The reason you get so many "opinions" is guys seem to route the PCV system on the fly...basically whatever looks good or offers the most convenient hose routing. The problem is these same people don't know how the PCV works on the 7M...kinda surprising since it's such a simple system.
A few facts on how the stock 7M PCV works:
- The engine requires vacuum to effectively remove combustion byproducts from the crank case/oil...primarily water vapor.
- The primary vac source is the TB port...it is an orifice designed to provide max vacuum and limit back flow from boost.
- The accordion hose provides near zero vacuum...it is actually a return path for boost back pressure on the turbo motor.
- Under boost, the flow from the TB port to the accordion hose produces a venturi effect across the cam cover ports, assisting flow to the accordion hose.
The same thing happens under manifold vacuum, but pulls crank case vapor to the TB...it is much more effective.
- Flow depends on the path of least resistance...the 7M PCV system is an elegant design in that respect.
- The PCV is a closed system. The design keeps metered air in a circuit eliminating any adjustments by the TCCS.
When installing a catch can, you want to mimic the stock system as close as possible...in reality, there is ONE WAY to install a catch can and route the hoses correctly. Pic #1 above is the best set-up and will work as depicted. Personally, I would install a check valve (PCV valve) between the "T" and the accordion hose that will only allow flow toward the accordion hose. This will allow max vacuum to be exerted on the catch can (shown as a compressor filter in the diagram)...it will not inhibit back flow under boost, thus avoiding catch can pressurization.
On the NA motor, the path to the accordion hose (or intake) is not required...there is no boost to consider. Here's the TSRM depiction for both:
http://www.cygnusx1.net/supra/Librar...Section=EC&P=5
Sticky...meh. If guys would just stop and think about this for a minute and reference the TSRM vs routing hoses helter skelter, there would be far less "opinion" on this subject. It's funny how when people do something, pride takes over and the brain cuts off
