Honda Insight w/Acura TSX engine - Ecomodding
 

Lately I'm seriously considering doing a K-series conversion to my Insight. My logic: at some point the IMA battery will need to be replaced. If I lived somewhere more flat it wouldn't be a big deal to just bypass it, but Vermont's mountains make the car a bear to drive without assist. I'm approaching 250k miles on the engine with zero problems so far, and have no idea how many miles I can put on it. My transmission needs a "tabectomy", it grinds when downshifting into first and second. Undoubtedly the least expensive option is to just keep it running with factory parts, but I can't help but dream and it might be best to do this while the components I'm taking out still have value.

My ideal swap would be the drivetrain from one of Honda's more recent hybrids. However, nobody knows how to do this. :rolleyes:

Next best would be a modern L15B out of the 2015+ Fit. This is the same motor as is in the 1.5T Civic, just without the turbo. These have an offset crank and a lot of low friction technologies. Despite the gearing they're pretty well tuned for economy. I could re-use the really tall ~3.2 final drive out of my Insight's transmission, or the entire transmission, since the Insight's engine is secretly an "L" engine too. Unfortunately the L motors are quite tall, the intake manifold tilts upward and sits on top of the engine (making it even taller!) and there are virtually no aftermarket options. So, I'm probably going K as I won't be able to make it fit under the hood.

My idea: Obtain one of the higher compression "K" engines with integrated exhaust manifolds which nobody wants. The king of K motors in my opinion is the K24W7 out of the 2015+ Acura TLX, with a mouth-watering 11.7:1 compression ratio and 182 ft*lbs of torque at 3900rpm, but the K24W out of the recent Accord and CR-V (at "only" 11.1:1) can run on 87 so that would be a decent option too.

Undecided on a 5 vs 6 speed. Weight and size may dictate that. However, whichever way I go, I'll likely have a custom ~3.4 final drive made for it, which would bring 65mph cruising RPM down to ~2200 with the Insight's stock tire size, lower if I go a hair bigger.

A shop in Florida has successfully tuned the older K20A2 motors to run at 19:1 AFR at part throttle, and reports in excess of 50mpg highway in the Insight body.

^ Mind you their low-3 second 0-60 is with a turbo, which I would not have.

49mpg at 85mph is actually quite close to what the Insight's stock engine gets, probably because it's running outside of peak BSFC at that speed.

:turtle:

Dry weight of the car is ~1850lbs with A/C.
Insight engine - 128lbs
IMA battery - 95lbs
Insight manual transmission - 56lbs
MDM + DC-DC - 20lbs? estimated
Total: ~300lbs
57:43 weight distribution

K-series 6 speed weight: 89lbs
K-series 5 speed weight: 87lbs
K24 engine - 283lbs
K20 engine - 275lbs
Total: 360-375lbs, plus maybe a bit more in brackets and alternator

I'd be adding ~100lbs to the car. More importantly, this will throw off the weight distribution, adding ~200lbs to the front and subtracting around 120lbs from the rear. Ideally I'd re-use the IMA power cables and migrate the 12v battery to the back of the car, maybe switch to an AGM battery for safety (and efficiency) reasons.

I've exchanged a few emails with a shop in NYC with a lot of experience with K swaps. We'll see where this goes.

Sounds great. You could develop the kind of project pgfpro had here on EM. Before his Talon, which was amazing, he had tuned a three-stage Civic for fuel economy in a specific RPM range and throttle position (IIRC) and power under some other conditions.

The weight distribution problem sounds kinda, well, dangerous maybe. Traction on the power wheels would be fine, but how would braking and especially cornering be affected?

The power/weight ratio, tho! Fun.

We could think of it as an ecomodded K series, lol.

I've made a mistake, the weight I listed was for engine and transmission. Edited post. ;)

So migrate the battery to the trunk and get a big ass and cheap lead acid one that you plug it at night, running the car mostly without the alternator like I do.Throw like 80-100 amp hours back there at maybe 70-80 lbs. That's 20 lbs reduced from the front and 80 added to the back. ??

Maybe add rear disc brakes since you have so much more power? That also will put a little more weight in the back.

You'd still have a really great weight/power ratio and somewhat more even weight distribution.

If you could gear down the engine for top-gear cruising, sounds like it'd still easily beat Geo Metro MPG on the highway. Neat trick.



Of course you'd throw some of the tank average away having fun in the lower gears. Compromises, compromises!

Yeah I wonder if I should call this a "TSX heart with an Insight wrapped around it", or a an Insight with a TSX guts. :D

Anyway will update as I go.

After thinking on it, aftermarket fuel management and then getting a good lean burn tune on an engine with several cam profiles for both intake and exhaust plus variable timing might be time consuming (read=expensive) because of all of the factors involved. I might just go with a factory ECU and give it reeeeaaaally long legs to start with. Swapping the ECU later doesn't require I put it up on a lift.

I'm guessing few to none here know much about different versions of the Honda K20 and K24, but I figure I'll throw this out there anyway, in case anyone has any useful feedback:

My understanding:

K20A2/Z1/Z3
+ high revving, slightly lighter, shorter engine (fits better), barrels of fun, short runners (fits better), well understood and relatively easy
- expensive, less torque, probably worse gas mileage (all else equal)

K24A2 (pre-2006)
+lots of torque, probably better gas mileage, less expensive, well understood and relatively easy
-lower rev limit (still plenty), heavier, probably hard to find one without a lot of miles, long runners (might need to cut radiator support)

K24Z3/Z7 (~2006-2012)
+ probably cheapest of all since nobody wants integrated header, easy to find low mile, wider powerband
- Aftermarket engine management might be absolutely necessary, since it's DBW. Adds cost overall, unless I go with an aftermarket ECU to begin with

K24W/V7/W7 (2013+)
+ Most torque of any K engine by a lot, probably best fuel economy, easy to find cheap low mile engines, crazy high compression ratio
- I have no idea about DI, probably would need entirely new fuel system? Probably not a well understood swap even if it can be done, so $$$$$

Not currently considering the lower revving, lower compression ~160HP K20's and K24's.

Some questions I have rolling around in my noodler:

Are the mounts the same on the newer W and V Earth Dreams motors? Should I rule those out entirely because of direct injection? Has this ever been retrofitted before? This is probably too ambitious, but I'm curious about them at the very least.

What are the major hurdles of keeping the factory ECU to save money? I'm willing to bet I can get away with this with the early K20A/K24A, but I don't know if it would be possible on the newer K24Z, due to drive by wire.

Are there any engine and transmission mount differences for the various K engines and transmissions? Are they all interchangeable? Does any transmission mount to any engine?

Am I correct in thinking the K24A's have VTEC on the exhaust cam, whereas the Z's do not?

I'm undecided on whether or not to go with aftermarket engine management, because I don't know where I'd find a tuner who knows how to tune for lean burn and fuel economy. On an engine with VTEC on both intake and exhaust, AND variable timing, AND variable length intake runners, trying to tune it myself sounds... difficult.

As for direct injection, from what i have seen, the high pressure pump is mechanically driven from a cam shaft. It may not be difficult at all if it is stock parts on the engine/ecu.

My question is, do you have 5-10,000$? Everyone says it's cheap if you DIY, but in the long run they just lost count of how much money they really spent, due to the fact the projects take so long. That or they give up.

I'm not trying to discourage you from doing it. Just being real.

Also, get a K20A motor. 8600rpm redline. Yummy.

Whatever K motor you go with(unless you get one with a redline above 7250). Use the accord manual transmission. It's got tall gearing and it shifts so, so SMOOTH. If you get one that redlines at 8400-8600, just go with a shorter geared trans (about 3500rpm at 75). Otherwise it will be an absolute dog off the line because those engines make no torque below 2000rpm.

I just read the questions about the DI motors. Unless you have experience and training I would not recommend you even attempt it. You are talking about 5-900PSI pressurized fuel lines. Not worth the risk.

Yeah, I set aside $10,000 from my checking account to cover this. Hopefully it comes out to less, but I'm prepared for it to go a bit over.

I figure if I can get a low mile engine (let's say 40k) it's a lot less expensive than a car with that many miles.

Currently looking at auctions for things like TSX or newer Si (K24) which have been in collisions. K24's, even the nicer ones, seem a fraction of the price and are much easier to find with low miles.

Definitely planning on a custom 3.4 FD, even if it's $$$$. Even with that crazy tall gearing, it's still going to be geared shorter than the stock 1.0L.

Love my 2006 TSX. The only thing that could be improved on the car is taller gearing, better sound proofing, and a tighter turning radius (turns worse than a bus). Oh, and VTEC should activate sooner than 6k RPM. When shifting at the redline around 7k, the revs fall below VTEC activation so the engine is sluggish again until building back up to 6k. It should have been designed to activate at 5k.

How hard would it be to change out the FD? Would love to get the revs down. 1st gear is so low that I can't imagine the car being difficult or sluggish to drive with a taller FD. Too much torque off the line anyhow.

Transmission needs to be drained and removed, of course. ;)

I'll see if I can find any good how-to's later. It would be very helpful to me if someone went in on a group buy for some taller final drives. 3.4 might be too tall for you though; you'd probably be sub-2000rpm with your stock tire size at 65mph in top gear... or maybe that's a good thing? You'd practically have a "2 through 7" trans rather than 1-6.

EDIT: A custom super tall FD (3.4) requires a group buy and is probably going to come out to $1200. A slightly taller FD (4.108) is available here for $450. Of course, it's not as taller.

https://www.afhparts.com/oem-parts/h...=41233-RAP-000
https://www.afhparts.com/oem-parts/h...=23221-RAP-000
Source

Trying to decide.

3.4 FD, stock 165/65r14 tire size
2180rpm @ 65mph
1680rpm @ 50mph

3.4 FD, common 185/65r14 tire size
2085rpm @ 65mph
1605rpm @ 50mph

4.105 FD, stock tire size
2635rpm @ 65mph
2025rpm @ 50mph

4.105 FD, 185 tire size
2520rpm @ 65mph
1949rpm @ 50mph


Honda Insight 1.0L gearing - 3.208 final drive
2350rpm @ 65mph
1810rpm @ 50mph


I really think a 3.4 FD is a good idea, but it adds considerable cost to the build. I suppose the 4.105 wouldn't be the end of the world if I moved to a larger diameter tire too.

Why not put the engine in the back? Welcome to Mini Tec

I support this build. While Insight's stock drivetrains won't last forever, their bodies will, so why not have fun with all that lightness?

I know the RSX has a taller FD, and was hoping there might be used parts for relatively cheap. I'm not willing to drop more than about $200 on the mod. 3.4 sounds too tall though, as I wouldn't want to start from a dead stop in 2nd gear. Something around 4.0 seems ideal for me.

http://img.photobucket.com/albums/v5...v3-28-08re.jpg

Send an email to Jeff Owen, at kiwi@specialprojectsms.com. He has some relatively inexpensive ~4.0 final drives. I may do the same.

While I'm thinking about it, it's very common for people with a 4.389 FD to want to swap out for a 4.7 or shorter. You can probably find oodles of 4.3's for next to nothing on forums and eBay. Definitely less than a new 4.0, and still good for an 8% reduction in RPM.

Fun fact: TSX gearbox WITH a custom 4.059 final drive has similar gearing in 6th gear to the Insight's 4th gear. TSX 4th gear is equal to the Insight's SECOND gear.

https://i.imgur.com/al21Sbw.png

I think of all the choices, I'd most want the L15...

Maybe you could hack up the stock intake to not be so tall?

Seems like that way would get you the best combo of gas mileage and fun...

Unfortunately:

Deck height:
R18A/R20 - 230mm
K20 - 212mm
K24 - 231.5mm
B16A - 203.9mm
B18/B20 - 212mm
L15A - 220mm

So the L15A is between a K20 and K24 in deck height. Not a deal breaker in and of itself, but it sits vertically rather than tilted back like the K series, because the Fit's engine bay is tall but not very deep. I bet it could be made to work, but when you combine the lack of any aftermarket intakes, that the intake is plastic and thus can't be cut and welded, that there are no aftermarket gears (though the Insight and Civic Hybrid's final drives most likely fit), and that the mounts must also be fabricated, whereas Hasport has off-the-shelf mounts coming out for K motors, it's a tough sell for me. All else being equal, I'd take an L15B any day of the week.

According to this: a CRZ manifold is a bolt up:
https://www.crzforum.com/forum/do-yo...d-30-mins.html


https://ahparts.com/buy-used/2011-Ho...RTW000/84576-1
https://ahparts.com/watermark/1/item...6/DSC02311.JPG

Maybe that would be a bit more doable?

I'll look into it!

The mounts are still a bummer, it will likely end up being more expensive overall.

Never mind, that's only the top part, it's shaped the same as the Fit unit.

http://estore.honda.com/honda/parts/...n=&b=E++03&dl=

http://estore.honda.com/honda//image.../SZT4E0300.png

Aha! Found one:

Golden Eagle turbo intake manifold:
https://www.speedfactoryracing.net/g...ntake-manifold

Here's a pic of it on an L15 (CR-Z):
http://www.motormavens.com/emAlbum/a...ybrid_copy.jpg

CENTER STAGE> Bisimoto Turbo Hybrid Honda CRZ | MotorMavens

$700 is a bit steep. ;)

Short runners will probably affect low end torque too. Buuut it makes it a lot more feasible.

Quoting myself here because I need to update this. Hybrid Racing's K series transmission guide had the wrong ratio for the 2012 Civic Si's 6th gear - it's actually a bit taller.

Looks like I'm not going to be able to get ahold of a 3.4 FD, no matter how much money I throw at it. The one person who makes these will only make them if there's a group buy-in, so 4.059 is the tallest I can reasonably get.

That said, with the new ratio, it looks like this:

Honda Insight 1.0L gearing - 3.208 final drive
2350rpm @ 65mph
1810rpm @ 50mph

Civic Si transmission + 4.059 FD
2556rpm @ 65mph
1966rpm @ 50mph

Civic Si transmission + 4.059 FD + 185/65r14 tires
2444rpm @ 65mph
1880rpm @ 50mph


^ To me that looks pretty reasonable. Ideally I'd have taller gearing to go with the bigger motor, but at least it's not significantly shorter.

In theory, if I could get the 3.4 FD and put on 185/65's though...

Civic Si transmission + 3.4 FD + 185/65r14 tires
2047rpm @ 65mph
1575rpm @ 50mph

What a dream. I might even be able to nearly match the 1.0's fuel economy with a 6th like that.

Here's this dream transmission, graphed again'st the Insight's stock ratios:

https://i.imgur.com/VyFxFHO.png

Looks like I'm getting the 3.4 final drive after all. :D After pestering him, the guy who makes them caved and ordered a run.

With gearing like that this really might not be un-ecomodding.

That's the Si transmission with a 6 speed. Wow. Tall combination. With the 3.4 FD your RPM estimates are really low. My 3.25 FD, 0.710 5th, and 175/70-r15 wheels/tires turn the tach about 1770 rpms at 55mph.

Thoughts on K24 vs K20 fuel economy potential?

K24 is basically a stroked K20 - both have (approximately) the same cylinder bore. The K24 produces around 20% more torque, almost exactly the amount you'd expect based on the considerably longer stroke and correspondingly higher displacement.

All else being equal, I'd expect a motor with a longer stroke to provide better fuel economy (e.g. 2.0L vs 2.0L) due to better cylinder geometry. However, the K24 has more displacement. As long as I'm not needing to downshift when cruising, I expect that would work against me. A K20 will be running at higher load in the same gear, but its peak efficiency will also probably be at a higher RPM.

Do you have a torque/hp graph for both engines? That would help show what kind of loads you'll be at cruising.

Yep.

K24Z7 is ~170ft-lbs torque peak, ~205HP on paper, redline is 7000rpm.

K20Z3 is 139ft-lbs torque peak, ~197HP on paper, redline is 8000rpm.


Sample K24Z7:
https://acurazine.com/forums/attachm...psvvjraqvo.jpg

Similar K24A2:
http://image.superstreetonline.com/f...arger_dyno.jpg

Sample K20Z3:
http://i1172.photobucket.com/albums/...tachment-1.jpg

Similar K20A2:
https://www.kseriesparts.com/product...t2.5/dyno2.jpg


Both motors have basically flat torque curves. The smaller motor would have a slightly shorter top gear (I doubt I'd bother switching that). With the Insight's stock tire size:

Stock engine - 1705rpm @ 50mph, 66 ft-lbs of torque and it cruises at approximately 50% load. So let's say it takes very roughly ~35 ft-lbs to cruise at 50.

K20 - 1680rpm @ 50mph, ~120ft-lbs torque, around 25-33% load
K24 - 1647rpm @ 50mph, ~140ft-lbs torque, around 24-28% load

Taller gearing, longer stroke, but lower load...

The only missing piece is a BSFC chart. The longer stroke may have better BSFC at lower loads. I'm not sure if we have any similar examples to look at though.

Every time I see one of these k24 threads
I have to wonder if
https://ecomodder.com/forum/showthre...fxe-27266.html

That would actually be cheaper and easier
Would need ecu, transmission, mounts, harness potentially halfshafts and wheel ends

But I bet even at that the cost of parts is a fraction, the power gains would be adequate to motivate the car in any terrain and I bet the work required would be no more, just different

Maybe, maybe not. I think it depends heavily on which K24 motor. The Accord's motor is extremely common, and can generally be found with low miles for <$500. It's only if you want one of the higher compression and horsepower variants that prices start to go up.

With the Insight, you can use off-the-shelf Honda parts from other Hondas, and it all basically bolts up. No welding, cutting or modifying.

There are off-the-shelf engine mounts available for the K series, which is not true for any other motors to drop into the car. To me this is a big plus.

The wiring harness is essentially 100% compatible, as is the signaling for most of the stuff in the cluster (depending on the year). Several companies make off the shelf adapters for the K series computers.

I'm willing to bet this swap can be done far more cheaply, I'm just insisting on a newer and more powerful engine. :D

Ah, so your just interested in this

https://m.youtube.com/watch?v=hbNlR-fMlOw

Going cheap on a project like this just ends up being a tedious process of replacing the cheap parts with the stuff that should have been put on in the first place over time, headaches, and ultimately more money than if you just splurged in the first place.

Glad to see you are being smart about it.

What do you think, K20 or K24?

I would go K24A2. It might get a little less mpg, but there is no replacement for displacement. Especially because you aren't going turbo. You are already spending the money, you might as well put the best engine you can find in there. Not only that, but you want tall gearing, so the extra torque from the increased displacement will help a lot. Not to mention the A2 was around for a long time, it shouldn't be hard to find one.

[Edit]: something like this would be great.

https://m.ebay.com/itm/04-08-Acura-T...-/323339441653

I'm leaning toward the K24 myself, but the math tells me that even a K20 will have considerably more power in 6th, which will be taller than the stock tranny's 5th. I've been keeping my eyes out for a complete doner, and there are basically no manual 04-08 TSX with low(ish) miles anywhere in the country. Presumably they're already parted out. Plus 180k miles seems high.

I can probably score a sub-60k mile 2012-2015 Civic Si with severe crash damage in the rear for $3-5,000. The K24Z7 is a better motor in most ways, and the car will have a complete wiring harness, shift box, transmission which already has the tallest 6th gear you can get in any Honda 4-pot plus LSD, ECU, and an exhaust which I can adapt over. I'm looking to have my car "California legal", and having a full doner car seems easier. Plus I'd also have stuff I can sell and recoup part of that, like a cluster, seats, etc., or perhaps just whatever a scrapyard will give me for the car after I yank out what I need.

My TSX is a 2006 with manual and about 100k miles on the OD. Not giving it up though; fantastic car with exception of the gear ratios and turning radius of a bus.

Sold my hybrid battery yesterday!

https://i.imgur.com/eqA4BUa.jpg


Friday commute to work with the hybrid system intact: 73.3mpg
Monday commute with check engine light and no hybrid system: 73.0mpg