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+--- Thread: Oil supply restrictor (/showthread.php?tid=239)
Oil supply restrictor - ForcedInduction - 02-09-2009
Problem: OM617 oil pressure will hit 7bar (100psi) when cold and above 3000rpm when hot.
Holset VGT turbo requirements:
Quote:13. The minimum oil pressure when the engine is on load must be 210 kPa (30 lbf/in2). Normal maximum operating pressure is 500 kPa (72 lbf/in2) although 600 kPa (88 lbf/in2) is permitted during cold start up.
Under idling conditions pressure should not fall below 70 kPa (10 lbf/in2).
14. Recommended oil flows for the turbochargers are 2 litre/min at idle and 3 litre/min above maximum torque speed.
Given those requirements, what diameter oil restrictor should I use in the supply line?
RE: Oil supply restrictor - 617.952 - 02-09-2009
god is asking us what he should do?
add a 90* bend
RE: Oil supply restrictor - ForcedInduction - 02-09-2009
I really like this idea and it could work with a banjo bolt too:
http://forums.hybridz.org/showthread.php?p=765490
Quote:I used an AN to NPT fitting in the turbo itself.
I ran a tap into the opening from the "top" (AN end), I don't recall the actual size or thread at this point.
Used a bolt and cut it off at about 3/8" long, so that I ended up with essentially a grub screw (Didn't have any handy, so used what was on hand), drilled a small hole .045" or so, again, it's been a while. Cut a groove across the end, to use with a flat tip screwdriver. Added some lock tight to the threads, screwed in, and voila, removable, or replaceable restrictor.
Between 0.085 and 0.100 are what most DSM and JDM owners with Holsets seem to be running with.
RE: Oil supply restrictor - totaldisaster - 02-09-2009
Do you know what their pressure highs are?
The only missing information to find the proper restriction is the diameter of the chamber where the 7bar blow off occurs. 100 psi in a truck tire is completely different from 100 psi in a bike tire.
this isnt the greatest idea. Once you diminish the flow to your turbo it is constant throughout the entire range of oil supply pressures.
Lets you restrict by 30% at full load. That could translate to 15 - 20% at operating load (continuous)
I don't know enough about turbos to say whether that is detrimental or not.
RE: Oil supply restrictor - ForcedInduction - 02-09-2009
(02-09-2009, 11:34 AM)totaldisaster Do you know what their pressure highs are?The Mitsu's relief at 7bar. Honda's are 60-75.
Quote:The only missing information to find the proper restriction is the diameter of the chamber where the 7bar blow off occurs. 100 psi in a truck tire is completely different from 100 psi in a bike tire.Not true, PSI is exactly the same all over a hydraulic system when its static. Restrictions limit flow and cause pressure drops.
The truck and bike tires both have the exact same forces at work, whats different is the surface area that 100psi is pushing against. When you put weight on a tire, the pressure inside doesn't change.
RE: Oil supply restrictor - ForcedInduction - 02-09-2009
(02-09-2009, 11:34 AM)totaldisaster Once you diminish the flow to your turbo it is constant throughout the entire range of oil supply pressures.Not quite. At low pressures the orifice isn't a restriction. As pressure increases it restricts flow and limits pressure based on the outlet load.
Quote:I don't know enough about turbos to say whether that is detrimental or not.All our cars have a 2mm restriction in the oil feed line. Since Holset's oil flow/pressure requirements and bearing clearances are different from Garrett's, I'm trying to figure out what size orifice will be best.
Running 100psi without an orifice would just blow out the shaft seals. At this point, I'm pretty sure I'll start off with 0.100 and go from there. I really need to see what the turbo has in its inlet and fittings first though. That HE341VE should be here this week.
RE: Oil supply restrictor - totaldisaster - 02-09-2009
forgive me, my wording is terrible. Here is some math:
7kN/(1 m^2) = 5kN/(x m^2)
we want to solve for x in your case.
I got .7143 m^2; (as the cross sectional area of the inlet) we now make a ratio to determine how much you should reduce and convert it to radius of the opening.
(New modified radius)/(Original radius) = .477m/.564m = 84.6%
you want to reduce your current inlet radius by 15.4%
..but I still think you are restricting volumetric flow.
RE: Oil supply restrictor - totaldisaster - 02-09-2009
I think I understand this mod a little better now.
The turbo was manufactured for for an application with much lower pressure supply - you are reducing because your pressure supply is much larger. You will get the volume you need because your pressure supply is there to force the volume at a greater rate.
OT: There are no restrictions against using a gasser turbo in a diesel application?
RE: Oil supply restrictor - ForcedInduction - 02-09-2009
(02-09-2009, 03:53 PM)totaldisaster OT: There are no restrictions against using a gasser turbo in a diesel application?
Nope. It will even last longer since most are water cooled.
RE: Oil supply restrictor - totaldisaster - 02-10-2009
I already bought a rebuild kit for my stock turbo a while back, wish I was more informed.
The math doesn't tell you that much mainly b/c it assumes the maximum flow allowed by your current inlet would produce 7bar on the turbo seals.
If you knew the pump's volume output @ 7bar as well as the smallest dimension before the inlet but after the main supply, we could come up with a pretty good number