Just curious, I've replaces the vacuum hoses in my car with silicon hoses, for the MBC, and noticed that it is actually softer than the original rubber hose.

Am just wondering if it is better than stock. Of coz, color wise is look better :-P

Since it's softer, under boost, wouldn't it expand more ?

Any comments ?

 

That all depends on the manufacturer of the silicone. Good companies like Samco use reinforced layers on their intercooler and radiator hoses to make them stronger and resistant to expansion.

Most of the vaccum hoses on the car from the factory are made of hard rubber and over a period of time they become brittle from the heat and develop cracks in them. The silicone while softer is designed to withstand higher temperatures than conventional rubber.

 

However, hard rubber will be more resistant to expansion while softer silicon will expand more right ? Wouldn't that cause inaccuracy to the MBC ?

 

I use silicone hoses... haven't noticed any dramatic change. Or even a slight change for that matter.

 

The only silicone hoses that would be prone to expand are the ones that see pressure like the ones that connect the intercooler piping ,and like I said those ones a reinforced. Vaccum lines do not see pressure so they are not going to expand and therefore do not need to be reinforced.


You would notice a difference by switching to silicone is if the other hoses that were on the car were leaking before.

 

My blitz sbc IS 3 came with silicone hoses, so it cant be bad. Actually the wall of the hose is almost as thick as the ID of it.

 

Yes, the walls are VERY thick, if not thicker than stock.

The hose that I'm concern is the one from the turbo nipple to the MBC, since I guess it probably withstand most of the boost first hand, as it's so near the turbo :-P

 

I wouldnt worry about it, just buy some thick ones.

 

The expansion, if any, is not going to affect boost response. It might be a good idea to zip tie the hoses if they don't already have spring clamps on them. I did that with all my small ID hoses.

 

Silicon vacuum line is extruded, not made from multiple reinforced layers. Reinforcment is unnecessary though untill you start getting into larger diameter hoses.

As the size of the hose increases, it's burst pressure rating decreases. Smaller hoses will handle higher levels of pressure, sometimes exceeded 100 BAR.

Extruded vacuum line depending upon it's sheer strength is typically very resistant to expansion. There are different sheer strengths of extruded hoses, however.

Try taking 3mm vacuum line and stretching it over a 6mm port. Won't happen.

There is very little give, so it won't noticably expand under boost.

Standard silicone, though, is not oil nor fuel resistant. Oil or fuel will deteriorate the silicone and make it porus so be sure to use flourolined silicone if you have any oil or fuel transfer needs.

Standard silicone should only be used for coolant systems and pressure/vacuum applications.

 

Thanks for the detailed explanation.

Now you mentioned, silicon is not oil resistance ! As with all hoses, I slightly oiled the barb with engine oil (just coat a thin layer) before inserting the hose. Does this really matter then ?

 

Not at all.

It would only be an issue when a larger amount of oil is flowing through or pooling inside of the hose. In this instance, the oil will begin to seap through the hose.

I don't mean to say it will melt nor deteriorate the hose at all, but a little used for lubrication is no big deal.