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Transparent Donaldson reducer fitting, tapered 4 to 3 inch ends

Donaldson

Donaldson P206321 Reducer 4-3 In 102-76 Mm engine tool

SKU CH-EX6E-QQ7W2

Reducer connects 4-inch and 3-inch (102–76 mm) engine components with a transparent finish

  • Product colorTransparent
  • Reducer connects 4-inch to 3-inch ducting
  • 102 mm to 76 mm inner-outer diameter fit
  • Transparent body lets you see flow
  • Donaldson engineering for engine-tool reliability
  • New stock listed February 2025

Reducer for 4-Inch to 3-Inch Connections

This Donaldson reducer adapts a 102 mm inner diameter opening to a 76 mm outer diameter. It is built for engine intake or exhaust routing where a step-down in hose or pipe size is required. The transparent colour allows visual confirmation of flow or blockage.

Suited for custom fabrication and repair work

Mechanics assembling intake systems, intercooler piping or turbo outlets can use this fitting to join mismatched diameters. Builders who need a flared, beaded or threaded end should look at a different component because this reducer presents plain ID-OD ends only.

102 mm to 76 mm step-down dimension

The critical specification is the 4-inch inner diameter reducing to a 3-inch outer diameter. Verifying that both the source and the mating part match these exact measurements determines whether the reducer will seal correctly in the application.

How it compares

Measured against everything we stock in Engine Service & Diagnostic Tools, at today’s prices. Recalculated every night.

Price $57.99
Pricier than about 82% of the 1,113 comparable items (median $19.99).

Specifications

Product
Brand nameDONALDSON
Product colorTransparent

Questions about this item

Does the Donaldson P206321 reducer come with clamps or gaskets in the box?

The reducer is supplied as a single component; clamps and gaskets must be purchased separately.

Should I choose the 4-3 in (102-76 mm) ID-OD reducer or a different size?

Select this reducer only when connecting a 102 mm ID pipe to a 76 mm OD pipe; otherwise choose the size that matches your exact diameters.

What does the 102-76 mm ID-OD figure mean once the reducer is installed?

It means the large end fits a 102 mm inside-diameter hose while the small end inserts into a 76 mm outside-diameter pipe.

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