KPower Industries K24 swap

[funkjaw]

Update on my AC

Got tired of it barely working, had a honda fab shop take a look and they diagnosed that the used compressor I put on was bad - even though the clutch was engaging as it should the suction/compression was just not working. Had them install a brand new Four Seasons 58886 compressor I got off Amazon then perform another evac/fill and the AC works absolutely beautifully now. Just drove 300 miles in 104 degree heat and it was ice cold the entire time... Very happy!
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Next will be tackling NVH issues as much as I can because they are pretty annoying (think I'm just getting old). I'll also be looking for signs of exhaust failure as it seems almost inevitable at this point.

[Irace86.2.0]

My NVH has improved a lot. There is decel noise that could be a combination of the motor, rear bushings, clutch and aluminum driveshaft, but the vehicle is pretty smooth and mild under power, as it pertains to NVH. Part of that could have been the dyno tuning because since then, and maybe with more long term corrections by the ECU, the car seems very smooth. Idle is pretty close to stock.

I have a Fluidampr pulley, I removed the transmission bushing, and I installed the Radium Fuel Pulse Damper. I also added back the stock cat over the high flow and put back the mini resonator on the frontpipe. After replacing the flywheel that backed out and getting dyno tuned and settling into the long term corrections, the NVH and car seem much closer to OEM at idle and cruising around.

[captain awesome]

I still don't understand the exhaust failures at this point. I've got over 6k miles on my car and yet to have the issue. Are these cars being ran on track for a larger amount of time at RPM than mine has?


Also it looks like their header is really close and possibly touching the tunnel under load? I would assume they would notice the vibration and noise from that but hard to say.

[RedReplicant]

Originally Posted by Irace86.2.0

My NVH has improved a lot. There is decel noise that could be a combination of the motor, rear bushings, clutch and aluminum driveshaft, but the vehicle is pretty smooth and mild under power, as it pertains to NVH.

Mine does that decel noise too and has some vibration >60mph, I'm going to chop the stock driveshaft and we will see if it goes away. I would agree that it is pretty quiet other than this though.

Originally Posted by captain awesome

I still don't understand the exhaust failures at this point. I've got over 6k miles on my car and yet to have the issue. Are these cars being ran on track for a larger amount of time at RPM than mine has?


Also it looks like their header is really close and possibly touching the tunnel under load? I would assume they would notice the vibration and noise from that but hard to say.

All the ones I've seen are track cars. Is your header to midpipe flange not like 1/4-1/2" clearance at rest too?

[Ebush]

Originally Posted by captain awesome

I still don't understand the exhaust failures at this point. I've got over 6k miles on my car and yet to have the issue. Are these cars being ran on track for a larger amount of time at RPM than mine has?


Also it looks like their header is really close and possibly touching the tunnel under load? I would assume they would notice the vibration and noise from that but hard to say.

My car is not a track car. When I first noticed the header being cracked at the head (cylinder 4) I had only driven the car about 2k miles. I'd say for every 300 miles there was atleast 20 miles of abuse on backroads though. Otherwise I drive my car like an old lady at all other times. I never did fix the crack since it wasn't (and still isnt) actually leaking. After my first 2k miles, I took the car on a 1500 mile trip through the mountains. During that trip I ran the car pretty hard non stop, alot of time was spent at the top of 3rd gear. Car ran great with no issues, on the way home while just cruising on the highway the oem trd midpipe decided to completely break with no warning. 300 miles later when I got home, the midpipe had broke in a second spot, and the muffler had nearly completely separated as well.

The exhaust is not touching my chassis or ever hitting it, but I do believe the oem impreza mounts are a bad item to have with this swap. I think they just allow the engine and Trans to flop around more than the exhaust can handle.

I now have a flex section in my exhaust, but haven't driven the car much or very hard with the ridiculous gas prices lately.

I've also wondered if vibration is causing the cracks. I don't feel like my vibrations are bad, but mine are probably worse than others. Aluminum flywheel, 3 puck trd clutch, and non dampened crank pulley. I rev my car to 8600. What rpm does your car see?

[captain awesome]

So a larger percentage of my mileage is with the trans poly bushing removed. That lets everything flop around a lot more than it would with the bushing. Yet I haven't had a single crack. Yet. I've only had the new exhaust with a flex pipe for a few hundred miles but hopefully it will help with future issues.


As for RPM I rev to 8200 when giving it the beans. No more than that really.


And for tunnel distance I feel like I have more clearance than 1/2" but it's been a while since I was under the car in that area.


I am curious what exhaust systems are being run on the cars developing cracks. I seem to recall someone mentioning that certain brands and years don't fit this header properly? Maybe they are forcing it to bolt up causing major pressure and stress at the 3 bolt flange?

[zuldajin]

Originally Posted by RedReplicant

The most recent one I saw was using the hanger and a Perrin flex pipe exhaust, it completely separated at the last weld before the flange on the header side. Seems like a weld issue to me.

There is also something to be said about the motor twisting on the motor mounts, header to midpipe flange bottoming against the chassis, and putting stress on everything.

I got these pictures from someone that is a friend of the owner, not sure if they are on the forum here too.

That's my car, just came off the dyno last Monday and took it to the track later that week.

Half way through a session my exhaust became way louder, looked under the car and found that.

I will also add, I took measures to minimize NVH as much as possible as well.
The engine I have is a 4Piston K24 short block and their Pro TSX head, I have a Fluidampr crank pulley and a Radium fuel pulse damper.

Currently working with KPower to try and sort out the issue.

[captain awesome]

Originally Posted by zuldajin

That's my car, just came off the dyno last Monday and took it to the track later that week.

Half way through a session my exhaust became way louder, looked under the car and found that.

I will also add, I took measures to minimize NVH as much as possible as well.
The engine I have is a 4Piston K24 short block and their Pro TSX head, I have a Fluidampr crank pulley and a Radium fuel pulse damper.

Currently working with KPower to try and sort out the issue.

What did your dyno numbers end up at? Any cams or compression change?

[Four_wheel_drifts]

Originally Posted by RedReplicant

The most recent one I saw was using the hanger and a Perrin flex pipe exhaust, it completely separated at the last weld before the flange on the header side. Seems like a weld issue to me.

There is also something to be said about the motor twisting on the motor mounts, header to midpipe flange bottoming against the chassis, and putting stress on everything.

I got these pictures from someone that is a friend of the owner, not sure if they are on the forum here too.

My friend's broke the first time in the same spot. The shop welded it correctly to fix it. The very next track day, during the second session, it broken again, but at the next weld forward.

Same failure more and diagnosis: bad factory weld.

Shop fixed the second break, then beefed up the exhaust mounting. We haven't had it up on a lift her to see what actually was done. It's got three full track days in it now and seems to be holding up fine.

[funkjaw]

Originally Posted by Irace86.2.0

....

I have a Fluidampr pulley, I removed the transmission bushing, and I installed the Radium Fuel Pulse Damper. I also added back the stock cat over the high flow and put back the mini resonator on the frontpipe. After replacing the flywheel that backed out and getting dyno tuned and settling into the long term corrections, the NVH and car seem much closer to OEM at idle and cruising around.

Can you elaborate on the fuel pulse damper? Which one did you get? This just installs on the end of the fuel rail? Where did you grab a vacuum source from?

[Irace86.2.0]

I feel like those failure points are pretty far away from the engine where heat cycles causing fractures are more common. These would seem like mostly fatigue fracture fails from bad welds that either had poor penetration, were off-centered or had porosity because they didn’t use shielding gas to fill the pipe (back purge), or it could have been a combination of those things. The welds don’t look sunken like there was excessive penetration or insufficient welding rod to fill the joint.

The fact that the lap joint (best guess based on the size transition) failed second is saying something about the welds because I could understand a butt joint, but not a lap joint; they tend to be stronger.

If anyone wants to take a picture of the inside of their welds, I could tell if this was a penetration problem or a sugaring problem from not back-purging. The latter is a common shortcut.

There is something to be said too about having a flexpipe so far down the system and sitting just behind an exhaust hanger and after an S curve in the pipe where the S curve provides leverage for torquing that section under torsional and shearing load. The hanger should keep the pipe from sagging, but it also might be dampening the flex that normally would be absorbed by the flex pipe. In a system, I wouldn’t have my two major flex support points stacked in series.

[Irace86.2.0]

Originally Posted by funkjaw

Can you elaborate on the fuel pulse damper? Which one did you get? This just installs on the end of the fuel rail? Where did you grab a vacuum source from?

It is in my turbo build below. I posted a video which showed the needle on my fuel pressure gauge oscillating about 4psi from 60-64psi rapidly. After it was locked at 62psi. The stock K24 rail has a damper. I didn’t know if that oscillation was causing some idle issues, so I installed the damper.

It is the Radium FPD-XR. The vacuum hose only needs to be hooked up if you are using a fuel pressure regulator that has a 1:1 function to increase fuel pressure proportional to boost/manifold pressure; ie, if stock fuel pressure is 62psi then fuel pressure at 4psi of boost is 66psi and 70psi at 8psi of boost. I don’t have that, so I just attached the hose and let it hang. I may eventually install a return fuel setup with a 1:1 FPR because my injectors were basically maxed out at my power goals because my fuel pressure was dropping, but that is a side note, and it would only be necessary to install the boost line in the event my boost was beyond the limit of the fuel pressure damper. I got the bigger unit, but both would probably be fine. EDIT: I forgot to add that this is the -8AN version.

http://www.radiumauto.com/Fuel-Pulse...Kits-P759.aspx

[funkjaw]

Originally Posted by Irace86.2.0

No one has done the update and can verify if the fuel gauge is working better? I'm hesitant about doing the update, as I don't have wifi or cellular in the garage, so I need to go do the update remotely.

I'm on 3.04.0, not sure if that is the latest but the fuel gauge issue is not fixed in my version. If there is a newer version to try I will happily be a guinea pig.

Edit: Checking for update in NSP says there is nothing to update....

[funkjaw]

Originally Posted by Irace86.2.0

It is in my turbo build below. I posted a video which showed the needle on my fuel pressure gauge oscillating about 4psi from 60-64psi rapidly. After it was locked at 62psi. The stock K24 rail has a damper. I didn’t know if that oscillation was causing some idle issues, so I installed the damper.

It is the Radium FPD-XR. The vacuum hose only needs to be hooked up if you are using a fuel pressure regulator that has a 1:1 function to increase fuel pressure proportional to boost/manifold pressure; ie, if stock fuel pressure is 62psi then fuel pressure at 4psi of boost is 66psi and 70psi at 8psi of boost. I don’t have that, so I just attached the hose and let it hang. I may eventually install a return fuel setup with a 1:1 FPR because my injectors were basically maxed out at my power goals because my fuel pressure was dropping, but that is a side note, and it would only be necessary to install the boost line in the event my boost was beyond the limit of the fuel pressure damper. I got the bigger unit, but both would probably be fine.

http://www.radiumauto.com/Fuel-Pulse...Kits-P759.aspx

Thanks a ton for this info, sounds like a very easy mod to do in my case since I am just running N/A. Think I'll pick one up!