S376 Turbo: Specs, Horsepower & Fitment Guide
The S376 is the top of the 300 frame in practical terms — a 76mm (2.99") compressor in a 300-frame centre section, paired with the largest turbine wheel the frame offers.
It is also the size most often ordered by mistake, because an S476 exists and the two are not the same turbo. That is covered below, and if you are shopping by compressor number alone it is the most important section on this page.
Black Sheep Industries builds the True North Turbos TNT376 76mm T4 to order in Canada.
S376 Specs
| Compressor wheel | 76mm x 102mm, billet, machined from forged 2618 |
|---|---|
| Compressor inducer | 76mm (2.99") |
| Turbine wheel | 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 |
| Rotor speed sensor boss | Cast and pre-tapped, M6x0.5 |
| Oil drain bolt centre | 50mm (1.97") — mid frame |
| Max power (crank) | 1,210 HP |
The S376 is offered with the 82x75 turbine only. At this compressor size a smaller turbine wheel would become the limiting restriction, so the pairing is fixed rather than optional.
The 1,210 HP figure is a compressor ceiling, not a recommendation. It describes what the 76mm wheel will support at the edge of its map. Our practical crossover to the 400 frame sits around 820 HP, so if you are buying an S376 to chase a four-digit number, read the frame comparison below before you commit to a manifold.
S376 vs S476: Not the Same Turbo
Both have a 76mm compressor. That is where the similarity ends.
| S376 | S476 | |
|---|---|---|
| Frame | 300 frame | 400 frame |
| Compressor inducer | 76mm (2.99") | 76mm (2.99") |
| Centre section | Physically smaller | Physically larger |
| Turbine discharge | 4.25" marmon | 4.62" (117mm) half marmon on T4, 5.75" (146mm) marmon on T6 |
| Oil drain bolt centre | 50mm (1.97") — mid frame | 50.8mm (2.00") — large frame |
| Turbine flange | T4 only | T4 or T6 |
| Response | Earlier | Later |
What this means practically: none of the fitment hardware carries over. Different downpipe flange, different clamp, different drain flange. If you order an S376 expecting S476 hardware to bolt up, nothing on the exhaust side will fit.
The 4.25" and 4.62" marmon flanges are the specific trap — they are close enough to look identical in a photograph and they will not clamp. See the S300 Turbo Flange Guide.
Which One Should You Actually Buy?
If you have arrived at 76mm and are choosing between frames:
- S376 if response matters, the truck is street driven, or you are already committed to 300-frame hardware. You get the 76mm airflow with earlier onset than the 400 frame delivers.
- S476 if the build is strip or pull oriented, if you want T6 as an option, or if you expect to grow past what the 300 frame supports. The larger centre section has more headroom.
See the S400 Turbo Guide and the S300 vs S400 comparison.
What the Build Needs at This Size
The S376 sits at the top of its frame, and everything around it has to be sorted.
- Fuel system. Non-negotiable at this airflow. A 76mm compressor on inadequate fuelling makes less usable power than a smaller turbo on adequate fuelling.
- Drain. 12AN at the 50mm (1.97") mid-frame bolt centre. This is not the size to economise on oil return.
- Downpipe. 4" off the 4.25" marmon. Restricting the exhaust here undoes the reason you bought a 76mm.
- Heat management. A turbo blanket is worth having.
- Head studs and transmission. Prerequisites, not options.
Fitment: What You Need to Order
- T4 manifold — open or divided to match the turbine housing
- 4.25" marmon turbine discharge flange and clamp — 4" recommended at this size
- Compressor discharge v-band sized to your charge pipe
- 12AN oil drain flange at 50mm (1.97") bolt centre, in a length that clears your install
- External wastegate and dump tube — see wastegates
Full detail: S300 Turbo Flange Guide and S300 Turbo Oil Drain Guide.
Buy the TNT376
- TNT376 76mm T4 — built to order in Canada, 82x75 turbine, billet forged 2618 wheels
- TNT380 80mm T4 — the next size up in the frame
- All TNT3R T4 turbochargers
Deciding between frames? Send your build details through the Turbo Spec Form and we will work through it with you before you buy a manifold.
Related Guides
Frequently Asked Questions
How much horsepower will an S376 support?
Up to 1,210 crank horsepower. That is the compressor ceiling — what the 76mm wheel will support at the edge of its map — rather than a build target. Around 820 HP is where we would normally move you to a 400-frame turbo, which makes the same power with less strain and more headroom.
What is the difference between an S376 and an S476?
Both use a 76mm compressor, but the S376 is a 300-frame turbo and the S476 is a 400-frame turbo. They have different centre sections, different turbine discharges — 4.25" marmon against 4.62" or 5.75" — and different oil drain bolt centres, 50mm (1.97") against 50.8mm (2.00"). None of the fitment hardware carries over between them.
Will S476 hardware fit an S376?
No. The turbine discharge flange, clamp and oil drain flange are all different. The 4.25" and 4.62" marmon flanges in particular look nearly identical but will not clamp together.
Why is the S376 only offered with the 82x75 turbine?
At a 76mm compressor size, a smaller turbine wheel becomes the limiting restriction on the whole setup. The pairing is fixed rather than optional because the alternatives would cap the turbo.
Should I buy an S376 or step up to the 400 frame?
Choose the S376 if response matters, the truck is street driven, or you are already committed to 300-frame hardware. Choose a 400-frame turbo if the build is strip or pull oriented, you want T6 as an option, or you expect to outgrow the 300 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.