Vorshlag BRZ Project Build Thread
BRZ Project Introduction - August 28, 2012: We here at Vorshlag have had a cautiously optimistic view of the FT-86 Subaru/Toyota RWD joint venture starting 3+ years ago when the car was first announced. As soon as the pre-production cars started circulating the USA (January-February 2012), we went to a local Subaru dealer and measured all sorts of things (which you can read about in my February 2012 post here).
We noticed several things about the pre-production car pretty quickly, such as the many similarities with production Subaru model parts and some notable exceptions. The placement of the engine was uncharacteristically far back for a Subaru, which helps explain its more ideal 56% front weight bias.
The basics looked good, but as with any production built car, it looked to have some compromises that we felt we can improve on. We had a quick pow-wow and came up with some plans, then the same weekend we took measurements on the blue pre-production BRZ, Matt here at Vorshlag placed an order for a 2013 Subaru BRZ Limited in the same World Rally Blue.
Months went by with his Dallas based dealer without any ETA for his order, while other BRZs were arriving for weeks at this same dealership. He lost patience with this process, cancelled his order, and found an identical car sitting on a lot in the state of Connecticut. His car finally arrived on July 18th and he began daily driving it while we worked on a Subaru build for Pikes Peak. Once that STi project was finished and the race was over, we finally got a chance to get his BRZ into the shop to corner weigh it, remove a few parts and scale them, and measure the suspension in more detail.
Purpose & Goals
Like we often do when a new chassis comes out, this particular BRZ is going to be a test mule for new Vorshlag parts. It will be primarily a daily driven street car, but also set-up to run in the SCCA autocross class called "STR" (until the Solo Events Board wises up and moves it to the STX class, where I think it belongs). The rules for that class limit the tire width to 255mm and the wheel width to a maximum of 9" wide. The suspension options are fairly open so we can do springs, coilover shocks, camber plates, bushings, some control arms, swaybars, and more - so long as we don't move any of the suspension pick-up points. Engine mods are pretty restricted, but full length headers are legal (with cat placement rules) as well as a lightweight cat-back exhaust, a cold air intake and engine tuning. We will either make these items or source them from other vendors.
Vorshlag camber plates for use with OEM springs require a new upper spring perch made with a modified stock or CNC aluminum perch
One of the first parts that we will test are our FT86 camber plates (which we've already sold for many coilover equipped FR-S and BRZ models). This car's front spring diameter is unique for Subaru and will require a new upper spring perch design to work with the FT86 chassis OEM front springs or OEM-style lowering springs. All of our camber plates include a new upper spring perch with a sealed radial bearing inside. Swift Springs has new Sport lowering springs coming from Japan that we will install as soon as they arrive. Whiteline has some bushings and bars that will be added to the car when they are available, too.
This weighing still had all of the "trunk junk", 3/4 tank of gas, and came in at 2775 lbs.
We don't plan on making this into a gut-crushing race car, but a better handling, fun street car and hopefully faster for autocross and track use. We had originally planned on testing the first pre-production AST 4150 monotube coilovers for the FT86 chassis, but they were sent to another dealer, so we're waiting for the second test set. As soon as we get coilovers on the car we will post in this thread with our impressions. The corner weight shown above shows 55.9% weight over the front axles, which is exceptional for any Subaru we've ever weighed. Many times their FWD or AWD models approach 60/40 weight bias, but the lack of AWD allowed the engineers to move the engine and transmission back (and low) for a better F/R bias and lower Center of Gravity (CG). We plan to lower that 2775 pound initial weight and will show the weight loss for each part we replace.
First Mod: Better Wheels & Tires
Look how narrow and "tucked" inboard the factory wheels and tires look on this wide sports coupe.
The first upgrade for Matt's car was a wheel and tire change, since any kind of competition on the factory rolling stock was going to be an exercise in frustration. This is a great handling car from the factory, for sure, but the one major deficiency of this car that almost all car magazines have agreed upon is the factory tires. The relatively narrow 215/45/17 Michelin Primacy HP tires are what come on the European model Toyota Prius, which tells you it is about as far from a performance tire as they come. This is a low rolling resistance tire, first and foremost.
I got a lot of grief earlier this year for calling the factory BRZ tires "Prius tires" (even though that's exactly what they were), and at the time it was from people who had never seen or driven these cars. I suspected at the time that these skinny, low grip tires would make the cars test poorly by the car mags (it did) and be a significant hindrance to the on-track performance of this new model. Once Car&Driver (article) got their hands on the car, they felt the same way and simply swapped the Prius tires for an identically-sized Dunlup Direzza Star Spec. They dropped over 2.3 seconds on their one minute and thirty second test course (article). These Primacy tires will help you eek out another ~1/2 mpg better on the highway than a wider performance tire, if you are a Hyper Miler. If you are an automotive performance enthusiast, you will very likely want to make a wheel and tire upgrade a high priority.
I've already seen dozens of BRZ and FR-S owners upgrading to 7.5" and 8" wide wheels, but we at Vorshlag have never been shy about stuffing as much wheel width under a car as possible. A larger wheel can support a larger tire and with a larger tire you can get more grip! Tire heights do have to be considered, but a taller tire can have an advantage in autocross situations where an extra 1-3mph in 2nd gear can make all the difference. I only stop adding wheel width when we get tire rub, and even then I'll roll a fender and try to get more if we can. After some early measurements before Matt's car arrived, then a bit of a gamble, we went with a 17x9" aluminum wheel that has an +42mm offset front and rear. These bolted on with perfect inboard clearance. The rear can take more wheel width, but the front is pretty maxed out until we can get some more negative camber with our camber plates. This is definitely a car where a "square" wheel set-up will be best for street/competition usage (same width front and rear).
Now I will point out that going from the stock 17" wheel diameter up to 18" wheel diameter gains you nothing performance wise but higher cost & weight on both the wheel and tire. If you keep the same tire diameter (to not alter gearing or speedometer) this +1 wheel diameter change would result in a shorter sidewall height, making the ride quality worse and the additional weight can adversely affect handling. That was failure number one in Car&Driver's article when they started messing with wheels and tires beyond just slapping better tires on the stock wheels. They used an 18x7.5" wheel (still too narrow) and a tall 235/40/18 Dunlop tire (almost a full inch taller in diameter) and slowed down 0.7 seconds from the 215/45/17 Dunlop tires on that same road course. Classic mistake where upping wheel diameter for no reason other than style bit them in the ass. Don't fall for the "+1" trap, just stick with 17" wheels on your BRZ or FR-S for the best performance. Competition racers might even look at 16" wheel diameters, which should easily clear the small-ish brake rotors, but trying to find wide performance tires in 16" wheel diameter is just about impossible these days, so back to 17's you go.
The tires installed were 245/40/17 Michelin Pilot Super Sport's. Personally, I would have used a 255/40/17 tire from Hankook (RS-3) or Dunlop (Direzza Star Spec), but Matt wanted to test this new PSS model. Since Michelin doesn't make a 255/40/17 in the new PSS yet, he bought the widest he could find in the right diameter (to not alter gearing), which was 245/40/17.
This 17x9 wheel is a big performance boost, being a full two inches wider than the somewhat heavy 17x7" stock wheels (20.4 lbs). The addition of wider aftermarket wheels and 30mm wider 245/40/17 tires was still a total wash with regards to weight: the original equipment 17x7" wheel and 215/45/17 tire was was 41.3 lbs, while the 17x9" wheel and 245mm PSS tire weighed 41.4 lbs. I've seen this same sized 17x9" wheel weigh as much as 2 pounds lighter per corner, so there could still be weight loss to be had here if someone makes an uber-light fitment for this car. This particular 17x9" is not a wheel we can sell (it is exclusive to another wheel dealer), so we will evaluate this sample set and come up with an alternative that we can market and sell, soon. From our search of many wheel catalogs there are barely any quality 17x9" wheels right now that fit this car (5x100mm bolt pattern is the tough variable), but I'm sure there will be if this car stays as popular as it is now.
I drove this car last week on the new rubber, which was the first time I have driven any car on the Michelin PSS, and I was impressed. They were MUCH quieter than Hankook RS3's or Dunlop Star Spec's (which end up being on about 80% of our customers' cars). Lots of dry grip, responsive as hell (it helped that these were 245mm tires on 17x9" wheel) and the ride was excellent. Matt didn't want to go with the RS3 or Dunlop in 255/40/17, because he's owned and driven on both of those tires and was tired with the noise and poorer street ride they tend to provide. However, for a "street tire" autocross class or track use I would use one of those other two models in a heartbeat.
The 2700 Calorie BRZ Diet
As usual, this car came in significantly heavier than the earlier claims made by the manufacturer, forum fan boys and magazine speculation. I'm not picking on this car in particular because this ALWAYS happens. Before the Honda S2000 was released many people bragged that it would only weigh 2400 pounds, but it came out at over 2850. It's an old story - the promise of a fly weight car that ends up being heavier when the actual production model hits the showrooms. Crash standards, luxury options, and emissions equipment all conspire to add pounds.
The FT86 chassis was supposed to be 2500-2600 pounds and it's nearly 2800, so we will focus some of our efforts on lowering that number. Each time we remove a factory part we will show the weight, as well as whatever goes on to replace it. Lower weight means more performance in every vector, be it cornering, braking or forward acceleration. 5 pounds here, 10 pounds there - it will add up.
Matt left his BRZ unattended when he went to lunch one day last week. It was on the lift so we could measure some things, so I pulled the exhaust off for a quick check (then sent him a text with pictures of his car in pieces - hehe!). The muffler was surprisingly light, as was the entire after-cat system. At a hair over 38 pounds, the after-cat exhaust is not a place where we are going to find a big weight loss. A typical exhaust on BMWs we work on can exceed 90 pounds, and dropping 30-40 out with a lightweight racing style exhaust and muffler on those is common... but that will not be the case here.
That suitcase-sized rear muffler is the heaviest part of the system, of course, but must not have much "heavy" inside. I was pretty bummed, thinking this was be a good place to lose weight. Most of the aftermarket mufflers we use are still 8-13 lbs, so there are still some weight savings to be had. The stock exhaust is quiet and could be restrictive - we shall see.
We did see a lot of steel in the control arms and such, which could be replaced with aluminum by the aftermarket or maybe a future, rumored "STI" model, like the STI model Imprezas often do. We will check what this stuff weighs and see what we can do. The factory exhaust manifolds might hold some pounds we can drop, so when we get a chance to pull those off we will get a weight and think about a custom header. Might unleash some power, too.
I have owned and driven a wide variety of sports coupes and roadsters and the BRZ does not disappoint. The normal complaint with a Miata that I run into with my height is a general lack of headroom, but that is not a problem on the FT86 chassis. The interior is roomy and the greenhouse has excellent visibility, with the exception of the B-pillar creating a bit of a blind spot on the left side (this can be mitigated with proper side mirror set-up). The chassis feels tight and has none of the cowl shake and rattle I always feel in a Miata or other roadsters. The car rides well and handles like a Miata (except less roll), with instant steering response and very neutral handling - especially on the 245 Michelins stretched out on the 17x9" wheels.
The interior quality is exceptional for a car in this market niche, and the radio sounds really good. The pedals, steering wheel and shifter are all placed perfectly, other than an unusual angle of the wheel relative to the dash when I have it adjusted so that I can see the gauges. It just looks a little off, but I don't notice it once I start driving. Exceptionally good seats that I would not be in any rush to replace, which is rare. The back seat area is more of a package shelf than room for even tiny humans, but this still makes the car more useful around town than something like a Miata. I like the fact that it has a trunk and not a hatch back, too.
We know nothing about this turbo kit, so please contact Dynosty with any questions! This is simply a reference for the stock power level.
Having driven it hard on the street I can say that I do like it, but of course I wish it had more power. The 200 horses that this motor is rated at are all up top, and you have to wind it up to get it really going. It doesn't help that my daily driver has nearly three times the horsepower, so I guess I am a bit biased when you hand me a car that makes around 155 whp. Drive it hard enough and around several corners on some grippy tires and you forget all about the lack of power, because horsepower was never what this car was about. It is a true driver's car, with a quick steering feel, easily darting around back roads or carving corners on a purpose built road course. Low(ish) weight and lower cost consumables, great controls with proper manual gearbox shift feel.
This car really is a blast to drive as long as you don't have a Viper or Z06 sitting in your garage, and I think Subaru and Toyota have a hit on their hands. The look and performance of the FT86 appeals to a fairly diverse audience and will likely turns heads for quite a while. After my very first drive in this car, I parked at a restaurant and had two random older gentlemen walk up and ask me "well, how is it!?" They couldn't take their eyes off the car and knew a lot about it, which was odd for "non-car-guys".
Some of the deficiencies I point to in my post exist because they have to sell it to just about anyone, from a grandmother to a teenager, so I get why it has the compromises it has. I am fairly confident we can improve upon the various performance aspects of this car for the true car enthusiasts that want to buy this car: to make it lighter, handle better, generate more grip, and maybe even accelerate harder.
Stay tuned and let's see what we can do.
Terry Fair - www.vorshlag.com
Vorshlag project cars: $2010 GRM Challenge E30 V8 + E46 DSP Autox Build + 2011 Mustang GT autox/track car
Last edited by Fair!; 08-28-2012 at 07:18 PM.
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