「Over 3000cc of Displacement?!」A “Twin Charged” S15 With Response Across the Entire Power Band

2020/03/14 17:06

Amazing output that reaches full boost in the 2500rpm range


The wastegate stays open! This is an S15 with unbelievable acceleration!


This S15 is an longtime project by tuners Bee-R. The concept of this car is not a general turbo tuning approach but rather a twin-charge approach that makes use of a turbo and a supercharger.


The Turbo is a Trust TD06-20G(8cm2)


A Trust TD06-20G turbo was selected to supply sharp boost in the low rpm range. Exhaust size is the smallest at 8cm2. An electromagnetic clutch is combined with ORC’s TX12 compressor, set to operate at a throttle opening of around 20% (2V).


On the right is the turbocharger and on the right, the supercharger compressor.


The intake route is turbo → intercooler → throttle → supercharger. Placing a supercharger behind the throttle, the response and feeling from blowback when not under acceleration is prevented.


The supercharger is an ORC TX12 unit with an electromagnetic clutch.

The effect of this twin-charged specification is pretty unbelievable. When reaching full boost around 2500rpm, power follows in the high rotation range. During full acceleration, the waste gate remains open all the time and continues all across the powerband.

A compressor and air tank for the air suspension is located in the trunk.

The suspension is an air equipped system. It has an adjustable damper function and supports the vehicles weight even at low air pressure.

A panel shaped from a factory instrument cluster surround is also installed on the passenger side to provide space for additional gauges.


On the interior, a passenger side instrument cluster hood was modelled from the drivers side one to house additional gauges. The original idea was to install a monitor here, but gauges were deemed more usable. To have doubled the instrument cluster panel and seamlessly integrated it on the passenger side is a novel idea.


Door panels are crafted from lightweight carbon.

The factory door panels were replaced with carbon ones. These are weight saving parts for circuit-spec vehicles but it was installed here mainly for visual appeal. Note that the genuine power window switches are transplanted here.

According to Mr. Imai of Bee-R who produced the vehicle, “We hit the mark we intended with this car, but the point it reaches full boost was a bit lower than expected. We may upgrade to a larger turbo in the next stage”.
The “twin charge” system was sold as a kit limited to 10 sets (540,000yen) but sold out extremely quickly. There were inquiries regarding this kit from both inside and outside Japan, but it remains a rare kit that was not produced again.

●Special Thanks:Bee-R  1704-1 Ogawa, Machida City, Tokyo Prefecture TEL:042-799-7800


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