Spearco puts the pressure

on Toyota's competition

BY KIM REYNOLDS

Examples of Toyota’s latest Celica Supra have been popular visitors to our Newport Beach offices. We've appreciated Toyota's more serious regard for enthusiast drivers, evidenced by a redesigned Supra that's a step up from the original both in measured performance and subjective driving pleasure. In fact, in our February 1 982 road test report we said ". . . the Supra has to rank as the most exciting Toyota we've driven since the short-lived (1967-1968) limited-production 2000 GT." That conclusion may now require amendment after driving the latest turbocharging magic of Spearco Performance Products, Inc, 10936 S. La Cienega Blvd, Inglewood, Calif. 90304; 213 649-4860.

And it isn't prestidigitation. The Spearco Supra is a high quality performance upgrading of Toyota's sports coupe courtesy of one of the country's oldest turbo aftermarket manufacturers.

A short history of Spearco Performance Products: Following a decade spent with Shelby-American, affable George Spears became a partner with his former employer to form Shelby Spearco, producing intake manifolds, performance camshafts and suspension modifications for Pintos and Vegas. The Capri 2600 was the subject of their first turbo kit and it's worthwhile to recall that, at the time, turbocharging anything but diesel semis was considered somewhat eccentric. Of course, OPEC's mischief altered matters, creating a national fuel economy imperative that left the automotive turbocharger in the catbird seat as a socially acceptable (and CAFE attentive) bolt-on solution to numb-performing production models. The turbo aftermarket industry benefited from the fad and Shelby-Spearco profited. Nevertheless, Carroll Shelby's broad interests continued to widen and Spears eventually purchased the Texan's share of the business. Spearco's current catalog features more than 30 turbocharger kits using Rajay and IHI turbos that will fit engines displacing from 1. I to more than 8.0 liters.

Now to the Supra. At the heart of this special Supra's driving excitement beats an IHI model RHB-6 turbocharger unit that has undergone some tailoring of its exhaust housing design and wastegate behavior to better suit the Toyota's engine characteristics. Generally, IHI's smaller-size units command considerable interest in the aftermarket turbo industry because of their quick throttle response and efficient performance. Indeed, execution and sophistication mark the Spearco-Supra's entire induction and exhaust systems. Spearco-designed castings are in abundance, beginning with a pair of elbow tubes which snake the incoming airflow to the turbo's compressor. Next, a ribbed cross-over pipe transfers the turbo-pressurized air over the enaine's dual-camshaft cover and into the Supra's standard induction tract where Bosch L-Jetronic injection attends to fuel mixing. On the exhaust side, the burned flow is collected in a Spearco exhaust manifold that delivers it to the new IHI's hot, turbine end. Lastly, the spent gases are directed through a special down-tube, which meets a new 21/4-in. exhaust system employing the Supra's catalytic converter. And, note, retention of this last device underscores an important point: The Spearco turbo is street-legal.

More than just these elements complete the conversion however. It is the remarkable attention to detail that is striking.

For example, exhaust gas will typically invade a turbo's oil supply as it passes through the turbocharger bearing, and Spearco has employed a gas-liquid separator downstream of the bearing to cleanse the lubricant. The extracted exhaust is routed to the cam cover while the oil returns to the sump, entering the oil pan through an adapter screwed into the drain plug (unseparated oil would be too buoyant with entrapped gas to allow such entry). Had the trouble not been taken to perform this separation, an entry hole to the sump would have had to have been drilled above the oil level, tempting later oil leakage and opening the door to stray drill filings finding their way into the lubrication system.

Spears is somewhat hush-hush about another design nuance. He describes it as "a device that senses airflow and alters boost pressure at the wastegate actuator to allow additional boost at low airflow conditions, and less boost at conditions of higher speed and higher airflow where detonation is more likely to occur." Respecting the system's proprietary nature, we can add that it's clever and it works.

Toyota's laudable 2759-cc double-overhead-cam six is stock internally, retaining its 8.8:1 compression ratio. Full-throttle boost pressure ranges between a maximum 7.0 psi to 5.0 psi when detonation is near, and overboost protection is provided by a failsafe pop-off valve that opens at 7.5 psi. At peak boost, maximum horsepower rises to a claimed 195-50 hp greater than the standard model.

So how does all this technical wizardry perform?

Very impressively. We ran the 5-speed Spearco-Supra through the acceleration segment of our test procedure and can report speeds and times essentially equal to Datsun's 28OZX Turbo (in its quicker 3-speed automatic guise): 60 mph requires 7.3 seconds and the quarter mile is spanned in 15.7 see at a speed of 90.5 mph. Subjectively, the Spearco-Supra is more responsive than most turbocars with a smooth, progressive buildup of power under acceleration. Further, the extra power provides delightful fun as it's fed through the chassis, suspension and tires; it allows many more driving options to the enthusiast who enjoys aggressive cornering

And the price? The installed system will run $2300. Added to the Supra's list price of $ 13,598, the Spearco-Supra matches Datsun's 28OZX Turbo in straight-line performance while costing less. Seven installation centers around the country will supply the converted car to Toyota dealers and Spearco provides a 12-mohth, 12,000-mile warranty on both the turbo componentry and the engine when its technicians do the fitting. Later the kit will offer a Stage Two version: its difference is an air-to-liquid (glycol) intercooler that will safely increase boost pressures 2.0 psi further. We're looking forward to it.

December 1982 Road and Track Reproduction