Option — Shōwa Car Tuning & Buyers Guide (2000 Edition)

A cam and turbo swap might make it sound like a top-speed build, but it is genuinely fun on a circuit. I thought the heavy Supra would be unsuited to circuit driving, yet its cornering speed is faster than expected. Power comes on around 4,700 rpm and pulls strongly to about 7,000. Even if revs fall below 4,700, torque does not disappear abruptly, so the throttle responds well during cornering. On corner entry… [continues].

The car’s weight is noticeable on corner entry, but the Ohlins-based suspension is well set up and provides firm traction on exit. Brembo brakes provide confidence, though they still use stock Brembo pads; ideally I would replace them with sport pads, says Tatsuzan Yamada. With the engine, suspension, and brakes balanced, this is a 70-series Supra that is fun on a circuit!

Part of the intake piping on early 1JZ versions has a sharp bend. Once an air filter or muffler improves engine breathing, that section becomes a restriction and can cause excessive blow-by—one cause of heavy white smoke. The fix is to replace it with the later-model suction pipe. Shops with experience tuning the 1JZ know about this, so check with them if you are concerned.

A Trust bumper is fitted with a Turbo A duct to actively draw in…

…cooling air.

NIGHTMAGIC

Ohlins-based CS-TOP version. Eibach springs use a dual-spring setup: front 20 + 9 kg/mm, rear 14 + 6 kg/mm. It is a machine that can be driven hard on any circuit!

CS-TOP JZA70 Turbo… [caption].

With cam and turbo changes: 390 PS.

Suspension… [fragment].

Get the suspension sorted and it can become a circuit build too!

The BOMEX rear spoiler matches the stock body lines beautifully. A model of an understated yet sporty style!

The intercooler has also been moved up front. Simply relocating it can raise coolant temperature, so the Turbo A duct is useful for eliminating that drawback.

The bottom end is stock, with only N256/E264 cams. The twin TD05-16G turbos are mounted on a stainless exhaust manifold. Fuel is controlled with the stock 370 cc main injectors using an F-Con; two additional 550 cc injectors are controlled by a Rebic II. At 1.7 bar boost it reportedly makes 390 PS, though that figure may be conservative.

The rear seat has been removed. The 70-series Supra is relatively flexible, so reinforcing body rigidity helps the suspension setup work properly.

…that is why.

Compared with modern interiors this cabin looks dated, but simply adding auxiliary gauges gives it a much more purposeful, Spartan feel. They are not decoration: they monitor the engine under hard use.

…with RE71 tires… [fragment].

Essential for a heavy car.

…a valve has been installed… [fragment].

The rotors and calipers… [fragment].

…wearing 55-18 tires… .

A rear-wheel-drive car running low-12-second quarter miles is seriously quick! More displacement builds torque, so it accelerates hard despite its heavy body.

The key to tuning the 1JZ!

On the earliest 1JZ versions, changing the air filter and muffler can sometimes cause clouds of white smoke!

Use a 2JZ bottom end to build a 3.1-liter setup capable of chasing top speed.

For a quarter-mile launch, hold 6,500 rpm and slip the clutch…

In first gear, accelerate while easing the clutch to keep traction. From second gear onward, shift crisply—bang, bang. That is enough to run in the 12-second range, leaving weak GT-Rs behind. As a street drag car, this 70 will certainly turn heads!

On the earliest 1JZ version, part of the intake/suction piping… [caption continues].

A 2JZ bottom end increases displacement to 3.1 liters. A T78 turbo at 1.7 kg/cm² boost produces a measured 600 PS. A labor of love by Speed House Alpha, specialists in drag racing (0424-74-7444).

Cooperation: CS-TOP, 160 Kanai, Nitta, Nitta-gun, Gunma 370-0341; 0276-57-1203.

Option

Option — Shōwa Car Tuning & Buyers Guide (2000 Edition)

About this issue

Page 143 — English draft translation