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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Sunday, September 14, 2014 11:27 PM
Been waiting for this article all season. Mike and the team have been pretty secretive about this car (for good reason), which makes its reveal all the more glorious.

The car is just unreal. I can't even fathom how you guys managed to fit all of that hardware in the diminutive FRS chassis. This has got to be the most tightly packaged car on the Formula D grid. Looking at it makes me feel completely amazed at how far the sport has come in ten short years. I feel like the Falken Tire FRS really represents the culmination of all that progress. It is a truly astounding motor vehicle.

I think we're really starting to see a bit of a "formula" for top-tier FD cars. Parts of the formula have been around for a while, such as the dog-shifted four-speed gearboxes mated to a quick-change rear end. Other parts, such as large-displacement, lightly-boosted V8 engines, have only just recently become the vogue.

To me, Formula D has become the spiritual successor to NASCAR. FD is as close to *real* stock-car racing as can be found in top-tier motorsport. Real unibodies from real factory cars duking it out wheel-to-wheel. It's some of the best automotive action anywhere in the world.

However, as the formula for top-level FD cars matures, it seems the roots of Formula D are being left behind. This is as it should be, but I think the FD organizers would be smart to re-capture some of those classic traits in a different way.

Mike, what do you think about a Formula D feeder series? Something like NASCAR's Nationwide Series for the American drift scene. It could be a series with a much more restrictive rule-set to keep the cost of the cars down and the speeds involved lower. This would allow fledgling car-builders and drivers to work their way up without being constantly obliterated by top-level teams like Falken.

Perhaps they could tweak the tire-to-weight rules way down instead of putting arbitrary caps on power? It would be great to see a ruleset that would allow boosted 4-cylinder engines to be competitive again. I've even heard the suggestion of limiting the engine selection to whatever the brand of the chassis happens to be. Only Toyota engines in Toyota cars, etc.

Do you have any visions for such a series, Mike? Any of your own ideas of what a feeder series should look like? Hell, you are largely responsible for how the current state-of-the-art FD cars are built. I couldn't imagine a better person to propose the layout of a Formula D feeder series.
Mike Kojima
Mike Kojimalink
Monday, September 15, 2014 1:05 AM
Well FD has Pro-AM and Pro-2 as feeder series for the Pro Series. Pro 2 is proving to be popular with fans.
Dan DeRosia
Dan DeRosialink
Monday, September 15, 2014 3:38 AM
... well damn. That was pretty comprehensive - the writeup and the car build. From here it very much looks like a culmination of a lot of ideas, on the order of taking everything you learned from doing incremental upgrades to the S13 and plunking it into a new chassis... which I suppose is pretty much the case. Especially like the uprights, though I'm waiting for someone who went through Formula SAE to bitch about rod end in bending. (I'm sure you sized them appropriately and have appropriate maintenance procedures on all the spherical stuff)
Dusty Duster
Dusty Dusterlink
Monday, September 15, 2014 6:59 AM
What are those covers over the coilover springs for?
Monday, September 15, 2014 8:08 AM
@Dusty, was going to ask the same thing, I assume they are to cover them while the car is being worked on to prevent contamination or damage. They way they are zip tied on makes it look like it is run that way in competition (I assume for the same reasons).

Also, I think it is pretty ironic that considering the engine size and packaging, the "usual" suspects like axles, transmission, etc. are all holding up just fine while things that are not unique to this engine are causing all the problems (fuel, spark, heat).
Monday, September 15, 2014 8:45 AM
Hey Mike, what's up with the suspension bags?
Mike Kojima
Mike Kojimalink
Monday, September 15, 2014 9:37 AM
Some of the things we do to the shocks are very maintenance sensitive. Dirt can easily damage some of the stuff we do.
Monday, September 15, 2014 10:14 AM
A little question about the naca ducts on the rear window ... aren't they located in a low pressure area ? I do understand how it would work when being sideways, but with the car driving straight, won't the air exit by there instead of flowing in ?
Mike Kojima
Mike Kojimalink
Monday, September 15, 2014 10:30 AM
@crousti, the rear ducts are not in the optimal place but there isn't much space available to put them.
Mike Kojima
Mike Kojimalink
Monday, September 15, 2014 11:33 AM
One of my ideas is to made a Pro Stock class where the tires size is limited to 245 with a minimum weight of 2700lbs. This would make a car with 500 whp competitive and not require exotic materials to have a minimum weight war. You typical pro am car would be very competitive in this and so would turbo 4 cylinders. It would not be a lesser class by any means but one that could still resonate with a large group of fans who might be getting alienated by the exotic current Pro Cars. It would be just like how Pro Stock is with drag racing fans. I would not want to see drifting go the way of import drag racing where the cars got too trick for the fan base to connect with anymore.
Monday, September 15, 2014 12:54 PM
Mike, a question regarding the front suspension. The lower hub mounts seem to be a little "fragile" given single shear and a bit of a moment arm with the spacers. I realize there isn't a perfect way of doing this, but it this deemed acceptable given the forces involved? Is this OK because of the McPherson strut setup?

Thanks for the time and effort you put into this documentation. I appreciate it very much.
Mike Kojima
Mike Kojimalink
Monday, September 15, 2014 2:01 PM
@Where, we have all the spacers for two reasons, one I was experimenting with roll center location and toe curve and two, I was trying to avoid designing a part that would require a lot of machining time on the CNC machine. I wanted to make a piece that could be waterjet cut and finished with just two set ups on the machine to save both time and cost. We also try to design some of the peripheral suspension parts to be somewhat on the weak side to sacrifice them when there is an accident or vehicle contact which happens all the time in drifting. We only have five minutes to fix the car so we try to make the LCA break before the subframe, the spindle bolt before the spindle or strut, etc.
Dan DeRosia
Dan DeRosialink
Monday, September 15, 2014 2:36 PM
Hm, different things with the shocks to the point of needing to cover them... interesting. I can make guesses and think about things, but I'm not even going to ask for more details. The mention of breakaway suspension parts is always something that puts other stuff in light too - the steering arm, for example, I automatically look at it from adjustability and ackerman (1st gen RX-7 uses that sort of thing too actually) but I bet on a good hit, the single shear bottom pivot may tear out of the steering arm, but that's just 4 bolts or so to change a new one in.

Lotta details to appreciate here.
Monday, September 15, 2014 10:19 PM
So 650hp at level one, 80hp per level conservatively. Thats 2010hp at level 18... I'd pay extra to see that.
Mike Kojima
Mike Kojimalink
Monday, September 15, 2014 10:48 PM
We think it can make up to 1500 hp. No dyno can take it though. We haven't run it past level 4 in testing and 3 in competition.
Micah McMahan
Micah McMahanlink
Wednesday, September 24, 2014 9:32 AM
hahaha I saw Dan's post about the rod end bending/FSAE comment. That was actually my first thought upon seeing that lower control arm!
Mike Kojima
Mike Kojimalink
Wednesday, September 24, 2014 10:04 AM
The control arm is designed to be sacrificial.
Dan DeRosia
Dan DeRosialink
Sunday, September 28, 2014 5:44 AM
Micah: Seriously, when I've seen rod-end-in-bending on stuff up to and including LeMans Prototype cars, I'm inclined to think that maybe, just maybe, people make too big a deal about it, you know? Some people are just traumatized by FSAE maybe.
Mike Kojima
Mike Kojimalink
Sunday, September 28, 2014 7:09 AM
A lot of it was influenced by Carrol Smith in FSAE. He would take points off for the rod ends. I personally have never had a failure of the rod end including several cars in hard accidents that broke the LCA.
Dan DeRosia
Dan DeRosialink
Sunday, September 28, 2014 8:51 AM
Yeah; I mean I know (we all know) it's theoretically less than ideal, but it's not that hard to size the suckers where in all practical terms it's fine. When I've seen it on one of the Nissan ZX-T GTP cars and a Riley and Scott MkIII LeMans car amongst all sorts of other things, I have to conclude that it's not that big of a deal.
Valters Boze
Valters Bozelink
Monday, October 13, 2014 1:31 AM
Finally had time to set everything aside and read the article.
Dear lord this is amazing build. Dai has steel balls to drive it and there maybe is a bit of a problem. The car is over-engineered and over-perfected for motorsports, especially for quick-swap-engine scrape-the-wall harsh wrecking steel bash that drifting actually is. Cant help noticing it when watching Daijiro finally run the car, especially against Joon in TX and Aasbo in Irwindale. Qualifying runs and lead runs were fantastic. But when it comes to follow runs its clear that it takes more than just courage to go all out when driving such a piece of art. When you dump a big engine or high power SR/RB in some s13 or popular drift tax shell it is not a problem to drive it like you stole it, crash it, replace parts and continue adjusting driving to car's shortcomings. But when there is so much effort and talent put into the greatest drift build on planet, even if it is ready for quick repairs, it is impossible to forget the worth of it and go all out. This is more of a museum queen.
If there was just one last car I could drive in my life this would be it :)
Thank you Mike for support and letting to see the car up close, it is mindblowing!
Hands down its in motorsports history, long live the Flog!
Mike Kojima
Mike Kojimalink
Monday, October 13, 2014 9:29 AM
In Texas and Irwindale we were dealing with some development issues. In fact this whole year we were. Remember it to Chris Forsberg 3 seasons to debug the 370Z and get it going. A tight budget and no test time made things difficult. This car can be very competitive with a little more work.
Monday, December 29, 2014 11:30 AM
Would pulling a vacuum before/while filling the cooling system be an easier way to avoid air bubbles?
Mike Kojima
Mike Kojimalink
Monday, December 29, 2014 12:22 PM
Having a properly designed cooling system is how you avoid bubbles.
Dan DeRosia
Dan DeRosialink
Monday, December 29, 2014 3:32 PM
Wait a sec, did this get updated? I don't remember the bit about the shock top mounts because, well wow, I'm pretty sure I would have remembered those. And I remember hinting around about the purpose of wider track but not details, and doing it for more steering angle isn't what I would have expected (but I'm not a drifter)

Like I said before, cool stuff.
Mike Kojima
Mike Kojimalink
Tuesday, December 30, 2014 1:19 AM
It might have gotten update there.
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