Brand new Garrett T28bb expired, less than 10,000km.. why?!

[Bazda]

what size line did u run for the oil feed?
I was told its meant to be very small, alot smaller that a bush bearing turbo.

[matt dunn]

[
Yeah its weird, it never went passed half way on the temp gauge but some how melted part of the wiring cover

Standard 4agze internals.

I was getting flames out of the exhaust down the straight so its definitely got enough fuel for this amount of boost.

The temperature in the combustion chamber and the Engibe temp can be totally related as the internal chamber temp can be sky high,
but the cooling system can cope and the gauge will read normal.

Lean mixture will cause excessive heat and can damage internals as well as the turbo. We had have a few garret BB ones melt the exh wheel due to bad tuning.

And flames out the EXH is not a sign of good mixture and ignition.
The burning should be in the engine not in the exhaust.

Matt

[Crucible]

It sounds like a lean out prob to me, for and engine to drop two cylinders and a turbo to die also, did you get a mixture readout with the tune?

[IH8TEC]

yeah sounds pretty much liek what i did. even though i was running more boost.

[matt dunn]

You do realise that on the dyno you do not get any fuel surge?

Does the car have a surge tank?, and does it work?

You can have it fully tuned to the exact right mixture,
but remove the fuel pressure and you run lean.

We had a puel pickup problem on one or our cars and it completely destroyed the engine internally and rooted the BB turbo.

Going back through the logged data on the motec you could see the pressure drop when the G force goes in one direction.

It was a huge mission to trace the fault in the system and caused a fair bit of damage.

[Crucible]

You can have it fully tuned to the exact right mixture,
but remove the fuel pressure and you run lean.

Good point. Have you guys seen these wideband gauges? I think I may invest in one. Gives you an actual digital readout of the air fuel ratio.

http://www.bmotorsports.com/products/wi ... TAodDnCM4g

Anyone know who stocks them locally? and if so price?

[tex]

Too many unknowns to correctly diagnose, but a note in regards to BB turbos.

Check that the oil feed is correct for the BB setup. Too fast flow and the bearing get starved...

Seen the problem before when changing from a floating to bb turbo, using standard floating bearing oil lines.

BB turbo can be rebuilt, but basically it is a complete core change. Which = $$$$ .Never quiet worked out why they cannot just design them where you
can just replace the races.

TEX

[Skin]

Gavin, who did your tuning?

[Ako]

I can do a wideband unit for $750 incl GST, 45 minutes worth of logging etc. Can also be set up to do individual cylinder tuning - rather interesting. Seen some interesting results from some manifolds - mainly one or two cylinders going lean, the other 2 or 3 going rich - but the wideband up the tailpipe would say 12:1 for example. Little did the tuner know that one cylinder was trying its damndest to kill itself off.

[~SlideWays~]

Update:

Have head off and pistons look perfect, headgasket has not blown either. Must be the rings on 3 and 4 which has caused the lower compression.

Mark: It was speedtech, I have confidence that it is not their tuning.

Tex: I am using a braided hose which I originally used with a normal t25 before putting the T28bb on. It looks like there is a restricter on the oil feed hole of the turbo. Is that not correct? Could you give an estimate for replacing the core? ie if both wheels are fine.

Matt Dunn: No surge tank, wasn't revving it much on the corners for fear of oil starvation which seems to be a problem with big ports. Good point though but I wouldn't have thought two 10min runs would have caused this much wear to the turbo?

QikStarlie: The exhaust wheel can just touch the housing but doesn't look damaged. I wouldn't try run it again. I am thinking about getting it fixed but from the sounds of the cost I might as well buy a new one?!


Must figure this bastard out, don't want this to happen again.


Thanks for all of the suggestions so far, you guys are legends.

[Mr Revhead]

you said you had flames out the exhaust on the straights.... how so?
when you lift off? under full throttle?

[Ako]

Restrictor on the inlet side of the oil feed is meant to be there, 0.6mm or something ridiculous from memory.

Centre cartridges aren't cheap - to be honest, they aren't far off the cost of a new unit altogether. I can get them rebuilt - BB stuff isn't non rebuilable, just takes specialist gear to do so.

Does sound like a bit of a freak occurence, but hate to say it but sh!t does happen! I've seen a brand new garret unit die quite quickly from a blocked oil feed, also seen them go from not having the restrictor in place - when its not there, too much oil = seals give up on life.

Wear from starvation - you'd be amazed just how quickly you can kill some things off.

Almost needs to be sent back to whoever you got it from, who will then (or should) flick it back to garrett, who can do their diagnosis on it. They tend to have a fairly good idea of whats done the damage. These turbos shouldn't die too quick from overspinning, but least they'll tell you if it was the cause or not.

[~SlideWays~]

Revhead: Not sure due to being in the car but Im sure I heared a pop or two when decelerating and changing down. Could also be when changing up at full throttle. Will have to ask someone who was behind me.

Ako: so that restricter SHOULD in thoery mean that my problem is not hte oil feed so I can take that out of the equation? (remember I said that it flowed lots of oil on idle).

Could you possibly pm me a rough price to rebuild the core?

The turbo was new but not bought from a dealer, so can't return it. It was obvious that it was new due to the perfect condition in and out plus even a strip of white paint across one of the compressor fins. It had little to no play at all when I got it less than a year ago. Now it has enough for it to touch the housings

Did anyone note my comment about the external? How the head (top) can be turned 360 degrees and Im sure it never did that before... Could this have caused a leak and the turbo to overspin?

[Skin]

Hmmm jeremy had his car tuned there too, and his turbo has done the same thing on the same day.....coincidence? More than likely. but ya never know

[sergei]

or maybe you got one of those chinese replicas?

[Crucible]

Matt Dunn: No surge tank, wasn't revving it much on the corners for fear of oil starvation which seems to be a problem with big ports. Good point though but I wouldn't have thought two 10min runs would have caused this much wear to the turbo?

Think matt was refering to a Fuel surge tank... as in fuel supply starvation lean out

[flygt4]

few comp wheel pics. the results of my outing. pics just dont do it justice , i havent got it off the car yet so they are average quality but you get the idea.pretty obvious where it has had a sexual experience with the housing. there a grind mark at bottom left where gravity has worked its magic. in person you can see the edge of all the fins is bent/folded back over

im fairly confident mine is a result of a boost leak , from trying to tune it at 20psi. it seems fairly obvious now i look at the dyno chart when the turbo kept tapering off once it reached 20psi. ah well ive and learn.

[IH8TEC]

thats small

[flygt4]

thats small

slapper , its not about size , its how u use it

[~SlideWays~]

Matt Dunn: No surge tank, wasn't revving it much on the corners for fear of oil starvation which seems to be a problem with big ports. Good point though but I wouldn't have thought two 10min runs would have caused this much wear to the turbo?

Think matt was refering to a Fuel surge tank... as in fuel supply starvation lean out

Yep but I was meaning the fact that I was being careful with corner speed would have made it pretty unlikely that fuel surge would occur.