Garrett GT4094R Turbocharger: Specs, Sizing & Performance Build Guide

The Garrett GT4094R Turbocharger is a GT40-frame, dual ball-bearing unit built for high-horsepower gasoline builds, and it sits in the sweet spot between a GT3582R and the bigger GT42-class turbos. If you are sizing a turbo for a serious street or race engine, the GT4094R gives you a large 94 mm compressor wheel on a proven ball-bearing cartridge with the quick spool that bearing cartridge is known for. This guide walks through its real specs, how to size it, and what the number on the nameplate actually tells you.

PT Turbo has been rebuilding turbochargers since 1978, more than 45 years, and we stock both new and remanufactured turbos along with CHRAs, housings and wheels. You can see everything we list for this model on our GT4094R turbochargers page.

Garrett GT4094R Turbocharger: Core Specs

In the Garrett naming system the first two digits are the frame size and the last two are the compressor wheel outer diameter in millimeters. So the GT4094R runs a GT40 frame with a 94 mm compressor wheel, and the R marks a ball-bearing cartridge. It carries the same outline as the GT4088R, oil and water cooled, which makes plumbing straightforward on most dedicated performance builds.

Here are the figures Garrett published for this turbo:

Specification	GT4094R
Frame	GT40 series
Bearing type	Dual ball bearing
Cooling	Oil and water cooled
Compressor wheel	67.8 / 94.0 mm, 52 trim
Compressor housing A/R	0.72
Turbine wheel	77 mm, 78 trim
Turbine housing A/R	0.85 to 1.19 (by part number)
Horsepower range (Garrett)	450 to 800 hp
Engine size (Garrett)	2.0 to 5.7 L (6.0 L in the 2015 catalog)

Garrett lists this turbo for gasoline performance engines and names no diesel application for it, so do not confuse it with the GT4094VA (773542), a variable-geometry turbo in our catalog that is a completely different unit. The GT4094R is a fixed-geometry ball-bearing turbo, not a VGT.

Part numbers and what you actually buy

The GT4094R family runs part numbers 751470-19 through -22, differing mainly by the turbine housing A/R. Our catalog lists the complete unit as 751470-5019S, along with a balanced CHRA, individual housings and a compressor wheel. In a Garrett number, the first digit after the dash tells you the sales channel: a 5 is new aftermarket and a 9 is remanufactured.

Because the turbine housing determines how early this turbo lights, the A/R you pick matters more than almost any other choice. A tighter 0.85 housing spools sooner at the cost of top-end flow; a 1.19 opens the top end but asks for more exhaust energy to get moving. Match the housing to your engine’s displacement and target RPM, and confirm the number stamped on the nameplate rather than guessing from a casting.

How to Size the GT4094R for Your Build

The 94 mm compressor wheel is the headline. That wheel can feed a lot of air, and Garrett’s 450 to 800 hp window is realistic on the right engine with the right supporting parts. On a small-displacement four-cylinder it is a big turbo that will spool late; on a V8 in the 5.0 to 5.7 L range it is far better matched and comes alive much sooner.

A good rule of thumb for airflow is roughly 0.10 lb/min of air per horsepower on a gasoline engine. Run your power target through that figure, then lay it against a GT40-series compressor map to confirm you land in the efficient center of the map rather than out on the surge line or choke edge. Sizing to the map is how you avoid a turbo that is technically “big enough” but running hot and inefficient at your boost target.

• Displacement: larger engines move the 94 mm wheel into its happy zone and cut spool time.
• Target boost and RPM: set your airflow number, then verify it sits mid-map.
• Turbine housing A/R: tighter for response, larger for top-end flow.
• Fuel and tune: a 94 mm wheel at full flow needs injectors, pump and a calibration that keep up.

Compressor surge is caused by a compressor that is too large for the engine’s airflow at a given operating point, not by an undersized turbo. If you oversize the GT4094R onto a small engine and ask for high boost at low engine speed, you can push the operating point into the surge region. Picking the turbine housing and boost target off the map keeps you clear of that.

Why a Ball-Bearing Cartridge Matters

The R in GT4094R means a dual ball-bearing cartridge rather than a floating journal bearing. The shaft rides on balls that handle thrust and radial load, while oil lubricates and damps the bearing. The practical payoff is faster spool and better transient response, which is exactly what you want from a large-frame turbo that would otherwise feel lazy off boost.

Ball-bearing cartridges also use an oil restrictor at the feed, unlike a journal-bearing turbo that typically runs a larger unrestricted feed. If you are plumbing one of these, follow Garrett’s oil feed guidance for the cartridge and do not add a second restrictor on top of a built-in one. For background on how turbochargers work, this overview is a solid primer, and Garrett’s own site carries the current maps and part data.

Checking shaft play on a used unit

On any turbo, some side-to-side rock at the wheel is normal; it is in-and-out play you can feel, or any wheel contact with the housing, that condemns a cartridge. Spin the wheels and look at the leading edges of the compressor and turbine blades for damage. Blade damage means the wheel is replaced, never cleaned up and reused.

GT4094R vs Other Garrett Performance Options

The GT4094R came out of the GT40R family and overlaps in power with several newer Garrett turbos. If you are shopping across the line, here is how the frame sits against common alternatives in our catalog. The newer G-Series names work differently: the number after the dash is a horsepower rating, not a wheel size, as on the G35-1050.

Model	Bearing	Notes
GT4094R	Dual ball bearing	94 mm compressor, 77 mm turbine, 450-800 hp
GTX4088R	Dual ball bearing	GTX generation, upgraded compressor aero
G35-900	Ceramic ball bearing	G-Series, rated by horsepower in the name
G40-900	Ceramic ball bearing	Larger G-frame for higher-flow builds

GTX and G-Series cartridges use newer compressor aero and ceramic ball bearings, which is where Garrett has put its current development. The GT4094R remains a strong choice when you want a proven GT40R unit with the exact 94 mm wheel and the housing options this family offers. Match the turbine housing A/R to your engine either way, and go by the map rather than the frame name alone.

Buying New, Reman or Rebuilding Your GT4094R

PT Turbo lists this model new, along with a CHRA, housings and a compressor wheel, and we also rebuild your own cartridge in-house. A rebuild kit holds the bearings, seal rings and thrust parts; the cartridge is then balanced on a VSR before it ships. On most rebuilds we ship in 3 days or less, with the rebuild price confirmed after inspection and before any work starts.

Option	What you get	Best when
New	Factory-fresh unit	You want an unused unit, no core
Remanufactured	Balanced, tested, core return in 30 days	You want quality for less, have a core
Rebuild your core	Your housings, new internals, VSR balanced	You want to keep your exact unit and housings

Remanufactured units carry a 30-day core return and come with our 12-month, unlimited-mileage warranty, same as new. If you need longer than 30 days on a core, call ahead and we can usually work with you. For real pricing on a rebuild, see our turbo rebuild price list, and you can start a job on our rebuild service page. You can also browse remanufactured turbochargers or reach us through our contact page.

For first start after a rebuild or install, follow the maker’s first-start steps: fill the oil inlet with clean engine oil, turn the wheel by hand, then crank or idle a few minutes before putting it under load. There is no break-in mileage schedule and no early oil change tied to the turbo itself.

Frequently Asked Questions

Is the Garrett GT4094R a diesel turbo?

No. Garrett lists the GT4094R for gasoline performance engines and names no diesel fitment for it, rating it 450 to 800 hp on 2.0 to 5.7 L engines. The similarly numbered GT4094VA (773542) is a different, variable-geometry turbo, so match the number on the nameplate before you order.

What size compressor and turbine wheels does it use?

The GT4094R runs a 67.8 / 94.0 mm compressor wheel at 52 trim in a 0.72 A/R housing, with a 77 mm, 78 trim turbine wheel. Turbine housings in this family range from 0.85 to 1.19 A/R depending on the part number, which is what controls spool versus top-end flow.

Can PT Turbo rebuild my GT4094R?

Yes. We rebuild GT40-series cartridges in-house with new bearings, seals and thrust parts, then VSR balance them, and our catalog also lists a new unit, a CHRA, housings and a compressor wheel. Send us the number on your nameplate and we will confirm exactly what fits; current pricing is on our rebuild price list or by phone at (909) 824-1020.