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Project Car: Exige + Honda K24A2 + MPx90 Supercharger

71975 Views 355 Replies 49 Participants Last post by  Butters
As some of you may know, I've been undergoing the process of swapping a Honda K24 into my 2006 Exige. As far as k-swaps go, this is probably making the record books as the longest running one! I started the process way back in March. Yeah, it's closing in on a year and a huge reason for the protracted build time is because I had it at a shop locally that was f u c k i n g me hardcore. It was basically sitting there for three months or so without progress. And any progress they WERE making was slow and billed like money was going out of style. Basically, it's a time that I'd rather forget and move on with my life.

So as it stands now, the project has been yanked (this was actually a few months ago) and I've been making progress every Saturday with another forum member in the Seattle area. There have been many problems that we've found with the build that we've had to sort. But we're well on our way and suspect that it'll be another month of weekends before it'll be ready to roll under its own power to get tuned. So... possibly end of Jan to middle of Feb.

Here it is the day we got it back to my friend's place. I love this picture.

General build specs:

- 2.4L Honda K24A2 (out of a junkyard 2006 Acura TSX). 73k miles.
- 2006 Honda Civic Si 6-speed manual transmission
- MPx90 supercharger + modified Jackson Racing manifold
- Hondata K-Pro ECU
- AIM MXL Pista dash
- Innovative Mounts swap "kit"
- HyTech full exhaust system
- Clutch Masters FX350 clutch
- Competition Clutch 8lb steel flywheel
- Hybrid Racing fuel rail + lines
- Fuel Injector Clinic 775cc injectors

(A note on the exhaust system. HyTech makes automotive products that are works of art worthy of being hung on a gallery wall. But they sure as hell take their sweet-ass time. They build race-car parts and their teams are probably way more of a priority than you and I are likely ever to be.)

This thread will not be the most organized in the world. (You should check out whatsADSM's k-swap thread for really great info that is organized well.) But I'll try to cover as much as I can when I can over the next few weeks. I'll also upload a spreadsheet with all the parts I've ordered for the project and their associated costs. For those who ask how much the swap is... well, it's going to be so different for everyone because there isn't a standard swap. Mine is different than anyone else's and so will yours be. All I can say, is that it will be VERY expensive --- even without a shady shop screwing you over.

Here is the K24A2 engine when it was first picked up:

Here is the car when the engine was first being yanked:

Honda on the right. Toyota on the left. Out with the old, in with the new!

The reason I decided to go with a K24 versus a K20? Torque. Mid-range grunt is what excites me. Why supercharger versus turbocharger? I want linear power.

Here you can see the engine assembled with the blower. Note the angle of the boost tubing. You'll need to hug the engine very closely to package everything into the engine bay:

K-Tuned Swivel Neck TStat Housing:

A note on the K-Tuned swivel neck tstat. I got this because the OEM tstat housing from Honda won't fit due to the way it points out. It would've interfered with the boost tubing. The swivel neck housing solves that issue. Unfortunately, the thermostat housed inside doesn't allow for bypass to function properly.

So we had to find a stat that worked. Eventually, after some digging my friend found one from a 1995 Corvette (!) that was close but the flange diameter was too small. It's from Stant. Part number 14068. You can get it from Amazon

We ended up backyard engineering something by hacking apart the K-Tuned stat and combining it with the Corvette one. It was crazy but it's legit.

Another note, the K-Tuned comes with a few ports on it. One of these for some reason didn't come with a plug. So we had to find one, luckily my friend had one laying around that actually fit. It's a US size, non-metric. It's not a very pretty solution but whatever --- it works.

Here is the original blower kit I received from Magnum Powers in Oregon:

The air-to-water charge cooler:

The original plan was to use the stock oil coolers up front as heat exchangers for the charge cooler. But that plan was eventually scrapped for an air-to-air intercooler setup. Less weight, complexity and cost. Plus, for the power levels I'm looking to make a2a will be just fine. So for now, the oil coolers will stay in the car with the lines capped off. Perhaps in the future, I'll re-purpose them for transmission cooling duties? Not sure on that one just yet.

Here is the new a2a intercooler:

It's from Z1 Motorsports, part of their intercooling kit for the Nissan 300ZX. Mounted in the driver's side scoop. The routing for the boost tubing was a bitch as there is not much space between the firewall and the engine. In fact, there is only about 1/4" between the firewall and the blower.

Really really tight. Routing the boost tubes was problematic due to the tubes coming out of the manifold being so close to the starter motor and clutch slaver cylinder. We had to measure and cut and weld very carefully. That was probably the most difficult part of the swap, in terms of packaging all the hardware, anyway. This is the day we picked up the engine from a local shop that welded our mock up:

And here you can see the a2a intercooler in situ:

As you can see from the last picture, we've had to route the intake a different way due to the space constraints in the side scoop area now that the intercooler is there. An airbox was built that will draw in air from the engine hatch. Pretty trick if you ask me...

I'll end this first post with how the car was the first weekend wrenching on her:

If you look closely, you'll see that the shop, perhaps as a last f u c k you, put the wheels on the right side of the car on wrong; the front and rears are swapped. Front looks great! But rubs... hahaha...
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Discussion Starter · #4 ·
Looks great. How did you handle the wiring?
The wiring harness was built by whatsADSM. He made it pretty much plug and play. We had to modify it a bit to extend some wires for the AIM MXL, but overall it was pretty cut and dry. I'd contact him for details. Comes with a pretty great install manual. Which is great because nothing else with this swap comes with instructions! I haven't been able to get a hold of whatsADSM lately so I dunno what happened. Maybe he just doesn't want to talk to me anymore because I ask too many questions!

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Discussion Starter · #5 · (Edited)
One thing that we're dealing with right now is the engine mounts. For some reason, the passenger side of the engine sits about 1/2" to 3/4" forward as compared to the driver's side. So this is causing the CV joint + axle on the right side to be cocked at a pretty extreme angle. The left side is also angled but nowhere near as extreme. It's a total head-scratcher. We need to sort this out.

Passenger side:

Driver side. It's difficult to tell, but the angle here is less severe than the other side:

I am not sure why Innovative didn't move the engine back in the bay another inch or two. They certainly have the room and would solve both the engine/blower to firewall clearance issue as well as the angle of the CV joints. I'm trying to reach Innovative for a fix.

Also, we found out that the axles we got from Innovative are a bit odd. For one thing, they are missing the axle washer, which is a show-stopper right there. On top of that, the axles also came with a dust seal pressed onto the hub end. This presents a problem with fitment because the seal butts up against the ABS sensor on the hub. So we had to remove that, the seal, not the ABS sensor. Which makes me believe I got the wrong axles? I dunno. The length is fine (save for the 8-10mm of exposed thread on the end of the axle) and everything else seems to fit.... Anyone have any ideas?


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Discussion Starter · #9 ·
Ah Butters

I just remembered you screen name. You truly have been through the wringer over your Lotus. I hope this all works out and you have a beast of a car after all of this!!!
You might be referring to my first Exige that I had --- the phantom black 2007 S. Yeah, that one was jinxed from the beginning. But this one, it was really my own damn fault for embarking on this kswap quest. It also doesn't help that I was screwed over by a shi tty shop. They wanted $50,000 for the project.

To which I quoted the Virgin Mary, "Come again?"

But yeah, when it's done, it'll be an absolute beast. I'll be pitting it against my friend's Elise when this is all said and done. I've got the ponies, but he's got a sequential with fantastic gearing. This, of course, is a straight line. On a road course, his experience and skill would take my lunch money.

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Discussion Starter · #12 · (Edited)
Intake manifold gasket. The one I received with the blower kit did not match up to the block. I can only assume it was for a K20 and didn't fit the K24? We noticed this when we went to route the vacuum lines and saw that one of the ports went to nowhere. Figured out that we need to drill a hole in the gasket in order for vacuum to work properly. The proper gasket should have this hole already in it. (I've indicated the hole we drilled with the red zip-tie.)

If anyone knows what happened here please lemme know. Neither my friend nor I are Honda guys so we're not intimately familiar with all the knicks and knacks of that world.

Starter Motor. The power for the harness didn't reach, so we had to (cleanly!) extend it. The little boot is zip-tied on there just to be sure as it wasn't really quite the right fit for some reason. :shrug:

Which brings us to the issue of the knock sensor. We're holding up the connector in that last photo. The harness we're using and which you'll need for the swap is for an Acura RSX Type-S (which had a K20 block). Apparently, the knock sensors are different from a K20 to a K24. You'll need to purchase the K20 knock sensor. Here you can see how they are different (the green one is the K20 sensor, the one you'll need if you decide to go with the K24):

Map sensor. Since we're blown, we went with a GM 3 bar MAP sensor. Built a bracket for it out of a little piece of aluminum and had to bend it out of the way of the shift lever ballast.


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Discussion Starter · #13 · (Edited)
Oil cooling. Originally, I had planned on using a Laminova to tie in oil cooling duties to the radiator up front. But the shop had convinced me that were wasn't any room to mount the Laminova so I said sure. But looking at it now, there is plenty of room! Urgh. Anyhow, probably for the better since it won't tax the coolant system more. (That's how I'm rationalizing it, anyway. Even though the Laminova would be so much cleaner of a system in terms of complexity, weight, and install.) So we went with an oil radiator in the passenger side scoop intake. Here is a photo of the oil cooler mount being welded up:

I've decided to go with a remote oil filter to make oil changes a bit easier. Pretty hilarious seeing a NASCAR-branded filter on a Lotus. Here it is all in situ:

The sandwich plate:

And of course it needs an oil stat. Here's the unit we went with from Improved Racing:

In situ:

Here is the setup with BOE's oil catch can. A bracket was made to relocate it into the side scoop:

Electrical mounting. This of course is just the beginning of the electrical phase. When it came time to find a home for all the fuse boxes, relays, etc. I made the suggestion of hacking up the old factory Lotus ECU mount plate since it already had really nice tabs for the fuse boxes and multi-function relay to clip into. This is what my friend came up with. Ingenious work on his part, really. Nice and clean. Looks damn near OEM. Better, even.

You'll notice that we went ahead and put new insulation on the firewall, too. Who knows if it'll do f u c k all, but whatever, we were in there so why not...

Dash replacement. For some reason, I decided to go with a new dash because racecar and... ugh, I dunno... because I decided the money pit was hungry so I threw more Benjamins at it in the form of an AIM MXL Pista display. Forum member Brent Baumann made this sweet mounting kit for it that is super clean. Check dis sheeit out:


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Discussion Starter · #14 · (Edited)
A quick post about some odds and ends of the build.

Air Conditioning. Since no one has come up with a good solution to retain the AC in this swap, I've decided to hang on to both the Honda AC unit as well as the stock Toyota one that came stock with the Exige. Most likely, whatever solution someone comes up with will utilize the Toyota compressor as it is much smaller. The Honda one probably straight-up won't fit. whatsADSM has already made the necessary provisions on the plug-and-play harness he built so that when it one day does happen, it'll be ready to go.

Adding to the cost of the project, I decided to upgrade a bunch of parts with stuff from BOE's toy box o' goodness. Here you can see the surge tank:

You'll also see the Skunk2 throttle body, which required modification to let the IAC valve work properly with the gooseneck we got, which was unfortunate.

BOE Full-floating rotors with ARP wheel studs. Of course, a month after I ordered these rotors, BOE came out with their black versions, which was maddening. :facepalm:

BOE vented caliper pistons:

BOE Clam Hinge:

Other parts.

Lightweight flywheel:

Moroso Baffled Oil Pan:

This is what the K-Tuned pedal looks like compared to the stock unit. The car is now DBC, not DBW.

When the clam hinge was installed, we decided to reinforce the subframe point to which it mounts (the exhaust hangers) by boxing it in.


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Discussion Starter · #15 · (Edited)
Engine prep. There are some items you'll need to change over from the K20 if you decide on a K24. Mostly oil stuff. whatsADSM has a good list going on in his thread. In the spreadsheet I'll be uploading will be a comprehensive list of directly engine-related items you'll need. For now, some Honda engine pr0n (before the valve cover was painted black):

We removed the balance shafts:

When we went to adjust the valves we noticed something worrying. There was a bunch of sand in the head! Motherf uckers didn't clean out the valve cover after it was sandblasted and painted. So we spent much of a morning cleaning everything out and flushing the engine. Oi...


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Discussion Starter · #16 · (Edited)
So here is where she sits as of this past Saturday:

Our next step is to sort out why the hell the engine is cocked all sideways in the engine bay. Anyone who has used the Innovative Mount kit, please chime in if you have any insight as to why this is happening.

Also, to find out what the hell to do about our axle situation.

Stay tuned, everyone!

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Discussion Starter · #17 ·
Serpentine Belt. If you're going to be replicating this setup, the serpentine belt we used is a Gates belt. Part number K070508.

•Number Of Ribs: 7
•Width (In): 0.947 Inch
•Width (mm): 24mm
•Outside Circumference (In): 51.375 Inch
•Outside Circumference (mm): 1305mm

Gates® Micro-V AT® K070508 - OEM Quality Serpentine Belt | O'Reilly Auto Parts

It's a bitch to get on, but does so without stretching. Perfect fit.

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Discussion Starter · #18 · (Edited)
Idle Air Control Valve (IAC Valve). The IAC valve on my K24 was rusted to hell. So I had to get a new one. The OEM unit is something awful like $236 or some nonsense. So I went with another one that was about $60 from AIP Electronics.

It replaces these OEM part numbers:

However we needed to modify the retaining tab on the IAC valve plug so that the harness plug would seat properly. Ended up just snipping off about 2mm of plastic and the sucker clicked in and locked. For a fraction of the price, I'll take it. :cool:

The nipple is unused in my application so off it came.
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