Dave's Gen 2 Boosted BRZ Build

[trippinbillies40]

I guess I should get back on this forum and make a long post to bring things up to speed on my 2022 BRZ.

Through work connections I was able to be the first one in the country to take their 2022 home. It was a fun few days waiting for others to pick theirs up knowing I was the only one rolling around in one.



I had an opportunity (again through work connections) to get my hands on a pre-production model in August of '21 to check fitment of first gen suspension parts and verify everything was the same, so I had MCS coilovers and RPF1s ready to go on as soon as I got home with it. So it was looking better after less than 24 hours.



Then I got to some of the aesthetic stuff a few days later and brought my photoshops to life, sporting the Subaru Motorsports USA livery.



It saw some time trials



And autocrosses



But just a few weeks ago I took it down to Counterspace Garage and had Zack work his magic on a flex fuel Harrop supercharger setup.



On e60, we saw a 63% increase in HP and a 66% increase in torque.



I added some aero:



And then some more aero:



So that brings you up to speed. The car is primarily an XA autocross build but will definitely see some more track time and time trials. I drive it around town a bit but it's not a daily driver for me.

[trippinbillies40]

Current build list (I'll edit this post to keep it current)

• Karcepts-spec Motion Control 2-way w/ remote coilovers
• 17x9 Titan 7 wheels
• Karcepts front and rear top hats
• Karcepts larger front sway bar (gen 1 spec)
• Perrin 16mm rear sway bar
• JDL catless UEL header
• Perrin gen 1 3" cat back lovingly known as Sir Dronesalot
• Racer X rear upper control arms
• ARP wheel studs
• Harrop supercharger w/ flex fuel and injectors
• Radian Dual Catch Cans
• CSG Spec OS Giken clutch
• Track spec hood vents
• Koyo radiator
• AP Enduro front brakes
• DS2500 pads for daily/autox, DS1.11s for track
• Castrol SRF fluid
• GPSport Traction mod
• Zebulon wing
• Racebred 4" splitter w/ Zebulon titanium rub blocks
• SPL Front lower control arms

Current to-do list

• Install Racebred tire spats
• 3.9 final drive diff
• OS Giken diff to Shaftworks spec
• Splitter tunnels
• Trackspec vent gurney flaps
• Spherical all the remaining things | tie rods, rear toe arms, RLCA's, etc
• Custom oil cooler setup (had to ditch the JR cooler, no room with the Harrop)
• 10" wide wheels
• Eventually an Annointed Aero kit to make room for some more rubber
• Whiteline diff and subframe bushings, transmission bushing

[trippinbillies40]

I had the car pretty dialed in for autocross in STR trim, and as soon as I wrote the check for the Harrop, I started in with the extra suspension allowances and did the traction mod first. The car became horrifically pushy and only got worse with the wing. I finally got it out a couple weeks ago for the first autocross since supercharging it and as expected, it was still really pushy. Since then, I went up 10% in rear spring rates, went up a couple steps in stiffness on the rear bar, and did the FLCA's which helped roll center correction. I also added the 4" splitter but I'm not sure what to expect for additional front end grip at autocross speeds with it. So, we'll see if all of that was enough for an autocross coming up the next two weekends. The immediate plan if it's still pushy is to take the last step out of the front bar and go full soft. I'm hesitant to go stiffer on the rear bar until I get the Giken diff.

Here's my first day autocrossing it. It was a bit of a mess but after a heat cycle on the new Yoks, it started to come to life a bit.

[trippinbillies40]

Now for driving impressions on the Harrop: it's effing amazing.

I've always been a proponent for these cars not needing additional power and I stand by that. I went with the supercharger over a turbo specifically for the throttle response. I wanted the car to drive like stock, just faster. Zach absolutely nailed that on the tune. The best way I can explain it is every gear feels like one lower before it was boosted. So 3rd feels like 2nd used to, etc. On heated up 245 Yok A052's, it's right on the line of not being able to put power down well. 1st and 2nd are pretty useless even on 245 Pilot Sport 4S's with the traction mod. Honestly my favorite part is that a small tip of the throttle in 5th or 6th gear really exhibits the additional torque. The car just wants to pick up speed even with a small press of the throttle. Zach's flex fuel tune is flawless. I have gone back and forth on the mix several times now without a single hiccup. The clutch is probably the worst part of the car now but I'm finally getting used to it. I've had no issues with water or oil temps even driving in stop/go traffic in 100+ degree heat, and no issues with temps doing back to back autocross runs.

I'm going to have to take a page out of Kyle's book for a custom oil cooler solution as the Racebred splitter brackets kill any chance of putting something in the corner, and there's no room for one to stand upright in front of the Harrop exchanger. So, it'll be awhile before it's track ready again, but for now it's just a blast to drive around town.

[trippinbillies40]

Some glamour shots along the way:











[img[https://i.postimg.cc/N0SHBQ4D/Daves-BRZ-15.jpg[/img]

And one messing around on ACH after picking it up from CSG:



And finally, my uber-nerdy matchy matchy tire trailer

[autoracer86]

I saw this car on reddit. Nice to see you have a build thread . Great list of mods as well

[trippinbillies40]

After the first autocross post-boosting, the car was stupid pushy so the main goal was to fix that. I went up 50lbs on rear spring rate and reluctantly went to the mid setting on the 16mm Perrin rear bar, fearing the stock torsen diff wouldn't like that. As it turns out, the stock torsen diff definitely did not like that. The handling was not perfect but much much better than before. This at least lets me know what the next steps are. I have the Packwood Pro Solo this coming weekend so no plans to make bandaid changes for that. But I'm going to do a 3.73 final drive diff, OS Giken, then go up in rear spring rate more so I can go back down on rear bar.

[trippinbillies40]

Back home from a work conference in Vegas, finally getting around to the pro solo write-up. The car was behaving much better as the courses weren't nearly as transitional. However, the right side had a really fast run out to the first turnaround. This was my first time really trying out some of the RaceRom features like launch control, flat foot shifting, and auto blip. By the time I got used to them, data said third gear on the right side was worth a couple tenths but I couldn't put a faster run together after that.

I spoke with Karcepts at length and it sounds like Shaftworks shares the same opinion that an OS Giken will cure most of the issues I'm seeing. I found a 3.73 final drive diff on eBay that should be delivered any minute. Going to work with Lugod on getting the OSG on order in the near future. For now I'm going to lay low on more mods until I can keep an eye out for black friday deals and such. Biggest things on the to-do list right now are the diff, custom oil cooler, and making the quick release splitter actually quick release.

[grippgoat]

I'd like more info on what you've got the tires sitting on on your trailer. Is that box under them just to lift them up above the fenders? Or do you have a bit of storage going on under there?

I'm planning to just lie my tires down in two stacks of two on the front end of the trailer (looks like same HF trailer) for now to keep it simple. But I'm always looking for better ideas.

Thanks,
-Mike

EDIT: tire tie downs look like maybe this?
https://www.homedepot.com/p/Erickson...9160/303421789

[trippinbillies40]

Originally Posted by grippgoat

I'd like more info on what you've got the tires sitting on on your trailer. Is that box under them just to lift them up above the fenders? Or do you have a bit of storage going on under there?

I'm planning to just lie my tires down in two stacks of two on the front end of the trailer (looks like same HF trailer) for now to keep it simple. But I'm always looking for better ideas.

Thanks,
-Mike

EDIT: tire tie downs look like maybe this?
https://www.homedepot.com/p/Erickson...9160/303421789

Yeah I just built a box to get them up over the fenders. And yeah those are the tie downs.

[trippinbillies40]

Last event of the season is done, so here's the current to-do list:

-Going from 550lb rear springs to 650lb and getting rid of the rear bar all together

-Going from a 10mm front spacer to 25mm

-Adding an OS Giken tuned by Shaftworks

-Throwing that in a 3.73 final drive diff

-Figuring out an oil cooler solution, but leaning towards a JR Dual Rad knowing it will likely not be enough for sustained sessions but we'll never know unless I try it. So, do that before cutting holes in splitters.

-Adding some tire spats

-Taking some awesome 3D printed parts DocWalt sent me and getting them installed. Intake snorkel and some splitter bracket pin guide rods.

-General systems check on the suspension parts to check bearings, etc

Possible list if the holidays deals are good enough:

-Apex SM10RS in 17x10

-RLCAs

-Might even go to a Zebulon splitter now that I made it a season without destroying the less-expensive Racebred splitter

[Code Monkey]

I have a freshly inspected Shaftworks OS Giken on the way back to me and will be selling it at a discount if you are interested. Set up for HPDE with aero, MCS coilovers, RE71RS or stickier tires. Story here.