John's JDM Honda K24A 818R Rebuild

[Hobby Racer]

It always seems like the last 10% of a project takes the longest! I'm just about done with the wiring. I've completed the engine harness and the body side harness. Getting all the separate electronics to talk with each other and cooperate was a challenge. I have a standalone ECU, separate wide-band controller, drive by wire controller, dash logger and a camera system that all need to play nice together.



When the dash powers up it displays a nice pic of my car!

[Hobby Racer]

Well I had to pull the intake manifold because the injectors would not fit into the predrilled holes. One thing about buying the cheap knock versions of things is that they don't always copy everything just right. The injector holes are slightly undersized and do not have the needed taper to allow the sealing o-ring to seat properly. Good thing I have a basic machine shop in my garage

After mounting the intake back on the mill I was able to put a 60 degree chamfer on the holes using a large center drill.
IMG_20230514_105752798.jpg IMG_20230514_105804160.jpg


I then modified a cheap Harbor Freight step-less drill to put on a 30 degree angle just below the 60 degree chamfer, giving the o-ring an easier path to seating in the bore.
IMG_20230514_113916502.jpg IMG_20230514_113858080.jpg

Hoping for a first start later this week. Then I need fab an exhaust and get it to a dyno for tuning.

[Rob T]

Hobby: you can now add "tool maker" to your already impressive resume.

[Hobby Racer]

My plans for a first start this week have been thwarted. After chasing my tail for days tracking down what I thought were electrical gremlins I have found out that my ECU is damaged and needs to get shipped back the manufacturer for repairs.

Hopefully they can turn it around quickly!

[lance corsi]

Hobby, what kind of stand alone are you using? Mine is a Haltech elite 1500.

[Hobby Racer]

Hobby, what kind of stand alone are you using? Mine is a Haltech elite 1500.

It's a Megasquirt MS3Pro unit. I used it on the EZ36 engine I had prior to swapping in the Honda.

[Hobby Racer]

I was able to start the engine for the first time yesterday. It was a large weight lifted to know the engine is good. Purchasing a used JDM engine with an unknown history can be a leap of faith.

Next on my list is to fabricate an exhaust and a new rear wing support.

Chipping away at the punch list

[Dave 53]

I've been frantically working on my 6 speed transmission and shifter swap project for weeks now trying to get it done for a track day this Sunday. I think I'll have it done in time. It's a much bigger job than I thought it would be as all car projects are. When I start thinking about the enormity of my project, I'll just think about what you're doing to humble myself. As you say with a smiley face... keep chipping away.

[lance corsi]

I've been frantically working on my 6 speed transmission and shifter swap project for weeks now trying to get it done for a track day this Sunday. I think I'll have it done in time. It's a much bigger job than I thought it would be as all car projects are. When I start thinking about the enormity of my project, I'll just think about what you're doing to humble myself. As you say with a smiley face... keep chipping away.

Dave, as I work thru the different challenges associated with my build, I focus on the task at hand, confident that my previous work has been done to my best abilities. Timelines and goals are not cast in stone, so I take as long as is needed on each element, timelines be damned. I get the major elements in place but I don’t put a final finish on anything until the entirety of work is finished. Then and only then do I concern myself with appearances. Functionality must come first, everything else is just icing on the cake. These kits have only received minimal engineering, so this leaves lots upon the builder’s plate to accomplish. I wish things were different, but this is the hand we were dealt. Good luck on your project.

[lance corsi]

Btw, looking at the project as a whole would make most people wither. You’re doing well, so keep your head up.

[Hobby Racer]

I was going to work on the exhaust but until the body and wing support are in place I can't know exactly where to route it. So, small detour. I'm putting the body back on the car and needed to cut the rear bumper and bottom diffusor to accommodate the lowered transmission.

I'm sure it will mess up the air flow under the car some, but you gotta do what you gotta do! Nothing hangs below the bottom of the frame so I'm not too worried about hitting it on anything. At some point down the road I'll probably build a nice cover for it.

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[Sgt.Gator]

I cut mine too. I gave up on trying to make it an effective diffuser so I took it of last week. Not planning on putting it back.

[Hobby Racer]

Finished the exhaust system today. It's incredibly simple. 3 inch 304 stainless steel pipes with mandrel bends. Only needed 3 welds! I'm using the factory header, including the OEM donut gasket and spring loaded flange.

Looks just like a sink P-trap doesn't it.

[Hobby Racer]

The exhaust is wrapped and installed. Here are some pictures of the factory header without, and then with the heat shield. It's really a nicely done header with no kinks, pinch points and smooth curves. Saved me a ton of work by reusing it.

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Notice how the pipe snaked through all the supports without needing me to bend it!

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[Sgt.Gator]

Retro Racing is putting a K24 with the Honda tranny mounted transverse. They say it fits fine, they can even use oem Honda CV axles. I expect they will have pics soon.

[Hobby Racer]

Retro Racing is putting a K24 with the Honda tranny mounted transverse. They say it fits fine, they can even use oem Honda CV axles. I expect they will have pics soon.

Wow! I thought about that but my initial measurements indicated it would interfere with the rear suspension pickup points. I didn't want to mess with redesigning that geometry.

Surprised they changed from the longitudinal setup they already finish? Did they have issues with it? I do hope they post lot's of pictures!

[Sgt.Gator]

They expect to have it at some of our races by the end of the summer. If they don't post some I will take some pics and post them.

[Hobby Racer]

They expect to have it at some of our races by the end of the summer. If they don't post some I will take some pics and post them.

Good to hear you will take some pics if Retro doesn't post their own.

Do you know why they abandoned the longitudinal layout? It appeared to be completely done.

[Hobby Racer]

All the last minute things are buttoned up. Now I am going to make an appointment at the dyno shop. Hope they can get me in quickly.

[Hobby Racer]

Ok, the tuning shop just got back to me and apparently they do not tune K-Series engines on the MegaSquirt ECU. Strange, as they list MegaSquirt and K-Series as supported but just not together apparently.

I'm in Syracuse, NY and there are NO dyno shops in my immediate area. Anyone know of a shop in the Northeast they would recommend? First hand knowledge would be great.

[roadrashrob]

I used DDA Tuned in Newburgh, NY. 3 hours from Syracuse, so not ideal. "Seven" was the tuner and loves MegaSquirt. Very hard to get in touch with though. But once I did, he was great and did the initial tune for me.

https://ddatuned.com/

His direct email was [email protected]

Mention it's a FFR 818. He had met Dave as a young boy, and was so excited when I brought mine in!

Not ideal, but hope it helps.

-Rob

[Hobby Racer]

Finally got the 818R to the dyno this morning. Mechanically, everything went well. The temps, pressures etc were great and it made decent power until we ran out of injector. Around 6200 rpm the injectors max out at 100% duty cycle and could give no more. You can see in the graph below right where it happens.

My Current Setup:
Stock JDM Honda K24A
Rotrex C38-91 supercharger making ~12lbs of boost near redline
AWIC intercooler
3" straight pipe exhaust
650cc/min injectors

Made 292whp @ 7000 rpm but we were unable to add more fuel after the injectors maxed out so we limited the rest of the pulls to 6200 rpm after that. We did not even try to advance the timing since we were running out of fuel and that would only exasperate the problem.

My tuner feels that with larger 1000cc/min injectors and more timing it should make around 350whp, that's almost 400hp at the crank! This thing will be a rocket ship.



Tuner says its ok to take to the track so long as I set the rev limiter to 6000 rpm so I'm going to see if I can get some track time between now and the next dyno session in early September.

Here is a short run to 6200 rpm.

[J R Jones]

Sounds like an angry bee. Does this engine have variable cam timing? I do not see a surge as I have seen on my J-V6.
What RPM are you comfortable with?
jim

[Hobby Racer]

Sounds like an angry bee. Does this engine have variable cam timing? I do not see a surge as I have seen on my J-V6.
What RPM are you comfortable with?
jim

It does have variable valve timing on the intake but we did not even try to tune that yet, so it's running at 0 degrees cam advance. There will be some more power to be had there as well!

The factory redline is 7100 rpm so I'm going to stick with that. I did remove the balance shafts and install the better K20A oil pump that is rated up to 8500 rpm but since I'm using the stock valves springs I do not want to push my luck by going any higher than the factory redline.

[cob427sc]

Who did you end up using for the tuner?

[Hobby Racer]

Who did you end up using for the tuner?

Local guy named Hal. Works out of an old school engine builder's shop that has an engine and chassis dyno on site. It's only 20 min. from my house.

https://www.dyno-shop.com/

He does not specialize in Honda, but works on most everything. Important that he was able and willing to take on my project.

[Sgt.Gator]

FYI Retro had heat related issues with their K24 turbo Miata at Qlispe. They had an aftermarket intake manifold which came with a thick gasket intended to separate the intake from the block for heat shielding purposes. However the intake cracked off a corner ear and even snapped the bolt securing that corner to the block. The issue was too much flex in the extra thick gasket. So they JB Welded the ear back on and used an OEM gasket. That worked fine in the cool morning air, but in the hot afternoon track conditions the intake manifold heat soaked, boiling the fuel in the fuel rail, and AFRs went crazy. No racing in the heat!
They are looking for heat resistant spacers for the intake-block connection and the injector rail.

[Hobby Racer]

Thanks for the heads up. I will keep a close eye on the intake air temps and the intake connections. I am using an OEM Acura MLS steel gasket so I do not expect sealing issues but heat in the fuel rail is yet to be determined.

However I do not think I will have an issue as I am using a traditional return style fuel setup so cool fuel is constantly circulating through the rail, unlike the the stock return-less setup where fuel sits in the rail until used.

[Sgt.Gator]

They run a return style too.

[Hobby Racer]

They run a return style too.

Wow. I'm at Watkins Glen on Monday and Tuesday. I'll report back any issues I come across.

[Hobby Racer]

All in all a positive first outing with the new power plant. The weather was 50% dry and 50% wet so not ideal but since it's my first time at the track since the massive carnage last summer, I'm glad to be out there again!

I put about 270 miles on the new setup and while the tune needs some polish it runs well and makes decent power considering I'm a limited to 6k revs until the re-tune with larger injectors. Others at the track loved the fact that it spits flames out the tail pipe when I shift.

The temps were fantastic. During my longest session, 18 laps, I logged the following after everything came up to temperature (air temps ~ 78 F). Oil pressure stayed around 75 psi while under load. I did not seem to have any issues with the fuel boiling like Retro did.

Parameter	avg °F	max °F
Oil	221	224
Coolant	185	188
Trans Oil	158	160
Intake Air	93	101
Inter-Cooler Water (cold side)	81	84

All of my various coolers and venting seem to be doing an excellent job!

[Rob T]

Hobby: Great news on the temps. I have two measurements on my AWIC "system". The first is in the water after the radiator and pump on the way to the intercooler. The other is the IAT. I'd be interested to see what your numbers were relative to the ambient air temp at the track. My last track day in May it was between 75-80. My water temp to the intercooler was 90-94 and my IAT was 104-106. So I see about 10-15 increase over ambient for the water loop and another 10 degrees after the intercooler.

[Hobby Racer]

Hobby: Great news on the temps. I have two measurements on my AWIC "system". The first is in the water after the radiator and pump on the way to the intercooler. The other is the IAT. I'd be interested to see what your numbers were relative to the ambient air temp at the track. My last track day in May it was between 75-80. My water temp to the intercooler was 90-94 and my IAT was 104-106. So I see about 10-15 increase over ambient for the water loop and another 10 degrees after the intercooler.

I see about the same increases as you are.

[Mitch Wright]

Cool swap, I have done a couple of K24 Miata swaps, excellent engine IMO.

[Hobby Racer]

Cool swap, I have done a couple of K24 Miata swaps, excellent engine IMO.

Thanks Mitch. I think the K24 is going to pair nicely with the 818R. Next dyno session and track outing should tell the tale!

I really want to get back to VIR once the car is sorted. Didn't get much time on track during my last visit.

[Hobby Racer]

Was at the dyno today with the larger 1000cc/min injectors installed. Made 328 whp @ 6878 rpm; that's about 370 hp at the crank. A bit less than anticipated but it was > 90 degrees and humid today.

I'll be back at Watkins Glen in two weeks to try it out.

[Rob T]

John: This looks great. I'll be curious how it feels on the track. I've had a few issues with some snap oversteer out of corners when my torque "spikes", especially when cold. Here is my dyno graph for the EJ257. I am running the lowest level tune.RT 818R EJ257 SD Tune Rotated.jpg

[Hobby Racer]

Turbo's are nice in that they build torque much lower in the rpm band but they can spike the torque at times. The supercharger is nice and linear, like a naturally aspirated motor. You can clearly see where the VTEC cam kicks in though a few hundred RPM before the 5252 rpm cross over point.

[Hobby Racer]

Updated the dyno graph in the previous post with a better colored version that has RPM on the X axis instead of speed.

[Hobby Racer]

Happy New Year's Eve to all. While I'm waiting for the ball to drop I thought I'd type out this post.

I started doing a deep dive on some of my data from the end of the season and came across a disturbing trend. I am losing oil pressure in left hand turns, starting at about 0.5 G's. The pressure drops low but never goes to zero. The data below was taken at Watkins Glen where there are 5 left hand turns. The top graph is oil pressure and the bottom is lateral G force. Every place above the red dashed line is a right hand turn and every place below is a left. You can see the clear correlation when I turn left, oil pressure drops. Never even wavers on right handed turns.

I already have a baffled oil pan from Unit2Fabrication but it would appear that is not enough. The main issue is that I am running a pan that is designed for a transverse FWD car (i.e. the stock Honda position). I of course am running the engine in a RWD longitudinal configuration. Looks like I will be redesigning my wet sump oil system. I am either going to modify the pan to be about 2" deeper and reposition the oil pickup or design and build a swing arm type oil pickup like I did for the EZ36 engine I ran previously.