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2005 STI Build HELP!

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Hello all! I have recently purchased a 2005 STI with no motor :) I figured this would be a perfect clean slate for me to work with and build this car how I want it. So far the parts I have collected to start the build are as follows…

EJ257 built block, Manley forged pistons and connecting rods

Manley steel intake and exhaust valves

Brian Crower valve springs

GSC valve guides and retainers

ARP 2000 11mm head studs

FP Red turbo

PLM up-pipe w/ Tial 38mm Ext wastegate

ETS Front mount intercooler

RCM ceramic coated equal length headers

ID 1050x injectors

Walbro 450 LPH fuel pump and rewire kit

These are the parts I have gathered so far. My goal is between 500-550 WHP. I understand I will probably have to get bigger injectors at some point to reach my power goal. I am tuning the car myself on a plug and play link ecu because of the added tuning parameters and I really like the Link G5 software. However, I’d really appreciate ANY help/advice you guys could give me to help me along with this build. I am getting the heads ported on this motor at the machine shop soon, so I wanted to know whether you guys think the AMS intake manifold is a worthwhile upgrade. It is expensive, and if I do decide to go with this manifold I’d like to have it before i send the heads to the machine shop so they can match the porting to the manifold. Thanks guys!!!

Looks like you're being smart and not taking short cuts.

A couple of points - NOTE, NOT a "Subbie" guy - what does a "built block" mean, different people have different ideas on that. No criticism of your "machine shop", but a lot of power can be gained, AND LOST, when "porting" heads - just make sure they have the experience and history to back up their working on THESE engines!

Depending on what you're using it for, I understand oil starvation can be a problem, especially in sustained cornering when oil can't return from the outer head - might be worth checking on? Don't forget the clutch - there will be a big increase in torque. I understand some transmissions can be a weakness with these vehicles - might be a good idea to double check what you have, and it's torque/power limits. Again, depending on what it's used for, you're going to be putting a lot more heat into the coolant and oil - you may need to address those, especially if doing circuit or "fast" road driving.


At 500 wheel HP on race gas like c16, those injectors are sufficient, but for E85 for example, you'd want ID1300.

You'll need an uprated MAP sensor, IAT sensor in the FMIC pipe, speed density conversion for tuning. Link PnP is a good choice. Get their CAN wideband as well.

Beyond that I always use the combo oil temp/pressure sensor, and a good fuel pressure sensor for safety measures and active fuel pressure compensation within the fuel model, but that's up to you.

Aftermarket cams, head porting, intake manifold aren't needed for 500 wheel HP.

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