Option — Shōwa Car Tuning & Buyers Guide (2000 Edition)
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About this issue
180 available scans from Option — Shōwa Car Tuning & Buyers Guide (2000 Edition), in right-to-left reading order. Japanese OCR and English translation drafts are available throughout. Drafts have not received exhaustive image proofreading; unreadable source remains recorded in the archival data.
Page 145 — English draft translation
This setup uses only Carl Schmitt 78 mm pistons for a 2.2-liter build. The ultimate version would use a long-stroke crank for 2.4 liters, but modern turbos have improved so much that the 2.2-liter version is still enjoyable. The car was built more than five years ago; today’s higher-performance turbos could make a combination powerful enough to make you ask, “Is this really a 1G?”
Captions and page details
Supra
GA70Z
1G
GA70 Turbo…
Tuning
Even the underpowered 1G can benefit from a displacement increase…
…which broadens the choice of turbos!
Despite its 1.5-liter square-stroke engine, the 1G does not rev especially high and lacks torque, making it less than ideal for sport driving. The most effective remedy is to increase displacement and spin a larger turbo. Trial once recorded a 306 km/h top speed with a 2.4-liter twin-turbo TD05 1G build in 1988… .
Built as the first stage of the project…
A 2.2-liter build uses Carl Schmitt 78 mm pistons. Both intake and exhaust cams are 264 degrees. Reusing a 1JZ intercooler improves cost performance.
An HKS exhaust manifold is paired with a T300 turbo, EVC, and wastegate. Boost is set to 0.3 bar .
uma
The key to tuning the 1G!
The gauge panel looks nearly stock, with only a boost gauge visible. The EVC, AIC, and GCC II are hidden in the glove box.
It can still be enjoyable, but the tuning cost is the big drawback!
4
Fuel is supplied by six 360 cc main injectors controlled by an F-CON; two additional 380 cc injectors are controlled by an AIC. A GT-R fuel pump is reused to maintain fuel pressure.
To be honest, heavily tuning a 1G-based engine is quite… [sentence continues].
…rare. Dedicated parts are scarce, and even a turbo swap requires many one-off parts, so costs add up. Converting to a 1JZ may seem simpler, but the intercooler, transmission, rewired harness, and ECU make it a ¥1,000,000-plus project. If you are buying a car with upgrades in mind, it is better value to start with a 1JZ model!
The muffler is an Apex’i Mega-horn. Tuning parts for the GA70 are becoming scarce, but mufflers are still readily available!
Cooperation: Trial, 87-1 Tanjo, Mihara-cho, Minamikawachi-gun, Osaka 587-0011; 0723-69-3539.
Option
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