air intake pipe silicon or alloy which is best?


Road Burner
Poole, England
VW T5 swb 2.5tdi
I'm not to sure if this is a stupid question or not but here it goes, iv got a vw bora tdi and have just replaced my oem air filter with a bmc cds induction kit which seems to of made my mpg very slightly better and given my engine a deeper note but my main question is im thinking of replace the air intake pipe to the filter and the pipe from the filter to the turbo but which would be best to use a silicone tube fir both sections or would a custom alloy tube be better?
Intake piping to turbo really doesn't matter as long as it's heat resistant and stiff enough not to collapse, running it over hot bits, silicone might be better as this won't pick up as much heat as an alloy, but generally the one's not better than the other except over long stretches where the silicone may start to collapse under vacuum.
With a low boost set up that may well be right but at high boost levels most tuned turbo engines will have metal pipes as there is no real disadvantage and they never distort or collapse
For aesthetic purposes polished is clearly better. I would have a flexible section in there somewhere though just to allow for expansion/contraction. It only needs to be short and therefore not liable to collapse under partial vacuum.
id say alloy would be best as sleeper has mentioned they dont collapse under vac while on boost.
downside can be cost if youve a lot of take offs on the pipe and bends
if you use 2 alloy pipes butted together ( or close to ) and joined by a silicone pipe that is all the fexibility you will need

You can also get flexible silicon hoses that have steel reinforcement so are completely flexible but dont collapse . I have such a chap as a balancing pipe from one turbo to another .
It is definately safe to well over 2 bar of boost which is easily enough for most engines.

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