S300 Replacement Turbo Cross-Reference: S363 to S380
If you are replacing an S300-frame turbo — because it failed, because it is worn out, or because you are stepping up — this page maps the common BorgWarner S300 sizes to their direct True North Turbos TNT3R equivalents.
Every TNT3R is built to order in Canada with billet compressor and turbine wheels machined from forged 2618, a 360-degree thrust bearing, and the standard T4 bolt pattern.
Cross-Reference Table
| Replacing | Inducer | TNT3R Equivalent | Turbine Wheel Options | Max Power (crank) |
|---|---|---|---|---|
| S362 / S363 / S364 | 63mm (2.48") | TNT363 63mm T4 | 76x68, 80x73 | 940 HP |
| S366 | 66mm (2.60") | TNT366 66mm T4 | 76x68, 80x73 | 1,090 HP |
| S368 / S369 | 69mm (2.72") | TNT369 69mm T4 | 76x68, 80x73, 82x75 | 1,120 HP |
| S371 / S372 | 72mm (2.83") | TNT372 72mm T4 | 76x68, 80x73, 82x75 | 1,140 HP |
| S375 / S376 | 76mm (2.99") | TNT376 76mm T4 | 82x75 | 1,210 HP |
| S380 | 80mm (3.15") | TNT380 80mm T4 | 82x75 | 1,300 HP |
All TNT3R turbochargers are T4, available in .88 A/R open or .91 A/R divided.
The power column is a ceiling, not a recommendation. It is the maximum crank horsepower each compressor will support at the edge of its map. If you are replacing like-for-like it is mostly a sanity check; if you are stepping up, note that our practical crossover to the 400 frame sits around 820 HP, well below the top of this table.
SKU Reference
TNT3R part numbers follow a consistent pattern: model, turbine wheel, then housing type and A/R. TNT3728073D91 is a TNT372 with an 80x73 turbine in a divided 0.91 housing. N88 denotes the open 0.88 housing.
| Model | 76x68 Open | 76x68 Divided | 80x73 Open | 80x73 Divided | 82x75 Open | 82x75 Divided |
|---|---|---|---|---|---|---|
| TNT363 | TNT3637668N88 | TNT3637668D91 | TNT3638073N88 | TNT3638073D91 | — | — |
| TNT366 | TNT3667668N88 | TNT3667668D91 | TNT3668073N88 | TNT3668073D91 | — | — |
| TNT369 | TNT3697668N88 | TNT3697668D91 | TNT3698073N88 | TNT3698073D91 | TNT3698275N88 | TNT3698275D91 |
| TNT372 | TNT3727668N88 | TNT3727668D91 | TNT3728073N88 | TNT3728073D91 | TNT3728275N88 | TNT3728275D91 |
| TNT376 | — | — | — | — | TNT3768275N88 | TNT3768275D91 |
| TNT380 | — | — | — | — | TNT3808275N88 | TNT3808275D91 |
If You Are Coming Off a T3 Flange
Plenty of S300s in service use a T3 turbine inlet — a smaller four-bolt pattern common on older and OEM-derived applications. TNT3R does not offer a T3 turbine housing, so a T3 replacement is not a bolt-in swap.
Moving from T3 to T4 means:
- New exhaust manifold. A T4 manifold, open or divided to match the housing you order. This is the significant cost in the change.
- Possible downpipe work. The turbine discharge is 4.25" marmon on the 300 frame either way, but the turbo will not sit in exactly the same position, so expect to modify or refabricate.
- Wastegate rethink. If the T3 setup relied on an internal wastegate, a T4 open or divided housing generally means an external wastegate and dump tube.
The upside is that T4 is the standard the aftermarket is built around, so manifold availability, housing options and future upgrade paths all get better once you are there.
What Else Changes on a Replacement
Even a like-for-like T4 replacement is a good moment to check three things:
1. Oil Drain
The 300 frame is mid frame: a 50mm (1.97") bolt centre. If the old turbo's drain flange is being reused, confirm the bolt centre with calipers — large frame is 50.8mm (2.00"), only 0.8mm away, and small frame is 38mm (1.50"). A drain flange that has been on a truck for years is also a good candidate for replacement on its own merits.
See the S300 Turbo Oil Drain Guide.
2. Turbine Discharge Clamp
The 4.25" marmon clamp is a wear item. If the old one has been heat-cycled repeatedly, replace it with the flange rather than fighting a leak later.
3. Why the Old One Failed
If the turbo failed rather than simply wore out, replacing it without finding the cause usually means replacing it again. Oil drain restriction, a drain that is not close enough to vertical, and oil feed pressure problems are the common culprits — all covered in the drain guide.
Stepping Up Instead of Replacing Like-for-Like
A failure is the cheapest moment to change size, because the labour is already committed. Before ordering the same thing again:
- If the truck has gained fuel since the original turbo went on, a size up may now be justified.
- If you have been unhappy with response, a smaller turbine wheel on the same compressor is often the fix — see the turbine wheel guide.
- If you are eyeing the top of the frame, compare against a small S400 first. See S300 vs S400.
Not sure what you have or what you need? Send us the details through the Turbo Spec Form and we will identify it with you.
Related Guides
- S300 Turbo Guide: Sizes, Specs, Flanges & Fitment
- What Size S300 Turbo Do I Need?
- S300 Turbine Wheels and Housings Explained
- S300 Turbo Oil Drain Guide
- S400 Replacement Turbo Cross-Reference
Frequently Asked Questions
Is a TNT3R a direct replacement for a BorgWarner S300?
For a T4 S300, yes — TNT3R turbochargers use the standard T4 bolt pattern, the 4.25" marmon turbine discharge and the 50mm (1.97") mid-frame oil drain bolt centre. If the turbo you are replacing is on a T3 flange, a new T4 manifold is required.
What do TNT3R part numbers mean?
The pattern is model, turbine wheel, then housing. TNT3728073D91 is a TNT372 with an 80x73 turbine wheel in a divided 0.91 A/R housing. N88 denotes the open 0.88 A/R housing.
Can I reuse my existing oil drain flange?
Only if the bolt centre matches. The 300 frame is mid frame at 50mm (1.97"). Large frame is 50.8mm (2.00") and small frame is 38mm (1.50"), so measure with calipers rather than assuming. A drain flange that has been in service for years is worth replacing regardless.
What does it take to go from a T3 S300 to a T4?
A T4 exhaust manifold, likely downpipe modification, and generally an external wastegate if the T3 setup used an internal one. TNT3R does not offer a T3 turbine housing, so the manifold change is unavoidable.
My turbo failed — should I find out why before replacing it?
Yes. Oil drain restriction, a drain routed too far from vertical, and oil feed pressure problems are the usual causes, and replacing the turbo without addressing them typically leads to a repeat failure.
Does a bigger replacement turbo mean more power?
Only if the rest of the build supports it. The figures in the cross-reference table are compressor ceilings — 940 HP on a TNT363 up to 1,300 HP on a TNT380 — not what a given truck will make. Fuel system, head studs, tune and turbine housing all cap the real number.
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.