Yashio Factory S15
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Yashio Factory — Full use of Silvia Specialist know-how
Packed with highly functional and innovative parts, Yashio’s approach is to aim for an S15 that drivers can truly enjoy.
Scans translated from Hyper Rev Vol. 49
Translation:
We steadily make everything we need, from turbines to radiators.
Okamura, also know as Oka-chan of Yashio Factory, is known for refining his machines while participating in Sunday races and track days. The original parts he creates as a result are often very useful and convincing.
The goal of the S15 that Okachan has completed is to run the Tsukuba Circuit in 1 minute 1 second. The key point is the “Okachan turbine.” By combining the GT3037S, which uses a ported shroud that is effective in preventing surging, with the GT2835, they have created an actuator-type turbine that is “the strongest you can just install.” And to fully utilize the performance of this turbine, everything from the equal-length exhaust manifold to the front pipe and muffler has been custom-made. As a result, they have been able to achieve a power of 430PS with 1.3kg/cm^2 of boost. Another area that Yashio excels at is their know-how in cooling systems. They have developed a system that can achieve “sustainable performance” during circuit driving. To achieve this, a cooling system with sufficient capacity is essential. It is worth noting that the original radiator is combines with a CPU-controlled water spray kit called “Okachan Spray” to create a system that reliably lowers the water temperature.
The suspension is fitted with an original coilover kit based on HKS’s Hyper Damper, which took about a year to perfect. The S15’s suspension needs to move properly, otherwise the car’s movements will be harsh. This suspension kit adjusts the suspension and sets it in a direction that allows for a certain amount of roll and turning, giving the car more freedom in its driving. AP also offers four-pot calipers to strengthen the brakes, but the greatest appeal of the Yashio Kit is that they can be combined with the original rotors.
In this way, Yashio’s original parts and tuning know-how are designed to provide excellent performance while keeping budgets as low as possible.
Translation:
The engine itself is left completely stock, but the exhaust system has been tuned with an Okachan turbine, an original CPU tailored to the actual car, and an original exhaust manifold, front pipe, and muffler, resulting in a specification of 430PS. It is characterized by being finished in a specification that is easily for us to follow.
Translation:
Yashio’s specialty is radiators. They offer several types to suit different applications, and all are reasonably priced, which is great. They have also released the latest cooling part, “Okachan Spray.” This powerful item sprays water onto the radiator, effectively lowering the water temperature.
Translation:
The original coilovers, based on the HKS Hyper Damper, are more flexible than expected and are easy to ride around town. The brakes are equipped with the original AP 4-pot calipers that can use the original rotors.
The interior is not overly lightweight, but still has the minimum necessary comfort equipment. The transmission is an HKS 6-speed sequential. The improved reliability of the power and the gear ration are a good match.
Translation:
To prevent surging in the GT2835, the 3037S compressor with ported shroud is combined with the exhaust housing for the 2835! This resulted in the creation of the strongest actuator type “Okachan Turbine.”
Translation:
The original aero parts consist of a front bumper that extends and lowers the nose tip, GT fenders that are 20mm wider on each side, making them the same width as the S14, as well as sides, rear bumper, and a GT wing, all of which create this look.
Translation:
YASHIO FACTORY S15 TUNING SPEC
Maximum power/torque - 430ps/6000rpm 50kg-m/5000rpm
Boost pressure - 1.3kg/cm^2
Boost controller - HKS EVC
Computer - Original CPU (starting from 65,000 yen)
Intake system - HKS Super Power Flow (+Z32 airflow)
Intercooler - HKS Type-S + custom piping
Turbine - Okachan turbine A/R 0.86 (258,000yen)
Actuator - HKS reinforced actuator
Extention - Original (39,000yen)
Front pipe - Original 80mm (includes muffler)
Exhaust manifold - Original equal length (128,000yen)
Muffler - Original main 90mm to tail 115mm (98,000yen)
Fuel system - Pump/injectors 550cc for BNR34
Radiator - Original Super Radiator (88,000yen)
Transmission - HKS 6 speed
Drive system - HKS twin plate clutch/NISMO selective LSD
Suspension kit - Yashio Spec F12kg/mm R10kg/mm (208,000yen)
Other suspension - Rigid collar (20,000yen) Pillow tension (45,000)
Brake caliper - Original AP caliper kit (228,000yen)
Brake rotor - R34 normal
Tire - Advan A038R F 235/45-17 R 255/40-17
Wheel - Advan RG F17x8.5+31 R17x9.5+35
Aero parts - F bumper (58,000yen) GT fender (58,000yen) S step (58,000yen) R bumper (58,000yen) GT wing (128,000yen) Carbon hood (98,000yen)