Honda K24 Swapped 2015 BRZ Ship of Thesus (NASA TT5)

[RedReplicant]

Not sure how to start this all off, so I will go with previous track cars. Excuse the rambling.


2002 Honda S2000
My first track car, bottom of class TT4 car but still managed to win a UMS Time Attack TA-B class championship, 2nd in points in TT4 my first season, and was on track to win my second TT4 season before I sold it. Still holds a couple NASA TT4 records.


2004 Mazda Mazdaspeed Miata
I figured this thing would be a massive upgrade from the S2000 in a lot of ways, unfortunately I got bitten my first session out on my first day driving it. Ended up stuffing it through a fence and mangled the car up pretty good, ruined the finish to my 2020 TT4 season. I ended up cutting both quarter panels out, trunk rails, passenger door, etc and had it ready for 2021. Car was stupid reliable last year and I was able to keep it together well enough to win the TT4 championship.

Car was a built motor with an EFR6258 making a flat tuned ~220whp from 3500 to 7500, Xida suspension, basic aero, and 100tw tires on 15x10 wheels. Put Continental Teves MK60 ABS into it out of an E46 M3 and was super happy with it, was stupid quick, etc.

In mid 2021 I bought my first BRZ from another forum member, a STX prepped 2016 Hyperblue car. It reminded me a lot of my S2000 and I was kind of like, okay, this is great, it'd be kind of funny to have another as a track car.



In November a super nice 2015 track prepped car popped up for sale on Facebook. Not sure how I came across it but I messaged, put down a deposit, and booked a flight to San Francisco. Pretty easy drive back down to Phoenix, I should have taken more pictures at the time.









Pretty extensive mod list, but the highlights were:
Harrop supercharger kit on E85
Ace A350 / Ace front pipe / CSG Touring
JRZ RS Pro coilovers
SPL everything in the rear
Voltex Wing / Marsh Performance 5" CF splitter
Stoptech 355mm / 345mm BBKs with CSG C2 pads
Cusco braces / bars
TC Design Cage (!!)
Sparco seats with Schroth belts
OS Giken diff and clutch
Fire suppression system
Complete Radium fuel setup with DW in pump tank with Radium hanger, filter, and surge tank

I took it out for its first event two weeks later. Times were close to my Miata, but the car was an absolute handful to drive and was off pace from where it should have been given the power it was making.


There were a number of issues that I fixed, it went something like:
* Took all of the adjustable arms out of the car and making sure they were actually the same length, this fixed the car going left on throttle and going right off throttle.
* Corner balanced the car so it didn't have a 36% cross weight, this fixed the car being a teter totter by lifting wheels mid corner
* Replaced the front links with RacerX so they weren't digging into the chassis under compression
* Re-routed the external reservoir lines for the front shocks so they weren't stretching at lock
* Swapped to an Eibach bar up front, stock bar in the rear, and added RacerX adjustable rear endlinks to fix the binding and help the balance a bit

My initial plan was to run ST and TT4 with it, so I was hoping to be able to turn it down to about 280whp and cut some weight. On the initial classing dyno it made 332whp, so I spoke with the tuner and swapped pulleys, but the car ended up making 320whp anyway on the same dyno/fuel/etc. I ran out of time so I was forced to ballast the car up to 3040lb with me in it.

Next event out I popped 4th gear second session out. Ignore my terrible driving, I had a sum of total of maybe two hours on track in the car by this point.

After looking through the options, I ended up coming across a Jack's Transmissions built box with 0 miles on it for a good deal, so I snagged that.


I also needed to build a new splitter since the Marsh one was 5", but I'm rule bound to 4" so I built one with birch based off of it.





Third event in the car was a NASA event at Wild Horse Pass East. Traffic was absolute garbage so I never got a good, clean lap. The one I had to throw away here was on pace to win, but the first lap was enough for second. I've been about half a second quicker here in the Miata and the S2000, so obviously terrible driving was done.

Car was making noise in right turns so I took it home early, I found a bad front left wheel bearing and a corded front left tire. I had a bit of a think about it and came to the conclusion for multiple reasons that the car was going to be a nightmare to run competitively for a complete season. NASA Chuckwalla was coming up so I figured rather than chancing the possibility of popping a motor or another transmission I'd just move to my alternate plan. Kinda sucked since Chuckwalla is my favorite track and I was curious to see what this car would do, I was kind of figuring in the 54 area.




I ordered an RBB3 JDM K24A, KPower complete kit, Sachs sport clutch, and a ton of OEM Honda parts. I also parted out the entire motor setup from the car, which took about a month at fire sale prices.



Decided to swap the huge Voltex for a Verus High Efficiency wing.



Current state is that the motor is complete, chassis prepped, and I am just waiting on my KPower kit to arrive.




This brings us to current day.

My intention is to run it in ST/TT5 to work out issues with the swap, get more comfortable with the car, and figure some stuff out. My target is 2750lb with me in it, 255 Toyo RR, and 196whp NASA average horsepower which will basically make it the same on paper as my old S2000 but be in 5 instead of 4. Should be competitive.

Assuming that goes well, I'll be putting together a second K24 that is a little more spicy but still NA to play in 4.

[GabeoHuncho]

Nice, thorough, work


Seems like you're only scratching the surface with the potential
Very relevant for me as I'm also trying to learn the dynamics of the platform


Look forward to seeing more

[RedReplicant]

Received my KPower kit earlier this week and started getting to work. A few kit notes from me so far:

1. Spend the extra $200-300 for a USDM TSX motor over a JDM K24A. Having to replace the alternator, water pump outlet, water pump outlet studs / bolts, crank pulley, and a few other little things easily push you well past that initial savings.

The K24A crank pulley is a different diameter than the TSX pulley, which I haven't seen mentioned anywhere, so a standard off-the-shelf belt size won't work.

2. The kit includes non-OEM intake and exhaust manifold gaskets and a 1320 serpentine belt that fits the no AC setup with a TSX crank pulley. I didn't see these mentioned on the official parts list so it was a double buy.



Oil pan went on first since I'd already assembled the motor otherwise. You can see it has trap doors to help keep the oil near the pickup. K20A2 oil pump is required since the pan needs to be chopped to clear the subframe.






Pieced together most of the intake manifold stuff, I'm debating just buying a set of ID1050x injectors now rather than reusing the crusty looking OEM injectors the motor came with. I intend to build another motor later where they'd be needed anyway.





Had to drill out the left side top left motor mount plate a 1/2" bit since the spacer and plate holes weren't concentric. Not a big deal.




KPower has you flatten out the little aux mounting loop on the stock battery tray riser so you can attach the alternator wire junction to it. Unfortunately, this means my OLM battery tray setup won't work. I have a STM mount in my other car that would work, but I initially swapped the battery setups between cars in the first place because the Braille would die on me when sitting for a few days - super annoying in a daily. Batteries are different sizes so I can't just swap the tray setup.

Going to look into battery mount options now and see what I need to do.



Kinda in a holding pattern right now while I wait for my waterneck to show up from KPower, I opted for the Miata right exit over the BRZ waterneck, hopefully that works out.

[Evil Rocky]

This build is amazing!! Awesome job! Looking forward to more videos and info.

How is the Jack transmission holding up?

[RedReplicant]

Originally Posted by Evil Rocky

This build is amazing!! Awesome job! Looking forward to more videos and info.

How is the Jack transmission holding up?

It has been fine so far but I don't have a ton of time on it yet.

I bought it unused since refreshed from a w2w racer back east who was running two of them on rotation in his flat tuned Harrop car (smallest pulley, limiting throttle body up top to meet horsepower limits in the mid 200whp area) until it got wadded up at Daytona and he moved to Global MX5.

He warned me that he still eventually broke them, but they lasted much longer than stock. I looked at the alternatives (PAR, Quaife, CD009, BMW ZF) and it is what started me down the swap path.

Thing shifts like absolute butter though, zero synchro hangup or notchyness. Front and rear seal were leaking right away, but that was probably just because it was sitting before I bought it or something. I replaced both seals when I pulled the motor for the swap.

On another note, I bought the Sachs Sport Metallic clutch disk and pressure plate from a shop in Germany for the swap since it was a far better price than the alternatives. After I received it I realized it was a 4 puck and now I kind of suspect I screwed up and should have gotten the Sachs Sport Organic disk. We will see, I'm not a fan of overly aggressive clutches for a given power level but maybe I'm worrying too much.

[villainous_frx]

LETS GOOOOOOOOO! HONDA BOIZ

[RedReplicant]

Decided to just buy a Costco battery for the blue car and move the STM to the white car. Also dropped the header and midpipe off to be cerakoted locally.

[RedReplicant]

Wiring changes done, transmission tunnel hopefully beaten back enough.




Picked up a Radium fuel pulse damper since some other swap people have mentioned it helps.


Swapped the rear main seal, it was the last original seal left in the motor other than the head gasket.


Adapter plate is on, there is one bolt that won't thread in, so I am working on figuring that out now.


Since I had to get rid of the OSGiken HTR clutch for this due to it being a package unit I picked up a Verus clutch fork, updated throwout bearing, and fork springs.


Clutch stuff all ready to go. Sachs Sport pressure plate, Sachs Sport Metallic clutch disk (hopefully not a mistake), KPower aluminum flywheel, K20 OEM flywheel bolts, BRZ pressure plate bolts


I intend to get the motor in the car tomorrow, but unfortunately my header isn't back from the ceramic coater yet so no start this weekend.

[RedReplicant]

Flywheel on, it wasn't clearanced enough around the bolts to get a socket on easily so that was annoying.



Clutch disk on using a 3d printed alignment tool



Pressure plate



Starter, need to use the one super long / thin OEM K series starter bolt and the M12 that comes with the KPower kit. The second K series bolt is too long.



OEM TOB and Verus fork



Currently trying to mate the trans to the engine solo, not fun




edit:


And if anyone was curious,


I'll have to build some kind of cover for that.

[RedReplicant]

Wrapping up for the day, I'm going to basically finish everything except the entire exhaust system tomorrow since I don't have any of it right now.

Something I'm not looking forward to is figuring out how to pump a tank full of two month old E95 out.

[Irace86.2.0]

Buy a Dorman 5/16 quick connect and connect it to a 5/16 hose and route that to some fuel jugs. Run the fuel pump to empty the tank. You can double check the tank is empty by checking both sides of the tank. Siphon the passenger side to the driver’s side, and then run the pump again or just siphon it out from there.

[RedReplicant]

Originally Posted by Irace86.2.0

Buy a Dorman 5/16 quick connect and connect it to a 5/16 hose and route that to some fuel jugs. Run the fuel pump to empty the tank. You can double check the tank is empty by checking both sides of the tank. Siphon the passenger side to the driver’s side, and then run the pump again or just siphon it out from there.

Thank you, I seem to remember reading something about the suction from the right to the left not working without fuel pressure. I was hoping my surge tank setup would generate enough pressure to move fuel, but we will see.

Been super busy so I haven't had much time to work on the car the last few days.

Got the header back from the cerakote guy.


Shifter in, seems like a pretty nice setup


Backtracking a bit, another forum member found that running a line from the left side of the waterneck to the thermostat housing port that is normally blocked off by the KPower kit has helped with warmup and bleeding.

He opted to drill and tap the BRZ waterneck, I opted to get the Miata water neck that KPower sells that already has a left port. There are two other differences between the Miata and BRZ waterneck, one of them is an extra port for the stock Miata coolant temperature sensor that I simply plugged with a M14x1.5 plug. The other is that the Miata main right exit is 1" or so shorter than the BRZ outlet, I figured this would be a bad thing but after getting the motor into the car I found it is probably a good thing.

Motor with Miata waterneck


Mocked up lines from Miata left exit to normally plugged thermostat housing with Tractuff port installed. Other small thermostat housing exit goes to the intake manifold.


I didn't want to cut the harness mount on the car so the shorter waterneck outlet buys me some space. This is what the line looks like out of the box, not a real fan of the angle or it touching the harness mount.

Ignore the heat shielded wires, I haven't final routed them yet.




My plan is to use two 1 1/4" couplers and a couple of pieces of 1 1/4 hose to jog around the wiring harness and connect to the water outlet without disturbing the harness mount. We will see what I can piece together at NAPA.

Should be able to get it started and driving this weekend.

[RedReplicant]

Used Perrin 3" showed up today, needs some cleaning but is in good shape.



Finalized the dual thermostat to intake manifold and KPower Miata water outlet



Connected the wiring harness, threw in the intake manifold, and intake. I scratched the intake tube up being a gorilla, unfortunately. edit: it is paint transfer, I can save it





Front bumper back on



The couple of hose couplers I ordered will be here tomorrow so I'll figure out my right hand side coolant line tomorrow, get the header in, and hopefully start it this weekend.

[RedReplicant]

Did some hose work at NAPA today, picked three candidates.



Ended up settling on an 8721 and trimming the plastic harness mount a bit, which I probably didn't need to do in retrospect
.



Used the entire stock right side line and cut up the KPower provided line a bit. I need to make a couple of brackets for my own mental sanity.



Had a bit of drama when I tried installing the header + overpipe without a jack to support the end under the car, but it turned out fine.



Header in, driveshaft in. I can't believe how close the header to midpipe flange is to the body and it was kind of annoying that you can't get a socket on the driveshaft bolts now, I'm probably going to have the stock driveshaft shortened.

I also moved the heat sleeved wires behind the plastic harness bracket, which I didn't take a picture of.




Remaining items not in any particular order:
1. Pump in transmission fluid
2. Plug extra fuel line under the car (3d printing fuel line quick disconnect tool now since they work but break every time)
3. Pump out old fuel and add a few gallons of 91
4. Install Haltech properly under the dash
5. Support right hand side coolant line somehow, wrap it in a heat shield, and bleed the system
6. Reinstall underbody panels after a good test drive
7. Figure out where I am going to put the negative battery terminal ground on the transmission/engine since I screwed myself
8. Install the Perrin catback

After it runs:
1. Dyno tune and figure out what (if any) detuning needs to be done
2. Build 10AN lines for the existing Setrab oil cooler
3. Add a catch can and a 10AN line to it
4. Build some kind of header heat shield
5. Corner weight
6. Start building a 10.5:1 motor with a 4Piston CNC'd TSX head