FA20DIT bore is 86 mm. How can they be used in 94 mm bore cylinders? Or did you mean FA24F, the turbo version of FA24?

My bad, you are correct. FA20DIT pistons would be a little loose....FA24 Turbo pistons. (Ascent, Outback XT, Legacy XT, WRX)

LOL - I was going to comment similarly, but figured someone else would sort it out. ;)

I'd be surprised if they swapped the pistons out, since they'd probably have to machine the heads either way. Also considering the claimed HP, I'd think it would be hard to hit that NA with the reduced compression of the turbo pistons (though again, I don't put a whole lot of stock in those dyno sheets).

IIRC one of the 2 engines uses a domed (sp) piston, so it protrudes out of the block and into the cylinder head, and the other does not...this causes a clearance issue when trying to use the FA24 block with FA20 heads...so pistons likely need to be changed out.

I saw it and knew what he meant to so I just lol'd and let it go.

Just quick math shows chamber volume should be about 40CC on the FA20 and 48cc on the FA24. Granted that is not taking into the fact the piston protruding into the head on the FA20vsFA24 isn't apples to apples, but we are talking about only adding 10ish cc's of volume to the FA20 head to make it work.

Speculating super hard of course :D

Careful! Don't pull a muscle.

More likely just a repetitive stress injury.

https://media.tenor.com/TbC7aFA3uhoA...mer-monkey.gif

Opie, you make any progress securing the shortblock?

I have also been watching this very closely. I understand there is now a U.S. based version of this but I can not seem to find the info on it. Anyone else made any progress. I do have access to all the parts required and am very much just considering doing this on my own and figuring it out. I will actually video and document all the changes required so as to make this available to the public. I think this is the future for the first gen platform. Also worth mentioning that I thought the FA24 has a 13.5:1 CR so machining the heads should put the CR somewhere in the 12-13 range.

This is incorrect. This was the result of PR publishing errors that mixed up the engine compression ratio with the steering ratio which is 13.5:1.

**Heavy Breathing** Watching very closely :P

I never reorderd one after my last two orders were cancelled. Definitly on the back burner now...

From Revolution Garage in Japan.

FA24 in MY12-13 TA LW86


http://revo-tune.jp/feature-areitcle.../02/14/id17999


2023-02-14 After successfully starting the late model engine in the first half of the ZN6, the second FA24 engine change & start confirmation, current car setting completed @ 264 horsepower (5th gear measurement, tcf1.15)


This project started a few weeks ago, and if we can put a late model engine on the early ZN6 and start it, we should be able to teach the FA24 as well. ? This question has been resolved today. Since the start of the late model the other day, I replaced the wiring of the crank angle sensor and some harnesses and redid it and succeeded in starting the FA24. The starting data was a normal ECU in the latter half of ZN6, but it ran normally, but it felt different. The bottom two lines of the graph are ZN6 late genuine data, and although it started at around 220 horsepower, it was a "poor" start. It's a set measurement, but the graph is completely different from ZN6, and the measured value is about 235 horsepower, well, I hit it well. . Then, while searching for the optimum value of ignition timing in the entire range, I set it to about 245 horsepower, but somehow the knock point was low, and the ignition did not enter at all compared to the FA24 data of GR86LW. Suddenly, I came up with the FA24 surge tank, and when I looked at it seriously, the capacity was completely different. ? ? I immediately installed the FA24 surge tank together with the throttle, and although some processing such as the auxiliary parts stay was necessary, I installed it. As soon as it was turned, 15 horsepower increased to 260 horsepower, and the ignition became easier, and the ignition map was corrected to 264 horsepower. The two FA24s, FT86LW and GR86LW, will run at Attack Tsukuba on Sunday and 18th.

Thanks for finding / posting that!

So from reading the article alongside the other photos there, it looks like a full FA24 motor swap using the 17-20 ECU and a number of wiring / sensor changes in the engine compartment to make that work. Also seems that the FA24 intake manifold (translated as "surge tank") is necessary for the best power output with the bigger block.

From the side-by-side shot of the two manifolds (linked below), it appears the FA24 manifold has both longer and larger runners (longer because of the "M" shape or "W" looked at upside down like in the photo, and larger because of the thinner walls of the plastic manifold vs. aluminum despite them looking comparably bulky), which explains the latter. (Begs the question could a 2nd gen manifold make power on a 1st gen without losing a lot of bottom end? :iono: Anyone want to spend $363.28 USD to find out?)

Link to article photo of intake manifolds (I tried to just insert the image, but for some reason it doesn't appear)

Gives us some more specific direction for how best to approach the swap down the road, anyway, which is great!

The bad (sort of) news is that it seems like the best route will be to pick up a complete FA24 engine including manifold, rather than just a short block, so cost will obviously be more. Good in that you won't have to monkey around with mating the FA20 heads to the FA24 block though. A complete motor was logically going to be the best route all along if the ECU was compatible, so no big surprise there.