The Fabulous Flog: A Look Inside Dai Yoshihara’s Falken Tire Subaru BRZ

The Fabulous Flog: A Look Inside Dai Yoshihara's Falken Tire Subaru BRZ

by Mike Kojima

What is the Flog?  It is the nickname that the Falken team has given their BRZ drift car.  Driver Dai Yoshihara, commented when he first saw the completed car that it looked like a frog but with his Japanese accent it came out Flog and no one knew what he was talking about.  Dai had to pantomime a sitting frog and say riibit, riibit before anyone could understand that he meant Frog. 

The Falken Tire Subaru BRZ has been featured by a few other media outlets in the recent past but not like this.  Let us take you beyond the pretty pictures for a look inside the car which has been one of the most anticipated builds of a drift car to date.   One of the best looking cars on the Formula Drift circuit, the BRZ was built on a compressed time schedule by SPD Motorsports, the same folks who built Dai's iconic Discount Tire/Falken Nissan S13.

The BRZ is a pretty complex car with a lot of technology and understandingly it has suffered from new car blues over the course of the 2014 Formula D season which caused some unfortunate DNS's in two rounds of the FD season which regulated Dai to a career first sub top 10 standing in the points. However, in the New Jersey round, the team's constant development efforts started to pay off and the car was very competitive, in Seattle the car continued to improve and Dai was able make a statement with a decent performance.  In the upcoming Texas round the car should be even better with continuing developments by Falken/SPD.

One thing's for sure, the Falken BR-Z is a technically interesting car and we are the first to show what it is like beneath the pretty green skin.

 

A look at the car's under side at SPD Motorsports reveals the overall clean construction and tidy layout of parts, plumbing and wiring that SPD is well known for.  The BRZ was stripped to a bare shell and seam welded as a first step in the construction.  The stock unibody is mostly there as per the Formula D rules.
The stock Subaru FA20 engine was not going to cut it.  In today's world of Formula D, you need power levels in the mid 600 range to reliably make the show.  To have some leeway most of the competitive cars have around 800 hp and many have even more.  To make competitive power, it was decided that a large V8 engine with forced induction running low boost and a relatively low redline would be less stressed, have a wider powerband and more reliable than a highly tuned high revving NA engine.  A FI engine would also have plenty of headspace to easily increase power as tire and suspension technology follows the natural progression and improves.   The engine in the BR-Z is a V8 based on Chevy LS Architecture.  The block as an alloy unit by RHS that has a 1″ higher deck height than an LS.  It is beefed up in the area of the main supports and has a thicker deck and cylinder walls.  The high deck allows for a long stroke and a log rod to keep the stroke to rod length ratio and piston speed reasonable. The engine has All Pro  cylinder heads with splayed valves, Jesel shaft mounted valve train and huge ports. A Brian Crower Roller cam moves the valves.  A Calles stroker crank, Carillo rods and 10:1 compression JE forged pistons give a displacement of 477 cubic inches or almost 8 liters.
Underneath the thermal blanketing lies a Garrett GTX50R turbocharger.  With a lot of hot side plumbing, underhood heat and heat soak is a big issue so insulation is critical.  The thought behind the engine's turbo sizing was to have a large engine that produced plenty of power on the motor and back it with a large turbo with minimum backpressure that would work like a turbo assist, much like the CART Indy car engines from the 80's and early 90's.  The GTX50R is highly efficient with the ball bearings working to improve transient response even with the large size of the compressor and turbine wheels and the large AR exhaust housing. 
It is somewhat difficult to tell from the pictures but the GTX50R is a huge turbo, about the size of a person's head and weighing nearly 50 lbs.  Due to the weight, the turbo is mounted solidly to the chassis with the hot plumbing and charge pipes flex coupled to the engine.  A twin scroll exhaust housing is used to boost turbine efficiency and to improve volumetric efficiency although with a conventional crank and firing order, these gains are not as much as they could be.  The GTX50R helps boost the engine to over 1100 whp and 1000 lb ft of torque at 9 lbs of boost although the car is not usually run that high in competition. The turbo creates an impressive powerband delivering power basically right off idle to 7200 rpm with the potential to run to 7500. The true power level is not known as the car can spin its tires on any chassis dyno.  This is probably the most advanced engine currently being run in Formula D and most of the team's development efforts have been spent learning how to contain its massive amounts of power and available torque.
There is a Dailey Engineering dry sump pump in there bolted to the billet oil pan.  The thick billet pan helps strengthen the bottom end by closing up the huge hole in the bottom of the block.  Additional rigidity helps support the crank even under the extreme loads that the turbo engine can produce.

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