The 18R-GTE reference manual ...

**MnToyGuy** · 16-04-2013, 08:01 AM

What have you guys been doing for crankcase venting? I've seen them vented through the valve cover to a catch can. What about venting from the block under the manifold?

Any downsides of venting into the intake plenum on a newly rebuilt motor? I'll be running MSII with 12PSI max.

I'd like to run crankcase into the bottom of the intake plenum. Tell me why that's a stupid idea.

I've been reading up on the SR20DET forum Crank Case Ventilation fully explained. (Turbocharged edition.) I guess I'm a little confused as to why you would have different pressure in the crankcase, vs in the valve cover?

**river** · 16-04-2013, 08:18 AM

Hi,

I run an external oil catch can and then feed back into the inlet plenum, on a freshly rebuilt engine running 12psi.

seeyuzz
river

**o_man_ra23** · 16-04-2013, 05:49 PM

You need to return the air pre-turbo. If you don't you will either use intake pressure to pressurise your crankcase and make things worse, or if you have a non-return valve, then you won't be sucking out the pressure on boost (which is when it is most likely to pressurise).

As for the difference in pressure between crankcase and head, these will be separated by the return oil. By allowing the crankcase to breath, you will help the return oil to reach the sump.

Note that unlike in the SR20 thread, there is no check valve natively in the 18R-G, so you can't have the bypass into the plenum that they do in addition to the hose that goes pre-turbo.

**MnToyGuy** · 17-04-2013, 12:14 AM

River, are you running a check valve like a PCV?

Owen, that makes sense, suck the crankcase out to help oil flow back from the head and pre turbo so it's never positive pressure. Do you run a catch can in between? Vent the valve cover?

**o_man_ra23** · 18-04-2013, 09:13 PM

A catch can is a good idea for any performance motor. I would always vent the valve cover, block is a great bonus.

**MnToyGuy** · 19-04-2013, 12:26 AM

I was hoping to keep things tidy especially out of the valve cover.

Oh well, after talking with Joel at Toysport (and your responses), I'll be venting block and valve cover with a PCV valve and catch can. Actually I'll use a coalescer that filters down to 0.1 microns with an adsorbant cartridge that filters the oil vapor as well.

Here's a good writeup on catch cans: http://www.conceptualpolymer.com/PCV...oval%20102.pdf

**o_man_ra23** · 20-04-2013, 12:03 PM

Just thinking about this further, I think I've had too many modern engines of late. In the 18R and variants, there is a timing case which provides a gas connect between the head and block via the top front of the sump. Therefore my previous comment about a pressure differential between block and head was slightly skewed toward engines with timing belts, and didn't give due consideration to the gas path in the timing case on the older chain driven engines.

Still a good idea to vent both though.

**psi1uz** · 23-04-2013, 01:31 PM

Has anyone put a twincam head on a stock 18rc and turbo'd it? How long would it last?

**ra_28** · 23-04-2013, 02:28 PM

Well I've ran an 18rg turbo with 18rc pistons it was ok but compression was too low. How long it would last is a very open ended question, depends on tune and boost.

**Unda Presha** · 26-04-2013, 08:38 PM

We run a very stock 18RC bottom end with twin cam head in my drag car. It lasted just on 2yrs thrashing it only on a Saturday. We only rebuilt the motor because it cracked a piston. We run as quick as 8.52 @ 154mph with this motor and hold the National ANDRA record in CC/MA. We run up to 40psi of boost on a standard head gasket so it can be done but for a streeter you may need to tame it a little though