Stock R34 PCV

Oily air sucked and burned in the engine, lowers the effective octane of fuel. It also coats the inside of the inlet manifold, intercooler piping,etc, and can end up with deposits on the valves. So, what happens if you just take all that “junk” off, and just put a breather on? Well under vacuum, air will enter the engine through the breather.  No big deal. No problems normally.  However under boost, air from inside the engine, will try and move out of the engine.  This would be no problem if it were just air, but its not.  It has oil suspended in the air. So even with a breather filter on the engine, you will have oily air come out the breather.  This oily air will get all over your engine compartment. For one it creates a big mess. For two it is flammable.

Auto select catch can and overflow

An RB moves a lot of oily air around. With combustion pressure leaking by the rings (totally normal in moderate amounts) the crank is pressurized.  The higher you boost, the more power you make, the higher you rev, the more oily air you are going to have.  Then the RB26 have oil squirters to cool the pistons.  These oil squirters whip up a ton of oily air.

What to do? Catchcan.  Now there are some best practices. There are some odd things we have seen through the years.  There are a ton of places that make catchcans. Some designs are good, some are awful.  Some designs I have seen, that will never ever have oil come in them, because they have been setup wrong.

Racecar parts. Catchcan that collects oil vapors, and returns to sump.

1) The oily air, has to want to move to the catch can.  You can not put an enclosed catchcan, aka no vent, at the end of some hoses, and expect much to happen.  It might capture some oil, but in the end, why does the oily air want to travel to it?

Nismo R32 GT-R catchcan that returns to sump/turbo drain

2) Returning caught oil to the sump. Some people don’t like the idea of it.  Knowing how much moves in an RB, I like the idea. NISMO sells a catchcan that has a sump return.  In the end, we replace oil fairly often, and as long as you get the oil warm every now and then, any water trapped in the oil, will want to burn off.

Stock R34 PCV

Oily air sucked and burned in the engine, lowers the effective octane of fuel. It also coats the inside of the inlet manifold, intercooler piping,etc, and can end up with deposits on the valves. So, what happens if you just take all that “junk” off, and just put a breather on? Well under vacuum, air will enter the engine through the breather.  No big deal. No problems normally.  However under boost, air from inside the engine, will try and move out of the engine.  This would be no problem if it were just air, but its not.  It has oil suspended in the air. So even with a breather filter on the engine, you will have oily air come out the breather.  This oily air will get all over your engine compartment. For one it creates a big mess. For two it is flammable.

Auto select catch can and overflow

An RB moves a lot of oily air around. With combustion pressure leaking by the rings (totally normal in moderate amounts) the crank is pressurized.  The higher you boost, the more power you make, the higher you rev, the more oily air you are going to have.  Then the RB26 have oil squirters to cool the pistons.  These oil squirters whip up a ton of oily air.

What to do? Catchcan.  Now there are some best practices. There are some odd things we have seen through the years.  There are a ton of places that make catchcans. Some designs are good, some are awful.  Some designs I have seen, that will never ever have oil come in them, because they have been setup wrong.

Racecar parts. Catchcan that collects oil vapors, and returns to sump.

1) The oily air, has to want to move to the catch can.  You can not put an enclosed catchcan, aka no vent, at the end of some hoses, and expect much to happen.  It might capture some oil, but in the end, why does the oily air want to travel to it?

Nismo R32 GT-R catchcan that returns to sump/turbo drain

2) Returning caught oil to the sump. Some people don’t like the idea of it.  Knowing how much moves in an RB, I like the idea. NISMO sells a catchcan that has a sump return.  In the end, we replace oil fairly often, and as long as you get the oil warm every now and then, any water trapped in the oil, will want to burn off.