A clean oil return is the difference between a turbo that lasts and one that doesn't — and this billet flange gives you the foundation to get it right.

Why Builders Choose This Flange

Precision Billet Construction

Machined from billet aluminium for exceptional strength and a leak-resistant sealing surface that holds up in the high-temperature environment of a working turbo oil drain circuit.

38mm (1.50") Bolt Centre for Small-Frame Turbos

Machined to the 38mm bolt centre used by small-frame turbochargers, making this a direct-fit upgrade over worn or undersized OEM-style drain flanges without the hassle of adapting ill-fitting generics. Bolt centre is measured from the centre of one drain pad bolt hole to the centre of the other — 1.50 inches on small frame.

35mm (1.38") Drain Length

The 35mm figure is the length of the drain — how far the drain body stands off the flange face before your hose connects. This is the shortest of the three lengths we offer, keeping the assembly tucked in tight where clearance around the drain pad is not a problem. Also available in 65mm (2.56") and 100mm (3.94") when you need more reach.

10AN Port for Standard Drain Lines

The 10AN oil drain port works with widely available braided stainless and rubber AN hose, so you can route your turbo oil return line exactly where you need it — no additional fittings or reducers required in most setups.

Reliable Sealing Surface

The precision-machined face ensures a consistent, repeatable seal at the flange-to-turbo interface — critical for preventing oil weeping that can foul your exhaust and mask larger issues down the line.

Versatile Across Builds

Whether you're building a boosted street car, a track day weapon, or a diesel performance setup, this flange fits the job. Compatible with a wide range of small-frame performance turbos across gas and diesel applications.

Backed by BSI Inc.

Manufactured by Black Sheep Industries, this is a universal BSI Inc. component engineered for builders who refuse to cut corners on the details that matter.

Stop chasing oil leaks — fit it right the first time with the 35mm billet 10AN turbo drain flange for small-frame turbos from BSI Inc.

Not sure which drain you need? See the turbo oil drain guide for bolt centre measurement, length selection, and full sizing charts in metric and US standard.

FAQ

What turbochargers is this flange designed for?

This flange is machined to the 38mm (1.50") bolt centre used by small-frame turbochargers.

What does the 35mm refer to?

35mm (1.38") is the length of the drain, meaning how far the drain body stands off the flange face. It is the shortest option and suits installs where nothing obstructs the drain pad. It is not the bolt centre or the port size.

What is bolt centre?

Bolt centre is the distance from the centre of one bolt hole to the centre of the other on your turbo's oil drain pad. It identifies the frame class: 38mm (1.50") small frame, 50mm (1.97") mid frame, 50.8mm (2.00") large frame.

What oil drain line size does this flange use?

It features a 10AN oil drain port that works with widely available braided stainless and rubber AN hose.

What material is the flange made from?

It is machined from billet aluminium for strength and a leak-resistant sealing surface.

Who manufactures this turbo drain flange?

This is a universal BSI Inc. component manufactured by Black Sheep Industries.