Garrett /HKS GT30 owners - do you use an oil restrictor ?

[the phantom]

I've been wondering this also for a very long time but have no definite answers. The standard R33 turbo runs a restrictor however....

[JasonO]

Sorry about the quality of the picture, but you can clearly see the restrictor sitting in the housing. It is closed onthe bottom and feeds oil through one port about 1.2mm dia. on the side.

Hope this helps B-Man

[the phantom]

What would you say is the diameter of the restrictor hole seen in your photo?

[JasonO]

The threaded portion of the hole is about 10mm dia. , the oilway is about 3.0mm dia. and it has two holes in the side of it about 1.2mm dia.

The oil does not feed straight through this restrictor, it comes out the sides, like this......

     Oil In

    3mm

    |  |

    |  |

    |   =   1.2mm Oil Out

    |  |

This is a brand new HKS GT3037 which I purchased recently.

[Sydneykid]

Hi guys, I feel the need to put up a question;

Car 1 is a Fowlcan that revs to 4,000 rpm and has 50 psi oil pressure.

Car 2 is a GTR that revs to 8,000 rpm and has 80 psi oil pressure.

Surely it would illogical to have the same sized oil orifices in a turbo on both engines. The oil flow from the GTR oil pump into the turbo would be almost double. So if the turbo is designed for the Fowlcan, then it will have excessive oil flow and pressure on its seals when used on the GTR. On the other hand, if the turbo is designed for the GTR, then it will have insufficient oil flow and pressure when used on the Fowlcan.

So it would seem logical to me to have all turbos designed for "low" oil pressure engines and use a restrictor if they are to be used on "high" oil presure engines. This would be particularly relevant on Roticeries that have up to 100 psi oil pressure.

What do you think?

[B-Man]

I think I am going to get a restrictor since I am running an N1 oil pump.

-4 , 0.8 or 0.9 mm should be ok since Jason's built in one is 1.2 mm - if it was larger than that I would be concerned.

[Scooby]

So it would seem logical to me to have all turbos designed for "low" oil pressure engines and use a restrictor if they are to be used on "high" oil presure engines.  This would be particularly relevant on Roticeries that have up to 100 psi oil pressure.

SK;

Does that mean stock GTRs will have restrictors plumbed inline, or are you saying that the restrictor is a modification specifically built into GTR turbos?

[Sydneykid]

SK;Does that mean stock GTRs will have restrictors plumbed inline, or are you saying that the restrictor is a modification specifically built into GTR turbos?

Hi Scooby, the oil flow control issue is for ball bearing, water cooled turbos. :idea:

[Scooby]

Hi Scooby, the oil flow control issue is for ball bearing, water cooled turbos. :idea:

My bad, I was implying GTRs such as R34s which I think came standard with bb and water cooling or at least could be specified with N1s that have these features?

[the phantom]

Based on JasonO's measurements, and if haven't missunderstood the description, a single restrictor would then have to be < 1.7 mm diameter to be actually restricting anything, based on the surface area of two 1.2 mm holes.

Sydneykid, I cant see anythign wrong with your logic. So are you assuming that the GT's would be designed for a 'low pressure' engine and that RB's may need the restrictor? Do you run one on your cars with your custom turbo setups? Does anyone have published Garrett specs on the oil requirement of GT series turbos?

[B-Man]

The one I am getting is 0.8 mm.

After explaining my situation to one of the turbo shops, they agreed that I do infact need a restrictor as I have a high revving engine with a high volume oil pump.

Hopefully I will get the restrictor tomorrow so I can test it at WSID on Saturday.

I'll either be happy that I have no white smoke on decelaration now

OR

I'll have a lunched turbo..........

[Sydneykid]

My bad, I was implying GTRs such as R34s which I think came standard with bb and water cooling or at least could be specified with N1s that have these features?

I thought that might be the case, Scooby. I suspect Nissan would have specified the turbos with the right amount of oil flow. This can be achieved with a restrictor or simply by machining the ports smaller in the first place.

[Steve]

B-Man, I didnt add a restrictor, I have the same turbo as JasonO

[JasonO]

Based on JasonO's measurements, and if haven't missunderstood the description, a single restrictor would then have to  be < 1.7 mm diameter to be actually restricting anything, based on the surface area of two 1.2 mm holes.

Sorry guys, I've double checked the turbo this morning, and found that it only has one hole not two as I described earlier. It's kind of difficult to see.

My original description should have read as follows --

The threaded portion of the hole is about 10mm dia. ,  the oilway is about 3.0mm dia. and it has one hole in the side of it about 1.2mm dia.

The oil does not feed straight through this restrictor, it comes out the sides, like this......

     Oil In

    3mm

    |  |

    |  |

    |   =   1.2mm Oil Out

    |  |

[Craved]

B-Man, would you have needed the restrictor if you weren't running the N-1 pump?

[B-Man]

Prolly not Chris - I just want to get rid of the smoke on decelaration - and this is the first and most obvious step in the troubleshooting.

It's not affecting performance - but could affect the turb if the seals are under pressure.

[raist60]

Compare the size of the oil feed vs oil drain. Also look at that cut section, I dont see how its possible to actually have sufficient pressure in the bearing cavity to push past the seals?

I still maintain that you shouldnt run one. As for the comparo i dont think garrett really had falcons in mind when they designed these cores.

I've seen my oil pressure up around 11kg/cm and i dont shoot out seals or have smoke shooting out of my exhaust.

[Craved]

if it was decelerating wouldn't the oil pump be winding down? so it would be more likely to blow smoke on acceleration when oil pressure builds up??? just a thought!!!

[B-Man]

Reviving this thread now as I have just taken delivery of my restrictor to test the theory.

Problem is - I reckon the restrictor is too restricive just bY looking at it.

The standard one has a hole of about 4mm - the custom one has a hole of about 0.8-0.9mm.

For those guys that are running restrictors with no problem - what size hole are you using ?

So here are some pics. Note the difference to the standard restrictor.

[Merli]

Brendan,

As far as I know, HKS make different turbos for different applications. e.g. An HKS GT2530 for RB25 is *NOT* the same as an HKS GT2530 for an RB26.

Secondly, as seen on Steve's GT3037, it already have a 1.2mm restrictor built into the centre housing, so obviously it was meant for a high oil pressure application.

So if they were to release different turbos, depending on what engine application you have, and taking into account the built-in 1.2mm restrictor on the HKS GT3037, how does that fit in with Sydneykid's "all turbos are built for low oil pressure applications" theory?

Have you looked at the centre housing of your GT3040 Brendan? Perhaps it already has a restrictor like the GT3037?

And white smoke blowing on decel could point to a lot of things, not just over oiling the turbo