scoooby slayer Posted July 7, 2012 Share Posted July 7, 2012 (edited) it seems the general consensus is use a 1mm restrictor for dbb turbos. my hks t51r spl which is basically a garrett gt4202r has been a bit whiney so to speak at idle. so i checked with garrett and the ball bearing turbos need to see around 40 psi oil pressure at the oil inlet to the turbo at max engine rpm/max torque and minimum 15 psi hot oil at idle. so i rigged up a gauge in my oil feed between the 1mm restrictor and the turbo inlet flange, i had 8 psi oil pressure warm oil flat out ! so ive drilled the restrictor out to 2.5mm and thats got me to 35 psi flat out oil at 90c. so just a word of warning really the restrictors are only to be used if the oil pressure is excessive. and a caption from garrett themselves " Ball Bearing Turbo "An oil restrictor is recommended for optimal performance with ball bearing turbochargers. Oil pressure of 40 - 45 psi at maximum engine speed is recommended to prevent damage to the turbocharger's internals. In order to achieve this pressure, a restrictor with a 0.040' orifice will normally suffice, but you should always verify the oil pressure entering the turbo after the restrictor in insure that the components are functioning properly. Recommended oil feed is -3AN or -4AN line or hose/tubing with a similar ID. As always, use an oil filter that meets or exceeds the OEM specifications. " "OIL LEAKAGE SHOULD NOT OCCUR ON A PROPERLY FUNCTIONING SYSTEM IF RESTRICTOR IS NOT USED UNLESS THE SYSTEM PRESSURE IS EXCESSIVELY HIGH. " " the slight whineing noise i had at idle is now completely gone so i can only put it down to a bearing whine due to not enough cushion of oil. so basically they are saying around 40 psi is recommended to prevent turbo damage. Edited July 7, 2012 by scoooby slayer (see edit history) Quote Link to comment Share on other sites More sharing options...
FOSTA Posted July 7, 2012 Share Posted July 7, 2012 Good word of warning mate, this should save some people ££££££ on replacing there expencive turbos Quote Link to comment Share on other sites More sharing options...
Jos Posted July 7, 2012 Share Posted July 7, 2012 Good research, thanks for the info:OK: Quote Link to comment Share on other sites More sharing options...
scoooby slayer Posted July 7, 2012 Author Share Posted July 7, 2012 Good word of warning mate, this should save some people ££££££ on replacing there expencive turbos well its potentially saved me £3000 for a hks t51r spl Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2012 Share Posted July 7, 2012 I used to post this link regularly, but unless it comes from a flash web site people seem to think a basic turbo is old hat, and pooh pooh Garrett stuff. http://www.turbobygarrett.com/turbobygarrett/faq Quote Link to comment Share on other sites More sharing options...
scoooby slayer Posted July 7, 2012 Author Share Posted July 7, 2012 I used to post this link regularly, but unless it comes from a flash web site people seem to think a basic turbo is old hat, and pooh pooh Garrett stuff. http://www.turbobygarrett.com/turbobygarrett/faq whats pooh pooh about garrett then ? Quote Link to comment Share on other sites More sharing options...
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