Fa20 with Fb25 block.
 

Not sure if it has been looked into enough but I decided to do a comparison with pictures.
The blocks are VERY similar apart from the few things.
One of these differences that could be the potential deal breaker is the fact the fb25 has no starter motor hump due to the gearboxes on the fa20 being sourced by Toyota, this could be sorted by milling out some of the fb25 block and drilling+tapping into hole for the starter motor lower bolt.
Another difference in the block is the huge threaded hole on the top of the block (about m16), the only reason this could give you issues is if you run a sprintex supercharger setup as it uses this hole.
The last and most obvious change is the fact the bores are now 94mm rather than 86mm. You can get around this by enlarging the combustion chamber on the fa20 heads with the use of a Cnc or a very steady porting hand (not recommended). The water jacket ports on the fa20 heads don't have any issues with the fb25 deck.

Pics being uploaded. Don't mind the speed hole in the fa20 block.

http://i213.photobucket.com/albums/c...ps5fafc73a.jpg

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Photos aren't working, which is a shame. Bandwidth exceeded errors.


That big bolt hole is probably an M14, not M16, if it's the one the Sprintex s/c fixes to.

Yea yiur probably right. I'm not at home so I can't check, I just remember it was way bigger than m12

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Il upload the pics in the morning, there is about 10 or so including head gasket differences

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Thanks, I look forward to the photos and further dialogue.

Damn, nearly identical!! I'm surprised no one has done a FA25 swap yet...

@jet86

https://lh5.googleusercontent.com/-S...lock%25202.jpg

https://lh4.googleusercontent.com/-a...ocks%25201.jpg

https://lh3.googleusercontent.com/-W...lock%25208.jpg

https://lh6.googleusercontent.com/-g...lock%25207.jpg

@jet86


https://lh3.googleusercontent.com/-J...lock%25206.jpg

https://lh3.googleusercontent.com/-p...lock%25205.jpg

https://lh5.googleusercontent.com/-Y...lock%25204.jpg

https://lh3.googleusercontent.com/-5...lock%25203.jpg

What would be the advantage of using the FA20 heads and not the FB25 long block altogether?

I understand the Honda frankensteins, you combine the bigger displacement of a non-vtec engine with V-tec heads having the best of both worlds, but what is the advantage here?

DI. I didn't think the FB25 had DI.

What is the bore spacing difference on the two blocks?

I could sure use more torque

Also flow. But depending on what's causing the top-end choke on the FA20, could just end up with same power at ~80% the revs.

Problem with DI on the FB25 is no fancy piston domes.

However, the 2GRFSE with D4-S is coincidentally also 94mm diameter. Anyone want to compare pistons now?

This is interesting, it this is cost effective I might consider this swap should my engine take an unfortunate blow.

It won't be. You're going to need a bellhousing adapter of some kind for the Aisin trans.

Damn, if not for the stupid starter this would work perfectly :mad0260:

Meh, better off getting an STI EJ. If I'm doing fab work and still keeping a boxer.

:-/ IKR? I dream of a Frankenstein FA25 with the right trans.

Let's get Cosworth to make a FA25 and offer a group buy.

For an extra $5000 more then 3MI will charge?

The main reason for the swap would obviously be the extra torque and power of having another 500cc to play with.
I've also looked at the fact of putting the fb25 crank in the fa20 block for an extra 4mm stroke to get just about 2.1L. The bore centers look to be the same as do the cranks.
Just some food for thought

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3MI :drool: He's actually semi-local to me. Super busy with a billion other projects though.

What's a 3MI? The people that make scotch tape? Or the people that don't seem to be able to make a functional website that apparently sells nothing?

http://3miracing.com/

If you have something useful to prove their track record and expertise matches that of Cosworth feel free to share. That's a pretty tall order btw. I'm sure I could pay a blind monkey peanuts to bore my cylinders compared to whatever 3MI does too so cheap ain't gonna sell me. Seems like they missed a finishing step on that piston they display on homepage. Should look like this:

http://www.carmodsaustralia.com.au/e...6-1153-lrg.jpg

:lol: Go to NASIOC, search longrod destroker.

Micah talked about it several times about a year ago, he still pops in once in a while and drops hints. Just one of the many things I'm waiting to see come to market before I decide which route I'm gonna take for more power. :party0030:

Id rather just raise compression, drop the spark plugs, boost the living hell out of it, and run diesel.........man the motors i could ruin if i just had money.

While I have been out of the Subaru game for a while, and had never heard of 3MI, a quick google search confirmed that Micah from 3mi was the same Micah know as "Homemadewrx" on NASIOC. Dude knows his stuff.

He went to school for this stuff and works with it everyday. He does indeed know his stuff.

Lol! You forgot the hydrogen powered turbine!! :lol:

People, please use Imgur.com for your photo sharing needs!

Only was able to pull this up: http://www.timeattackforums.com/foru...emade-wrx.html

I'd like to know more, maybe someone could invite him in here?

Cosworth also has teams of people that went to school for this stuff and have been in F1 and WRC for ages off and on. I also 'went to school' for some of this stuff. Suggesting you can get the same level of expertise and production quality for $5000 less requires some form of proof beyond a general unproven claim.

Regardless, I'll look into 3MI. Seems worth the inquiry.

I'm all for spending less money to get the same quality product. Just prove that it is if you are going to say it. Otherwise we'd all be buying Visconti who definitely did NOT go to school for this stuff. Oops, did I say that out loud? :D

Man, I have no idea what the price difference would be between a cosworth and 3mi kit, or if either will ever come to market. Cosworth makes awesome stuff, zero doubt there. They also charge an arm and a leg for it. All I was trying to say is that there will likely be other options aside from cosworth. Options that may not require a quality loss.

Go to NASIOC's Built Motor sub-forum. Read posts by Homemade WRX and 3MI Racing. The engine in the @Turn in Concepts is at partially of his design; look at the Honey Badger build they offer (I think it's his) and look at some of Dom's posts as well (Maxwell Power aka MPS).

He is already here; I haven't seen him post in ages though.

I am fairly sure he is on this forum and looking into the FA/FB hybrid. @Homemade WRX @3MI Racing

Someone posted a thread on a FB25 hybrid engine a long time ago, before the car even came out but I can't seem to find it. I wish it was as simple as it is with all of the EJ engines. Bellhousing adapters can definitely be made especially if enough people are interested.

After seeing the kind of torque Crawford made with their twin-scroll turbo FA20, I'm not convinced building a FB25 hybrid is worth it unless you want to stay NA and then I'd worry about spinning the engine to higher RPMs, the FB25 has a 6400 RPM redline. I just don't think it's going to be worth it.

http://www.ft86club.com/forums/showthread.php?t=2158

That was my thread.

Fb25 heads are the reason the red line is so much lower. Fa20 heads are just amazing.

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