Subaru WRX Forum banner

2004 STI Ground up build to 550whp - what stock parts will hold up?

3620 Views 5 Replies 4 Participants Last post by  WRX-maniac
What up community?

To start I am looking to build a 2004 Sti with over 550whp (Would prefer 600whp). I know it will take time and money but I am thinking this will be a 2 year project and would rather spend the money on robust parts than sacrifice durability.

Engine - What are the component brands to avoid? Lessons learned? Anyone have a line on a blueprinted short block that will hold up to 150 bar firing pressure? Strong turbos that come with compressor maps and temperature limits?

Transmission - I really don't know much. Hoping I could rely on you guys for recommendation of gearing and a strong system that will hold up to track days (Circle and straight)

Drivetrain - Any stock parts that hold up to 600 whp? Do I need to upgrade everything?

Brakes - planning to keep the sti brakes unless you guys think differently?

Hoping for technical answers but always appreciate input.

Engine engineer for an OEM that isn't Subaru :(
1 - 6 of 6 Posts
There's tons of info out there pertaining to this, you just have to look around. No one is going to be able to give you a magic parts list or magic numbers. I'm sure you already realize it, but 600WHP is going to be nearly useless for anything but a drag strip as well. It just depends on what you're looking to get out of the car. For it to be somewhat reliable? Plan on dumping at least another 20K into the car with those numbers.

Closed deck shortblock on E85
Pistons, Rods, etc.
New Fuel System big lines, injectors, and with double (or triple) pump setup
Oil Baffle and Pickup tube
Air Oil Seperator
Rotated turbo setup
Big Turbo (GTX35R, Precision 6266, Blouch 4.5XTR, etc)

Trans will hold. Clutch will not.

Driveshaft and axles will need replaced at the least.
See less See more
Somewhat reliable sounds about right. I am planning on setting up multiple calibrations for daily driving and several for different fuels when I go to the track. I might be in left field here but Im planning to set up for methane injection and running 93 RON when Im not at the track.

Differently hear you on the lower end components. All forged with over kill on the cooling system. Engine oil cooler ... probably go dry sump just because of my circle track days. Will probably do some weight distribution, suspension and chassis reinforcement so I can make some tight corners.

Thanks for the turbo setup comment and the turbo suggestions. I will def look into them
No problem. The STi already has an oil cooler (at least my '15 does.. i'm unsure about other years).. and just a heads up, a lot of tuners refuse to tune on methanol anymore since E85 has come into the picture and is more reliable.

You can definitely have a very fun very fast car for track days, but just be forewarned that the engines are wildly expensive to build (even when you do it yourself), and reliability for daily driving with a race engine will not be ideal. Some people have daily driven a $12,000 build for 5K miles and had the engine go, and some people have driven stock block cars with 400whp for 70K without a hitch.

Some of it is luck of the draw. Keep us updated, and good luck!
The only real bit of advice I can give you is you will need plenty of fuel, and a true closed deck block. I've seen people talking about pinning but that creates uneven expansion and can cause issues.

Outside of that you'll probably want to check out mainframes build, I think he is in that area. Keep in mind there are a lot of little things like headstuds that are going to be important.

Sent from my Nexus 6 using Tapatalk
The brakes will be ok, but you will need to replace some of the components. I would get nice rotors and pads, stainless lines, and I prefer motul brake fluid.
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.