Revised OEM PCV and Crankcase Breather Tube

06F129101P Front Detail

In my current quest to return some parts back to OEM spec, I’ve recently purchased the latest revision PCV components.  The latest revision PCV valve is “P” with the part number 06F129101P.  There is also another revision of the rear breather tube, part number 06F103215B.  The valves in the latest revisions seem much stronger compared to my old “G” revision.  The check valves are now spring loaded instead of free moving.  I don’t know when they switched to the spring loaded valves because I completely skipped over the 2 or 3 other revisions.

06F129101P Valve Detail

If you’re wondering why I went back to stock, I wanted to remove the catchcan I’ve been running.  An intake manifold teardown by a forum member  revealed that catch cans do little to aid in preventing the intake valve deposits inherent to direct injection engines.  I have also been thinking about the lack of intake vacuum working on the crankcase.  In the catch can setups, vacuum is sourced from intake air moving over the rear breather tube exit.  I think it is a max of 3″ of mercury according to BSH and this occurs in the higher rpms under boost.  At lower rpms, actual vacuum may be much lower.  Too little flow or stagnant flow through the valve cover may allow the blow-by gasses to start forming deposits.  I’ve noticed a little grime building up around the oil cap area, despite the regular oil changes.  The accumulation of these blow by gasses can contaminate oil and deteriorate it much faster as well.  Another side effect of routing all gasses through the rear breather tube seems to be, ironically, more oil in the charge pipes.  If a recirculation type catch can does not catch all the vapors, the rest end up condensing in charge pipes and intercooler.  The stock system sends them directly to the intake manifold to be burned off.  The way the stock system works, it only reroutes vapors through the charge piping and intercooler under boost.  When I installed my throttle pipe, a good amount of oil came pouring out of the pipes.

06F103215B Check Valve Detail

Now oil vapor in the in the intake charge is detrimental to performance.  This is where a catch can does help.  Oil vapor can effectively reduce the octane level of the intake charge and lead to more knock, which would then decrease performance.  I haven’t noticed a performance difference since I switched back to the stock system but then again, my car isn’t exactly a horsepower monster.  It is a compromise situation but after many miles of thought, I’d rather have the stock system deal with the evacuation of the crankcase gasses.  The stock pcv system flows a lot and I don’t think some of the catch cans flow enough.

06F129101P Rear Detail

The stock pcv valves have not been models of reliability, which is one of the reasons catch catch cans have sold so well. Modified and stock cars alike can blow through them.  These newer parts are now several revisions deep and they seem to be much more robust pieces.  The rear check valve in the breather tube looks much better.  The front pcv check valves have a more positive engagement compared to the “G” revision I compared it to.  I guess only time will tell!

06F103215B

BSH Diverter Valve Kit – Review

 

Forge Diverter Valve

The BSH kit is well spec’d and doesn’t scream aftermarket even with the large Forge valve dominating the view.  Granted it does ruin the illusion with the requirement of an aftermarket intake but it’s forgivable.  BSH had a few performance goals with the installation of the kit:  better part throttle engine response and reliability.  It hit both of these targets.  Lets go into more detail as to how it reaches its goals.

BSH uses the noise pipe as a recirculation pipe, routing to big Forge valve in the front of the engine bay

Better Part Throttle Response

This one seems to baffle people the most.  How can installing a replacement valve result in better response?  To answer that we need to delve into the details of the stock system.  The stock 2.0t diverter valve resides on the compressor housing itself.  This is not a bad design.  It is very efficient in terms of packaging and cost.  No need for extra hoses, pipe and other support hardware.  However, it does require the airflow to go through the intercooler when not under boost.  The BSH kit reroutes the air flow through the stock noise pipe, bypassing the intercooler and routing air straight to the throttle pipe when the engine is not requesting boost.  The mechanical operation of the Forge valve keeps it open under vacuum.  Shorter path for airflow – slightly better part throttle response.  Under boost pressure, the valve is closed and air follows its normal path through the intercooler.

Practically Unbreakable Forge Valve

The Forge valve used in the kit is massive.  It carries 1.5″ ports to match up to the stock noise and throttle pipe inlet/outlet.  The valve controls airflow with piston design instead of the diaphragm stock valves.  (Note that newer D revision valves now use a piston as well)  Constructed out of aluminum, this will last the life of your car and then some.  You can rebuild the valve several times over.  The only downside is that you’ll have to grease the valve occasionally.  Regreasing is a quick procedure that any owner can do at home.  Mechanical valves are also slower to react than electrical, but it seems to be a none issue in this kit.  The vacuum source is provided with a boost tap on the manifold.  Because of the short length of the vacuum hose (less than 5 inches) reaction time is quite quick.

Overall Design

As with most of BSH’s designs, this one isn’t pretty or gussied up.  It’s very functional and to the point.  There are no fancy pieces to decorate the engine bay.  Even the boost tap is anodized black.  You get a few specific silicone hoses and then the shiny Forge valve.  Very clean look overall as it utilizes a few stock components such as the noisepipe and and one of the hoses.  Not fancy, but it gets the job done cleanly.

Installation

The installation is not too difficult.  Follow the instructions on BSH’s site and you should be good.  It requires a few tools so make sure to have those before hand.  Here are a few suggestions though:

-The wipers do not have to be removed to move out the noisemaker/speakerbox.  In fact my wipers were frozen onto the posts.  Just a little careful lifting around the rain tray will help you.  I actually just left it in there and just disconnected the hoses I needed.  You can do that too and it will help when you have to reinstall things back to stock.

-The diverter valve blockoff will require removing the diverter valve bolts which are a 5mm hex.  Use a 1/4″ ratchet with a short extension maybe.  It’ll help immensely.

Other than these few tips, just take your time and don’t rush.  The proper tools help a lot.

Grade?

I really like this kit.  It does it’s job and does it well.  The sound the valve puts out is nice and not too loud.  It’s rather addicting actually.  It has everything you need to put it all together.  It solves your diverter valve issues and provides a nice performance uptick.  The only knock on the kit I can find is that it requires an aftermarket intake.  And if you don’t have the BSH intake with it’s built in bung, you will need to hack off a portion of the rear to fit BSH’s own rear section.  It’s not difficult but other competitors have figured out ways of using your aftermarket intake without cutting.

MazdaSpeed 3 Installation

 

Stock Diverter Valve Piston

My friend came over to install a Forge bypass valve and a midpipe.  He has a Mazdaspeed 3.  Wicked car.  Here’s a few pics from the install.  This car sounds totally mean and is on a different level than the GTI stockwise.  The GTI seems almost placid compared to this car.  I don’t have any pictures of the midpipe, we were both under the car wrenching it out.  Meanwhile, enjoy the pics.

 

 

 

Stock midbrace – These things are solid!  I wish the GTI had stock bracing this solid.  The front and middle of the chassis have these braces.

Forge valve installed – Has a nice sound to it, seems much louder than in the GTI

Forge Valve

 

Stock MS3 Diverter Valve

Top Mount Intercooler

 

 

DIY Series: Forge SuperSize Valve Cleaning/Regreasing

For consistent performance, the Forge (supersize) diverter valve needs to be regreased occasionally.  Otherwise the grease gets pretty contaminated from the oil flying through the intake system.  Here’s a little writeup on how to do it.

DIY Series:  Diverter Valve Maintenance

The pictures, as usual, are coming a little late.  They will be up soon, sorry!

Forge Diverter Valve Picture

forge

Just another picture.  This is a Forge part from the BSH DV kit.  This thing is huge.  And also very well made.