Re-Building a bulletproof '98 DOHC

JoelR · 07-24-2001, 04:49 PM

I'm in the middle of figuring out whether my engine ('98 2.5 RS with Minnam Stage I turbo) which lost oil pressure recently will be covered by my powertrain warranty or not. If it is, great, I'll let Subaru rebuild the damn thing back up to std. specs. If not, I want to rebuild it to better-then-new specs so I can avoid such troubles in the future.

1. Crank: What should I do to the bottom end to bullet-proof the crank, its bearings, oil supply to bearings (esp. cyl. 3), etc?

2. Oil Pump: Is there a high-flow oil pump that's worth using as a replacement? I've heard high-flow is better than high-pressure.

3. Pistons: I love the torque that the 9.7:1 compression + boost gives me so I'm hesitant to drop the compression much. However, stronger pistons might be a nice improvement. I've also heard the '98 DOHC has short-skirted pistons, which is bad (on an engine, not a girl).

4. Rods: Worth replacing? I've heard bad things about the way that our rod ends bolt on.

5. Block: Should it be required to swap the actual block, what about swapping to a '99+ Phase II block with the crank's thrust bearing relocated? I've heard people call a 2.5L DOHC phase II the "magic engine". I understand that my 4 bolt transmission would still mate to this engine, just with some unused lugs on the block.

Any other ideas?

Thanks!!

Joel

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TR · 07-24-2001, 04:52 PM

better than stock head gaskets would be nice too.

07-24-2001, 04:49 PM	#1
JoelR Scooby Newbie Member#: 713 Join Date: Jan 2000 Location: Redmond, WA, USA	Re-Building a bulletproof '98 DOHC I'm in the middle of figuring out whether my engine ('98 2.5 RS with Minnam Stage I turbo) which lost oil pressure recently will be covered by my powertrain warranty or not. If it is, great, I'll let Subaru rebuild the damn thing back up to std. specs. If not, I want to rebuild it to better-then-new specs so I can avoid such troubles in the future. 1. Crank: What should I do to the bottom end to bullet-proof the crank, its bearings, oil supply to bearings (esp. cyl. 3), etc? 2. Oil Pump: Is there a high-flow oil pump that's worth using as a replacement? I've heard high-flow is better than high-pressure. 3. Pistons: I love the torque that the 9.7:1 compression + boost gives me so I'm hesitant to drop the compression much. However, stronger pistons might be a nice improvement. I've also heard the '98 DOHC has short-skirted pistons, which is bad (on an engine, not a girl). 4. Rods: Worth replacing? I've heard bad things about the way that our rod ends bolt on. 5. Block: Should it be required to swap the actual block, what about swapping to a '99+ Phase II block with the crank's thrust bearing relocated? I've heard people call a 2.5L DOHC phase II the "magic engine". I understand that my 4 bolt transmission would still mate to this engine, just with some unused lugs on the block. Any other ideas? Thanks!! Joel * Registered users of the site do not see these ads.

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07-24-2001, 04:52 PM	#2
TR Scooby Newbie Member#: 28 Join Date: Jun 1999 Location: now w/100% less turbo Vehicle: 1997 M3 Sedan Blue	better than stock head gaskets would be nice too.