GT86FRS Banana Build

[avishenoy1]

So I've been thinking about making this thread for a while and finally decided to bite the bullet since I want a journal of the car's progress from start to finish. Hopefully you guys will appreciate the build and provide some feedback.

First off, the primary goal for this build is on-track performance and as cliched as it sounds, function over form. I'm a big fan of racing, especially production based series, and have taken a lot of inspiration from GT and Time Attack cars. I'm an engineer and I have the utmost respect for the engineers at Toyota/Subaru that designed this car, so I always do my research before messing with what truly is a well designed sports car in stock form. That being said, I also understand that cost dictates design in the corporate world with very few exceptions, which leaves plenty of room for improvement.

I'm also a big fan of another cliched phrase, built not bought. Anyone with enough money can go out and buy a Lotus or a BMW that is track ready off the lot, but where's the fun in that? I love working on the car myself and learning how it works, plus I can't stand paying for labor, so I do all of the work on it myself. That being said, I did buy the Release Series 1.0 because it came with a lot of very nice TRD parts already installed and I got it at an insane bargain since it was "Used" (4500 miles). I wasn't a huge fan of the bright yellow but it's grown on me.

Eventually I would like this to be a dedicated track car but for now it's also my daily. I firmly believe that the FT86 platform has huge potential in GT racing, but due to fact that it's a relatively new car, cost is a big factor keeping it out of competition in most entry level classes.

Last but not least, it's an Automatic. At this point you're probably wondering, why did I read this far? Why would anyone buy an automatic, let alone build it? Really, a slush box track car?

Hold the jeers. When I first drove this car in automatic form, I was expecting to be disappointed. I was expecting slow shifts and flappy paddles. I was expecting to be bored.

Let's just say that after the test drive, my expectations were shattered. The shifts in manual mode were crisp and quick, and I enjoyed being able to use either the paddles, or the stick to shift in Manual mode. I was also pleasantly surprised when in Drive with sport mode engaged. The car revved high, shifted almost telepathically, and even engine braked for me. The whole experience was unlike anything I've had in an automatic and offered plenty of driver engagement when desired, as well as daily driving convenience. The main thing that sold me on the auto was that the car was still FUN to drive.

After having the car for almost a year I have no regrets, and actually find that I'm able to focus more on steering input and line at the track without having to take my hands off the wheel. On that note, I'll finish with another cliche that sums up why I love the automatic, it may be slower, it may be less engaging at times, but it's the driver, not the car. Here are some pics from when I first bought the car, more updates to come.

[avishenoy1]

The banana was running with an Openflash Header and Stage 2 tune for a few months which was a good setup, however I still felt that the car would benefit greatly from a bump in power.

After extensively researching boost options, I went with the Vortech V3 kit because of it's reliability and ease of installation. I also recommend this article for anyone deciding on how to boost their car. There are pros and cons to each, but in my opinion the centrifugal supercharger provides the optimal boost curve in terms of power delivery and reliability for a high compression engine such as ours. Basically too much boost near the engine's torque peak at mid range rpms will cause detonation, however at high rpm past the torque peak, cylinder pressures drop off due to efficiency losses, allowing the engine to accept much more boost before detonation occurs. Also, a centrifugal blower with a larger compressor housing will flow more air than a small one at low boost pressures meaning, you don't need as much boost to make power. The Vortech blower is huge compared to the rotrex units for a good reason. Compared to a turbo or a Roots type supercharger, a centrifugal blower is going to put the least stress on the stock internals while providing the most linear power delivery.

It also didn't hurt that I got a killer deal on a used kit with a rebuilt blower from @Enalband24.

The car was ECUTek remote tuned by @moto-mike at Moto-East who did an excellent job getting the car running smoothly. There were a few minor hiccups with a rough idle, however remote tuning is never completely straightforward, and Mike was very thorough and sent me many revisions until the kinks were worked out.



Along with the supercharger, I installed a few supporting mods:

Saikou Michi Dual Catch Cans - Installation is very simple and with some extra 3/8" and 1/2" OD tubing, they look amazingly stock tucked away by the battery. These will keep blow-by oil out of the supercharger, intercooler, and intake manifold. NA engines don't produce much blow-by oil which is why our car did not have catch cans from the factory, but under boost much more oil is pushed out of the crankcase into the intake. Also, catch cans are useless without properly designed baffling to condense the hot oil vapor. Saikou Michi makes properly designed catch cans that are relatively cheap compared to other brands, so I highly recommend them.

Mishimoto Radiator - This radiator is MUCH thicker than the stock one and thus has a lot more surface area and cooling capacity. That being said, the stock radiator is highly efficient so even with the added heat from the supercharger many people say it's not necessary. I got it for a great price so I decided to be on the safe side. One thing I highly recommend is to reuse the foam insulation around the stock radiator as this will direct flow through the radiator core rather than around it. With the added thickness, there is more flow restriction, so despite the added surface area, without adequate airflow, a larger radiator won't necessarily be more efficient.

AEM Failsafe Wideband Gauge - A wideband afr gauge is extremely helpful for tuning and monitoring a boosted engine. I installed the sensor in the rear O2 sensor bung since I'm running a catless header and don't really need it. The install was pretty straighforward and I wired the gauge signal output to the rear O2 input for data logging and tuning. Any good wideband will do and I don't use the added features of the failsafe gauge since the same thing can just be put into the tune via ECUTek.

[avishenoy1]

Gauges galore! I got a single and a double universal A-Pillar gauge pods from Summit Racing for less than $10 and Bosch electrical oil temp and pressure gauges for under $20 and a Sunpro (Bosch) boost gauge for $3!!!

The universal pillar pods required some molding with a heat gun to get them flush with the factory A-pillar trim. The gauge wiring was straightforward and I mounted the oil temp and pressure senders to the TRD sensor plate which mounts right under the oil filter. I used an Add-a-fuse for gauge power and lighting and routed the ground wire for the gauge lights to the black wire on the dimmer dial so that they dim with the dash lights.

I'm pretty happy with how they came out, even though it's not as clean a a custom pillar pod, you can barely tell the difference, plus i'll sleep better knowing I saved about $100 on a piece of plastic.

One last thing, it would seem that the TRD sensor plate is not a great place for the oil pressure sender since it sits high above the engine. Once the oil warms up, the gauge reads 0 at idle and low rpms so I'm assuming the pressure drop is too great for the sender to get an accurate reading, which is a shame since it looked so clean tucked away behind the AC compressor. I'm planning to relocate the pressure sender to the port on the engine block.

[avishenoy1]

Sard LSR Wing - This wing is a perfect example of a part that provides both function and form. It is a very well shaped airfoil and the way it curves on the sides makes it blend into the car's body lines for a very OEM look. The mounts clamp to the sides of the trunk so it's very easy to install and can be removed at any time without leaving holes in your trunk. The carbon fiber weave is immaculate and the glossy resin finish is flawless. It's incredibly lightweight and the angle is fully adjustable from about 0-8 degrees.

Valenti Clear Red Tails with Sequential Turn Signal - These simply look fantastic and the sequential turn signal makes me smile every time I see it, plus it's pretty hard to ignore so the person behind you will definitely know you're turning.

TRD Aero Stabilizing Cover - This mod is very subtle but actually significantly improves the aerodynamics of the car. It's custom molded piece of ABS plastic that fills the large gap between the rear windshield and the trunk. If you've ever seen a flow visualization video of this car you know that this gap creates drag and flow separation over the car and the Aero cover eliminates this.

FTEightySix/GCS Fourth Brake Light - Got these for an insane deal and they look fantastic at night with the valenti tails. Plus they add an extra brake light and brighter reverse LEDs for safety.

Intec Combattente High Mount Fourth Brake Light - This was another aesthetic mod that turns out to improve safety as well. With the stock brake light on the rear deck I had very little visibility in the rear view with the wing, not to mention the fact that the wing basically blocks the person behind from seeing it, especially if you're lowered. It's plug and play and mounts to the roof, putting it at eye level of the driver behind you, while greatly increasing rearview visiblity.

Toyota Badges - I have always been a fan of Toyota and think that the T badges look a LOT better than the Scion ones. I wanted the GT86 badge but also kept the FR-S one. Another little thing that makes me smile, especially with the matching plate and plate frame.

Backup Camera -Was pretty simple to install, you just need to splice into the headunit wiring or purchase a plug and play harness.