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

[RedReplicant]

Surprisingly, probably due to the surge tank setup, I was able to pump the fuel tank dry with the normal in tank pump. Car took 12gal of 91 from jugs and wasn't overflowing so I'm fairly confident it'll be fine.

Radiator hose got heat shielded, funnel for bleed ready, etc.



First start happened

Found that the car wasn't charging and the car cut off at 8v indicated in Haltech, with some help from the KSwapped FB group I found that I'd inadvertently swapped relay positions when removing the Harrop kit on my car. Looks like charging is good now




Found a few more things to add to my quickly growing to-do list:
1. Secure the fuel lines in the engine bay so they can't vibrate
2. Oil temp sensor calibration is way off
3. Need to make the throttle body mapping updates Tyler posted on FB (https://i.imgur.com/S3PTOtF.jpg)
4. The out of the box tune is looking for 43.5psi fuel pressure, my surge tank FPR is set to 60psi, need to fix that. I greatly prefer a fuel pressure sensor so I can add a failsafe.

[RedReplicant]

First drive went super well

Few notes:
1. The Sachs Sport Metallic 4 puck that I was worried about feels like a stock clutch, absolutely zero issues and a massive relief.

2. I forgot to plug in the wideband after moving everything to its final location, the car felt like it wasn't going into VTEC but still felt about as quick as my FA20 bolt-on BRZ so I wasn't positive. Plugged in the O2 sensor and now we're getting somewhere, feels pretty good on the base map for what it is but I'm sure a proper tune will be night and day.

3. I left my breathers open since I'm waiting on my catch can stuff to show up and I also overfilled the crankcase by a quart thinking I was going to plumb in my oil cooler before first drive. Yeah, now I have a bit of an oil mist mess to clean up.






Got a decent checklist of little things to get done.

[RedReplicant]

Knocked out some aluminum remote reservoir brackets to bolt down the Rennscot JRZ mounts.




Bought a Vibrant catch can, which ended up being a lot larger than expected. Mounted it to a couple of existing holes on the left strut tower and used some pushlock 10an fittings to connect it to the valve cover.




Currently working through insane oil temp readings, ensuring the cooling system is has a full bleed, and a bit of smoke that I'm not entirely sure of the source of. The catback I bought had a ton of burned oil in it, so that is my hope.

[RedReplicant]

Cooling system was fully bled, I ended up figuring out that someone had wired the Verus Spal fans to the stock plugs and it was just popping the 25a fuses. Ordered two Spal fan relay kits, wacked them to a piece of aluminum, and wired it all up. I hate wiring, I should probably get some harness wrap for it.




Also figured out my smoking issue after resigning myself to pulling the cams and ordering valve stem seals.

When I put the car together I filled it with enough oil to account for the large Setrab cooler, but it ends up that making two AN lines is still on my todo list. I bought a safety wire drilled drain plug, which showed up today so I figured I'd just try draining the extra oil and swapping / wiring the plug.

Surprisingly (to me), no more smoke. I'd always figured a not excessively overfilled car would just push extra oil out the breathers (and into my catch cans), rather than somehow pull it up past the rings. Lesson learned.

Car actually feels pretty sorted and I'm pretty happy with it right now. My todo list is down to:

* Build two 10AN oil cooler lines
* Dyno tune
* Build bell housing cover
* Swagelok the stock fuel hardline to 6AN, make a 6AN line to the fuel rail, and wrap it in Aeroquip fire shield
* Corner weight
* Build a exhaust side heat shield
* Plumb in a flex fuel sensor

[RedReplicant]

Put together two AN lines today out of leftover Aeroquip stuff I had and some Aeroquip StreetLite hose. Still paranoid about the whole thing, I want to figure out how to secure it better too. I might end up moving it to the right side of the car, but there are a few complications in doing that.




Tuner can't get to me until July 5th so I picked up a new set of ID1050x injectors from a friend that works at ID and recrimped my injector harness to USCAR from the Honda plugs. I bought an ethanol content sensor, mount, and KPower flex plug but was shipped the wrong thing, so that'll have to wait.




I set up the dead times that ID specs for 400kpa, chopped the base fuel map by about 70%, and did a little bit of adjusting at idle to get everything back in the right AFR range. I'm not planning on driving it except to the tuner so we should be good.

[RedReplicant]

Had the car tuned at UMS and made 206whp/178lbft on 91, which is about what I expected. I still need to do a NASA classing dyno run, but I am expecting around 200whp average.

Corner weighted the car yesterday. The below pictures are without me in the car and before the corner weight was done. Fuel loads were comparable, but the basic gist is that moving from the FA20 and Harrop to the K dropped about 200lb from the car.

2901lb to 2687lb

Before:


After:


I've also been chasing oil pressure and oil temp issues since I first started the car, which I think I've finally reduced to being a wiring harness shielding issue. DBW is interfering with the other sensors.

A few notes:
1. Base TDC angle was 304* in the KPower map, Haltech lists 311*, my tuner got 300* with the timing gun. Who knows.
2. Knock sensor settings on the base map are basically unusable
3. We were only able to update to v3.05.1 firmware. Haltech support line confirmed that their stuff is broke af.
4. Tuner found that 90% was the highest power for throttle opening, this made a 6whp difference from the stock 100%. You can create a Drive By Wire Max Throttle Position map with your axes as dbw throttle position and RPM then set it to 90*
5. The base map target lambda table is rpm vs cable throttle position, so it is always 0. It needs to be changed to DBW throttle position.

A few other common KPower issues have cropped up that I intend on addressing sooner than later:
1. Driveshaft vibration - I'm going to have the stock driveshaft shortened at a local driveshaft shop
2. Throttle body bolts shearing - I bought IAG WRX street mounts that look to have significantly less movement allowed than the stock WRX mounts. If this isn't enough then I will cut the intake tube shorter and use a longer silicone coupler.
3. Header cracking - Hopefully the IAG mounts also help with this, I'm also going to replace the existing flex joint in the Perrin with a larger one. If it cracks at all I will have the entire thing rewelded.

Anyway, where this brings me to is that I've made a pretty dumb mistake with the NASA calculator. I expected the car to slot right into the top of ST/TT5 as it sits, but I now realize I forgot to check the box for suspension external reservoir.

2830 min comp weight
Toyo RR or Maxxis RC1
Non-OEM Brakes
A-Arms Modifier
Suspension Arms Modifier
Suspension Bushing Modifier
External Reservoir Modifier

This comes out to 191whp avg. Removing the res modifier would make it 200whp avg.

Bumping to 4 on Toyo RR / Maxxis RC1 at the same weight would give me a 285whp avg. Dropping the ~100lb of easily removed weight in the car would still give me 275whp.

The three options are, in preferred order:
1. Buy Xidas and sell the JRZs
2. Set the rev limit lower, which would lower the average whp a bit since the power is basically flat from 7300rpm to 8200rpm. I can also set a max DBW throttle position if I need to chop more.
3. Run the car as a ST/TT4 underdog for now and build the ~275whp K24 sooner than later. I did this with my S2000 and it went well, but that was before the new tire point rules.

[gt5759]

Is E85 an option? I would think your only a set of cams and a tune away from the pointy end, figuring the weight removal as well with the fuel change. I just feel the car is really good but over developed for 5. To be on the pointy end of 5 (imo) would take quite a bit of changing parts out - going back to stock brake calipers, stock arms, none spherical bushings and shock change, at least from my experience. Plus I am biased towards more cars in 4

[RedReplicant]

Originally Posted by gt5759

Is E85 an option? I would think your only a set of cams and a tune away from the pointy end, figuring the weight removal as well with the fuel change. I just feel the car is really good but over developed for 5. To be on the pointy end of 5 (imo) would take quite a bit of changing parts out - going back to stock brake calipers, stock arms, none spherical bushings and shock change, at least from my experience. Plus I am biased towards more cars in 4

I completely agree with you - I think the optimization for 5 would be stock arms, non-spherical bushings, PP Brembos, weight removal, and cams/E85.

Maxing out 4 wouldn't be too difficult with hohos, but I don't want to run them.

Only tires that make sense are the RR or RC1 for contingency, which isn't always met in my region versus 5 making it every single event. Making the power to max out 4 on those tires would cost about $8k or so, I think.

[gt5759]

Originally Posted by RedReplicant

I completely agree with you - I think the optimization for 5 would be stock arms, non-spherical bushings, PP Brembos, weight removal, and cams/E85.

Maxing out 4 wouldn't be too difficult with hohos, but I don't want to run them.

Only tires that make sense are the RR or RC1 for contingency, which isn't always met in my region versus 5 making it every single event. Making the power to max out 4 on those tires would cost about $8k or so, I think.

I very much agree on the r7's, I'm going to try to stay away from them if I can as well. I plan on doing some tire testing once the new car is built between the rr and r7.
My thoughts are why spend money to go slower? Granted it will cost less and even possibly be profitable to make it a pointy end 5 car.

[RedReplicant]

Originally Posted by gt5759

I very much agree on the r7's, I'm going to try to stay away from them if I can as well. I plan on doing some tire testing once the new car is built between the rr and r7.

My thoughts are why spend money to go slower? Granted it will cost less and even possibly be profitable to make it a pointy end 5 car.

GRM put out an AR1 / RR / RC1 test today, might be worth a look if you've got a subscription

https://grassrootsmotorsports.com/ar...100-tire-test/

I get what you're saying, in my mind the move from JRZ to Xida would (hopefully) be lateral financially, a bit less weight, less to deal with being a 1 way, and a benefit in terms of the experience 949/SuperMiata brings to the table.

The car for sure wouldn't be competitive nationally, but I think I'd be able to run free or at least subsidized tires regionally, which is about as much as I can ask for.

I really think you went the right way with your plan, it'll be a multi class / organization weapon. I probably should have considered the LS route, haha.

[gt5759]

Originally Posted by RedReplicant

GRM put out an AR1 / RR / RC1 test today, might be worth a look if you've got a subscription

https://grassrootsmotorsports.com/ar...100-tire-test/

I get what you're saying, in my mind the move from JRZ to Xida would (hopefully) be lateral financially, a bit less weight, less to deal with being a 1 way, and a benefit in terms of the experience 949/SuperMiata brings to the table.

The car for sure wouldn't be competitive nationally, but I think I'd be able to run free or at least subsidized tires regionally, which is about as much as I can ask for.

I really think you went the right way with your plan, it'll be a multi class / organization weapon. I probably should have considered the LS route, haha.

Dang, I'm tempted to subscribe to them as I really want to read that article!

I agree, Xida's are good stuff and have great development behind them, if they had a double adjustable I would buy some. I think the car could be very competitive if you go through the full gambit of changes for 5.
Your K swap is an excellent choice for power, I might have gone that direction if the balance shaft issues were sorted, mix matching them or removing never goes well for the secondary harmonics in a inline 4. I deleted the balance shafts on the 2.4L ecotec I put in the miata and it vibrated so bad it broke electronic throttle bodies, cracked manifolds, caused crank trigger pick up issues and cam pick up issues. I chased that for a long time, finally started to get it all under control towards the end but I will never deal with that again. Cost me several races
If it feels like the right direction for you then do it to it! I look forward to see what you choose!

[RedReplicant]

KPower was nice enough to send me shielded wires for the throttle body to test, but they don't appear to have made a difference. I have another idea and will have the pins/junction box/wire from Corsa Technic to test that plan tomorrow. Pretty optimistic about it though.

I managed to wrangle up the opportunity to run a day at the new private track (Attessa https://www.attesa.com/) here in Arizona, so I'm pushing to get the loose ends tied up to run that this month.

I made some clearance between the Perrin exhaust to the Cusco diff cover with a ball hammer and a file since they were sitting on each other at rest.



In prep for the classing dyno I dropped the rev limit to 7800 from 8400 in effort to both preserve the motor and to drag the average whp number down a bit.

So, since everything here is fairly comparable I give you:
* note: K24 and S2000 dyno graph scales go to 9k, both FA BRZs go to 8k

My dyno today - bone stock KPower K24 swap, pump 91


Full bolt-on first gen BRZ NASA TT5 car, pump 91


Stock plus Cleib catback and air filter second gen BRZ NASA TT5 car, pump 91


Full bolt-on AP1 S2000 TT4 (lol) car, pump 91


Redline600 was nice enough to overlay the K24 with the BRZ here:


Average WHP comes out to 196. Where this leaves me is:
2882 min weight
196whp avg
255 Toyo RR
A-Arm modifier (required)
Non-OEM brake size modifier
Non-OEM control arm modifier
Non-OEM bushing modifier
External res shock modifier
No front splitter
Rear wing (non-btm aero)

So basically, I can put a bit of ballast ...or a cool suit... in the car and be fine as-is minus the splitter. Changing out the JRZs would buy me 2764lb comp weight or the ability to run my existing splitter at 2860lb.

We will see, we will see.

[RedReplicant]

EDIT: CLIFF NOTES:
Oil temp grounded to ground instead of sensor ground. Switch the oil temp sensor ground wire to AC1 pin 34.
Use this temp sensor calibration: https://drive.google.com/file/d/1ws1...usp=drive_link

Success, both oil temp and pressure are working as expected now.

I talked to Gerald and he agreed with my grounding idea, so I made a list of grounds at the junction box, as shown left to right:



1. VTC solenoid / oil sensor
2. Crank position sensor / VTEC solenoid
3. Both cam position sensors
4. Ground ring, back of head
5. Coil 2
6. Coil 4
7. Coil 3
8. Coil 1
9. Ground ring, front of head
10. AC1 pin 44
11. AC1 pin 40
12. AC1 pin 37

I decided the cleanest way would be to add a new sensor ground junction box, so I bought:
1x https://www.corsa-technic.com/item.php?item_id=1697
1x https://www.corsa-technic.com/item.php?item_id=1698
10x https://www.corsa-technic.com/item.php?item_id=1104
10x (bought spares / expansion later) https://www.corsa-technic.com/item.php?item_id=698
1x https://www.corsa-technic.com/item.php?item_id=381
1x https://www.corsa-technic.com/item.php?item_id=291

Depinned ground junction box pin 1, cut off the second wire, pinned the VTC solenoid into the existing junction box, pinned the oil sensor into the new junction box (sensor junction box)

Depinned AC1 pin 34, cut one of the wires, pinned it into the new sensor junction box, soldered/heatshrank a new wire from the wire I cut on AC1 to the sensor junction box.




Nice thing is the junction boxes clip together to keep everything tidy. I think a cleaner way would be to crimp a new pin for AC1 instead of splicing, but whatever. I also intend to move the cam sensors and crank sensor to my sensor junction box since Haltech expects them to be sensor grounded.

This is an improperly working sensor graph (green line, bottom graph)



This is what a working sensor graph looks like (green line, bottom graph)



EDIT: CLIFF NOTES:
Oil temp grounded to ground instead of sensor ground. Switch the oil temp sensor ground wire to AC1 pin 34.
Use this temp sensor calibration: https://drive.google.com/file/d/1ws1...usp=drive_link

[949 Racing]

Originally Posted by gt5759

..I agree, Xida's are good stuff and have great development behind them, if they had a double adjustable I would buy some.

Xidas are effectively double adjustable. The two are simply combined so it's not an independent adjustment. This has worked for all our Miata applications and works for the GT/GR86 platform. Independent adjustments adds a small measure of versatility but no greater performance intrinsically. However independent adjustments does add cost, complexity and reduces durability.

Short video on how we valve Xidas: