The Resounding Roar of an NA Peripheral Port 4-Rotor Engine! | Circuit Spec FD3S Tackles Tsukuba

Published : 2021/04/06 15:16 Modified : 2021/04/06 15:24

Sound stirs up memories of 787Bs of old!


Shows proof of top notch abilities during shakedown!


Center stage is this FD3S, packing a 4 rotor engine just like the 1991 Le Mans winning Mazda 787B. This is the ultimate incarnation of the track day-loving owner’s relentless march to create their ideal rotary sports car. 



Where else to start but -that- engine? The custom 13B 4 rotor engine that Scoot Sports spent such a long time developing employs peripheral porting to boast a naturally aspirated 585ps and 60kgm of torque. It’s a super high revving unit with a 9500rpm limit, and gets a dry sump conversion into the bargain. Linked to all of this is a Quaife transmission.



Concealed by the air box are four independent Toda Racing throttle bodies,and an equal length exhaust manifold. Under the management of a Vi-pec V88 standalone ECU, all of this provides a flat torque curve that is easy to use in time attacks.




Central to the handling are adjustable dampers based on a Crux kit. The spring rate is 20kg/mm. At the rear, the power plant frame says goodbye, making way for a fully rigid setup in a bold move. The LSD is a carbon fiber ATS module.



The wheels, which hark back to the 787B, are FLS-13s by Japanese maker of forged wheels, FrontLine. On the day of the race, the car had Advan Racing GT rims wrapped in Advan A050s.



The interior, with its racing-car like fully welded roll cage, has a strong “track car” vibe. Apparently the owner removed all of the trim themselves. Thanks to thorough slimming down of every area of the car, weight is down to 1005kg.



The exterior has numerous track-oriented modifications, from the front and rear fenders and the aero parts connecting them, to the half-height doors. As a result, the car achieved a very decent 57.594 second time – and that was only the shakedown.


By the way, the current fastest NA rotary-engined machine is a 3 rotor FD3S (“Shark” Fullstage Endless driven by “Shark” Iiri) at 55.595 seconds, set in 2018. We hope to see the day that this machine, with its gem of a 4 rotor engine, becomes fast enough to beat that time.


Original article・日本語版はこちらです