2012 BMW 328i - N20 Evolution

Pushing the limits of the 328i’s 2.0L N20 turbo motor

Clearly Fred Su, the owner of Evolution Racewerks, knew something I didn't when he declined to ride shotgun during my test drive of his modified 328i. "Motion sickness," he claimed, but there was more to it than that...

Having just completed a full line of upgrades on his '12 F30 328i, Su knew he had created a monster and was concerned that a ride in the passenger seat would induce terror rather than motion sickness.

This ER 328i first appeared in EC 10/12 as the test mule for Su's new intake and downpipe. Coupled with a Burger Motorsports Juicebox engine management system, the setup netted an average of 35whp and 36 lb-ft over the baseline, resulting in best dyno runs of 271whp and 292 lb-ft of torque. To give you an idea, these numbers produced by the N20 2.0-liter four-cylinder turbo engine are similar to or better than we've seen from the stock N55 3.0L six-cylinder turbo.

Since that first test, Evolution Racewerks added its new intercooler, charge pipe and exhaust system. Burger Motorsports also introduced a stage 2 tune for the car to exploit the lower intake temps.

The new ER intercooler has double the frontal surface area of the stock part. It measures 20x11" (versus 20x5.5" stock) and features high-density bar-and-plate cores with more cooling fins than regular intercoolers (18-20 fins per square inch vs 14-16 fins/sqin stock).

The new charge pipe has been made from 6061 aluminum and was, therefore, stiffer than the stock plastic pipe, which was never designed to handle higher boost pressure. The new part was also mandrel bent for smoother airflow, benefiting turbo and throttle response.

The new exhaust is referred to as a "modular" system. Its 3" stainless steel piping was cut in sections of standardized length that can be attached with V-band connectors, allowing easy changes between the downpipe, mid-pipe and rear sections. It means owners can switch from a street exhaust with mufflers to a track setup without mufflers in as little as 5min.

The Stage 2 Burger Motorsports software raised boost from 21psi to the 23.38psi it registered during the strongest dyno run we witnessed on the european auto source Mustang Dyno.

With its new parts, the 2.0L turbo motor produced an impressive 312whp at 5400rpm and 355 lb-ft at 3100rpm. This amounted to a gain of 51whp and 63 lb-ft to the wheels.

Even with its improved air flow, drivability hasn't suffered. It still only required a light throttle and little boost for the twin-scroll turbo to blend into stop-and-go traffic. A look at the dyno graph showed there was slightly more torque than stock at 2100rpm and, by 2500rpm, ER's setup gave more than 300 lb-ft at the wheels. This was more than the stock 335i produced at maximum and dwarfed the stock 328i maximum output of 220 lb-ft.

Fred Su confirmed that his test showed the dual exhaust sacrificed some torque in the low- and mid-range when compared to a single-pipe system, but the dual setup made better power in the second half of the rev range. Consequently, ER offers both single- and dual-pipe exhaust systems for the F30 328i.

As one of the most highly modified N20 conversions available, when you want to achieve serious speed, the Evolution Racewerks engine responds willingly. It provides a hefty shove of torque that transitions to horsepower as the revs climb. Yet with power peaking at 5400rpm, and seeming to drop off quickly after that, you don't have to redline the engine. Instead, we would short-shift to keep the motor on the boil, then glance at the speedo to realize you're making the kind of progress normally associated with BMW's M products.

The speed is deceptive, as the F30 chassis is extremely composed. Yet ER tightened it further with a set of CKS C1 coilovers that utilized Swift springs and wider 235/35 front and 265/35 R19 rear Toyo Proxes T1 Sport tires. These were mounted on 19x9" front, 19x10" rear MORR VS8.2 flow-formed wheels.

During our drive, the coilovers were set at six on a scale of ten, making them well suited to both daily driving and high-speed work, especially since the lighter N20 helps the car turn-in to corners more eagerly than the heavier 335i. While the Toyos stuck like fresh epoxy resin, holding a tight line through all kinds of turns.

Slicing through a series of long, fast, sweeping turns at ridiculous speed was easy, with only your comfort level with nearby guardrails, canyon walls and steep descents governing the pace. And after several miles of exploring the car's limits, it was easy to understand why Su declined the ride-along. Yet he should have known the six-piston Brembo front calipers, along with braided lines meant the brake pedal provided a strong bite and good modulation.

On the outside, ER's 328i was the epitome of clean, featuring subtle but distinctive touches such as the 6 Series M Sport front bumper conversion executed by our friends at LTMotorwerks. It fuses the 645i M Sport bumpers' lower section to the stock 328i upper.

The car also wore a pair of BMW M Sport side skirts, carbon fiber rear spoiler and rear bumper with a 335i dual outlet valance and diffuser. The overall effect was a car that gets itself noticed but without fully hinting at its true speed potential.

Many people lamented the loss of the normally aspirated straight-six engine when BMW introduced the N20 2.0T in the F30 328i but, with emissions and fuel economy regulations getting tougher, the BMW turbo engine is winning many fans. And while it lacks the smoothness of the N55 engine, ER's tuning program shows that extracting more power is a lot easier than the comparatively small gains you'd get from an ECU tune and exhaust on the naturally aspirated motor. With the right parts, the power gains are similar to a mildly-modified N55. So for minimal expense, you can punch with the heavyweights while benefiting from improved cornering and better economy that the 328i provides.