Opie, thanks for doing the needful. It will be interesting to see what comes of this.

I'd still call using the FA24 heads a possible win when you consider what a K swap costs. If it all still works that is, which I believe it will. I would be over the moon happy if this thing does at least 220whp with bolt ons. I am not looking for big power.

Are you familiar with interference testing? I’ve never done it, but the K crowd does for cams and high compression builds. Apparently you have to apply puddy to the piston head and then torque down the head and then remove and analyze, and then repeat. It is fairly laborious.

Or allow a taller port

More commonly known as clay checking. I've done it and its time consuming but necessary when using different cams, pistons, valve sizes etc.

Unless something has been vetted already.

That's overall good news for performance with the FA20 heads then!

If you *did* end up going with the FA24 long block option, once you figure out everything that's necessary, you could maybe put together and sell a kit for adapting everything to the FA20 intake manifold and ancillaries.

Based on the interest in this thread, I'm sure there'd be at least a few takers... ;)

Yes, please think about doing that. A package / kit

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Never done it, but have heard of it. Also will be using a borescope to see what happens....

In other parts of the world....Subaru sells long block assemblies that would make this a much easier decision...but in the US you can buy all the parts and build an engine, or buy a complete engine assembly including exhaust manifold, intake manifold & accessories....not a long block.

Score, both engines use the same timing chains!

On using the FA24 cylinder heads....finding other issues, different High pressure fuel pumps, & mounts. May not be interchangeable. Also will need to find a solution to additional water lines that feed the cooler....

Yikes. I'm guessing that's the same for Canada, and I'm guessing the complete assembly is P-R-I-C-E-Y! Likewise trying to piece together complete FA24 heads with cams, etc.

Makes working with the FA20 heads definitely seem like a better option.

EDIT (2): Found a listing on one dealer's parts website that said "Engine Assembly - Long Block" priced at $7,393.82 US. Contacted the dealer for more info, and they said it isn't available to order and won't be available period very shortly after the 2022's start heading off of dealer lots. Basically, they're only available to dealers in case of a DOA motor with a car they receive, or something along those lines, and once cars start getting into customer hands, the availability for even that will go away, and as Opie said, only short blocks will be available.

Regardless, that list price is more than the price of every supercharger kit on the market...LOL. Heck, the difference in price vs. the short block is about $5,500. I can definitely see a STRONG cost argument for sticking with the FA20 heads, even without all the other complications.

Yay...and ouch.

May have just found something useful....the FA24DIT pistons are a flat top design...they are not domed like the FA20/24 N/A engines.....possibly a fix for 2 issues....FA20 N/A cylinder head clearance and not increasing compression ratio......

Interesting... So, flat piston with just a minimal blending of the combustion chambers in the heads to allow for the bigger bore (removing the stepped profile). It'd be interesting to see how close to the factory 12.5:1 C/R you could achieve with a flat-topped piston.

Could work, but is there a performance (E.G. combustion control) reason for the pent-roof / domed profile of the FA20 and FA24 pistons, or is it just to increase compression? My guess from the fact that the peak of the dome on both pistons is offset to one side is that it also helps with combustion control, although that *could* just be due to the angles of the intake vs. exhaust valves.

EDIT: For those that aren't familiar with the idea of piston shape controlling cumbustion, here's an article that talks a bit about the concept of the offset dome being used to control combustion for both power and detonation resistance. It's talking about an even more complex design, the "Endyn Roller Wave" produced by the company, but explains the basic principle pretty well. http://www.theoldone.com/articles/rollerwave-intro/

Thinking further about it, if the dome is offset for combustion control and the valves have been moved further outward in the FA24 head, it's possible the FA24 piston's offset would be in the wrong place to work properly with the FA20 valve placement. That said, it probably wouldn't be that big a deal as long as the peak didn't end up too far inboard of the intake valves (which I think would cause the mixture to move the wrong way) and it would likely be the opposite - further outboard than the FA20 piston.

That could be another argument to go for a flat-topped piston, I guess...