B48E Turbo Retrofit - Mini Cooper Guide

B48A20T1 Turbo Retrofit Guide for Gen 1 B48 Mini Cooper vehicles.

Mini Cooper Advantage: B48 Gen 1 engines in Mini Cooper cars require less adjustments than F Series Gen 1 B48s. OEM intake and charge pipes work without modification!

This guide covers the specifics required when swapping in the B48A20T1 (also known as "B48E" or "B48T1") turbo. The turbo is labelled MGT22Z on the compressor cover.

Found in: F44 M235iX, F40 M135iX, F39 M35iX, F60 JCW (Mini Cooper)

This turbo surpasses current Stage 2 turbos for Gen 1 B48s and B48TU equipped cars. Rated up to 410HP on E85 with a twin-scroll internally waste-gated 0.61 A/R turbine housing.

This guide is not 100% complete. You may experience some issues during the swap on some cars.

If you experienced issues, please let us know: [email protected]

OEM Part Numbers

BMW Part Numbers

11658658211

11659845817

11658662074

Garrett Part Numbers

MGT2256KSZ

894017-5001S

858537-5010S

858537-5007S

894017-5004S

Turbo Manifold Cylinder 4 Mounting Flange

On B48TU and B48A20T01, BMW moved the bolt hole location for the cylinder 4 flange closer to the exhaust port. Below are photos showing how our Mini Cooper S community member addressed this:

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Turbo Oil & Coolant Lines

Part	Options	Part Numbers
Turbo Oil Feed Line	B48E recommended (original B48 Gen 1 would clash), needs modification	B48E: 11428629969
Turbo Oil Drain Line	Must use B48E	B48E: 11425A028A6
Turbo Coolant Feed Line	Can use Gen 1 B48 or B48E	B48 Gen 1: 11537643094 \| B48E: 11538629971
Turbo Coolant Drain	Can use either B48 or B48E	B48 Gen 1: 11537643226 \| B48E: 11539488188

Coolant Feed Line Modification

Cut and slide the coolant hose over the fitting section, secure with a hose clip. Apply heat shielding to ensure the hose does not melt.

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Down Pipe

Re-using the Gen 1 B48 Down Pipe is possible on this turbo swap.

Diverter Valve

The B48E diverter valve is designed to remain closed when de-energized and open when powered. Since B48 Gen 1 cars don't utilize a diverter valve, you have 3 options:

1.Leave it attached to the turbo and electrically unplugged - it should remain closed under pressure.

2.Wire it up to a boost-activated hobbs switch set to open at your maximum targeted boost pressure (consult with your tuner) - adds additional engine safety.

3.Remove the diverter valve and install a blanking plate. Contact [email protected] for their design, or have your shop fabricate one.

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IPOS DV Blanking Plate

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Valve Cover Heat Shield

The factory B48 Gen 1 heat shield must be modified to prevent interference with the wastegate actuator. Two options:

Cut the factory Gen 1 B48 Heat Shield to suit
Buy and install the B48E Heat Shield

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Heat shield cut to fit

Turbo Intake

No Modification Required! OEM Mini Cooper (or aftermarket) intakes work for this turbo and do not require modification.

Turbo Charge-Pipe Outlet

No Modification Required! OEM Mini Cooper (or aftermarket) Charge-Pipes work on this turbo without modification.

F Series Retrofit Guide G Series Retrofit Guide