Intercooler piping - radiator hose vs. silicon

[Otis2]

Ok, so I'm finally trying to hook up the intercooler on the AAZ-powered Vanagon.  I'd like to know who has used rubber radiator hose for their intercooler piping, and how well it has stood up.

I've looked at the photo of "Smog's" intercooler install on the VW Quebec web site, and he suggests that he just got some rubber radiator hose pieces from Canadian Tire, with a few metal tubes for joints between the rubber rad hose sections, and he was good to go.

I'm a little worried that radiator hose isn't going to stand up to the heat and pressure of the turbo (I'm still using the stock, tiny, KKK).  The turbo runs pretty much all the time in a heavy Vanagon, so those radiator hose pieces will take a lot of heat and pressure in a pretty short time.

The FLAPS people warned me that rad hose flat out will not work, and I need silicon rubber, like the VW factory "L" angle that usually connects the turbo outlet to the intake manifold on the AAZ.  Trouble is, I can't find any silicon pieces in the lengths, diameters, and angles that I need.  (The piping run on a Vanagon install is much more convoluted than the long straight runs in Smog's Golf/Jetta example.)  

I see Smog's example with ordinary rubber radiator hose, and I am sorely tempted to try it.  What's the real-world experience of the board members on this point?

[VWRacer]

The only drawback to radiator hose is that it is flexible and therefore will somewhat modulate the boost to your engine. This was first widely recognised in the Mitzu GSX/Eagle Talon world, where simply switching from the OEM radiator hose type to tubular metal IC lines (connected by rad or silicon hose) produced as much as 3 psi more boost with no other changes.

In your case, build it from rad hose and see how it goes. Any sections where you can use tubular metal sections is good, but don't worry about it at first. Ultimately, though, I think it'll be worth it, since you sayyour turbo is already always on boost.

[Otis2]

Thanks, VW Racer.  I had already made up my mind to do it with the rad hose, but it's nice to have someone else support the decision.  

Pioneering in the interests of science, I suppose...

Have you had experience with rad hose on any of your intercooled vehicles?

One other issue has come up that, regarding routing the oil supply line to the turbocharger.  After I turn the aluminum intake manifold snorkel around 180 degrees, in order to clear room for the radiator hose to mount that snorkel, the oil supply line to the top of the turbocharger has to be bent quite some way off the heat shield.  It's new route takes the oil line out over the exhaust downpipe, and the back of the turbocharger.  Very hot places, unfortunately.  I'm going to try to get some sheet metal and bolt it to the existing heat shield, extending it out over the new path of the oil supply line as much as I can, but still I'm wary of cooking the oil supplied to the turbo.  I'm not keen to do much more bending of that line, as the metal must be pretty work-hardened now, and likely to crack.

[fspGTD]

Since there is a flow of oil through the turbo oil supply line that will cool it, it is doubtful it will overheat.  But some heat shielding (you could get a tube-style of shield that slips over the metal line) doesn't certainly isn't a bad idea.  If you bend this line, use a tube bender that has a tight-fitting "U" shape groove in it so you don't crimp the line.  If it's secured by a clip to the the water outlet fitting by the head, I wouldn't worry about it fatiguing from vibration.  Mine is supported like that and has been re-formed vs original (for intercooler plumbing clearance) and seems to be holding up fine.

Not only have I used radiator hose on my intercooler piping, but I've used non-reinforced drain/waste/vent (household supply) rubber hoses!  They are not ideal but they are very cheap.  I've heard on high boost systems they can baloon up because they have no reinforcing.  Mine however having been run at 9-14psi through it's life, is working fine!  The best part is that you can get a 2.25" 90 degree bend for about $5.    (Yeah, I want to redo my intercooler hoses one of these days...)  Another downside to using rubber products is that it probably isn't technically oil-resistant.  And there can be some oil in boost lines, especially if you've got the blowby recirculation going back into the intake like the stock setup has.  Over time I would expect that oil to attack the rubber eventually, but practically speaking and based on my experience, it seems to hold up for years.

[type53b_gtd]

I used rad hose and cheap exhaust tubing on my intercooler setup.  I've had the runs apart a few times and after 50,000kms ish of driving there is no visible damage to the hoses from collected oil.

They do balloon under boost though, and  I'd like to replace them with madrel piping/silicone hose - some day.

I'd start with the rad hose for the reasons mentioned above - and then once you've ironed out all the bugs and finalized your tubing runs, you can replace them with the more expensive long term solution.

Drew

[Otis2]

Thanks for the replies.  I've gone with 2" rad hose, which is hose-clamped over 2" exhaust pipe.  The exhaust pipe stretches the rad hose a lot (I probably should have gone with tube, not pipe), and there are no barbs on it, so I'm a bit worried they will blow off.  But whatever.

I'll post some photos next week, if there's any interest.  What's holding me up is plumbing in an air-water intercooler taken from a GMC Typhoon.  I'm not convinced an air-air intercooler is particularly efficient in a Vanagon, even with an electric fan mount.  Who knows, maybe this intercooler isn't very efficient either, but at least the heat exchanger can be mounted up front under the bumper, in a clean air flow stream.

Intercooling turbocharged Vanagons seems to all be experimental, and hasn't really reached a stage of common consensus yet.  Everyone who has done it is a partisan of their own particular choice.  If I ever get really motivated (not likely in the near future...), I'll plumb in an ice reservoir under the back seat, beside the rear heater core, and so drop intake temperatures below ambient for as long as the ice takes to melt.