S363 Turbo: Specs, Horsepower & Fitment Guide
The S363 is the entry point to the 300 frame — a 63mm (2.48") compressor in a turbo chosen for how quickly it responds rather than for how much air it moves. It is the size for builders who want a real step up from stock without giving up the low-RPM behaviour that makes a diesel usable.
Black Sheep Industries builds the True North Turbos TNT363 63mm T4 to order in Canada.
S363 Specs
| Compressor inducer | 63mm (2.48") |
|---|---|
| Compressor wheel | Billet, machined from forged 2618 |
| Turbine wheel options | 76x68 or 80x73, 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) | 940 HP |
The centre housing carries a boss cast and pre-tapped for a rotor speed sensor, plus a standard 1/8" NPT pressure port.
The 940 HP figure is a compressor ceiling — what the wheel will support at the edge of its map — not a build target. Very few S363 builds are pointed at that number, and it is not where we would advise running one.
Where the S363 Fits
The First Real Upgrade
If the truck is stock or lightly modified and you want more without changing its character, this is the size. A 63mm compressor is enough airflow to feel like a different truck while still lighting up early enough to be useful merging, climbing and pulling away from a stop.
Towing and Hauling
Towing is a low-RPM, sustained-load job. The S363 is well suited to it precisely because it is small — boost arrives when the load does, rather than after you have already lost momentum on a grade.
Compound High-Pressure Charger
The S363 is a common choice as the high-pressure turbo in a compound arrangement, fed by a larger atmospheric charger. In that position it is breathing already-compressed air, so a 63mm compressor moves considerably more mass than it would as a standalone. Builders regularly find the S363 is the right high-pressure turbo on setups where they would never consider it as a single.
Turbine Wheel Choice
The S363 is offered with two turbine wheels, and on a compressor this size the choice matters.
- 76x68 — the quickest-responding combination in the entire 300 frame. Choose it for towing, daily driving and compound high-pressure duty.
- 80x73 — more turbine flow, slightly softer off idle. Choose it if the truck sees higher RPM use or you want a little more room at the top.
Given that response is the reason to buy a 63mm in the first place, the 76x68 is the more consistent choice here than it is further up the range.
See the turbine wheel and housing guide for the full picture.
Fitment: What You Need to Order
- T4 manifold — open or divided to match the turbine housing you choose
- 4.25" marmon turbine discharge flange and clamp — available in 3", 3.5" and 4". On an S363 a 3" downpipe is usually adequate.
- Compressor discharge v-band sized to your charge pipe
- Oil drain flange at 50mm (1.97") bolt centre. A 10AN mid-frame drain is generally sufficient at this size unless the truck works hard.
- External wastegate and dump tube — see wastegates
Full detail: S300 Turbo Flange Guide and S300 Turbo Oil Drain Guide.
S363 vs the Next Size Up
The honest comparison is against the S366. Three millimetres of inducer is not a dramatic difference, and if you are torn, the S366 is the more common all-round choice.
Stay at 63mm if: the truck tows regularly, it is daily driven, you value response over peak, or it is going in the high-pressure position of a compound setup.
Step to 66mm if: the truck sees higher RPM use, you have fuel to support it, or you expect the build to grow.
Buy the TNT363
- TNT363 63mm T4 — built to order in Canada, billet forged 2618 wheels
- All TNT3R T4 turbochargers
Not sure it is the right size? Send your build details through the Turbo Spec Form.
Related Guides
- S300 Turbo Guide
- What Size S300 Turbo Do I Need?
- S366 Turbo Guide
- S300 Replacement Turbo Cross-Reference
Frequently Asked Questions
How much horsepower will an S363 support?
Up to 940 crank horsepower. That is a compressor ceiling rather than a build target — the number the 63mm wheel will support with the turbo working at the edge of its map. Most S363 builds sit far below it, and if you are planning past roughly 820 HP it is worth comparing against a 400-frame turbo before ordering.
Is an S363 good for towing?
Yes. Towing is a low-RPM, sustained-load job and the S363 suits it because it is small enough to build boost when the load arrives rather than after you have lost momentum.
What turbine wheel should I run on an S363?
The 76x68 is the quickest-responding option and generally the better match on a 63mm compressor, particularly for towing, daily driving and compound high-pressure duty. The 80x73 offers more turbine flow for higher-RPM use.
Can an S363 be used as a compound high-pressure turbo?
Yes, and it is a common choice. In the high-pressure position it breathes air already compressed by the atmospheric charger, so it flows considerably more mass than it would as a standalone turbo.
What oil drain does an S363 need?
A 50mm (1.97") bolt centre mid-frame drain flange. 10AN is generally sufficient at this size unless the truck works hard, in which case 12AN gives more margin.
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.