“80’s Tuning Memoirs – Mine’s representative, Michizo Niikura” The secret story behind the birth of the VX-ROM【Tuner Biography】
Everything traces back to the R31 Skyline GTS-R
Smart tuning practices that the times demanded!
In the late 1980s, Mine’s used two GTS-Rs as demo cars with different specs in the Yatabe (high-speed test road of the Japan Automobile Research Institute) max speed tests. They later developed their famous genuine (OEM) remapped ECU, “VX-ROM,” on Yatabe along with their GTS-R. Thirty years ago, Mr. Niikura was far ahead of his time with visions of the coming era.
CP tuning has now become a common menu item. From a different stance, as electronic control becomes more complex, it may be a crucial feat that one cannot avoid in order to actually tune the car.
Mr. Niikura, representative of Mine’s, was the first to make said CP tune. In terms of the Skyline, they started ECU analysis in the R30 era, and completed the subsequent VX-ROM commercialization with the R31.
In the mid-1980s, the engine control method reached a major turning point. The fuel supply system switched from the carb to the injection, and the ignition system changed from the mechanical distributor to the ignition coil.
However, there was no concept of CP tuning at that time, and everyone treated the genuine ECU as a black box.
“When I worked on increasing power back then, I had to solve a fuel cut that intervened when the boost pressure exceeded its set value. Using a fuel hacker that cheated with a pseudo signal was the most common solution. But in the R31 era, when people used a fuel hacker on an engine with a hot-wire airflow, the issue of ignition timing arose. In order to solve this and perfect my work, I knew I had to tweak the genuine ECU,” says Niikura, explaining the start of his CP tuning journey.
At that time, the demo car owned by Mine’s was the limited R31GTS-R–a Group A homologue model (apparently, more than the announced 800 exist). It was also a two-unit system with a boost-up specification and a full turbine specification. They eventually expanded its displacement to 2.2L and fitted it with an IHI RHC6. Both had a normal exterior. How many km/h can one get by purely engine tuning? To find answers, Niikura took on Yatabe, where it became the main stage for their VX-ROM development.
“I ran a full analysis of the genuine ECU and decided to do the same thing that the manufacturer controlled. So I looked at data from morning to night. Hexadecimal numbers from 0 to 3FFF lined up. The map–now that I think about it–was only about 1/48 the capacity of the latest ECU. But because of that, I now understand everything about the GTS-R address without looking at anything.”
Niikura changed the ROM data to cancel the fuel cut. In addition, he expanded and reset the map area. He further set fuel control for over boosting or increasing the capacity of the injector, and removed the limiter for ignition timing. With this, Niikura deepened his understanding of CP tuning. For example, although it is necessary to remove the rev limiter with CP tuning, there was no particular problem in sending a pseudo signal from a speed limiter with retrofitted electronic parts. He certainly accumulated a lot of knowledge through repeated trial and error.
At the same time, in addition to experience and taste, tuners are also required to have data analysis capabilities. There is no doubt that the CP tuning that Niikura pioneered greatly affected the tuning industry.
“Tuning has always had an oily image–wearing a dirty jumpsuit, getting my hands all black while tweaking the engine. Of course, that’s a big part of tuning, but I aimed for smarter tuning. CP tune is just that. You can drive in the city normally, but if you step on the accelerator, it’ll be ridiculously fast. CP tuning made what wasn’t possible with previous tuning types into the possible.”
The max speed attacks on Yatabe with the GTS-R, developed with the VX-ROM, took place from 1988 to 1989. From changing the boost pressure, the muffler, and the CP setting, Niikura commuted once a week. He changed the ROM to a socket type, then prepared several ROM types with different settings. For every ROM change, he collected various data including its maximum speed. At this time, Mine’s already had a CP setting using an air-fuel ratio meter from Horiba, and introduced a telemetry system that could check the vehicle information using radio during the attack.
According to the OPTION Magazine max speed ranking at that time, it recorded 266.67 km/h (about 165.701 mph) with boost-up specification. Since the normal is 228.65 km/h (about 142.076 mph), with the intake/exhaust + CP tune alone, it increased about 40 km/h (about 24.854 mph). On the other hand, the other demo car with 2.2L + RHC6 specification marked 292.00 km/h (about 181.44 mph).
“Boost-up specs were around 1.4-1.5 kg/cm2. A/R was gentler because of the genuine TO4E, but I strongly remember the strong acceleration and the upward growth. I also learned more about Garrett turbines. The 2.2L spec was a rival to GTS-R from HKS, which serialized at OPTION. At first I was winning and losing, but over time, they output over 300 km/h (about 186.411 mph) with their 2.4L TO4S. We also applied a boost of 1.8 kg/cm2, but didn’t reach 300 km/h. Even though there was a difference in displacement, I was still disappointed.”
Niikura witnessed an unforgettable sight at Yatabe. The GTS-R entering the straight after leaving the bank at 270-280 km/h, clearly showed the front was floating. The front and rear were equipped with genuine spoilers, but the downforce on the rear was too effective. Because they were loyal to the normal exterior, this aerodynamic discovery was possible.
The Mine’s demo car obtained a good record in Yatabe, albeit a limited model of 800 units, the VX-ROM for GTS-R sold well. In the morning, when Niikura went to the store, there were times when fifteen GTS-R’s were lined up. It was from this time that people began to call them, “Skyline Mine’s.”
Though the VX-ROM widely spread in the BNR32 era, that was due to the groundwork made with the R31. Thus, the history of Mine’s all traces back to the GTS-R.
Special thanks to: Mine’s TEL: 046-857-3313
PHOTO: Katsuyoshi Kobayashi / TEXT: Kentaro Hiroshima