It was my mission to come away from Sunday’s Idlers Club event at Tsukuba Circuit having explored totally new angles.
Given that this was the second Idlers ‘Sprint’ race I’ve attended at Tsukuba this year, I decided to look deeper and showcase some of the aspects you probably wouldn’t associate with the event. Because contrary to what you might think, it’s not all about RWB Porsches.
Rotaries at Idlers? They’re quite possibly the last sort of cars you’d think of when imagining Nakai-san battling it out on track with his friends, but yes there are.
Granted, there were only three examples – and all FD3S RX-7s – but each was different and worthy of a closer inspection.
I’m going to kick off with the rawest of the trio, an RX-7 so obviously and wholly devoted to function that it instantly brought back memories of the first times I covered Japanese time attack events.
That scene has evolved greatly in the years since, to point where some privateer builds are rivalling professional builds when it comes to execution, presentation and of course the aero component.
But the “I don’t care” approach this grey FD3S exuded really appealed to me. It has a brutal presence.
I never managed to get a look at the engine, but from the way it sounded as it screamed down the Tsukuba straight it obviously runs a single turbo with external wastegate and has plenty of power. Back in the pits, its brap-brap-brap idle hinted at a generous bridgeport.
One quick glance into the stripped-out hatch/trunk area revealed an oxidized aluminum surge tank and some fuel big lines.
The exterior features a mishmash of aero parts, including pumped FRP fenders to contain a wide wheel and slick combo.
Looking at the way the wing stays used a couple of extenders, the owner probably realized that the more unpolluted airflow the rear wing gets, the more effective downforce it can generate.
Balancing downforce at the front end is a carbon fiber splitter and a pair of universal-fit canards to complete the conversion.
A few pit garages up I found a lighter grey FD; this was a far more involved creation that was recently pieced together from a stripped-out shell.
During the morning, the RX-7 was running a series of test and setup laps, its crew carefully checking over the engine and suspension every time it came back in. Like the first FD3S I showed you, this one’s also on full-slick racing tires, something that’s quite common in the more extreme classes of this event. It’s an obvious advantage on any track, but at Tsukuba the extra grip makes the cars visibly quicker around turn one and through the infield hairpin.
Of course, more grip means braking can be used more effectively, and with this build that’s also possible thanks to StopTech calipers and Project µ slotted discs.
There are telltale signs of the seriousness of the build and prep work, from the one-off cage gusseted to the pillars, to the shift lever that operates the sequential transmission.
As a dedicated race car headlights aren’t required, and that’s made good use of on the right-hand side where a duct feeds air into the engine bay.
Specifically, right into the mouth of a large Trust turbo running an HKS Super Power Flow filter housed inside a custom airbox that seals once the bonnet is dropped and locked in position. The obligatory v-mount ensures the pipework is kept as short as possible, and the idle of motor also hinted at a ported 13B.
Last but not least is this white FD, this time a sought after RZ model running amongst more street-oriented competition.
That of course makes it far more simple in execution, but there’s no denying that even a lightly tuned RX-7 can be potent in the right hands.
The sequential turbo setup remains, but the original airbox has been ditched in favor of twin HKS filters. There’s also a v-mounted intercooler and radiator setup, which on top of making better use of air flow through the bumpers and out of the vented hood shortens the piping from the turbo compressors to the intake plenum, improving response.
With modern day coilovers and a decent wheel and tire package, and this is a car that will make many contemporary performance cars look slow around Tsukuba.
This rear shot ends my quick post on the rotaries of Idlers. Next up, we’ll take a closer look at a side of this event that’s rarely talked about – drifting.
Dino Dalle Carbonare
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dino@speedhunters.com