Breaking Records with the Solo Motorsports 624HP Time Attack BMW 135i


A Sparco 350 sueded steering wheel and factory pedals let Mr. Fuentes command the 135i as he desires.

The factory shifter has been augmented with a taller shift knob for gear selection on the OEM BMW transmission. Speaking of the transmission and drivetrain, it’s time to get into what makes this golf club hauler go around the track so fast.


The heart of this BMW 135i is an EFR powered 3.0-liter N54 inline six engine.

With Solo’s current configuration as of this article’s writing, this “little” motor put down 624HP and 597 ft/lbs with 28psi of boost being forced through it. They have some upgrades planned, but let’s go through what’s in there now.


We start with a BorgWarner EFR 8374. The BorgWarner EFR 8374 turbocharger has a few turbine side options to choose from and Solo went with the twin scroll T4 option with a 1.05 A/R. It is mated to a DOC Race N54-specific twin-scroll T4 top-mount exhaust manifold. 


The EFR-series is known for having an integrated bypass valve and Turbosmart makes a replacement block-off plate for those that do not wish to use it. Turbosmart has also designed their own Internal Wastegate Actuators and Bypass Valves for the EFR series turbos.


What’s this? It’s a solenoid, dummy.

OK sure, but what is it for? It’s the solenoid that is controlled by the Motiv Motorsport Boost Box. The interesting thing about the Boost Box is that it is designed to work with the factory BMW engine management system.

Solo’s 135i is still using the factory N54 Digital Motor Electronics (DME – they don’t call it an ECU because they’re BMW and it’s not fancy enough). The DME, however, has been re-programmed and re-mapped for Solo’s needs to achieve the power numbers. Working together with the Boost Box, the engine runs like a factory unit, factory key and all, albeit with a lot more horses running around under the hood.

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