GTR Oil Blow By??

[STOCKGTR]

Hi Guys.

I am having some trouble with oil blow by with my GTR when I go to the track. I have just rebuilt the bottom end with standard internal and know it is in good condition. I make over 270 kw at all 4. After running about 6-10 laps I blow a fair bit of oil into my catch can. I have seen a Mines Cam Cover Baffle Plate which seems like it will reduce the amount of blow by. Someone has recommended a Tomei oil restrictor also, but I thought you need a bigger oil pump to run this?????

Has anyone had expereience with this???

Your opinion will be greatly appreciated.

Thanks Guys.

[Sydneykid]

Hi Stockgtr, did you leave the standard restrictor in the block to limit the oil flow to the head? Did you block off 1 of the 2 oil supply holes in the block? One is blocked off standard, but I have seen some people unblock it. Did you fit an external drain from the rear of the head to the sump? Did you relieve the drain holes in the head? And match them up with the head gasket and block?

The #1 object of the restrictors and blocked holes is to limit the oil flow to the head, standard it gets too much. So why would you need a larger oil pump?

The #2 object of the restrictors and blocked holes is to limit the oil flow to the head, so that the bottom end of the engine gets more flow.

The #3 object is such that the oil needs to be in the sump so it can be picked up by the oil pump. Otherwise you get premature oil surge when the level is too low.

So the rules are simple, limit how much goes up and make sure what does go up comes down fast.

Hope that helps

[STOCKGTR]

Thanks Sydneykid.

I didn't do any of what you mentioned. I left the block standard. When I rebuilt the engine I was still learning about the RB26 strengths and weaknesses.

Though I would like to plumb another line from my catch can and return it to the sump. Not sure if it's a good idea though?

The oil restrictor sounds good too. But I don't want to take the head off at the moment. So I am going to try and find more out about the Mines cam cover baffle plate.

[Craved]

I thought the RB26 already had on oil line blocked, and the rb25 had 2 open to the head?

[Sydneykid]

I thought the RB26 already had on oil line blocked, and the rb25 had 2 open to the head?

That's right Craved, but you have to remove the restrictor to machine the top of the block. Most machine shops do this to make sure the head gasket mating surface is perfectly flat. It may only be a very light skim, but you still have to remove the restrictor. Sometimes it does not get put back, accidentally or deliberately.

Hi StockGTR, it has been my experience that the baffle does nothing, the air goes past it and therefore so does the oil mist. The only real way to fix it is to reduce the amount of oil trapped in the head. Either slow it down on the way up or speed it up on the way down.

Since you can't slow it down on the way up because you would have to remove the head, I would suggest increasing the size of and access to the oil return galleys in the head is the go. If you pull the cam covers off you can see where a few minutes with the die grinder will improve the oil flow (return) to the sump.

If you do decide to plumb the catch can back into the sump, don't "T" into the oil return from the turbos, it's under pressure. So instead of all of it going into the sump, some of the oil goes up the line to the catch can and fills it up even faster.

Hope that is some help

[STOCKGTR]

Thanks SydneyKid!

You have been very helpful. By any chance does anyone have a photo of which oil galery should have the restricotr in it?

[GZ R33]

Stock GTR - can I ask how you plumbed your catch can.

[Sydneykid]

HiStockGTR, there are 2 oil feeds from the block to the head, one is around cyl #2 (on the inlet side of the block) that is the one that is blocked on GTR's. The other is around cyl #6 (aslo on the inlet side of the block) and that is one with the restrictor in it.

Hope that helps some more

[STOCKGTR]

Yeah Thanks heaps!!

So the way I understand this is that the Tomei one replaces one of these restrictors???

[STOCKGTR]

GZ 33 I have plumbed the catch can the way the instructions said.

The greather on exhuast side that goes to turbo i ran to the catch can and blocked the hole in the plubing.

I am also considering run a line from the inlet side to the can.

[B-Man]

Has anyone tried restrictors on an HiPo RB25DET ?? I understand that not neccessary due to the differences in soild vs hydrolic lifters ??? Not sure on this though.