Street Power June 1997 Vol II Issue 3

New Math

Two May Not Be Better Than One

By Ray Thursby

Photographs By E. John Thawley III

WE'VE ALL BEEN WARNED, VIA A SUCCINCTLY-worded proverb, to be careful what we ask for. If our desire is somehow impractical or a less-than-perfect realization of a pleasant dream, we'll get it. In the world of tuner cars, the result of asking too much from a given piece of machinery can best be expressed by another proverb: There is no such thing as a free lunch.

Before we get into the nuts and bolts and results of Rytek Projektz Tuning's reworking of a semi-innocent Toyota Supra Turb, lets be clear on one point: This car does exactly what Rytek and a very satisfied owner wanted it to do. But to enjoy the large dose of added muscle that separates it from everyday Supras, you have to be willing to put up with a couple of major compromises made in the name of ulimate performance. Given a large enough stable of rides to choose from, along with enough open-road space to screw the righthand pedal into the floorboard whenever the urge struck, I'd consider having Rytek build me a supre Supra powerplant just like this one.

The car's owner certainly has choices. Among the desirable pieces in his garage are a Ferrari Testarossa, a Lamborgini Countach and a handful of BMW's and Mercedes-Benzes, several of which are massaged in varying degrees for added performance. According to the Rytek folks, the Supra is his current favorite, and his preference for daily driving.

And its easy to see why. The Supra putters around town just like and stock Toyota, smooth and quiet. But, should the Supra's driver be challenged, either by the driver of some other piece of high-performance machinery or by his own inner demons, there is an estimated 600 bhp under the hood waiting to be unleashed. Do that, and a second personality emerges.

All it takes is pressure on the throttle and a little patience. Patience is the key. Below 4000 rpm, the Rytek Supra's engine is soft as fudge, gaining speed with agonizing slowness. Past four grand, its a different story. The boost guages swing smartly up to 17 psi -- dialed back for our test run from a piston-melting 22 psiavailable to the owner-and, accompanied by a large cloud of unburned hydrocarbons billowing from the 3.0 inch exhaust pipe along with turbocharger/wastegate noises more familiar to CART drivers than to operators of more sedate dforce-fed cars, speed builds in a great rush. Fast it definetly is; subtle, it ain't.

A look into the engine bay tells you why. In place of the pair of turbochargers plumbed in sequence that help a stock Supra Turbo churn out 320 bhp, there's a single huge Greddy puffer (with a 100 mm inlet) that, had it not been acquired for this project, looks as though it would have been assigned to help push an 180wheeler down the road instead. The blower is part of a package of Greddy pieces -- stainless-steel exhaust header, wastegate, adjustable bypass valve, air filter, a huge intercooler (24x12 inches, and four inches thick) that sits in front of (and dwarfs) the stock water radiator-- and some Rytek components (boost and pressure return lines and an adapter for the Toyota mass airflow sensor) attached to an otherwise unmodified Supra engine, which keeps its factory-issue fuel injectors, pump and regulator.

At the very heart of the system is a reprogrammed ECU from G-Force Engineering. Using proven computer technology and exhaust-gas analysis, the ECU remaps the electronic controls to provide a fuel-air mixture that delivers both power and a measure of reliability. Toyota's built in rpm, fuel delivery, turbo boost and vehicle-speed restrictions vanished in the process, leaving restraint--or lack of same--in the drivers hands.

"The Rytek Supra does an

admirable job of keeping its owner

entertained in a way no stock machine would"

Keeping the fuel mixture nice and wet is a key factor. The air/fuel ratio is a rich 12.5:1, good for fast burning and cool cylinders--and keeping detonation at bay--if not exactly ideal for passing emissions tests, which, since the catalytic converter was lost during the installation of a big bore exhaust system, the car would be unlikely to pass anyway.

Joining the G-Force module on the electronic side of things are an Electronic Valve Controller and a Turbo Timer, both from HKS. The former provides drivers adjustment of boost level, while the latter keeps the engine running (and the turbo bearing's oil supply steady) after the key is turned off to allow the turbo a minute or two to cool down. This is essential after any hard run, as the Greddy turbo lacks the water-jacketing that wraps around the stock Toyota units.

At this point you may be wondering why Rytek would scrap a factory-issue twin turbo setup, one that works exceptionally well in terms of developing a solid power band from just avove idle to redline, for a larger single turbo that inevitably suffers from significant lag at low speeds. The answer is simple: The big blower's 22 psi maximum boost is just about double the pressure available from the stock units. THe goal was top-end surge, shove-you-back-in-the-seat acceleration from about 70 mph right up to velocities on the dark side of 170 mph. That's the proverbial lunch, a very tasty meal indeed, paid for by a noticeable lack of push off the line.

There is, of course, another bill to settle for this meal. A duplicate of this setup--minus, perhaps, the paint-and-graphics treatment that makes the engine a major attention-getter every time the hood is raised-- would set you back a cool ten grand or so. That seems reasonable when you consider the number of components that are changed, the quality of the Rytek pieces, and the amount of labor involved in the conversion process.

As is the case with many redos of this kind, little else is done to the drivetrain. Internal engine upgrades were considered unnecessary, and the stock Supra four-speed automatic transmission was left alone. It is a tribute to the safety margins built into the Toyota pieces that none have wilted under much harder use thatn they could ever have been intended for.

The factory's braking system has been left alone as well. So has the suspension, except for addition of a Greddy front strut tie-bar and replcement of the stock coils with a set of Eibach Pro-Kit springs that loer the Supra's ride height some 1.5 inches. These have no downside, delivering a ride that's virtually as smooth as the factory springs, while benefitting handling and giving the Supra a hunkered-down look that suits it perfectly. Equally suitable are the wheels and tires, HRE three-piece modular rims (18.5 inch front, 18x9.5 inch rear) wrapped in Dunlop Sp8000 rubber (235/40zr-18 front, 265/35zr-18 in back).

Outwardly, the Supra appears unmodified, sporting only large "Rytek" decals on its sides. Inside, a pair of Sparco racing seats-clad in light blue cloth that provides a vivid contrast to the stock black trim-and a new head for the sound system set this Toyota apart from others. The engine's 600 ponies are complemented (and sometimes drowned out) by 800 watts of Alpine audio power, channelling sounds from either the radio or rear-mounted six-disc CD changer through an equalizer, tweeters and woofers and a pair of 10-inch subwoofers (all speakers are from OZ).

A few tweaks are planned for this steamed-up Toyota's future. Bigger brakes ar eon trhe menu--a definite must, I'd say-- and some fine-tuning of the fuel injector system. As it stands, however the Rytek Supra does an admirable job of keeping its owner entertained in a way no stock machine would while feeding his hunger for maximum speed. Which, in the final analysis, is what tuner cars are all about.