Reducer Coupler, 4.00" I.D. x 5.00" I.D. x 3.00" long - Blue

Stepping a 4 in pipe up to a 5 in inlet with hard tubing means a welded cone, extra length and one more joint that can leak. Vibrant 2777B handles the same change in a 3.00 in long silicone sleeve, with a 4.00 in I.D. on one end and a 5.00 in I.D. on the other. Dealers list this size for spots such as turbo compressor housings, intercooler end tanks and charge pipe assemblies, and it works just as well joining a large air filter adapter to a smaller intake tube.

Construction

The coupler is hand wrapped from four plies of silicone with aramid reinforcing fabric between each layer. Vibrant rates its transition couplers from -75°F to 392°F and offers them in black or blue, and resellers list this size as meeting the SAE J20 hose standard. The blue color is mostly a styling choice, though it also makes oil residue and a weeping joint easier to spot during a quick under-hood check.

Measuring before you order

Coupler sizes are inside diameters, so measure the outside of each tube or fitting it will slide over rather than the old hose. The target here is a 4.00 in O.D. pipe on one side and a 5.00 in O.D. inlet on the other. Leave enough tube inside each end for a clamp to sit fully on it, and bead-roll aluminum pipe ends if the system runs meaningful boost.

Frequently Asked Questions

Is 2777B the same part as Vibrant 2777?

Yes, apart from color. Both are 4.00 in by 5.00 in I.D. reducers, 3.00 in long, with four-ply construction; 2777 is black and the B suffix marks the blue version.

What clamps should I use?

A reducer needs two different clamp sizes, one for the 4 in end and one for the 5 in end. T-bolt clamps give the most even squeeze on four-ply silicone and are far less likely to cut the hose than worm-drive clamps.

Can it be used on an oil or fuel line?

No. Vibrant limits its silicone transition couplers to air, water and coolant service. Oil mist and fuel soften silicone over time, so breather and fuel plumbing need a hose rated for those fluids.

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