S400 Turbo Guide: Sizes, Specs, Flanges & Fitment

The S400 turbo is the workhorse of the big-power diesel and drag racing world. It is BorgWarner's 400-frame turbocharger family — the platform behind most 1,000+ horsepower Cummins, Duramax, and Power Stroke builds, and the size class that defines what "big single" means in the diesel performance market.

This guide covers what an S400 actually is, how the sizes are named, what separates a T4 from a T6, and exactly which flanges, clamps, housings, and drains you need to make one bolt to your build. Black Sheep Industries manufactures S400 fitment hardware in-house and builds the True North Turbos TNT4R 400-frame turbocharger line in Canada.

What Is an S400 Turbo?

"S400" refers to BorgWarner's 400-frame turbocharger series — most commonly sold today as the S400SX and S400SX-E. The number does not describe the compressor size. It describes the frame: the center housing rotating assembly (CHRA), bearing system, and the physical envelope the compressor and turbine wheels live in.

Within that one frame, manufacturers offer a wide range of compressor wheels. That is why you will see S464, S467, S472, S475, S476, S480, S483, S485, and S488 — all of them are S400-frame turbos, and all of them share the same core architecture, oil feed and drain geometry, and mounting hardware.

The S400 originated in heavy-duty commercial diesel applications — Detroit Diesel, Cummins ISX, and similar over-the-road engines — before the performance aftermarket adopted it as the default single-turbo upgrade for high-horsepower builds.

What Does the Number After "S4" Mean?

The two digits following the frame designation refer to the compressor wheel inducer diameter in millimetres. An S467 has a 67mm (2.64") compressor inducer. An S480 has an 80mm (3.15") inducer. An S488 has an 88mm (3.46") inducer.

Larger inducer means more airflow and more horsepower potential — but also more rotational mass, later spool, and higher exhaust energy required to get the wheel moving. Sizing an S400 is a trade between how much power you want and how early you want it.

S400 Turbo Sizes and Power Ranges

Every S400 uses the same frame, so stepping up in size does not change your mounting hardware — only the airflow. Here is how the common sizes map to real-world power on a well-built diesel:

Size Compressor Inducer US Standard Typical Application Approx. Power Range
S464 / S467 64–67mm 2.52–2.64" Street, towing, sled pull entry, first big single 820–995 HP
S472 72mm 2.83" Street/strip, compound top charger 995–1110 HP
S475 / S476 75–76mm 2.95–2.99" The most popular all-around S400 size 1,110–1,230 HP
S480 80mm 3.15" Serious drag and pulling builds 1,230–1,405 HP
S483 / S485 83–85mm 3.27–3.35" Dedicated race, large-displacement 1,400–1,520 HP
S488 88mm 3.46" Top of the 400 frame 1,520+ HP

Power figures are directional and depend heavily on displacement, fuel system, head studs, tune, and turbine housing selection. A 6.7L Cummins and a 5.9L will not make identical numbers on the same turbo.

Full sizing walkthrough: What Size S400 Turbo Do I Need?

Replacing an existing turbo? The S400 replacement turbo cross-reference maps S467 through S488 to direct True North Turbos equivalents.

Above 88mm you leave the 400 frame entirely and move into 500-frame territory — see the TNT5R 500-frame turbochargers for 92mm and larger.

Shop S400-Frame Turbochargers

S300 vs S400: What Is the Difference?

This is the most common question builders ask before committing to a manifold and downpipe, and the answer matters because the two frames are not interchangeable.

  • Frame size. The S300 is a smaller 300-frame turbo, typically 57–80mm (2.24–3.15") on the compressor. The S400 is physically larger in every dimension.
  • Where we move you across. Around 820 HP is the point at which we would put you on a 400 frame rather than a 300. An S400 starts near there and runs to 1,520 HP and beyond.
  • Spool. The S300 spools noticeably earlier, which is why it remains the better choice for towing and daily driving.
  • Mounting. Different turbine flange footprints, different exhaust outlets, different oil drain bolt centres. Moving from S300 to S400 means new manifold, new downpipe hardware, and new drain fittings.
  • Compound setups. Many high-power builds run both — an S400 as the atmospheric charger feeding an S300 or stock-frame turbo.

If your target is under 820 HP and the truck tows, an S300 is usually the smarter pick. If you are chasing four-digit power, the S400 frame is where you start.

A note on ceilings versus choices. The largest 300-frame compressors will support four-digit power on paper — the biggest is rated to 1,300 crank HP. That is a compressor ceiling, not a recommendation. At that number the turbo is working at the edge of its map, hot and inefficient, while a 400-frame turbo makes the same power comfortably. The 820 HP figure above is where we would move you across frames, not where the 300 frame stops.

Full comparison: S300 vs S400 Turbo — Which Frame Is Right for Your Build?

Everything about the smaller frame: S300 Turbo Guide: Sizes, Specs, Flanges & Fitment

S400 T4 vs T6: Choosing a Turbine Flange

The turbine inlet flange determines how the turbo mounts to your exhaust manifold. S400 turbos are available in both, and the choice affects manifold selection, flow capacity, and downpipe hardware.

T4 Flange

  • The most common S400 mounting standard, available divided or undivided
  • Wider manifold availability across Cummins, Duramax, and Power Stroke platforms
  • Uses a 4.62" (117mm) half-marmon exhaust outlet
  • Ideal for street/strip builds up to roughly 1,285 HP

T6 Flange

  • Larger flange footprint with more turbine inlet area
  • Better flow at high power, less prone to cracking under heavy load
  • Uses a 5.75" (146mm) marmon exhaust outlet
  • Preferred for 1,285+ HP, sled pulling, and dedicated race applications

Neither flange changes the compressor or the power the turbo can make on its own. It changes the manifold you need and how much turbine-side restriction you carry at high flow. Pick based on your manifold and your power target, not on size alone.

S400 Flanges, Clamps, and Fitment Hardware

This is where most S400 swaps stall. The turbo bolts up, and then the downpipe, the compressor outlet, and the oil drain all need parts that are not in the box. Black Sheep Industries machines this hardware in-house so you are not sourcing four parts from four suppliers.

Exhaust Outlet — T6 Marmon (5.75" / 146mm)

Exhaust Outlet — T4 Half Marmon (4.62" / 117mm)

Compressor Outlet Discharge

Full breakdown, with measuring instructions and a complete SKU table: S400 Turbo Flange Guide

Oil Drain

A drain flange is defined by three independent specs. Get all three right and it fits, flows, and clears.

1. Bolt centre — what physically bolts on. Measure from the centre of one bolt hole to the centre of the other on the turbo's drain pad:

Bolt Centre US Standard Frame Class
38mm 1.50" Small frame
50mm 1.97" Mid frame
50.8mm 2.00" Large frame — this is your S400

Mid and large frame are only 0.8mm apart, about 1/32 of an inch, so measure with calipers rather than a tape.

2. Port size — whether it flows enough oil. Run a 12AN drain on any S400; 10AN is undersized for the frame.

3. Drain length — what it clears on the way out. The figure in each product name below is the length of the drain, meaning how far the drain body stands off the flange face before your hose connects. Pick the shortest one that clears everything around your drain pad.

Running a 300-frame turbo instead? The mid-frame 50mm (1.97") drains and the 10AN-versus-12AN decision are covered in the S300 Turbo Oil Drain Guide.

Full breakdown, with routing rules and a leak diagnosis table: S400 Turbo Oil Drain Guide

Complete Fitment Checklist

  • Turbine inlet: T4 or T6 manifold to match your turbo
  • Exhaust outlet: 5.75" marmon flange + clamp (T6) or 4.62" half marmon flange + clamp (T4)
  • Compressor discharge: V-band flange + clamp sized to your charge pipe
  • Oil feed line and restrictor appropriate to your bearing type
  • Oil drain flange matched to your bolt centre — 50.8mm (2.00") for a large-frame S400 — in a length that clears your install, plus 12AN drain hose and return fitting
  • External wastegate and dump tube if running a divided or open housing
  • Turbo blanket for underhood heat management
  • Turbine and compressor housing gaskets — see replacement o-rings and gaskets

S400 Turbine Housings and A/R

Turbine housing selection has as much effect on how an S400 drives as compressor size does. The A/R ratio controls exhaust gas velocity into the turbine wheel: a smaller A/R spools earlier but restricts at high RPM, a larger A/R gives up low-end response for top-end flow.

Common S400 turbine wheel and housing combinations include 83/74, 87/82, 96/88, and 103/92, in A/R ratios from roughly 0.90 to 1.45.

Picking an A/R

  • 0.90–1.00: Earliest spool. Street trucks, towing-adjacent builds, sled pulling where response off the line matters.
  • 1.10–1.25: The balanced middle. Most street/strip S400 builds land here.
  • 1.32–1.45: Top-end flow. Drag racing and high-RPM applications where you can afford the lag.

The 300 frame does not work this way — its housings run 0.88 open and 0.91 divided, so turbine wheel choice carries the decision instead. See S300 Turbine Wheels and Housings Explained.

Full breakdown: S400 Turbine Housings and A/R Explained

S400 Turbos by Platform

Cummins 5.9L and 6.7L

The 5.9L 12v and 24v Cummins and the 6.7L are the most common S400 hosts. A T4 S467 through S476 is the standard first big single on a built 5.9L; 6.7L builds chasing four digits typically run T6 S480 and up. Both require an aftermarket T4 or T6 manifold and full drain hardware.

Full guide: S400 Turbo for Cummins

Duramax LBZ, LMM, LML, and L5P

Duramax S400 swaps almost always use a T4 or T6 kit with a dedicated manifold and up-pipe setup. Because the Duramax mounts its turbo in the valley, conversions require more fabrication than a Cummins swap — plan for a full kit, not just a turbo.

Full guide: S400 Turbo for Duramax

Power Stroke 6.0L, 6.4L, 6.7L, and 7.3L

The 6.0L Power Stroke is a very common S400 platform — the factory VGT is a known weak point, and an S400 conversion is a durability upgrade as much as a power upgrade. 7.3L builds typically pair an S400 with an intercooler and fuel system upgrade to see the benefit.

Full guide: S400 Turbo for Power Stroke

Compound Setups

An S400 is frequently used as the atmospheric (low-pressure) charger in a compound arrangement, feeding a smaller S300 or factory-frame turbo. This preserves low-end response while giving you the airflow ceiling of the 400 frame — the standard approach for trucks that need to tow and race.

Choosing the Right S400 for Your Build

First Big Single, Street Driven

S467 or S472 on a T4 flange with a 0.90–1.10 A/R. You give up some peak power for spool you can actually use on the street.

Street/Strip, 1,170 HP Target

S476 on T4 or T6, 1.10–1.25 A/R. This is the most common configuration in the diesel performance market for a reason — it does everything reasonably well.

Drag and Pulling, 1,405+ HP

S480 through S488 on a T6 flange, 1.25–1.45 A/R. Fuel system, head studs, and a built transmission are prerequisites, not options.

Compound Top Charger

S472 through S480 depending on the bottom charger. Match the S400 to the manifold pressure your high-pressure turbo will actually see.

Not sure? Send us your build details through the Turbo Spec Form and we will spec it with you.

Why Buy S400 Hardware From Black Sheep Industries

  • S400 flanges, clamps, and drains machined in-house — not resold imports
  • Flange and clamp sold together so fitment is right the first time
  • 304 stainless and aluminum options for every major flange
  • Metric and US standard thread options on drain hardware
  • True North Turbos 400-frame turbochargers designed, assembled, and balanced in Canada
  • Priced in CAD with US customs and duties covered
  • Direct support from people who build these setups, not a call centre

The Complete S400 Guide Series

Sizing and Selection

Fitment and Hardware

By Frame Size

By Platform

The 300 Frame

Shop

Background Reading

Frequently Asked Questions

What is an S400 turbo?

An S400 turbo is a BorgWarner 400-frame turbocharger. The designation refers to the frame size — the center housing, bearing system, and physical envelope — not the compressor wheel. S464, S467, S472, S476, S480, S485, and S488 are all S400-frame turbos with different compressor wheels.

How big is an S400 turbo?

The number after S4 is the compressor inducer diameter in millimetres. S400-frame turbos commonly range from 64mm (2.52") to 88mm (3.46") on the compressor. All of them share the same frame, oil drain geometry, and mounting hardware regardless of compressor size.

How much horsepower can an S400 turbo support?

Depending on compressor size, an S400 typically supports 820 to over 1,520 horsepower. An S467 sits near the bottom of that range and an S488 at the top. Actual output depends on displacement, fuel system, tune, and turbine housing selection.

What is the difference between an S300 and an S400 turbo?

The S300 is a smaller 300-frame turbo, recommended up to about 820 HP, that spools noticeably earlier. The S400 is a larger 400-frame turbo supporting 820 to 1,520+ HP. They use different turbine flanges, exhaust outlets, and oil drain bolt centres, so they are not interchangeable without changing hardware. Note that 820 HP is our crossover recommendation rather than a hard limit on the 300 frame — individual 300-frame compressors are rated higher, up to 1,300 crank on the largest.

What size downpipe flange does an S400 use?

S400 T6 turbos use a 5.75" (146mm) marmon exhaust outlet. S400 T4 turbos use a 4.62" (117mm) half-marmon outlet. Both require a matching flange and quick-release clamp, which Black Sheep Industries sells together as a set.

What size oil drain does an S400 turbo need?

S400 turbos are large frame, which means a 50.8mm (2.00") bolt centre drain flange with a 12AN port. Bolt centre is the distance between the centres of the two bolt holes on the drain pad — 38mm (1.50") is small frame and 50mm (1.97") is mid frame, so measure with calipers before ordering. Drain length, the 35mm/65mm/100mm figure in the product name, is a separate clearance choice.

Should I run a T4 or T6 S400?

T4 is the more common standard with wider manifold availability and works well up to roughly 1,285 HP. T6 offers a larger flange footprint and better flow at high power, and is preferred for 1,285+ HP, sled pulling, and dedicated race builds.

Will an S400 work as a compound turbo?

Yes. S400-frame turbos are commonly used as the atmospheric charger in compound setups, feeding a smaller S300 or factory-frame high-pressure turbo. This preserves low-end response while providing the airflow ceiling of the 400 frame.

Power ratings on this page are quoted in crank horsepower (HP). Figures previously published in wheel horsepower (WHP) have been restated using our in-house tested conversion — the hardware and its capability are unchanged.