Hawkeye STi 2.5 - Forged rebuild
I purchasd my Hawkeye in May 2011 with just 18k miles. Soon afterwards I had a Miltek 3" and sportscat added along with a remap. For the last 6 months it has been using oil and recently it has gotten much worse with oil getting in to the coolant too. As my daily drive this was obviously not good. After chastising myself for not getting a JDM I set about deciding who was going to do the rebuild.
Saw Lee's thread ...
https://www.scoobynet.com/projects-4...ini-build.html
... Last weekend I set off from Buckinghamshire down to Plymouth to drop the car off with Alan.
I'm not after a huge build. My goal was something around 400bhp that would be a reliable daily driver and wouldn't keep burning oil. Might go higher in the future so didn't want to have to take the engine apart again. Spec will be
- Mahle forged pistons
- H beam rods
- ACL Race bearings
- ARP head studs
- RCM uprated oil pump
- Cosworth head gaskets
- Remap
I'm keeping the same top mount and turbo - so I see this as being a benchmark build to remove the weak points of the 2.5 engine.
Pictures after Week 1


Chocolate piston failure


Saw Lee's thread ...
https://www.scoobynet.com/projects-4...ini-build.html
... Last weekend I set off from Buckinghamshire down to Plymouth to drop the car off with Alan.
I'm not after a huge build. My goal was something around 400bhp that would be a reliable daily driver and wouldn't keep burning oil. Might go higher in the future so didn't want to have to take the engine apart again. Spec will be
- Mahle forged pistons
- H beam rods
- ACL Race bearings
- ARP head studs
- RCM uprated oil pump
- Cosworth head gaskets
- Remap
I'm keeping the same top mount and turbo - so I see this as being a benchmark build to remove the weak points of the 2.5 engine.
Pictures after Week 1


Chocolate piston failure


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Yep, sorry. Been a bit busy this past week. Results below after the remap last weekend. Was hoping for more bhp but the standard turbo runs out of puff. SC46, silicon inlet hose, ported headers would be next. Note: This is running with a Miltek 3" exhaust and sports cat that was already fitted. Still, I'm very impressed. Engine feels great when warmed up and you can certaily feel the torque. Main thing is that it should now be reliable with all the weak ponts removed and just bolt ons to get over 400bhp.
Last edited by Flight; Jan 10, 2015 at 05:21 PM.
On a top mount with an uprated turbo you'll see just North of 400bhp quite comfortably.
As I maintain it is quite shocking that Subaru continued to market an engine with known problems for so long, but it is a fantastic unit when forged. This is the engine it should have been all along.
As I maintain it is quite shocking that Subaru continued to market an engine with known problems for so long, but it is a fantastic unit when forged. This is the engine it should have been all along.
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