FB25 shortblock FA20 heads
 

Has anyone ever successfully installed a FB25 short block on fa20 heads?


Saw some discussion where the starter needs to be moved to other side transmission, fa 20 piston domes have a (bigger?) dish in them for direct injection, and possibly the combustion chamber on the head possibly needed milled.


https://www.ft86club.com/forums/show...t=45926&page=4



Looks to me like the transmission could possibly be milled out to have a left side starter without an adapter plate, and one only one bolt appears it would need left out of bellhousing. But unsure of other issues, thoughts?

Nah, Subi engine families don't lego like Hondas.

Not sure if accurate but I think Jet86 (post#70) on this thread said the heads would bolt on the block

https://www.ft86club.com/forums/show...?t=2158&page=5


Just wanting to know what the exact issue with it was- if it was just not worth the trouble or not possible

Not to mention thinner and smaller in diameter rod journals. No thanks.

https://www.ft86club.com/forums/show...3&postcount=66

Is there evidence that this change makes it less robust? I see a stiffer crankshaft swinging less mass at the rod ends. The smaller diameter also results in lower speed between bearing and journal but that probably wasn't the main goal. I'm sure the decision to give up some bearing surface for a stiffer crank involved considerable R&D.

No, but you know my monkey brain just looks at it and goes "smaller bad."

I know it was discussed in that dudes NA build thread but I don't remember the outcome. I think he went with the FA20 crank and a custom rod/piston. If I get a chance I should reread the thread even though it is like 49 pages and 1/3 of it not even involving the build.

https://www.ft86club.com/forums/showthread.php?t=63901

Oh, I hear you. I'm sure there was quite a bit of hand-wringing during the whole development cycle. Maybe they trimmed out some capacity for boosting. We'll see as they start popping down the road. :iono:

Why???

FA20 heads from our engine are ported nicely from factory, I imagine that is the angle here

-5 missed gif


https://i.giphy.com/media/1M9fmo1WAFVK0/giphy.gif

never mind about converting from belt to chain:mad0259:

Seriously, why not swap instead??

If doable, I might consider it over back-converting all the sensors. Isn't that a thing too?


edit: Wait, no. I'm dumb. Already have to do that. Actually, I can't think of a good reason.

Are they not for the FB?

I haven't seen an FB. But the FA20DIT heads are far less ported than ours so I can only assume ours were quite generous compared to their normal offering

its been done.
FB25 block and pistons
FA20 Crank and rods, heads, and timing cover.
There is a fb post about this somewhere I'll have to dig it up.

But honestly FA24 short block is about 2k shipped and doesn't require machining to the block to fit the starter.

BUT that would only work on 2017-2021 cars as the timing ring is the same for both 2nd gen fa20 and first gen rwd fa24.

Saw this post on FB from Malaysia about a complete fa24 swap into the gen1

https://www.facebook.com/groups/329984590429807/user/100063487306385