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How to Build a B20 VTEC Part 11: Positive Crankcase Ventilation

Honda Info and DIYs How to Build a B20V

When you slap a VTEC head on a non-VTEC block you need to have a plan for how to allow crankcase pressure to escape while the engine is running. On a B20B (or LS) the PCV valve is located on the head but for the GSR or B16 engine the PCV valve is on the block and that’s a problem.

Note the lack of a PCV valve hole on the VTEC valve cover.

A PCV Valve And/Or Catch Can Is a Must

You absolutely must run a PCV valve and/or a catch can on your engine. When an engine is running some of the combustion gases sneak past the piston rings (this is known as blow-by) and that pressure needs to be allowed to escape. Otherwise it’ll lead to leaking oil gaskets because the pressure found it’s way out via force, and your oil will get contaminated faster from moisture in the combustion gases.

It’s up to you to decide whether a PCV valve is sufficient or if you need to step up to a catch can for your engine. PCV valves are not recommended for boost applications but they are more than sufficient for naturally aspirated builds and since my b20v is NA I went with a PCV valve.

Off The Shelf Options For A PCV Valve On A B20V Are Limited

The main problem with trying to hook up a PCV valve on a B20V is there’s nowhere to put it and a lack of off the shelf solutions to address that. With a bit of work I came up with my own design.

It’s a 3d printed custom scavenger oil cap housing that allows for using an OEM PCV valve and grommet. It’s printed in two pieces out of pccf and connected together via 4 m3 bolts and some o-rings.

For the oil cap I used the cap and adapter from a Jackspania Racing oil scavenger cap. This isn’t a cheap solution but I had already bought the Jackspania setup because prior to making this custom housing because I was exploring making a breather chamber that would mount somewhere on the block.

It looks decent as well and is dang simple.

I’m not the biggest fan of the oil cap because it’s a little hard to grip when your hands are oily but all things considered I like the setup. I’m not worried about oil accumulating below the PCV valve because it’s fairly difficult for the oil being flung around by the cams to get up there but I’ll keep an eye on things and reassess if needed.