What Boost Line Hose Size with Manual Boost Controller?

[BASS]

Ok, I'm in the process of installing an RJC boost controller (and thus removing the factory Y-hose & restrictor), and was wondering what size hose to install? I would like to order some high-temp silicone hose. I see that the silicone hoses typically come in 4,5, and 6 mm sizes.

Some people say its 1/4" hose, while other say it's 5/32" hose? Some people say to use 1/4" hose from turbo compressor to bottom of boost controller, and then use 5/32" hose from the top of the boost controller to the wastegate.

I believe that the factory GM y-hose has 7/32" written on it (and same size for the entire y-portion)??

Again, this is for the boost hose that will connect from turbo compressor--->Boost Controller--->adjustable wastegate.

What are all of you guys using? I want to use high-temp silicone hose vs normal vacuum hose due to the high temps created by the turbo being so close to the hoses...Thanks...

 

[earlbrown]

If it's one of mine, you need 1/4" on both ends just like on the turbo and wastegate. If it's a 'normal' brass MBC, those have .170" ends on them so you have to do a little balancing. You'll need a hose small enough to seal on the .170" ends yet pliable enough to stretch over the .250" fittings on the car.

Don't forget the QUALITY zip ties too (or use safety wire like I do). The last thing you need is to blow a hose off on the wastegate circuit. That's almost a guaranteed head gasket failure at WOT.

 

[BASS]

Thanks. I've been doing some test fitting with regular vacuum hose (before I order some high-temp silicone hose), and it seems that the best fit is 7/32" hose (from turbo compressor to bottom of boost controller) and 5/32" hose from top of boost controller to the wastegate using this RJC boost controller...

 

[earlbrown]

Based on those numbers 3/16" would be the average. It won't work if you can't stretch it over the 1/4" nipple though.

 

[marleyskater420]

I just installed one of Earlbrown's boost controllers on a customer's car and used the 6mm hose from this site; http://www.siliconeintakes.com/silicone-boost_vacuum-hose/

 

[earlbrown]

6mm and 1/4" are only a few thou different.

I re-read the original posting and he has an RJC unit that uses much smaller hose barbs than the cars 1/4" nipples. Unfortunaly that's no right answer on the sizes for those (short of using a reducer coupling on both ends).