RomRaider

(quote) After staring at this block for so long, drop in pistons are gonna work just fine. The block is semi-closed, the liners are pretty damn thick, and the weak spot is simply the pistons. I think just some forged CP pistons will do the trick with a quick hone so the new rings seat.


You really should have the rotating assembly rebalanced. It cost about two hundred bucks and your motor will thank you. Any engine builder will tell you the no two pistons weight the same so by just throwing in a set of after market pistons in you are asking for possible trouble later on down the road. Bore matching the pistons would be a plus too but not really need. Just my two cents.

Well it is almost a trade off. What I really want is to ductile iron sleeve it, Blueprint and Balance, etc, but I do not have the $$$. So basically all I want to do is get it running for now and be reliable at 400 WHP. All of the machine work and associated costs of getting it built by my local builder almost comes to the price of an Axxis Stage 2, but then I get all of that (balanced assembly), longlbock put back together for me, etc. It is going to cost about 2.5K just to do this. If I went real cheap I could get the pistons and just drop em in, but I'd prolly be pulling the motor in 6 more months or so. :/ It will prolly just have to be down until I have enough funds to do it right which will be about 5-6 months.

Got all of the pistons out (also bought a micrometer and a digital caliper).

Block and crank are fine. Clylinder bores are fine (cross hatching still visible, no scuffing).

#1 has a broken compression ringland (possibly due to the casting defect)\
#2 has a hairline crack on the oiling ringland and one on the compression ringland
#4 has 2 hairline cracks on the compression ringland
#3 has no cracks.

The top end of the rod has visible wear in it's built in ring. I guess they should be replaced.

Piston 1:





Rod 1:







All 4:



Crank and sidewalls:



So I can either drop these 2 rods back in and torque them down or split the block. I suppose I should split the

block.

obviously factory sleeves aren't going to be nearly as thick as aftermarket ones. I've seen failed sleeves before but normally they were caused during an overheat that someone just laid their foot into.

Sadly these motors aren't nearly as stout as they were once touted to be. It seems like once you get a 2.0 over 300 WHP for extended period of time(and i'm not talking DD time) they blow out ring lands but it seems like the 2.5's are dropping much harder and much faster.

Sadly you'll never find out who is at fault because let's face it, if the car was 100% stock the chance of anything going wrong was probably next to none but once you modify it and hit the right frequency and just find that weak spot it's game over.

Gabe: if it were me and i was doing rods/pistons i'd go the full monte, but if i was trying to get the car running i'd just throw a set of 99.5MM pistons in it and deal with a bit of piston slap.

Well, if I have the funds to just get it running then I will. If not then I will save and get it sleeved. The plan is to get it running then have money saved to do it right next time (buy a spare block in the meantime).

Well, I think since I still have the lift, I am going to split the block tonight. Now, I have the $$$ for the pistons or the injectors right now. Do I go ahead and get the pistons? I need more $$$ (which will be a bit) before I can re-assemble the longblock. Plans are to just do new OE bearings (main and rod) and a set of 90.5mm CP pistons with OE bearings and wristpins (still debating on the OE part of this).

Gabe

I ordered the injectors. Basically all I need now is bearings (rod and main), pistons, full gasket kit and a timing belt. The water pump I may replace, but I doubt it.

I am going to split the block this weekend.

I know how it feels.

I must not be the type of customer Subaru is looking for as they are slowly but surely eliminating me as a customer with their decisions:
1. No MT on the new Forester. Possibly no MT on the upcoming LGT/OBXT except for the pricey spec. B.
2. No real upgrade in the powertrain for the 08 WRX (same power, same 5-speed, same turbo, etc.)
3. Same s*** paint on all models.
4. Forester would be on the list of potential cars for the wife (she wants an AT), except for the obsolete 4-speed AT they are offering. RAV4 270 HP V6 on regular gas, 5-spd auto with decent gas mileage is a much better choice.
5. STi is overpriced (approaching $40k) and with the problems with the 07 STi, it is unclear if the issues were addressed in the 08 STi.
6. Eliminating the wagons (WRX wagon, LGT wagon). Hatch is better than sedan, though.

They're also pretty far behind from a technological aspect as well...

They just now got around to full valve timing on the 4's, and still haven't implemented variable lift on them... Something that other manufacturers have been using and perfecting for years. Same goes for direct injection... Not to mention the 5mt is bandaid upon bandaid on a ~20 year old design, and it still isn't up to par.

Niche market ftl.

Pardon my ignorance.

I am just wondering, surely the car's ECU defense mechanism will come into play i.e. IAM will drop and will retard timing, boost will disable (assuming still using ECU boost functions) and high detonation fuel map will be activated to prevent damage?

I am assuming that the ringland damage is caused by detonation or is it due to something else?

Thanks

Well on my car, I think it was fueling. I actually had the pistons labeled wrong after I cracked the block this weekend. It was pretty easy to split. Working on getting it all cleaned up and put back together.

#3 was actually the piston that went. I monitor IDC/IPW off of #1 of course, so #1 was the piston that was pristine. I am thinking that at more than stock power levels, the #3 injector went bad and caused a heat increase which expanded the casting bubble creating the broken ringland. Of course, #4 had a couple hairline cracks in the compression ringland and #2 had one hairline crack in the compression ringland and one in the oiling ringland. :/

Goes like this (rear passenger side blew the ringland):

3 4
1 2
Front

So, I have ordered all the fueling system upgrades save for fuel rails (I wish I had the $$ to get those, but I am going to eventually). Left to order is just the gasket kit and pistons. Everything mics out in spec, even the crappy small rod bushings.

So I started to clean the block and used a solvent with Muratic acid (been awhile since I did a full aluminum rebuild, forgot about the brake cleaner after the dip), so I have to pick up some carb cleaner to get rid of the dark grey film on the side of the block that I already dipped. OOPS. The metal parts cleaned up really well. I am still debating on whether to pull the valves, replace the seals and re-lap them. I prolly will just clean the heads with brake cleaner and dip the other block half, then clean with brake cleaner. I want to make sure to get all of the oil and coolant mix out of the block before re-assembly. Neway, here are some pics:








Gabe

Oh I see.

I have seen problematic ringland cracks in #2 and #4. I was wondering whether this is due to PCC that was being discussed, high boost or just inferior pistons in 2.5 motors. Rarely see this in 2.0 motors.

I think it is just the pistons. The v8 and above 2.0L STI motors have cast pistons and make more stock power.

I got an 08 STI intercooler + bracket now. Traded it for my 07 IC + tune (oh I also got steak dinner). That thing is huge compared to the older STI IC.