Posts Tagged ‘ GC8 STI ’

Project STI – Greddy Boost Controller Install

With the new engine up and running I had a bit of a scare one night as the turbo over-boosted. Afraid of hurting my new engine, I decided that the old bleeder valve had to go.

For those of you unfamiliar with bleed type, or manual, boost controllers, they are good for a small boost increase but are prone to over boosting when turning up the wick a fair bit from standard and in cold weather.

After consulting a few people in the know I decided on the Greddy Profec B electronic boost controller, and here’s how to install one in true Shift Up style:

1) Take all the parts out of the box. Place them in a neat fashion on the garage floor and take a photo.

 
 
 
 
 
 

2) Check that Rally Pig approves.

3) Remove dash, lose one screw in the process.

 
4) Find a spot to mount the control unit. It’s impossible to read the display if you can’t see it straight on so I opted for the space under the head unit using the supplied double sided tape.
 
5) Now find a power source. Being a car nerd who’s had too many Imprezas and knows exactly which wire you can get power from makes this step easy. Failing that, I’m sure a wiring diagram for your vehicle type will help; see interwebs.
 
6) Once a power source has been found, connect the red wire to it and the black wire goes to a good earth – make sure you solder the wires and use shrink wrap stuff or I’ll be very upset with you.
 
7) I drilled a hole in the back of the dash piece where the unit will sit so I can get the power wires and the vacuum hose through to the back – smart huh.

8) Run the wires and vacuum line through the rubber grommet in the fire wall and into the engine bay. On a GC8 WRX this is located above the clutch pedal and comes through just under the clutch master cylinder.

9) Mount the boost control solenoid in the engine bay. I chose to bolt it to an existing bracket which holds the factory boost controller.
 
10) Plug in the wiring harness from the in-cabin controller and connect all the vacuum hoses. Keep them as short as possible. Check the manual for specifics as what goes where varies a bit from car to car.
11) Once you’ve double-checked that everything is where it should be, you’ve earned yourself a five minute break.

Smoke if you got ’em…or down a Red Bull.
 
12) Time to turn the key and set it up. The supplied instructions are good enough to get you through the setup process. A couple of hints I’ve picked up though are: try and test in all gears – luckily we have a ‘private’ road handy for just such occasions; when accelerating keep a sharp eye on your boost gauge (or get a friend to help) and accelerate gradually, if you just floor it you might not have enough time to back off if you get too much boost and possible detonation; adjust “set gain” to 4psi below the desired boost; adjust “gain” to ensure boost is holding all the way through the revs; adjust “set” by 2 per cent increments until desired boost is reached.
13) Give yourself a pat on the back and enjoy consistent boost levels! And try and find that lost dash screw.

Keep it rubber side down,

Benji

2012
09/13
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Project STI – Pear Shaped

So it’s been a little while since I did the brakes and wheels and I absolutely love it.

The car has been transformed into a proper all round package. The grip and brakes match the power and it’s just a joy to point at a twisty road. But it’s a modified car. And there’s no “happily ever after” in these stories.

One afternoon I was casually driving down the freeway when all of a sudden the engine started to sound like it was full of ball bearings. I didn’t need to pull over and pop the bonnet as I already knew what had happened – it was definitely the all-too-familiar clunking of a bottom end bearing failure. Just to add to the drama, I tried to restart the car after pulling over but the battery was completely dead. Not even a jump helped, so I had to enlist the help of Dave and the ever reliable Polo GTI to fetch us a battery.

We got Koop started and then nursed him home trying to keep the revs low, now I know I probably should have gotten a tow then and there but I figured it’s already broken.

A week later Koopa was towed down to Subaru for the damage to be assessed. It didn’t take long for them to confirm what I had suspected; the bottom end was scrap. Luckily both heads and the entire top end were undamaged. Faced with a few options for a new motor I needed to do some homework.

The now broken motor was a re-built ’99 STI 2-litre which was stock save for forged Wiseco pistons which were 40 thou overbore. This engine always had very loud piston slap and used a lot of oil so I’d like my new motor to behave more like a factory item this time. Seeing as the stock STI motors already have forged pistons from the factory I didn’t see the need for an aftermarket re-build this time considering I’m not after big horses.

The 2.5-litre EJ25 has become a very popular engine swap for the older 2 litre models. However I have driven a 2008 STI sporting said motor and it’s very linear all the way through the revs compared to the 2 litre. I found it to be very underwhelming as it never delivers that turbo punch that I want from an Impreza. And even in STI form it doesn’t have forged pistons and only revs to a lowly 6500rpm redline. There’s nothing actually wrong with it but it doesn’t feel like a Japanese performance car motor should, I want high revs and aggressive power delivery.

So a new 2-litre it is! The only slight problem is that Subaru Australia doesn’t have any replacement 1999 STI motors anymore. Luckily though they do have Version 7 (2001-2004) STI short motors in stock which are identical to the original 1999 motor except for the deck being semi-closed instead of open; making it stronger and lighter.

A surprisingly quick two weeks later and Koop was back with a brand new motor. After some gentle running in it was off to the dyno for a tune. The end result is 180kW at all four on 20si. On paper that number seems a bit low but as a comparison, its previous tune saw 201kW atw on 18psi and the car is much quicker now. It just goes to show how much you can’t compare different dynos.

Benji

2012
07/02
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Project STI – New Anchors

Front Calipers Old vs New

Fitting up the shiny new wheels has resulted in a small catch; the old brakes look terribly small! Time to fix that!

After a few weeks scouring internet forums and online auction sites I finally scored a set of 2002 STI front and rear calipers, front rotors and braided lines. Getting the rears sorted would require a few choice bits.

I needed a special rotor from DBA that suits the GC hub and the GD rotor.

Front Discs Old vs New

They have it listed as ‘Brembo Conversion Rotor,’ which is really awesome as it saves you having to change the hubs. I had to pick up some ‘dog bone’ adapters so the rear calipers would sit in the correct spot. And finally, I decided on Project Mu Spec B pads and some Dot 5.1 fluid.

Front

Rear Discs Old vs New

Changing over the front brakes really was as easy as unbolting the old calipers, changing discs and bolting on the new calipers. We flushed the old fluid out, did the brakes lines up and that’s it.

The rears were a bit trickier as the ‘dog bone’ adapters didn’t fit properly so we had to modify them a bit with a hacksaw and a heavy file. Then it was new fluid in, a lot of pedal pumping and we were done.

Rear

So just a quick summary. The standard front rotors were 292mm and the new fronts are 330mm. Not sure of the exact size of the rears but the new rears are bigger than the old fronts!

Tyres have gone from 16-inch 205/50 to 17-inch 225/45. If the car doesn’t feel good after this I’ll be very surprised!

Benji

2012
01/31
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Project STI – New Boots

With all the bits back on the car post-defect, Koop was running well. Unfortunately stopping with the standard brakes was becoming more of a problem. While fairly capable, they always left me wondering if the middle pedal was going to do anything after a few hard stops – not what you want for spirited driving.

After a bit of homework I decided the best option was to bolt up the Brembos from the 2002 WRX STI. This conversion is very common and there’s loads of help available on the net.

For this to happen I’d first need some bigger wheels as the standard 16s have no chance of clearing the bigger brakes.

I’d always wanted some BBS GTs in gold, a la STI 22b, but then I discovered the OZ Superleggera. This is the wheel Subaru used on the WRC car for tarmac events. Just to complicate my decision, I then discovered Yokohama Advan RGIIs, a very aggressive looking wheel. Ultimately though, all three options were just too expensive. The cheapest being the Advans and they came in at an eye-watering $830 per wheel…for 17s!

After wearing out Google images I eventually found the Rota GRA in gold, which are very similar to the Superleggeras.

An order was placed and two weeks later, like a kid at Christmas, I was opening my four new wheel-sized boxes. A quick trip to my local tyre shop for some semi-slick Bridgestone RE070 rubber and Koopa was looking very old school WRC indeed – Mint.

Next up; Brembos!

Benji

2012
01/11
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