Technical Question:

Does anyone know the purpose of the bellows hose attached to the intake plenum? It is the rubber hose wrapped in a spring. See pic below:



One partial bit of information is that it may allow for some of the oil to sit in the hose instead of going into the intake. That only makes sense until you realize that eventually the small space will fill up with oil and the excess will enter the intake anyway.

So with that said, should I remove it since I believe it allows for boost pressure to expand the hoses?

A few images from other 3rd modification companies, show that they remove it and replace it with straight connectors.

 

I believe it's just for flexibility.

 

remove them! looks way better and it will smooth up the intake track a bit as well.

 

Can't imagine how oil might get in there... I believe the purpose for them is to allow them to flex as the engine moves within the chassis when you accelerate/decelerate - it's so they won't break - just like they do with some parts of the exhaust system.

 

^^^this is true

 

Thanks guys... I think I will replace them with silicon connectors. This should still allow some flex, smooth out the air intake, and possibly reducing swelling under boost.

 

Real silicon is a rare-earth crystal.. it's what your semiconductor chips are built on. It's also quite brittle. I suspect you mean "silicone" - which is a product derived from sand (silica) and is a liquid or grease. Some rubber is also made from it (as are some breast implants.)

Downside - out-gassing (google it) can end up with silicone vapor entering the engine. This is not good for O2 sensors, it coats the active surface of the sensor and poisons it.

As far as smoothing out the intake - on a turbo it just doesn't matter unless under full acceleration you're pulling a vacuum on the intake. The convolutions don't slow the airflow since it's a positive airflow, in excess of what the engine can use. Smooth sounds like it should do something, but if it did - Porsche would have used the less expensive smooth connectors vs the bellows type they did. As was pointed out - they are used because the engine moves in it's mounts relative to the air-filter housings. If you put a rigid (or near rigid) coupling there - you can expect something to give, if not sooner, then later. Plastic fatigues just like metals do.. flex it too many times and it breaks.

Other then that - I guess it's a fun thing to do to your truck..