Thanks for sharing this info. Looking forward to updates no matter how long between updates.

 

Probably the most important part of a swap, in my opinion, is the transmission.

Currently the only commercially available mounts are Innovative's, and they only fit the RSX transmission. Here are the ratios for that transmission:

RSX
1st: 3.266
2nd: 2.13
3rd: 1.517
4th: 1.147
5th: 0.921
6th: 0.738
FD: 4.764

Ratios for the Insight's transmission:

1st: 3.461
2nd: 1.750
3rd: 1.096
4th: 0.857
5th: 0.710
FD: 3.208

I see a few issues with this transmission. First off, 6th gear is basically equal to the Insight's 3rd gear. At 70mph the engine would be turning at 3700rpm, vs ~2400 for the Insight transmission. I've read reports of owners getting around 30-35mpg by using an RSX-S 6 speed transmission due to the gearing. Also, due to the extra torque you basically have to start off in 2nd or even 3rd gear (if you have the larger K24) - 1st just spins the tires, as does 2nd if the roads are even remotely damp. 4th gear is effectively the same as the Insight's 2nd. So rather than a 6 speed, you'd get a 4 speed transmission with very high highway cruising RPM.

To make matters worse the RSX transmission has a large lump sticking out on the drive's side rear which causes clearance issues. To make the transmission clear Innovative moved the engine forward and down - far enough forward that you have to cut the radiator support, and low enough that the oil pan hangs well below the car, exposed to speed bumps and road debris. I consider this unacceptable.


The Accord and TSX transmission do not have this protrusion and both have taller gearing, but nobody yet has commercial mounts that use them. Hasport is expected to release their TSX/Accord transmission-compatible mounts any day now and pictures I've seen show the engine very centered in the bay with the oil pan on level with the lower radiator support - still a hair low but acceptable for a street car. The ratios are a little better too, with 70mph cruising RPM reduced to ~3300rpm:


TSX transmission

1st: 3.266
2nd: 1.88
3rd: 1.355
4th: 1.028
5th: 0.825
6th: 0.659
FD: 4.764

This is still far too short for me. 6th gear is halfway between the Insight's 3rd and 4th and with an engine 3x as powerful 1st and 2nd would be effectively useless. The proper fix is a taller final drive.

The tallest aftermarket final drive is around 4.059. This would drop 70mph RPM to 2800 - a tremendous improvement. ProAweMike took it a step further and had a custom 3.4 final drive made though, dropping his RPM all the way to 2350 - even taller than the Insight's gearing! There was one more step that could be taken though, which was to get the marginally taller 6th gear out of the 2012+ Civic Si, which brings cruising RPM down to just 2300rpm. Here's what that looks like:

Essentially the gearbox has the same ratios as the Insight box, only you get more choices in between. Reportedly with a lean burn tune the K24 can deliver in excess of 60mpg on the highway with gearing like this. I'll definitely report back with real-world numbers.

Low gears would still have traction issues. With an open differential cars basically only send power to one wheel, and from my experience it's very possible to break the wheels free from the road with the Insight's 1.0L in 1st gear (and even 2nd with the IMA functional). Honda shipped most years of the Civic Si with a helical limited slip differential however, a part which splits power to both wheels if one breaks free, effectively giving double the grip when accelerating. I thought this might be a nice addition to my unicorn gearbox.

 

After shopping around, I found HMotorsOnline sells the TSX motor (K24A2) for a song, at $900 with low miles. This is the most powerful K series motor available and was a no-brainer for me. There's some low-hanging fruit though, and I decided that much like Mike, I would frankenstein this motor with parts from other K series to get the best of all worlds.

One notable improvement the K series engines have over the Insight's is the inclusion of a variable cam phaser - basically the ability for the ECU to advance or retard the intake cam. This allows for greater torque and efficiency across the entire rev range. The TSX's cam phaser has 25 degrees of movement, which testing has shown doesn't extract all available torque from the engine at mid and lower revs. Stealing a 50 degree phaser from the K20A3 however is dangerous, because at 45 degrees or more advance there's a risk (under certain specific conditions) of the valves colliding with the pistons inside the combustion chamber. Solution? A guy in Slovenia makes small pins you stick inside the cam phaser which prevent it from advancing more than 40 degrees. So, safe for the K24 engine and allows greater torque and better fuel economy.

The K20A3 from the base RSX also has a wideband O2 sensor much like the Insight's. By using the RSX engine bay harness and O2 sensor it's possible to get lean burn with any K series engine.

The TSX stock flywheel weighs 23lbs. By using a Type-R flywheel (10.25lbs) it allows the engine to rev up and down far more rapidly. More power reaches the road, and the engine is over-sized enough for this light car that it shouldn't cause any drivability issues.

The TSX only ever came with drive-by-wire. The Accord, however, was cable throttle for the first couple of years, and luckily the Accord's throttle body fits the TSX intake. Re-using the Insight's cable throttle and converting the engine is a much easier solution than converting the car to DBW. This, however necessitates aftermarket engine management, in this case K-Pro in an RSX ECU.

 

K series axles won't fit in the Insight's knuckes. EM2 and EP3 knuckles are both available with 4 lugs, but don't bolt right onto the Insight's control arms, suspension and tie rods. Mike is kind enough to make adapters for them though, available on his site.

Along with the knuckles you also have to get matching brake calipers, pads and rotors, so I'll have the front brakes from a ~2002-2003 Civic Si. A little heavier, but they should provide less brake fade during long mountain descents - something I get without the IMA active.

 

So anyhow that's all sitting on a pallet waiting for engine mounts. In the mean time I've been tinkering with the car to get it ready. Everyone loves pictures.

First step was to get rid of the extraneous IMA system. I managed to get $800 for my working battery and donated the rest of the stuff in the rear to a local college for students to take apart.

For a while, this was what the back of my car looked like:

 

Quite a bit to do back there!


First thing I noted was that to get a completely flat and level hatch area, the fuel lines would have to be relocated.

So, I cut them to pieces and re-routed them.

 

Lots of extraneous bits of metal removed, which previously supported the deck and held the IMA box in place:

Battery box removed from the front of the car, and 2 gauge braided copper ran to the rear well behind the driver's seat:

 

Battery relocated to the rear for better weight distribution and to make room under the hood. Also, sound dampening added to most of the surfaces in the rear:

Building up the deck to make it level:

 

Some more sound dampening, speakers mounted to the doors. Wow, what a difference!

 

For the record, I've continued driving my car this entire time.

Rear speakers needed somewhere to go!

 

Fully carpeted! Tons of extra room back there now.

New subwoofer enclosure:

 

Unfortunately taking all of this weight out of the rear caused it to lift something like an inch and a half on the springs. A third of a coil removed fixed that.

With Scott's rear springs to stiffen things up and probably 150lbs out of the rear, the handling is now, dare I say, almost sporty. No body roll in turns, lots of confidence when taking corners at speed. It's a treat to drive, aside from the lack of power.

 

While waiting on the mounts to come out my 12v battery failed, and, rather than replace it with another battery, I decided I could build a better mouse trap.

Supercapacitors! Completely unaffected by cold, many times the cranking amps, last basically forever, and good for a ~25-30lb weight reduction.

They should hold a charge for around a month and are good for starting the car 5-7 times in a row on a 12v starter before being depleted, which I'm not sure if you can do on all normal 12v batteries. However it would be a lot easier to end up with a dead "battery" if I left my lights on, so I paired them with a small lithium battery, protected from starting current by a 0.3 ohm resistor:

 

Not exactly related to the swap, but these seats were a tremendous improvement.

Car as it's sitting today, waiting for a new engine. Currently 244,000 on the clock. Transmission grinds when downshifting into 2nd or 1st, but the engine burns no oil, leaks no oil, and runs very smoothly even in lean burn. I have to say, I'm quite impressed by our little 1.0L. Anyone want it when I'm done? :grin:

 

Anyone want it when I'm done? :grin:

Please tell me you're kidding.

Nice work btw!

 

Awesome post. Would love to see what kind of performance and efficiency you will get with this combination. I want to do something like this eventually, but I have an Audi project, an Porsche 911 project, and multiple boat projects, so.... yeah. It'll be a while.

 

Later this afternoon I'll drop a post on how to do this swap for 1/3 the cost using an Accord.

 

Nice job.

Where is the meanwell psu etc going?

 

I have a local buyer who's going IMA-less in one of his Insights. If that falls through I'll post it for sale here.

 

Sorry that wasn't what i meant.

I was wondering where you were mounting it/ covering it up etc?

 

Ah, presently I have it underneath the driver's seat. For a while it was floating around in the rear. I'll draw out a wiring diagram when I get home from work showing how DC-DC, supercapacitors and battery are set up, and where I stashed everything.

 

Here's a nearly complete list of what you'd need for a K series swap that's going to have halfway reasonable gearing, no major complications, and at the lowest price:

From the doner car:
-K24 engine out of an 03-05(?) Accord, later years were drive by wire
-Accord transmission
-Factory Accord ECU
-Accord engine bay wiring harness
-All sensors attached to the harness
-Catalytic converters, resonators, muffler (if you choose to keep emissions systems)

Additional parts:
-Rywire or Wirewox or CJs harness adapters (CJ is cheapest)- let the Accord harness "talk" to the car's body harness ($200) - you could in theory do this yourself for nothing if you're very good with electrical diagrams
-Civic EM2, EP3 or DC5 spindles (also called knuckle) (4 lug EP3 is 2002-2003) (Might be <$20 from junkyard) + brakes
-02-05 Civic front lower control arm ball joint adapters (fits EM2/DC5/EP3 spindles and lower ball joint) - *IMPORTANT* With these adapters, machining of the stock lower control arm will be required, needs to be drilled out slightly. You may or may not be able to do this, but a machine shop could do it in 10 minutes. ProfessionalAwesome has these for $150.
-~2.25-2.5" exhaust ($$??)
-Hasport engine mounts (no price yet, but could be ~$500 on the upper end)
-axles will be specific to engine placement, we'll know this once Hasport has their mounts out

And that's it. The Accord engine is almost a perfect drop-in replacement, and everything else is off the shelf. Any other swap requires fabrication. I could see spending maybe another $1000 on top of the parts car in miscellaneous parts to have it all going with no check engine light and everything working.

I find a replacement longer final drive gear to be a good idea, or you'll want to put much larger tires on to get RPM down. The 03-07 Accord transmission has the tallest factory final drive at 4.388 which would give you 2800rpm @ 65mph with the Insight's tire size - not too bad but higher than is ideal for me, leaves some gas mileage on the table. There's a $600 4.059 final drive available which would reduce that to 2600rpm. I opted to have a custom gear made for $1200 (ahhh the pain), which brings that down further to 2140rpm, actually taller than the Insight's original gearing!

 

Hey Ecky, kind of unrelated, but do you recall how big the hole was in the rear glass when you removed your wiper? I'd like to order a plug for mine and remove it.

Cheers!

 

This is what you want:

https://www.amazon.com/gp/product/B012M6IISU/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

 

Hi Ecky, this is a great thread, thanks for all the details and pics. I like the budget K24 parts list you posted, especially the transmission gearing info. About that Accord K24 - with tuning, can you get the Accord K24 horsepower to be closer to that of an RSX Type S? Or is it even relevant given it is going into something so light to begin with? Thanks!

 

The Accord K24 doesn't breathe as well at the top-end, and it has to do with the valves, cams and intake. It will probably feel similar to the TSX engine up to ~5500rpm (that is, 20% more torque than a Type-S engine) and then drop off, whereas the TSX will pull hard to 7,000. The ~166ft-lbs of torque will feel monstrous at low RPM though and 0-60 even with the lesser Accord engine will smoke an S2000, 350Z, Porsche Boxster, Mustang Cobra, and maybe even overtake a period-equivalent Corvette with the right tires.

Put another way, if you look at horsepower and torque per ton it would be similar to if a recent (let's say 2016) Accord had ~400-450 horsepower.

 

That's awesome! Thanks

 

This is going to be fun to watch

 

Hi Ecky, one more question: who is making you that custom final drive gear? Thanks

 

John Frana at Frana Vehicles:

Custom Final Drive Gears

Total price: $1200, needed a total of 3 orders for him to start a production run.

 

Replaced 12v battery with a bank of 3000F supercapacitors. Should be good for a ~25lb weight reduction. Starts the car far better in subzero weather than the battery did.

Engine and transmission are fully assembled and just waiting for a home. Got 50 degree VTC actuator installed, new alternator, new thermostat + housing, new A/C compressor. Turns out the JDM K24A has a different water pump housing which doesn't line up with USDM accessories so I replaced that too. All I need now is for Hasport to release their mounts and axles.

 

No way to keep the Insight's original DC-DC converter and skip the alternator?

 

Let’s think about this for just a moment. A K24 swap, also commonly called a K-sight is a 4 cylinder gas engine and transmission that is put in place of the original 3 cylinder, gas/electric hybrid system.

When you go K swap, you eliminate the electric motor. The DC/DC converter is just a boat anchor at that time. Let alone there is no room for the electric motor as in the original configuration it takes the place of the fourth cylinder.

The alternator is necessary to run the 12v system.

Scott