CAC Transition Hose Coupler Hose I.D. - 3.50 in. x 3.00 in.

Two different pipe sizes meeting at an intercooler is a common headache, and Vibrant 11865 solves it without any cutting or welding. It is a flexible silicone CAC transition hose that steps from a 3.50 in I.D. on one end to a 3.00 in I.D. on the other, so a 3.5 in intercooler outlet can feed a 3 in charge pipe, or the other way round. Unlike a welded reducer, the hose slips over both tubes and clamps in place, which also lets it absorb engine rock and small misalignment.

Build and ratings

The hose is made from four plies of silicone with aramid fabric between each layer, plus three stainless steel rings that keep it from ballooning under boost. Dealer spec sheets list a 0.200 in wall, a 6.00 in overall length and a 55 psi maximum operating pressure. Vibrant rates its CAC transition couplers from -75°F to 392°F for hot side and cold side charge air, limited to air, water and coolant service.

Fitting it correctly

Because the listed sizes are inside diameters, the hose needs one tube with a 3.50 in O.D. and another with a 3.00 in O.D. Use a correctly sized T-bolt clamp on each end, and bead-roll the tube ends on high-boost systems so the hose cannot walk off. Mark each end with a paint pen before final assembly so you can see at a glance if the hose has crept on either tube after a few hard pulls.

Frequently Asked Questions

Does this coupler need to be welded in?

No. Part 11865 is a silicone hose, not a metal reducer, and it installs with two hose clamps. If your project calls for a weld-in aluminum or stainless reducer, that is a different type of part.

Which way round does it go?

Either direction works, since the hose only cares about tube sizes. Put the 3.50 in end on the 3.50 in O.D. tube and the 3.00 in end on the 3.00 in O.D. tube, whether air flows from large to small or the reverse.

How long is the hose?

Dealer spec sheets list a 6.00 in overall length, although some listing titles show 3.00 in, which is actually the smaller I.D. Measure the gap between your tubes and allow for clamp engagement on both ends.

Fitment: Universal. Confirm the sizes and thread types listed above against your application before ordering.