STi #4 ringlands blown! Time to build it!
I'm now officially another person on the list to have blown the ringlands on my STi. SOA won't cover anything because the car had a DP on it. I get that I SHOULD HAVE reverted it to stock, but the nearby dealership is pretty lenient on mods, and I didn't think it was going to be something major.
The car was having erratic boost and a misfire between 2500-3000 rpm. I thought it was spark (ignition) related, and that a warranty repair wouldn't be that big of a deal. It was intermittent and I figured something mechanical would be consistent. I could clear the ECU learning and it would run smoothly for the first few miles, only to go back to running weirdly. I replaced the A/F Sensor, and got no result out of it. I pulled the spark plugs, as the dealer didn't compression test it while they had it for the first 3 trips, nor the 2 weeks they had it when they were "working on it." They kept reverting back to assume that the ECM was bad because of the AP. I kept on the assumption that the ECM wasn't bad and continued the diagnosis beyond what Subaru figured I had screwed up. Now on to the good part.
I know that the stock motor isn't very well designed for even stock boost levels, let alone 18-19 PSI for stage 2. I've been trying to read up on pistons and I'm looking into Wiseco, CP, and Crawford forged pistons. I know from BoostAddict's experience not to go with Mahle's. The other thing I've been reading is that many built motors don't last as long as stock??? Here's my objective and I'm asking for advice from the people who really know.
I use this car as a regular DD, but I might want to increase the power to somewhere north of the 350 whp range once the car is paid off. I will resist the desire to push the motor to higher power than stage 2 if that means I get something that will last me 100K or more. I'm looking for power but with am emphasis on reliability. I would appreciate quieter forged pistons, and I read that the CPs are quieter, but I haven't heard the difference anyway.
My last option is to repair the car to completely stock, only working on the side that's bad, replacing the piston and rings, and trading it in for a new one that's not modified at all so the warranty won't be denied. I'll also be looking at an EVO X if I explore trading in the car. The car made no additional sounds with the ringlands blown, and we're not expecting to see any scarring in the cylinder, but can't know until it's torn down.
I'm weighing my options to build the motor to handle 20-ish PSI if I can keep it reliable, or I guess I'll be going completely back to stock with this vehicle or moving on to another car.
The bore will remain 99.5mm, 1.208 height, with the stock compression ratio as well. Which pistons would be best for my intentions with the motor? Wiseco, CP, or Crawford? Also, I've found a built block by Outfront Motorsports that's preassembled for 1800 EDIT: 2600 shipped. The 1800 is for a stock short block.shipped for the short block. That one doesn't say what brand of pistons are in it though. What would you guys do?
It sucks to have a car with 19K on it and have a toasted motor, huh?