Irace86.2.0's KPower Turbo K24 Swap

[Irace86.2.0]

Originally Posted by M0nk3y

curious how the twin disk goes. Currently running a FX350 on my FA20 w/Steel Flywheel and I have some pretty awful harmonics 2500-3500 on both accel and decel (decel being much worse). To the point I want to rip it out. Might be worth a ping to Kevin to see if he as any thoughts, but going twin disk has crossed my mind. Though all I see is the 725 offered for FA20s unless it's just a call away to inquire about something different

The setup will be several hundred more than a standard kit considering this will have a custom flywheel setup. After shipping and tax, sub $2k still. I wanted a steel flywheel, street setup, so one race ceramic disc and one fiber tuff disc, which looks a little organic style disc. I'll do a review once I get this thing in, installed and broken in.

[Irace86.2.0]

Started to tear out the transmission once again. Fourth time’s a charm with a new clutch? I’ve had the transmission out of this car over half a dozen times that it doesn’t seem to take more than a couple hours to jack up the car and get the transmission out.

Here is the old clutch. The Exedy Stage 2 ceramic pucked clutch looks like it was skipping some and developing some hot spots on the pressure plate and flywheel. I’m not exactly sure why. I still feel like it is more than just me making more torque because others have made more, but then again, every dyno is different, so maybe I’m putting down conservative numbers than what it is actually making. I hope the new clutch solves the problem.

[Irace86.2.0]

This is a custom Clutch Masters FX725 with a steel flywheel and with DLX-like clutch discs. Both are rigid with a ceramic and organice (street) combo, but they are attached to each other, joined together into a single piece that interfaces with the input shaft. Hopefully this isn’t too loud and can hold the power. I’ll install the clutch tomorrow and try to break it in for 500 miles before I am good to open it up. I’ll review the basics once I have the car running this weekend.

[spcmafia]

I was reading all the way from the previous page, and I have to ask. Throughout all your clutch changes, have you tried adjusting the clutch pedal travel or maybe re-calibrate it? Im not an expert at any of this but Im also willing to learn if it would affect clutch engagement in any way. Maybe also go for a forged fork?

[Irace86.2.0]

Originally Posted by spcmafia

I was reading all the way from the previous page, and I have to ask. Throughout all your clutch changes, have you tried adjusting the clutch pedal travel or maybe re-calibrate it? Im not an expert at any of this but Im also willing to learn if it would affect clutch engagement in any way. Maybe also go for a forged fork?

I have the Verus forged fork and billet pivot. These help to reduce flex, which would lead to poor disengagement (more engagement), and they reduce the risk of breaking. Neither would affect engagement ability of the clutch to clamp well.

I adjusted the clutch pedal every time, and it couldn't be the problem. If anything, I initially had a problem with getting the clutch to disengage until I re-bled the system after introducing air into the hydraulic system.

If the pedal was too low then the clutch would always be engaged. Pushing the pedal in wouldn't disengage the engine and transmission enough, so it would be impossible to put the car in gear, but the clutch would be maximally engaged all the time, so slipping wouldn't be an issue.

I've never seen a pedal so high that it could cause the clutch to slip. It is typically the other way around; the pedal is higher than normal because the clutch has worn so thin over time, and then, the clutch slips because it is worn.

I think the issue is more specific to vibration and harmonics along with the level of torque that I am putting out when I am putting it out. Dynos are relative, so the numbers could be conservative. My dyno turner said the numbers looked low compared to what he was use to seeing. The G25-660 at 12 psi put 470whp for Kpower in this article. Maybe their A/R is bigger than mine, but the dyno we were using/renting was known for conservative/low numbers. That could be throwing off the expectations at the power I think it is making.

https://chromjuwelen.com/network/237...70-whp-on-dyno

There are many threads of people running the same tune on the same day on different dynos with significant differences. Dynos are just for tuning, but not for accuracy. Example:

https://www.1addicts.com/forums/showthread.php?t=891688

There are only a few ways a clutch would stay disengaged, and it would be if the TOB that was pushed in ends up sticking on the snout/sleeve it glides on, but then the clutch pedal would feel loose with no resistance, which isn't the case. The other is the clutch bolts backed out, which was never the case. The other is internally damaged pressure plate, but that is not the case either.

[Irace86.2.0]

The good thing is clutch holds the power. Car is stupid fast. I’m losing traction in ideal conditions.

The bad is the car is that much more race car now. The driveability from a stop is ehh. It just grabs instantly, which feels good to have something hold so well, but it is hard to slip, and when it does, there is chatter. I haven’t stalled a manual in decades, but I have stalled this several times. It is a decent step up from the single disk three puck Exedy clutch in how hard it is to drive from a stop in traffic and on hills.

There is some decel NVH around 2500rpms, especially in 5th and 6th, that is louder than before. Occasionally there is gear lockout, which typically happens from the center plate sticking to the pressure plate on twin discs. I’ve read that this can happen with heat as different materials expand at different rates and with new materials with surfaces that still need to be worked smooth from machining. Rev matching typically resolves this issue or double clutching instead of granny shifting, like I should. Overall, the car belongs on the track.

I’m considering selling the car or keeping it as a track car and buying a different daily driver. It is just too much of an unrefined beast now.

[alex87f]

How about a CD009 swap?

[Irace86.2.0]

Originally Posted by alex87f

How about a CD009 swap?

With what I spent on the clutches, I should have done that, but I’m done with the money pit. We are looking to buy a house in the next few years if the rates drop, so I’ll likely pass the car on to someone who will take it to the track and have some fun. I’ll probably do an EV or 911/Cayman for a daily. I’m done with project cars for a while. This one has me burnt out.

[alex87f]

Gotcha.

It's a bit of a shame as this seems like the most sorted swap I've seen on an 86. Taking some time to step back from this build is probably the better option.

We've all had moments when we feel like hanging up on the whole car thing. And getting a Tesla M3 seems like a very sane option that would free up time and money. But you'd likely get bored quite quickly.

[Irace86.2.0]

Originally Posted by alex87f

Gotcha.

It's a bit of a shame as this seems like the most sorted swap I've seen on an 86. Taking some time to step back from this build is probably the better option.

We've all had moments when we feel like hanging up on the whole car thing. And getting a Tesla M3 seems like a very sane option that would free up time and money. But you'd likely get bored quite quickly.

Thanks, but it is far from perfect or ideal. It is my daily, so I can't really step back. The NVH is race car annoying. The power isn't worth the daily drivability. As a track car, it would be fine, but not as a daily. It just isn't enjoyable to drive on the streets for even a few miles.

Selling the car is contingent on finding a buyer, so if I can't find a buyer then I'll have to keep it.

I would like a Carrera 997 or 991 or Cayman 981 or 982, or I will get a beater, and I'll wait for an EV sports car like the NE Miata. I would consider the Tesla, but a compact/midsized sedan is not interesting. The perfect platform was what I had with the Harrop SC, so maybe I should have done the built motor, but at this point, I think I would like to pass on this project to someone who could use it. I'm not going to sell the parts and go back to the FA20/24 platform having the hindsight of knowing now how good the old setup was. I could see myself getting a Harrop setup on a GR86, if it comes out one day, but I don't know. I'll have to see how it goes. We want to focus on a house now and some other things that are more important than money pits.

[B T]

Originally Posted by Irace86.2.0

It just isn't enjoyable to drive on the streets for even a few miles.

Selling the car is contingent on finding a buyer, so if I can't find a buyer then I'll have to keep it.

Sorry to see it didn't turn out quite like you wanted. It was an interesting build to say the least. Good luck!

[K7XZenith]

Originally Posted by Irace86.2.0

Thanks, but it is far from perfect or ideal. It is my daily, so I can't really step back. The NVH is race car annoying. The power isn't worth the daily drivability. As a track car, it would be fine, but not as a daily. It just isn't enjoyable to drive on the streets for even a few miles.

Hey Irace,

I've been budgeting and acummulating knowledge to K24 swap my 2017 BRZ, but this comment has me questioning that decision. If you could do it again, barring buying a different car in the first place, what decisions would you have made differently(LS swap, built FA20, different clutch, quieter exhaust, etc)? Ultimately my car will be a street car, so I don't want to make it undriveable and fall out of love with it. Any input would be appreciated.

Thank you in advance.

[Irace86.2.0]

Originally Posted by K7XZenith

Hey Irace,

I've been budgeting and acummulating knowledge to K24 swap my 2017 BRZ, but this comment has me questioning that decision. If you could do it again, barring buying a different car in the first place, what decisions would you have made differently(LS swap, built FA20, different clutch, quieter exhaust, etc)? Ultimately my car will be a street car, so I don't want to make it undriveable and fall out of love with it. Any input would be appreciated.

Thank you in advance.

For me, I came from MKIV Supras, Evos, and other turbocharged cars, so the idea of an inline engine with a turbo was enticing, but I just didn't know how much I loved the FA20 with the Harrop SC. Hindsight is 20/20. I thought I would enjoy the drama and sounds of turbo spool and BOV sounds, but I've matured away from that, apparently. I appreciate the sound, linear hp/flat torque, and predictable and immediate power of the supercharger. The turbo can build boost off of load, so power can come on faster once turbo threshold and lag are overcome, but it just doesn't compare to the joy of immediate throttle response and predictability that comes with a PD supercharger.

The K24 is a nice engine, but I think there are a few flaws for me for this setup. The RSX Type S oil pump just leads to too much engine vibration. Going from an incredibly smooth and balanced boxer engine to this is a big change. Certain rpms, there is just too much vibration, especially at 2500-2750, which is the meat of cruising, and the decel vibration is crazy loud. The issue might be the angle of the driveshaft, the extension of having an adapter plate, and/or losing the balance shafts. Whatever it is, it is too much for me.

Maybe someone can preserve the balance shafts, get a stouter transmission like the CD009 or T56 Magnum and get a bell housing that doesn't add thickness from the end of the engine, get a driveshaft shop to install/make a driveshaft that is at ideal angles or something if that is an issue.

The K24 is a beast, and it is cheap, so it is a hard swap to beat for the buck for the track. I would probably do the same swap with a CD009, light build of pistons n rods for a stronger bottom end and then boost 30 psi to legit power.

I don't have much experience with many V8's, but I'm not a huge fan of large displacement motors. I did not enjoy a V12 Aston Martin, V10 Gallardo, V8 Mustang GT, numerous trucks, etc. I don't know how I would feel about a LS3 swap, but I think six cylinders is about large enough for me. I don't care much for the weight, sound, or nature of how it builds power or how it responds.

If I had to do it again, I probably would have sold the car after the motor blew, and before that, I should have done a built FA20 motor with a single disk clutch on the stock transmission at the lowest pulley, and that would have been fine for this platform. If Harrop released a CARB legal supercharger tomorrow for the GR86, I would love to swap a FA24 into my car and sell my setup and do all that, but my wife won't let me do anything so crazy. It is a pit that will never end, and we are working on saving for a house when the market changes. I'd probably just buy a new GR86 at that point anyway, even though I prefer the look of my car. I need a break from projects, want something more reliable than something modified, want to not have E85 anxiety because it isn't plentiful here, and I want something legal with less concerns about CARB.

[K7XZenith]

Thank you for a very comprehensive answer!

I also came from turbocharged cars, though on a more modest scale (MKIV and MKV GTi, GD WRX). I originally purchased my BRZ with the intent of turbocharging, as I quite enjoy the dramatic sounds and "elastic" feel of the powerband even at low-load commuting scenarios. Boost is just too much fun, and I haven't quite matured out of it just yet.

Ultimately I ended up installing an Edelbrock Supercharger, as I also found myself unwilling to deal with inspection issues in a CARB-heavy state (MA). The kit has been great, and I've had zero issues over 2+ years and 30k miles. One of the things I also miss from my previous vehicles, however, is torque. With an estimated ~220ftlb at the wheels on 93, the BRZ feels a bit gutless relative to VWs and EJs which tend to put out plenty of low/mid-range torque, which is why I had intended to move on from the FA.

The BRZ itself is sentimental to me, and the chassis is just too much fun for backroad commuting, though the motor itself is a bit lacking to me. It is much improved with the SC, and it feels like a larger naturally aspirated motor, however I've learned that I find naturally aspirated motors to be a bit boring in their power delivery. The BRZ was actually my first NA car, so this was learned after purchase.

I'll certainly take your experiences to heart, and I appreciate you sharing them. Despite having a few other projects/beaters, my BRZ is the car that I daily drive most often, including frequent ~300mile round trip drives to CT. Because of this, I can't make the NVH compromises that the K24 has forced upon you. I can tolerate engine/exhaust noise, but any buzzing/vibrating just makes the car feel low quality, for lack of a better explanation.

I'm not sure what to do with this information, but I appreciate it nonetheless. A smart man would sell the BRZ and buy an A91 Supra, but I'm not a smart man. Thank you for sharing your experiences.