ISR Performance - Silicone Coupler - 3.50-4.00" - Black

Sized for big intake plumbing, the ISR Performance 3.50 to 4.00 inch silicone reducer joins 3.5 inch pipe to 4 inch pipe. It is a black straight reducer intended for the inlet side of large turbos, oversized intake systems on V6 and V8 engines, and any build where a 4 inch compressor inlet or filter has to meet 3.5 inch tubing. Silicone makes the joint installable by hand, keeps it flexible, and prevents the collapse that cheap hose suffers under strong inlet vacuum.

Specifications

• Straight reducer coupler, 3.50 inch to 4.00 inch
• Black silicone construction
• Half-inch step between the two sizes
• One reducer per listing

Applications

Universal part for connecting 3.50 inch OD tubing to 4.00 inch OD tubing on turbo inlets, intakes and intercooler piping across any chassis. Both sizes are large and easy to misjudge, so measure each pipe with calipers before ordering.

Install guidance

Clamp the small end with a 3.5 inch T-bolt clamp and the large end with a 4 inch clamp. Deburr the pipe edges so they cannot cut the silicone, and avoid routing the reducer through a tight bend. Inspect periodically, since an inlet leak at this point lets unfiltered air into the turbo. Figure on roughly 1 lb packaged.

All ISR Performance products are designed for off-road use only.