Hey everyone! I'm a proud new owner of a '06 Sti, and I'm putting together a plan for upgrading (already!) it. I had a '98 Integra that was heavily-modded internally that got swiped and the insurance sounds like they're going to give me a decent payout. I'm not new to the world of imports or upgrading, having rebuilt the engine on said Integra twice, and the transmission a couple of times.

On the Honda board one of the most commonly asked questions is, "How much boost/hp can the (pistons/rods/block/intake/cams) support before I have to upgrade?" In response to this, a lot of people pooled their knowledge and experience, and put together a number of charts or lists that could be sent out to newbies that explained how much power their stock components could take before they broke or got overloaded and had to be upgraded. (Injectors at 225, clutch at 225, cams at 275, p&p the head at 300, etc)

Does anyone have a sort of comprehensive list for that, here?

 

I've driven an 04 STI that was 400 whp (550 crank hp) with stock internals. I'm not saying it is a good idea to do that, but it had 30,000 miles on it in that configuration, about 8,000 of those were track miles. Didn't leak a drop of oil, got 26MPG highway. You've got plenty of room before you start doing internal work with the boxer engine -- they just have bigger safety margins than the Honda or Nissan mills.

 

I guess there's guys going 300+ now on stock Integra engines, but after dealing with the mulitidude of d00d-t00ners that I have in the past with my former car, I don't know how anyone could trust them to do it. I had mine turbo'd and it ran great that way for about 3k miles before the shoddy machine work took over. The pistons called for .001" clearance to the wall, and the machine shop decided he'd do a "V-8" clearance instead, as he obviously knew better than the manufacturer, opting for .008".

I don't really know what my upper threshold is going to be for horsepower on the STi, so I want to take baby steps. I figure the best way to do that is by replacing the weakest links one at a time and ratcheting up the horsepower slowly. My biggest complaint with the Integra in turbo trim, was that I built the engine for 300hp and found out after doing it that was nearly unstreetable in that condition, even with the various suspension and brake upgrades.

Here's a picture of my old baby the night I put the head on and fired it up for the first time:

 

Not to belabor the point, but you're comparing a turboed N/A built motor to a factory 2.5l turbo engine. There's really no grounds for comparison. My personal advice is learn how to drive the car really, really well as it is, and then after about 36k miles start modding it for power. A stock STI with a good driver can give almost anything on the road or track a run for the money.

You can get 300 WHP with just bolt-ons and engine management, no internal work, well within the safety margins of the car and engine. But if you want a car to live as long as it would normally live stock...

...leave it stock

 

I'm just trying to find out what I can do with what I've got. The last message was more of a "hey, I'm not a jackass who wants to throw a bunch of random, expensive parts on my car, I've done this sort of thing before and know what I'm getting into" post. The only comparison I was trying to draw was one of build experiences.

Driving is fun and all, but I take joy in being a mechanic first. Leaving the car stock simply isn't acceptable.

 

No list.

Spend sometime on the boards and you can learn all this.

The bad thing is you have a 06...i have heard their plastic motor mounts break easy...also i have heard things about the rear diff being weaker for 06.

I would avoid hard launches until you have taken care of the mounts.

Then go with the normal EM/TBE..then pick up a good turbo...decide Rotated or regular mounting styles...think about FMIC/Fuel upgrades aswell...if you plan on going into the 11's figure a nice clutch.

6-7.5k would get you a total package good for 11's on race fuel..maybe even 11's on alky injection.

 

Yeah, I get it.

The problem you have is that you've got an 06 model; it has some significant changes from previous years, and a lot of the mod makers and parts makers out there will take some time to catch up. There are still a few mods and parts that don't fit the '05 models.

The important thing to know about Subaru engines in particular is that if you want to see any gains, you have to do ECU work. Any significant change to the engine, intake or exhaust requires a "reflash" of the ECU in order to maintain the car's performance and safety margins. If you want to do this yourself, look into a Delta Dash ECUtek unit first. If you want to be a mechanic but not a computer hacker, install everything else yourself and then have it towed(!) to a tuner and have it tuned.

The big brands for the STI engine and exhaust are Perrin, Helix, APS and Borla. A typical uber-upgrade path is turboback exhaust (no cats), bigger turbo, bigger injectors, fuel pump, fuel rails, high-flow (but not cold air!) intake and a FMIC. Note that you don't see cams, valves, throttle bodies, underdrive pulleys, ignition wires or many other typical N/A engine mods on that list; on the boxer engine these seem to have a very minor effect or are so rare that they are extremely expensive (especially cams!). Unless you really want to get to 160MPH and need to move the redline beyond 7k, deep internal work in the engine is rare.

My personal advice (only one person's opinion!) is to pick one of the big-name parts makers and stick with them all the way through, rather than do a patchwork job with bits and pieces from all over. Some of the big Subaru vendors (Cobb, Vishnu, Gruppe-S) rebrand or manufacture their own parts and sell them as packages.

Here's an example of a parts list for a killer STI (look at Stage 3 and Stage 4)

http://www.dyno-comp.com/subaru.php?view=subaru

Note that they went with APS as the sole parts vendor, from intake tumbler delete all the way to exhaust. I think the Stage 4 kit they describe should also have a racing clutch and a package of suspension and wheel/tire upgrades to go with it, as with that much power you're going to have serious problems with traction.