Being impressive means making an impression. Whether you are a fan of performance or aesthetics, making an impression comes down to the fine details. Paying attention to the details and being precise and deliberate about the building and tuning of an engine can be the difference between respectable power and a ground-breaking performance. Style-wise, checking the fine print when addressing paint and polish as well as dreaming up modifications and treatments that have rarely, if ever, been seen help elevate status. A problem with such intense concentration is that it can lead to tunnel vision where a single aspect is scrutinized exclusively. Performance dominates and style doesn't even get a second or third thought, or style is prevalent, but there is nothing under the hood but road dust. True visionaries are able to focus on all aspects while keeping their quality standards high. There are less than a dozen of these elite tuner/fabricators out there and Alex Chen of SP Engineering is definitely part of the club. Over the past two or three years, we have featured many of his creations in these pages. Including Andrew Chu's wicked RX-7, he has landed two covers in 2001 and this is only the eighth issue. Why is this? His street cars make big power while looking like museum pieces.
It is a given that one cannot be an expert at everything. This is true with Chen. When it comes to bodywork, he finds someone with similar high standards. He has a few avenues to pursue, but for the RX-7, he enlisted the skills of Kevin Blakely. Blakely had a hill to climb; the Mazda was slated to wear crazy eye-popping R.E. Amemiya flared body armor. The kit was so finely molded onto the car, it looked like sheetmetal stamped at the factory. The transitions between kit and car are seamless and the wild Lambo orange paint was applied so carefully it looks like the Mazda is still wet.
The Mazda's sparkling 13B illustrates that the engine bay is where Alex and SP are most at home. The list of polished pieces is a long one with some of the more notables being the radiator and mounting bracket, GReddy intake plenum, piping, alternator, catch cans, turbo shield and, of course, the twin turbo system. The weapon of choice is a package featuring twin 2835R GT series turbos with .61 A/R compressor housings and 56-trim compressor wheels. HKS Racing wastegates and a Blitz i-D SBC controller rope in boost to a conservative 19 psi. A custom 3.25-inch SP downpipe ensures the turbos can spool to their heart's content, while a Blitz front-mount intercooler puts the chill on the charge.
Fuel enrichment is handled by a Cosmo in-tank pump, -6 Earl's lines, a custom fuel rail and SX regulator. The staged fuel injection set-up consists of 850cc primaries backed by two 720cc secondaries, all controlled by a HKS AIC. The stock ECU is still the main engine management component, but it has been ROM-tuned by SP Engineering for maximum efficiency. On the spark side, an HKS Twin Power amplifier boosts current to a set of NGK plugs by way of Ultra wires. SP's Jason Reinholdt grafted the fuel and ignition components into place.
Power meets pavement through the stock Mazda gearbox, an O.S. Giken clutch and flywheel combination, a carbon fiber driveshaft and a trick Japan-spec R.E. Amemiya rear-end with a 3.73:1 gear ratio. G-forces are subdued by a Tein coil-over system. Tein Circuit Master RA Type suspension system. The Tein system consists of four shocks, four main springs, four helper springs, spacer spring seats, thrust washers, bumper cushions, dust boots, upper pillow ball mounts, height measuring gauge and damping adjustment tool. The dampers are aluminum bodied mono-tube designs that utilize large diameter piston rods and big piston valves and feature 16 points of adjustment. Racing Beat bars add further stabilization to the suspension, which sees a good deal of g-load when the proper conditions present themselves. Brembo four-piston calipers put the bite on big drilled rotors, enhancing Chu's confidence when heading into a hairy apex or panic stopping in traffic. With the labor-intensive body tuning performed on the Mazda, upgraded brakes are excellent insurance policies.
Chu's RX-7 will be tuned as a driver delivering its power at a conservative 19-psi. Since Chu was out of the country when this article went together and the Mazda's registration lapsed in the interim, the engine could not be properly broken in. As a result we have no dyno charts to illustrate the the car's bottom-line power. If things line up properly we hope to bring you the tuning portion of the story at turbomagazine.com.
The orange hue of this Mazda is loud, so is its 13B at full song, but the RX-7 really screams of craftsmanship and, like our duo of old schoolers on last month's cover, this rotary flexes upper echelon craftsmanship in spades.