S372 Turbo: Specs, Horsepower & Fitment Guide
The S372 is where the 300 frame stops being a bolt-on and starts being a build decision. A 72mm (2.83") compressor moves serious air for the frame, and it is the first size where the rest of the truck has to be ready for it.
It is also the first size offered with all three turbine wheels, which makes it the most configurable turbo in the range. Black Sheep Industries builds the True North Turbos TNT372 72mm T4 to order in Canada.
S372 Specs
| Compressor inducer | 72mm (2.83") |
|---|---|
| Compressor wheel | Billet, machined from forged 2618 |
| Turbine wheel options | 76x68, 80x73 or 82x75, billet |
| Turbine inlet | T4 bolt pattern, .88 A/R open or .91 A/R divided |
| Turbine discharge | 4.25" marmon |
| Compressor housing | 4" inlet, 2.5" outlet |
| Bearing | Journal, 360-degree thrust bearing |
| Oil drain bolt centre | 50mm (1.97") — mid frame |
| Max power (crank) | 1,140 HP |
Note: on the TNT372 the 1/8" NPT pressure port may need to be drilled through.
The 1,140 HP figure is a compressor ceiling — what the 72mm wheel will support at the edge of its map — not a recommendation. Past roughly 820 HP a 400-frame turbo makes the same power more comfortably, so treat this number as the top of the envelope rather than the target.
What Changes at 72mm
Below this size, an S300 is forgiving. At 72mm three things start to matter that did not before.
The Fuel System Has to Keep Up
A 72mm compressor can move more air than a lightly modified fuel system can match. Buying this size without the fuelling to support it means paying for airflow you never use, and paying for it in spool.
The Turbine Wheel Becomes a Real Decision
With three wheels available, the S372 can be configured as a relatively responsive street turbo or as a top-end-biased strip turbo. Two builders can own the same S372 and describe completely different turbos. Choose deliberately.
The Drain Works Harder
Higher boost and sustained load put more demand on oil return. This is the size where stepping from 10AN to 12AN starts being worth the routing effort, particularly on hard-worked trucks.
Turbine Wheel Choice — All Three Available
| Turbine Wheel | Character | Choose It For |
|---|---|---|
| 76x68 | Earliest response, will restrict at the top | Street-biased builds where you want the 72mm's airflow but refuse to give up low-RPM feel. Accept a top-end ceiling. |
| 80x73 | Balanced | The default. Broadest useful range on this compressor. |
| 82x75 | Most turbine flow, latest response | Strip-biased builds and higher-RPM use, where the exhaust side needs to keep up with the compressor. |
The 76x68 on a 72mm compressor is an intentional mismatch — you are deliberately restricting the exhaust side to buy response. It works, but know that is what you are doing.
See the turbine wheel and housing guide.
Fitment: What You Need to Order
- T4 manifold — open or divided to match the turbine housing. At this power level a divided manifold and divided housing is worth considering for the pulse separation.
- 4.25" marmon turbine discharge flange and clamp — 3.5" or 4". Do not undersize the downpipe here.
- Compressor discharge v-band sized to your charge pipe
- Oil drain flange at 50mm (1.97") bolt centre. 12AN recommended on hard-worked builds.
- External wastegate and dump tube — see wastegates
- Turbo blanket — heat management matters more as power climbs. See turbo blankets.
Full detail: S300 Turbo Flange Guide and S300 Turbo Oil Drain Guide.
S372 or a Small S400?
This is the point in the range where the question becomes legitimate rather than premature.
Stay with the S372 if: the truck is street driven, response still matters, or you already have a T4 manifold and downpipe set up for the 300 frame. Changing frames means changing the turbine discharge from 4.25" to 4.62" and the drain bolt centre from 50mm to 50.8mm.
Look at a small S400 if: the truck is strip-biased, low-RPM response is not a priority, or you are still specifying the manifold. Deciding before the manifold is bought is far cheaper than deciding after.
Full comparison: S300 vs S400 Turbo
Buy the TNT372
- TNT372 72mm T4 — built to order in Canada, billet forged 2618 wheels
- All TNT3R T4 turbochargers
Send your build details through the Turbo Spec Form and we will spec the turbine wheel with you.
Related Guides
- S300 Turbo Guide
- S300 Turbine Wheels and Housings Explained
- S366 Turbo Guide · S376 Turbo Guide
- S300 vs S400 Turbo
Frequently Asked Questions
How much horsepower will an S372 support?
Up to 1,140 crank horsepower. That is the compressor ceiling — what the 72mm wheel will support at the edge of its map — not a build target. Past roughly 820 HP we would generally move you to a 400-frame turbo, which makes the same power with less strain and more room to grow.
Is an S372 too big for a street truck?
Not necessarily, but it depends on the turbine wheel. On the 76x68 it can be configured as a street-usable turbo at the cost of top-end flow. On the 82x75 it is decidedly strip-biased. The compressor alone does not determine how it drives.
Do I need a bigger fuel system for an S372?
A 72mm compressor can move more air than a lightly modified fuel system can match. If the fuelling has not been addressed, the extra airflow over a smaller S300 goes unused while the spool penalty is still paid.
Should I run 10AN or 12AN drain on an S372?
12AN is worth the routing effort at this size on hard-worked builds. Higher boost and sustained load put more demand on oil return than smaller sizes in the frame.
S372 or a small S400?
Stay with the S372 if the truck is street driven, response matters, or the T4 manifold and downpipe are already set up for the 300 frame. Consider a small S400 if the build is strip-biased or the manifold has not been bought yet — changing frames also changes the turbine discharge and drain bolt centre.
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.