Building a FA20
 

I've got a 2014 BRZ, 66k miles. I'm planning on getting a second motor to build during the summer. My goal is to build the motor to handle 400 hp. This will be the first motor I've ever built so I want to do it right.

I'm planning on going with forged internals (obviously) but I am unsure of which brand is best. I am going with a turbo for FI and need to learn everything I can about what goes into this build. The information I'm looking for is what compression ratio should I go with and what parts are going to give me the "reliability" to hit 400hp. Money is no object in this build but I'd prefer to keep it around the 10k mark.

As for the transmission, I've found a forged gear set claiming to support 800whp but it's 7k so I am also needing to know any information on what people are running for transmission's in their builds.

If y'all could throw out some links to other builds or even links to information that could help, that would be extremely helpful.

Why not just buy a built IAG short block?

The issue with the transmission isn't the gear set. The synchro's are a bit sensitive and there is a clip on the 4th gear idler can get kicked off. Jacks transmissions has fixes for this but they are expensive. A lot of guys putting down big power use a CD09. Mazworks has a kit, I am sure others do to run that transmission.

Definitely an IAG. Has better oiling capabilities also. I have the Stage 1 and it handles 550 hp. I'm NA so should have no further problems. Price went up a grand this year from when I bought mine but you can see here what they use


https://i.imgur.com/2CrRw3M.jpg

T56 or CD009. There are some kits out there.

I would just buy a built short block and assemble from there. The IAG one has improved oiling which is kind of the achilles heal of the FA20. This engine is pretty complicated especially if it'll be your first one. There's a ton of sealant you have to apply in a specific way and several of the steps involve torquing bolts in a specific order to a specific spec, backing them out a bit and doing it again. You'll have your hands full just buying a short block and going from there yourself.

That being said, you'll want:

• Killer B pickup
• There's a rocker-retainer kit out there that might be worth getting for longevity. I don't know anyone who runs it though so YMMV.
• NEW head bolts
• NEW flywheel bolts
• NEW crankshaft bolt
• Full engine gasket kit
• Likely new gaskets for the direct injectors
• New clutch/pressure plate/TOB/flywheel (might as well with engine apart)
• New water pump
• Clean out the oil pump (it's in the timing cover)
• New spark plugs (might as well if at 66k)
• New timing kit (chains, guides, tensioners)
• If you go IAG, you'll need about 18 quarts of break-in oil for their break-in interval, then you're expected motul
• Probably new bigger injectors

As far as tools/other stuff goes, you'll need:

• Nice digital torque wrench
• Engine stand
• Engine hoist
• Get some 12 point sockets for the head bolts (12mm I think, might be 14mm)
• Everything is pretty much 10mm/12mm/14mmm except the crankshaft bolt which is 22mm (pretty sure)
• Permatex Right Stuff Grey. You can buy threebond from the dealership too but I think that's more expensive. I think the can is 7oz of the permabead type, which is plenty
• Blue loctite
• Assembly lube
• Loads of brake clean, shop towels and plastic scraping tools. Really anything that'll get the existing gasket off without damaging the mating surface.

I'm sure I'm missing something but that's just from memory. The longest part is cleaning the gasket off of everything. Getting gasket off the screws can be a pain, but I found a soak in vinegar + a brass one of those brass brushes you can attach to a drill did the trick.


From there I'd say get a decently reliable NA build then go FI from there once you learn more about those. Probably the 10.5:1 if you want big power an are going FI.


I'm sure most of this you already knew, but I know seeing a post like this would've been helpful for me before I got into replacing my short block.

How much of the work are you planning on doing yourself? From everything I've experienced, rebuilding an FA20 for power and reliability is not for novice mechanics.

How much you paid? I want oil capability, maybe FI in the future

3,200.

I was under the impression that the gear set is still weak, even with the fixes done by Jack's and 4th gear will still eventually lose its teeth if you're tracking heavily.

Maybe I've been misinformed. The guy I bought my Jack's transmission from had two of them and I know they both went back to be refreshed due to broken things. He ran the car competitively in ST4 with small pulley Harrop torque with the top chopped off for power to weight reasons.

You are probably right.

Wow, thank you! This is extremely helpful! My plans have been pushed since I got distracted and dumped 1k into my suspension (another 2k coming for the wheels hopefully by the end of the year lol). I'm guessing somewhere by end of next year I'll have a built engine. I should have specified more, I've never upgraded an engine like this before but I have completely rebuilt 3 engine's given they weren't boxers) by "I've never built an engine", I meant upgrade.

Most of the work myself apart from any machining. I have rebuilt 3 engine's from the ground up previously. I used the wrong wording and what I meant was I've never modded/upgraded an engine before.

As someone that is a novice mechanic that did most of the work myself it can be done. BUT whats in bold is key...my built engine is sitting garage right now. Ive pulled that thing wayy too many times to count. Anyways, make sure your ready for lots of waiting and down time.

Are you still just working with the stock block?


Where are you seeing weakness/problems? Asking as the guy who just replaced my small block. I'm just wrapping up my break-in period.