MARKSTI

iTrader: (4)

I know a few people have asked me to keep them posted...as to what went bad on my STI...

2 Bad con. rods...
1 WAYYYY toasted rod bearing
1 slighty crisp rod bearing
1 BAD crankshaft
ALOTA oil in the intercooler...,maybe indicating a broken ring/piston??

I did not want to spend big $$$$ getting everything sent out to the machine shop just so i would know for sure about the piston/block etc...since i have already decided on gettin a new shortblock.

Next up for my car:
New factory shortblock
Forged pistons
ARP headstuds
Coated heavyduty bearings
aftermarket clutch/flywheel
more gauges
???

pbchief2

iTrader: (3)

Sounds like my motor, alot of oil in the intercooler. I hope your happy with your future set-up. I'm on the fence on whether or not to do the sbr gt30-12 right now. You gonna stick with the green?

MARKSTI

iTrader: (4)

For me going from a green to a gt3012 would not yield much extra HP...as they are real close in power output.
I was thinkin about the gt30-13 or 14...maybe??

Imprezer

iTrader: (9)

Sounds like lubrication problem.

Oil in the intercooler with all of the above is perfectly normal. I doubt that broken piston or ring would destroy the crank, 2 conrods and a bunch of bearings. Especially since there are 2 bad conrods. You got it in there after the fact. Plus, I don't know if you are running an oil catch tank, because if you are not, oil in the intercooler is normal on Subies.

Its like if you were driving 170mph, crashed into a pole, one of your wheels flew off and eventually hit the wall and popped the tire. "Bad tire" would be a wrong guess if you are trying to determine why the crash occured. You were going 170mph. Just just an example of how you cannot draw a parallel after the fact, especially with the other failed parts inside the engine...

I am pretty sure it is oil related. Add the power you were pusing and drag racing and you have a perfect combo to destroy a motor. That is perfectly normal.

If I were you I would add an oil cooler to the list of things you are getting. Also, I would ditch the STi oilpan and strainer and get the regular EJ20 units. The twin scroll friendly oilpan used on the STi is just asking for oil problems. The oil cooler will also add about 0.6-0.7 quarts of oil to your oil system. And, I would also change the oil filer adapters so that you can use normal WRX filters and not the dinky STi ones.

Getting an aftermarket radiator and a cooler thermo wouldn't be such a bad idea either.

MARKSTI

iTrader: (4)

The theory a few people tossed around was,cracked piston ring/piston (causing the oil to move upstream into the intercooler), binding piston/ring/rod, causing the bearing to go out on the lower half of the motor.
I normally haven't heard to much about oiling problems on STIs...mostly Pistons/Rings.


The bad part was that i have was forced to drive the car 200 miles after my motor had this failure..so i'm sure that wasn't good.

The lubrication or lack off could also of been a cause....
......either way i'm glad the cars on a fast lane to gettin up and going, this time stronger and faster then before.

Thanks for the tips,....i guess my wish list just keeps on growing

Imprezer

iTrader: (9)

Hmm... With you driving 200 miles after the motor "blew up" makes it absolutely impossible to determine what caused it. You, me and anyone else can only guess. No way to say for sure. That is the only thing for sure.

Why did you drive it after the damage was done?

Which shop is doing the teardown for you if you don't mind me asking...

MARKSTI

iTrader: (4)

I was reassured that driving it home was O.K. by my tuner on the cell phone that night @ the racetrack...along with going back and forth to the shop to have the motor looked @..


The last time, i had my car flatbedded out.

As far as the shop whos tearindown the car/motor...lets just say its not in the bay area, but they are a REALLLL good place.

Imprezer

iTrader: (9)

Fair enough.

Was the car smoking when you drove it from the track? If you had failed piston and/or piston ring, your car would be smoking like a steam locomotive.

I don't think you would have been able to drive with busted conrods. If a bearing failed, you would be able to drive it, but it would be noisy. Eventually, the bearing would seize and brake the rod and damage the crankshart.

My theory is that one or both of the bearings failed. To some degree due to the lubrication problem (oil starvation, oil temp, oil pressure) and/or extreme loads on the motor. Eventually the conrods and crank failed too.

How do the pistons look like?

MARKSTI

iTrader: (4)

It was somewhat smoking., but not like a steam locomotive.

The best way to get to the bottom of this would of been to send the motor out to a machine shop so they could take a look at it, ...but i just cut my losses and went with a new short block with new pisons etc.

That extreme load and to some extent oil problems theory seems to make sense.
U live and learn, i guess.

Imprezer

iTrader: (9)

It was was not smoking that bad, your pistons and rings were fine. Even if you turbo oil seal starts seeping a bit, you car will smoke like a locomotive.

Zoeb2s

iTrader: (38)

why are you being secretive about the shop you are taking it to just out of curiousity.

UK n00b

iTrader: (3)

I have to concur here, when I drove my old 2.0 setup that ran 34psi on 91 octane with a GT30 the 1.4 miles from my house to the shop I had to have my mate follow me blocking the smoke from my car as it looked like I was driving a smoke machine (the cause of this was a cracked ring in 4th, barely cracked at that)

To be honest given the information now that you drove the car for 200 or so miles since the engines initial failure I would have been inclined to not even bother looking at the motor at all simply yanking it and replacing it, there is no information any shop, machine or otherwise that will conclude what actually grenaded the motor.

Glad to hear your car is finally getting put back on the road, sounds like a long and painful road but I guess a lesson or too learned as well...

What pistons are you using?

Mike

Krinkov

iTrader: (21)

Hey Mark! You ever think about running those cobb longer rod/shorter piston combo? mmmm.....Rod ratio

Im about this -[ ]- close to runnning those when I do my build, just looking for someone to talk me out of it

UK n00b

iTrader: (3)

Not intending to talk you out of it but based on your pump gas daily driven requirements is it necessary?

Also I have not seen anyone show any decent results with them yet, not saying that nobody has but more that it's not something that has gotten out if they have.

Mike

P.S Bump for 8.5:1 Weisco piston'd STI blocks making 350whp+ on pump gas....

Krinkov

iTrader: (21)

well technically running longer rods/better rod ratio is across-the-board beneficial regardless of what octane your running, though no I dont feel that beefier rods are needed on 91oct,

thanks alot Mike, you talked me out of it...