Acura TSX engine in a Honda Insight

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
This has been on my wish list for a while, and I'm finally getting around to doing it. Hasport will be coming out with their engine mounts at the end of July and I hope to have all of the parts collected ready to go by then. Plan on doing a low mile TSX 4 cylinder engine or equivalent (2.4L, 205hp, 172ft-lbs torque), Civic Si 6 speed with LSD, 3.4 final drive (compared with 4.7) so I don't need stupidly large wheels. Keeping ABS, air conditioning and factory electric power steering. Slightly larger brakes in the front (probably from ~04 era Civic). Removal of IMA components from the rear, recarpeting and approximately doubling cargo capacity. Estimated dry weight of the car with the new engine is around 1950lbs. It'll throw off weight distribution a bit. ;)

Mike Lewin over at ProfessionalAwesome has already done something similar. With a 3.4 FD and a tune that leans the engine out to 19:1 at low load and low RPM, he's reporting 53mpg @ 80mph, will still having 200+ on tap. 0-60 time will likely be in the high 4's and quarter mile, the low 13's. For now I plan to just use the factory ECU and tune, but a tune may be in my future.

Can you say "ultimate sleeper" ?

fwdl1eB.jpg



Electronics in the rear to be removed:

UexkQzt.jpg


The little 3 cylinder that could:

v8PVQlU.jpg


It's surprisingly not-tired after 240k miles and doesn't burn a drop of oil between 7500 mile changes. I'm willing to bet it has another 100k+ in it before it even has noticeably below factory compression. Hopefully someone wants it.
 
Last edited:
Feb 25, 2011
16,927
1,565
126
My housemate had an '08 TSX. Those are nice engines. Looking forward to pics of the conversion!
 
Mar 11, 2004
23,326
5,759
146
I'm actually bummed that you're removing the motor, and I couldn't give up regen braking. I'd be totally onboard doing that to the newer CRZ. My dream way of hotrodding an Insight would be putting in a bigger motor (maybe scavenge a Model S one from a wreck) in the rear powering the rear wheels, and up the battery.

If money was no object, I'd want to extend the length (give the hatch a more pronounced tear drop shape, make the fender flares a bit curvier and pronounced to fit bigger and wider tires), tube framing the whole car, and putting a nice engine mid-mounted (and visible through the rear hatch) paired with a more potent motor in front. I'd love to see Honda take the new NSX powertrain and fitting it to a heavily reworked Insight body (but have some familiar styling cues, retain stuff like the head/tail-light shape and kinda the sideglass but make them more elegant, same with the swept front wheel arch and the rear fenders, keep it tasteful instead of the huge whale mouths with fake grilles all over and sharp light shapes that modern stuff has) that makes you think of old boattailed classic cars. Redo the interior to a bench seat, and make it more of a luxury cruiser.

Er, just realized you might've already removed the motor, so the IMA stuff in the back wasn't doing anything.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
I think in a perfect world I'd shoehorn the Clarity's drivetrain into the Insight. It would probably deliver 75-100 miles of EV range and 75mpg+ after that, but that isn't in the cards, I haven't heard of any tuner shop which knows how to swap a hybrid drivetrain.

One problem with adding a 300lb electric motor and 1000lbs of batteries to the back of an Insight is that the chassis just won't support it. The entire car is rated for 500lbs of passengers plus cargo. Upping weight by more than ~200lbs basically puts you over that with two adults in the car.

Anyhow I haven't removed anything yet. I'm collecting parts first, before I tear my car apart. A K24 is one of the cheapest swaps and makes oodles of power, and fuel economy will still be far and above any non-hybrid, if not in the same league as it is now.
 

Midwayman

Diamond Member
Jan 28, 2000
5,723
325
126
If money was no object, I'd want to extend the length (give the hatch a more pronounced tear drop shape, make the fender flares a bit curvier and pronounced to fit bigger and wider tires), tube framing the whole car, and putting a nice engine mid-mounted (and visible through the rear hatch) paired with a more potent motor in front. I'd love to see Honda take the new NSX powertrain and fitting it to a heavily reworked Insight body (but have some familiar styling cues, retain stuff like the head/tail-light shape and kinda the sideglass but make them more elegant, same with the swept front wheel arch and the rear fenders, keep it tasteful instead of the huge whale mouths with fake grilles all over and sharp light shapes that modern stuff has) that makes you think of old boattailed classic cars. Redo the interior to a bench seat, and make it more of a luxury cruiser.

Turning it into a rear drive would be amazing. I know I've seen some hatches done like that. Golfs and pugeots. I wouldn't bother with the hybrid stuff, but it would be a fun car for sure.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
My big hurdles to overcome are engine mounts and gearing. The Insight's tires are smaller than the Civic Si's, not to mention it has half the drag and weighs 40% less.

The TSX and Civic Si from 2008+ and 2012+ respectively both have a very nice 6th gear for highway cruising (0.647), but a very silly short final drive (4.764). An Si would normally be turning around 3000rpm at 70mph, or ~3400 at 80mph in 6th gear. With the Insight's smaller tires that becomes 3250rpm and 3700rpm. Owners of K20 swapped Insights (less torque!) report not having any any traction at all until 3rd gear, and even then they're able to break the tires loose. My solution? Custom 3.4 final drive, reduces RPM by around 30% in all gears, or ~23% when you take tire size into consideration.

With a 3.4 FD, highway cruising in 6th gear drops to 2300rpm at 70mph, and 2650rpm at 80mph. This is, in fact, almost the same gearing the Insight's 1.0L has and it's able to maintain speed and pass in 5th gear just fine with the car's light weight and excellent aerodynamics. The close ratio 6 speed, tripled torque and horsepower will ensure it's still fun to drive in lower gears. Due to the car's weight, it will still have better power to weight in every gear than the TSX or Civic Si. The tall top gear will allow for excellent fuel economy and quiet highway cruising, effectively giving the car a "7th gear".

Insight stock transmission is in blue, TSX/Si transmission with 3.4 FD is in green:

k9NbwPL.png


Just sent off for a custom 3.4 final drive. ;) Estimated turnaround is 3 months.

As for mounts, Hasport is claiming theirs will be released by the end of July. They're not a direct fit for the later K series transmissions, but will work with some small modification. I may need to use Innovative's transmission mount and Hasport's three engine mounts.
 
Last edited:

PeterScott

Platinum Member
Jul 7, 2017
2,605
1,540
136
Cool. This car has always seemed like it had super swap potential. One of the lightest and most aerodynamic bodies you can get. So you can really have it all. Awesome performance and efficiency. Looking forward to following this swap.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
Friday commute to work with the hybrid system intact: 73.3mpg
Monday commute with check engine light and no hybrid system: 73.0mpg

When I'm not in a hurry, it's hard to tell it's even gone. I don't recommend driving one without a battery if you're in any kind of hurry, however.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
Here's a nearly complete list of what you'd need for the swap:

From the doner car:
-K24 engine
-Transmission
-Factory ECU
-Factory engine bay wiring harness
-Catalytic converters, O2 sensors, resonators, muffler (if you choose to keep emissions systems)
-Gas pedal (needed for dbw system)

Additional parts:
-Rywire or Wirewox or CJs harness adapters (CJ is cheapest)- let the engine bay 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)
-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. ProfessionalAwesome has these for $150.
-~2.25-2.5" exhaust ($$??)
-Hasport engine mounts (no price yet, but could be ~$500 on the upper end) OR modify factory mounts. If using a 2003-2007 Accord or 2004-2008 TSX transmission, all of the mounts will work. If using a later transmission, the transmission mount will need some fabrication.
-Axles will be specific to engine placement and transmission used, I'll know this once Hasport has their mounts out. Some combination of Civic and RSX mounts will fit though.

I find a replacement longer final drive gear to be a good idea, of course.

Beyond that it's going to be puzzling out how to convert everything so all of my gauges work.
 

HarryLui

Golden Member
Aug 31, 2001
1,518
33
91
When I'm not in a hurry, it's hard to tell it's even gone. I don't recommend driving one without a battery if you're in any kind of hurry, however.

I disagree. Sure, the car is slow to accelerate, but I bet you'll get to work the same amount of time if you obey the speed limit and traffic lights.

I once was lined up at the traffic light with a WRX, he took off like a rocket while I move as fast as my IMAless Insight could. We got caught by the next traffic light, then the next one, and the next one, then he made a left turn. From the first light until the moment he turned, he was maybe 5 seconds ahead of my Insight.

I've seen countless of cars that passed me while I'm doing the speed limit, then they have to stop for the red traffic light, they gain all of 10 seconds of getting to the redlight faster.

Redlight and speed limit are the equalizer.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
Ohh certainly. It keeps up with traffic just fine, and if you wring it out it can safely merge in even the worst situations. We have a lot of hills here and I'll occasionally find the spacing of 1-2-3 difficult, but it's a very reasonable car to drive even in the mountains without the IMA.

I more meant that it just doesn't accelerate quickly. There's no urgency about it, no "kick in the pants" like the IMA provides <2000rpm.

As an aside, I've ordered an 850w Meanwell power supply and bridge rectifier, and plan to gut the entire rear of the car as soon as they come in. I'll only need the PSU for maybe 3 months, but I'd like to continue working on things while I wait for my final drive and the mounts to arrive. The Meanwell is a replacement for the DC-DC converter, you just connect it to the exposed 3 phase wires coming directly from the motor, making absolutely everything in the rear unnecessary. I plan to drop the deck area back there a good 12-14" and ~double my cargo space. I can also adjust the rear springs and get the ride height in the back situated before I have the new motor in.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
Engine and transmission ordered!

Some fun facts:

TSX OEM flywheel weight: 18.2lbs
Insight flywheel weight: 13lbs + IMA motor mass
RSX Type R flywheel: ~10lbs (using this)

Insight rim weight: 11lbs
TSX rim weight: 21lbs

RE92 tire weight: 13lbs
TSX tire weight: ~23lbs

Compared with a TSX, I'm reducing rotating mass at the flywheel by 45% (8.2lbs), and at the tires by 80lbs, which is also almost exactly 45%.

The TSX weighs around 3300lbs. The Insight with TSX engine will likely be around 1950lbs (maybe a bit less). This is a 41% reduction in weight. If I can get it down a little bit, to its stock weight (might be possible after gutting the back, lightweight 12v battery), it would also be an approximate 45% weight reduction.
 
Feb 25, 2011
16,927
1,565
126
It's a freaking go kart.

Consider wider tires. You're going to be breaking them loose pulling into parking spots.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
I'm hoping to get by with my current tires (165/65r14) until they wear out. 185/65r14's are on my wish list after that.
 

Yuriman

Diamond Member
Jun 25, 2004
5,530
141
106
We'll see what I end up with. Tires are key to getting good fuel economy, and I'd really like both. It's easy to lose 10-25mpg in this car with a different set of tires. They just need to be sticky enough that I'm not losing traction all the time.