care of the rest.
We paid a visit to BRG Racing in Pacheco, California for dyno time and tune tweaking from KC Cager and Chris Doig.
In stock form, our 272,000-mile SSP stick coupe laid down 226 hp and 270 lb-ft to the tires on its Mustang dyno. Torque production was stout, but the show was over above 4,500 rpm—it was out of breath.
The combo performed admirably as it churned out 313 hp and 340 lb-ft for total gains of 87 hp and 70 lb-ft over the baseline. The boost motor made huge torque from 3,300 rpm to redline where it never dipped below 300 lb-ft. A proper NA motor would have a bigger cam and more compression, but our low-comp boost motor still had a pancake-flat torque curve from 4,500 rpm to redline.
Finally, the moment we'd been waiting for, the boosted pulls. Armed with nothing more than a timing light, the MSD BTM, and the BBK FPR, Chris Doig of BRG Racing tweaked our little boost coupe to the tune of 422 hp and 419 lbft at the tires on 91-octane pump gas with 10 degress of base timing. The gains over the NA 347 combo were 109 hp and 79 lb-ft with total gains over the baseline ringing in at 196 hp and 148 lb-ft. The AFR was a fat 10.8:1, but without being able to read the timing properly, it was a safe bet for our track outing the very next day.
Equipped with worn Lakewood shocks, Eibach Drag springs, 3.73 gears, stock axles, a weathered differential, and a crusty T5 that prevented hard launches and powershifting, our baseline run produced a best of 13.79 at 101 mph. There was little drama, as we simply ousted the clutch, matted the gas, and shifted at 5,500 rpm.
With the boost-friendly motor running in naturally aspirated form, we again hit the track and came away with a best of 12.71 at 109 mph for a total drop of 1 second and 8 mph.
We returned to Sacramento Raceway for the third time with the Vortech V-3 Si strapped on and ready for boost. With the worn-out T5 and stock axles ready to blow, we avoided hard launches and power shifting. Instead, we rolled off the line and put it to the wood. As for the shifts, we lifted for fear of scattering the T5's guts all over the track.
The result? A slow first eighth followed by a big backend surge. In just 11.99 seconds at 121 mph, the boards flashed and the little coupe was crossing the stripe. Boost rolls in around 3,000 rpm and by 4,000 rpm it's getting serious. In fact, the worn-out differential had the one tire spinning on the 2-3 shift even with the ET radials aired down.
Truthfully, there was a lot more left in the combo with a prepped drivetrain and a better tune. What initially felt like a complete project was unknowingly just getting started.
More In The Bag
While we were excited about our smog-legal LX, the sense of accomplishment soon wore off and 11.99 wasn't enough. With proper drivetrain parts and a few more motor mods, 10-second e.t.'s were within reach. With that said, welcome to the new ground zero. A lofty goal indeed, but worth a shot.
We decided a proper dyno tune was in order. A quick call to SCT unearthed a Switch Chip, which allowed us to custom tune the ol' EEC-IV much like you'd tune the modern Mustangs. In addition to features like an easy install and a built-in anti-theft mode, the SCT chip has the ability to flip between up to five maps with the optional Dial Selector. This means you can flip between race gas, pump gas, nitrous, and valet modes with the turn of a dial. But deadlines were upon us and there was only enough time for one custom map, a 91-octane pump-gas "kill mode" tune from Bob Kurgan of Kurgan Motorsports.
"Many people no longer like to tune the old Fox-bodies, but it's where I got my start. I have so many years of experience with them that I understand a lot of the tricks needed to get them running right," Kurgan said.
Bob Kurgan ggot his start in the late '80s and has literally tuned thousands of Mustangs in the 10 years he's been tuning at the professional level. Kurgan took his knowledge from his years as a racer and applied it to building and tuning badass Mustangs. So when we heard he was coming to the West Coast to visit BL Motorsports, it made sense to reserve some dyno time.
On the morning of the event, there was a last-minute venue change to the Dynojet at Advanced Engine Development (AED). After driving 110 miles, we hit the rollers for another baseline. We opened the day with a Hail-Mary run after the car had been sitting for over an hour—472 hp and 516 lb-ft. After a succession of pulls to bring everything up to temp, our new (and more accurate) baseline settled in at 451 hp and 510 lb-ft at the tires—not bad for just an old-school tune.
It only took but a few runs to dial the perfect AFR and ignition timing. Our baseline pull was pig rich at 9.0:1, so Kurgan leaned it back to 11.0:1. While that might still seem rich, Kurgan explained that he tunes forced-induction street cars on the conservative side. The extra fuel not only cools the combustion chambers, but it also leaves some wiggle room in the event the car leans out. On a race motor where max horsepower is everything, he explained they'll run 'em hard and run 'em lean just like an NA setup.
Speaking of lean, with Kurgan's new tune, our little boost coupe was making so much power that the Summit Racing 42-pound injectors were at 100-percent duty cycle near the upper end of the powerband. There was still enough capacity in reserve at 11.0:1, but larger injectors are in order.
Kurgan left the base timing at 10 degrees, but instead of using the MSD BTM, he used the SCT software to add 16 degrees of timing at peak torque and 19 degrees at peak horsepower. The results were spectacular as the coupe shot to 512 hp and 550 lb-ft at the rear wheels through shorty headers, a catted H-style mid-pipe, while spinning the smog pump and whirling the stock mechanical fan, all on 91-octane fuel.
"The heads and cam really helped the blower since those are good numbers considering the emissions-friendly restrictions, the 91-octane gas, and the 10-psi pulley," Kurgan said. "There's certainly more left in it by adding a Power Pipe, a larger exhaust system, and a smaller pulley, but the stroker setup is making substantial torque," he added.
There's over 500 lb-ft from 3,500 to 5,300 rpm and over 500 hp from 4,800 to 6,000 rpm. Kurgan's chip tune picked up power and torque from idle to redline, and the first drive proved the driveability was also improved. Kurgan utilizes the SCT chip's extreme versatility to add such things as an "anti-stall feature" that holds the idle up around 1,200 rpm until the car is under 4 mph.
"I use this on many of the highly tuned Fox-bodies since they want to die when you turn the wheel or have the A/C on. This way they'll keep running no matter what," Kurgan said.
How's that for cool? The car now has factory-like drivability and it pulls infinitely harder. A romp in Third Gear has the ET radials fighting for traction.
For now we'll enjoy 512 hp and 550 lb-ft of smog-legal power, but hang tight because now that we have a proper tune, we're going to beef up the drivetrain and suspension. Our eyes are set on a well-rounded Fox that's emissions-friendly and still stops, goes, and turns with the best of them. We're just getting started.