New bottom end and head w/50 miles or so on it - wrecked by yet another blown turbo...shaft sheared, bearing retainer ring parts made their way back into the head.

Ok, alright, enough already - no events this year because I'm buying a Garrett 2871r - no more 15-20yr old turbo's from used cars. Lesson learned

Head and pistons tried to chew the bits and spit them out - but no love there. All cylinder bores are ok though. All pistons got hit to some degree - worst ones are in pics below.

My question to the Anarchy: Can I try to smooth out the damage on the piston faces and re-use the pistons (no sugar coating here, see lesson learned - its another $750 for a new set w/rings)...but I wont find another new bottom end for the same $$, + the head, + the shrapnel into the turbo, etc...

Damn dude. That sucks. That is the exact thing that I fear happening with the engine I'm building and why I'll probably buy a new turbo instead of using the 20 year old ones I have.

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vbares
New bottom end and head w/50 miles or so on it - wrecked by yet another blown turbo...shaft sheared, bearing retainer ring parts made their way back into the head.

Ok, alright, enough already - no events this year because I'm buying a Garrett 2871r - no more 15-20yr old turbo's from used cars. Lesson learned

May I suggest you consider a BorgWarner EFR-6225

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vbares
My question to the Anarchy: Can I try to smooth out the damage on the piston faces and re-use the pistons (no sugar coating here, see lesson learned

I would run them again. Smooth out the damaged parts with a scotch-brite. Just check the piston ring gap anywhere there is an edge hit to make sure it's not distorted.

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Tim Taylor

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vbares
New bottom end and head w/50 miles or so on it - wrecked by yet another blown turbo...shaft sheared, bearing retainer ring parts made their way back into the head.

Ok, alright, enough already - no events this year because I'm buying a Garrett 2871r - no more 15-20yr old turbo's from used cars. Lesson learned

May I suggest you consider a BorgWarner EFR-6225

Quote
vbares
My question to the Anarchy: Can I try to smooth out the damage on the piston faces and re-use the pistons (no sugar coating here, see lesson learned

I would run them again. Smooth out the damaged parts with a scotch-brite. Just check the piston ring gap anywhere there is an edge hit to make sure it's not distorted.

Mr Injur-near Tim means ring side clearance or simple to not corn-fuse the whole issue: check the gap still allows the rings to float in the top groove.
Buff em and stuff 'em back in.

---

John Vanlandingham
Sleezattle, WA, USA

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Already have the Garrett on order - but, why the Borg Warner 6225 - I imagine the numbers have something to do w/the turbine or compressor wheel sizes?

No concern w/the "v" shaped gauges right at the edge?

(I've taken the pistons out to make sure there isn't any debri on the landing area of the rings - will clean them before re-installing)

I've seen, heard different suggestions on how to smooth these out - can i use a cookie or is that too aggressive? Scotch bright seems too tame?

Doh, John's right I meant side clearance to make sure the rings don't stick. On the EFR it's just a better engineered turbo. http://www.motoiq.com/magazine_articles/articletype/articleview/articleid/1750/borgwarner-efr-turbo-feature-set.aspx
The new Garret GTX series compressor wheels haven't made it down to 2871 sized yet.

Machinist stone, or really fine file. How did the parts make it through the intercooler?

Went through from the other side.

We were street tuning the car, felt the turbo go, motor was running fine - no more than 100yds from the driveway - so turned around and when I put the clutch in to turn into my buddy's street - that's when the motor started sounding funny...

Theory is that under low RPM's, w/the hotside still spinning rapidly, the bearing retainer broke and had enough momentum from the turbine to make it back into the head. You can actually see the hits in the exhaust manifold, and the exhaust ports of the head...

I was also under the mistaken assumption that the IC is a great filter - which it is - but only if the cold sides spits junk - not the hotside...

Gotta ask,

are you properly priming the turbos?

We did the same thing on my Evo last summer after a snapped timing belt. We bolted the built bottom end to a stock head and buffed out the marks the valves made on the pistons. That engine lasted ~8 miles and we had to replace it due to low oil pressure issues.

I've heard good and bad about the EFR stuff. Lots of trick new features which are good if you're designing a turbo system from scratch, but probably duplication if you've already got a turbo on the car. Also, from what I've seen/read with these turbos on Evos, they're not some crazy leap forward "every other turbo is obsolete now" kinda deal. They're also made of unobtanium so good luck actually ordering one and having it show up within 6 months.

Dave

I know on turbine blades we use machinist stones as well. Smoooooooooth is good. Take the time to round out the bottom of the gouges, its worth it. More lost metal isnt as bad as a hotspot.

Again, this is on turbine blades... No idea how it will work on a piston.

Chris - not sure what you mean by "Priming the turbo" ?

well...

if the turbo has been sitting on a shelf for a while, you should pour some fresh oil through it before installing it.

Then once installed, with the oil lines hooked up, you need to crank the engine without starting it for like 30-60 seconds. Although i suspect you probably did this with a new motor.

If you fire the motor up with the turbo "dry", the bearings are gonna get damaged really quick. Turbo spins really fast even at idle, and those little bearings will get damaged.

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vbares
Scotch bright seems too tame?

Scotch-Brite deburring wheel like this:

I would suggest a medium hardness and you're just trying to remove all the sharp points. This is how all of the Cosworth pistons get prepped before the go into an engine.