This guide will touch on some of the specifics required when you swap in the B48A20T1 aka “B48E” or “B48T1” turbo. The turbo is labelled MGT22Z on the compressor cover! This model number is important besides the OEM part number.
This turbo is found in the following cars: F44 M235iX, F40 M135iX, F39 M35iX and F60 JCW (Mini Cooper).
You may consider this swap as this turbo surpasses current stage 2 turbos for Gen 1 B48s and B48TU equipped cars (This turbo is rated up to 410HP on E85 with a twin scroll internally waste-gated 0.61 A/R turbine housing specs are very close between G25-550 and GTX2860R Gen 2).
This turbo does require a bit more retrofitting for Gen 1 B48s vs B48TU cars, B48 Gen 1 engines found in the Mini Cooper cars do require less adjustments than F series Gen 1 B48s
Please note this guide is not 100% you may experience some of the swap to not be 100% on some cars, if you experienced issues during the swap please let us know so we can add your info to the wiki: navardituned@gmail.com
OEM Part Numbers BMW: 11658658211 11659845817 11658662074
OEM Part Numbers Garrett: MGT2256KSZ 894017-5001S 858537-5010S 858537-5007S 894017-5004S
Below is the required adjustments for F series B48 cars:
On B48TU and B48A20T01 BMW decided to move the location of this bolt hole for the flange in closer to the exhaust port, this poses an issue with correct fitment on Gen 1 B48s. Below are some photos of what our Mini Cooper S community member did for his B48 Gen 1:
Turbo Oil & Coolant Lines:
Turbo Feed Line - The B48E oil line was selected to used (original B48 Gen 1 would clash), but also needed to be modified (OEM 11428629969)
Turbo Drain Line - must use B48E (OEM 11425A028A6)
Turbo Coolant Feed Line - Can use Gen 1 B48 or B48E. (B48 Gen 1 OEM 11537643094) (B48E OEM 11538629971)
Turbo Coolant Drain - can use either B48 or B48E (B48 Gen 1 11537643226) (B48E OEM 11539488188) Photo’s of how the B48 Gen 1turbo coolant feed line can be modified to suit:
You can then cut and slide the coolant hose over this section of the hose and use a hose clip to secure the hose, ensure you apply heat shielding to the hose to ensure it does not melt.
Down Pipe:
re-using the Gen 1 B48 Down Pipe is possible on this turbo swap.
Diverter Valve:
The diverter valve found on the “B48E” is designed to remain closed when it is de-energized and open when powered. Since the B48 Gen 1 cars do not utilize a diverter valve, as a result you have 3 options:
Leave it attached to the turbo and electrically unplugged, it should remain closed under pressure.
Wire it up to a boost activated hobbs switch set to open at your maximum targeted boost pressure (consult with your tuner), this would add addition engine safety over the existing B48 Gen 1 Boost control strategy.
Remove the diverter valve and install a blanking plate, contact kevin@iposmotorsport.com if you would like their design of blanking plate. Alternatively you can have your shop fabricate something.
IPOS DV Blanking Plate:
Valve Cover Heat Shield:
The factory B48 Gen 1 heat shield that protects and deflects heat from the turbo onto the plastic valve cover has to be modified to prevent issues with interference with the wastegate actuator. To get around this issue you have 2 options:
Cut the factory Gen 1 B48 Heat Shield to suit.
Buy and install the “B48E” Heat Shield.
Heat Shield cut to fit
Turbo Intake:
OEM Mini Cooper (or aftermarket) Intakes work for this turbo and do no require modification.
Turbo Charge-Pipe Outlet:
OEM Mini Cooper (or aftermarket) Charge-Pipes work on this turbo without modification.