The TNT366 66mm T4 is a journal bearing turbocharger built to order in Canada, featuring billet compressor and turbine wheels machined from forged 2618 aluminum. It is the most-installed size in the 300 frame, and it earned that position honestly — 66mm sits at the point where you get a genuine power increase without the truck becoming something you have to drive around.

Key Specs

• 66mm (2.60") inducer, billet compressor wheel
• Maximum 1,090 HP (crank)
• 360-degree thrust bearing with increased thrust surface area
• Optimized compressor stage aerodynamics
• 4" inlet, 2.5" outlet compressor housing
• Boss cast and pre-tapped for a rotor speed sensor
• Standard 1/8" NPT pressure port
• Available with 76x68 or 80x73 turbine wheel, T4 flange (.88 A/R open or .91 A/R divided)
• Interchangeable with existing turbine housings for upgradability

Replaces / Cross-Reference

The TNT366 is a direct bolt-on replacement for the S366 and other 66mm 300-frame turbochargers. Built on the same frame, it uses the mounting hardware you already have:

• Turbine inlet: T4 bolt pattern — fits your existing T4 manifold
• Turbine discharge: 4.25" marmon — same flange and clamp
• Compressor discharge: v-band, sized to your charge pipe
• Oil drain: 50mm (1.97") bolt centre, mid frame — 10AN or 12AN

Full model mapping: S300 replacement cross-reference.

Why the 66mm Is the Default

It does not force a trade-off. Smaller sizes trade top-end for response; larger sizes trade response for top-end. The 66mm sits where most builders find they are giving up neither — the truck still behaves at low RPM and pulls meaningfully harder than stock.

It matches common fuel levels. Most builds reach a single-turbo upgrade with a fuel system that is modified but not extreme. Going larger frequently means buying airflow the fuel system cannot use.

It leaves room to grow. Turbine housings are interchangeable across the frame, so a TNT366 is not a dead end — a wheel or housing change can shift its character without replacing the turbo.

The 80x73 is the more common pairing and the better balance for mixed street and higher-RPM use; the 76x68 is the call if the truck tows or is daily driven. Unlike the TNT363, this one genuinely goes either way — decide on how the truck is driven rather than on the power number.

Frequently Asked Questions

What turbine wheel options are available?

The TNT366 is available with either a 76x68 or 80x73 turbine wheel, in T4 .88 A/R open or .91 A/R divided configurations.

How much horsepower will a TNT366 support?

Up to 1,090 crank horsepower. That is a compressor ceiling rather than a target — what the 66mm wheel will support with the turbo at the edge of its map. Most builds run far below it, and past roughly 820 HP a 400-frame turbo makes the same power with less strain.

Is the TNT366 a direct replacement for an S366?

Yes, for a T4 S366. The T4 bolt pattern, 4.25" marmon turbine discharge and 50mm (1.97") mid-frame oil drain bolt centre all carry over. A T3 turbo requires a new T4 manifold.

Is the TNT366 a good first single turbo?

Yes. It is the most-installed size in the frame precisely because it does not force a trade-off, and interchangeable housings leave room to adjust character later without replacing the turbo.

Is this turbo built to order?

Yes. Every TNT366 is built to order, assembled and balanced in Canada.

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.