Fuel enrichment is provided by a quartet of 850cc injectors, which are fed by a Rotary Performance competition fuel pump. An SX regulator monitors and maintains correct fuel pressure. Fuel management is actually overseen by two computers, the stock Mazda ECU and Haltech Fuel Management computer. The Haltech unit is normally used as a stand-alone ECU replacement. To keep this car street-legal, Rotary Performance linked the two together so the Haltech computer controls air/fuel ratios and ignition mapping while the RX7's ECU handles emissions-monitoring duties The ignition system has been upgraded using Jacobs Electronics' Rotary Pro Pack, Jacobs Performance Coil, and NGK wires and plugs.
With the necessary performance components in place, Rotary Performance turned its attention to the second part of the quest for true street legal power: upgrading and fine-tuning the emissions system. First, the 13B's exhaust passage was opened up using a Japan-spec GReddy race exhaust with 3 3/4-inch (90mm) stainless-steel tubing. According to Ott, the new augmented power output was causing the car to spit increased levels of hydrocarbons (unburned fuel) out the exhaust ports and into the exhaust tubing itself. Such foolishness leads to the demise of many a catalytic converter, and is also often the cause of chronic smog test failure. To help properly combust these fuel particles, Rotary Performance installed a remote air pump to direct air into strategic points along the exhaust passage. Air is now injected through the nozzles at the exhaust ports and through a special conduit that leads to the catalytic converter.
"The trick is to minimize emissions before they enter the cat," Ott testifies; that was the easy part, apparently. "The tough part was finding a cat that could hold up to the heat, punishment and exhaust flow that we were going to subject it to," he continues.
The answer was a massive (7 inches across) catalytic converter that Rotary Performance sourced from Bonez, which features stainless-steel internals that, according to Ott, make it virtually indestructible on this application. In fact, the guts in this cat are of the type more often found cleaning up the toxic emissions from industrial smokestacks.
According to Ott, there haven't been any real problems hooking the 400 horses up to the pavement; more problems have stemmed from weaknesses in the drivetrain, specifically the standard torsion-type differential. While the increased torque in this application tends to eat up helical gears found in the torsion-type diff, Rotary Performance went with a Kaaz clutch-type differential that so far has proved to be unbreakable. A new Bonez Street Comp clutch with a braided flex hose assists in transferring power from the flywheel to the drivetrain.
The emissions report is a "pass."
Interior treatments were kept to a minimum. The only additions you'll find inside are a GR