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+--- Thread: Master Power R444-2 on OM617a failure (/showthread.php?tid=4398)
Master Power R444-2 on OM617a failure - kmaser - 03-06-2013
It's been a long time since I have really posted on this board, I have been working overseas. I have been driving my OM617a G-wagen with MPR R444-2 turbo, A\W intercooler and MW pump with Tomnik's 6.5mm elements and had the turbo fail today after 4-5000km's since the turbo was installed. It has a huge amount of radial play and has rubbed the housing, I am looking for advice on whether this is likely caused by overboost (25-29Psi at 4000+rpm) from what I can gather from the turbo map http://www.hevosvoima.com/shop/index.php?main_page=product_info&cPath=1061_139&products_id=7250
I should be within the limits of the turbo at this boost pressure although I am not well versed in reading turbo maps?
The other thing I thought of was excessive oil pressure supply to the turbo as I was not sure of whether I would need a restrictor in the supply line but I thought that since the stock turbo used the same line from the same location and the new turbo also had what looked like to built in restrictor in the housing that it was good and from searching on here nobody installed a restrictor unless going to a ball bearing turbo? I would greatly appreciate some insight as I need to get a new turbo and want to avoid a repeat!
RE: Master Power R444-2 on OM617a failure - aaa - 03-07-2013
At 4000rpm/29psi you have a guesstimated .16kg/s and a pressure ratio of 3, which is well within the map. Now if it 3000rpm/29psi you'd be pretty close to the surge line at .12kg/s.
RE: Master Power R444-2 on OM617a failure - kmaser - 03-07-2013
So if I'm at the surge line at 29psi/3000rpm and lower is the solution lowering the boost everywhere or is turbo sizing wrong ( too big or too small ) I want the most boost possible at lower rpm but also need to run 3500-4000rpm in the highway?
RE: Master Power R444-2 on OM617a failure - Simpler=Better - 03-07-2013
I'm no turbo expert, but a larger wastegate might help you out
RE: Master Power R444-2 on OM617a failure - kmaser - 03-07-2013
It's internally wastegated so I guess on the next turbo using an external waste gate is an option of needed?
It's nicer space wise with the internal but I can do what is necessary.
Would the external waste gate just give less back pressure ?
RE: Master Power R444-2 on OM617a failure - Simpler=Better - 03-07-2013
If your issue is overspinning the turbo at high rpms, a wastegate could help. I'm nto the turbo expert though-I just slap shit together and hope for the best.
RE: Master Power R444-2 on OM617a failure - kmaser - 03-07-2013
Well I have been checking everything over and it looks
Like the stock turbo line flange has a 2mm orifice and the banjo fitting I used does not so its possible the failure was due to overpressuring the oil supply?
RE: Master Power R444-2 on OM617a failure - willbhere4u - 03-07-2013
It's fairly normal on Subaru's to port the internal waste gate in the exhaust housing to make the casting smoother so it will flow better