What is the difference between b48b20a and b48b20b?
4 Answers
B48B20A and B48B20B differ in their compression ratios, with the B48B20B having a lower compression ratio. Additionally, the B48B20B offers greater power, higher horsepower, and increased peak torque. Below are the relevant details: 320i powertrain: Equipped with the B48B20A engine, delivering a maximum horsepower of 184Ps/5000rpm (135kw) and a peak torque of 270N·m/1350-4600rpm. 330i powertrain: Equipped with the B48B20B engine, delivering a maximum horsepower of 250Ps/5200rpm (185kw) and a peak torque of 350N·m/1450-4800rpm.
The B48B20A and B48B20B are both BMW's main 2.0T engines, and I've disassembled them many times during repairs. The most obvious difference lies in the power tuning: the A-type is the low-power version, with around 184 horsepower; the B-type starts directly at 252 horsepower, delivering a noticeably stronger push-back feeling. Torque is also key—the B-type boasts at least 350 Nm, making overtaking on highways much easier. In terms of hardware, the B-type features higher piston strength and an upgraded water-cooled intercooler for better cooling efficiency. Pay attention to this when tuning—I've seen cases where someone forcefully tuned an A-type to 300 horsepower, resulting in cracked piston rings. For B-type users, I recommend replacing the turbo pipe with a reinforced one for better stability.
Last time when helping a friend choose a used BMW 3 Series, I specifically researched these two engines. The B48B20B's direct injection pressure is increased to 350bar (compared to 200bar for the A-type), resulting in finer atomization and about 0.5L lower fuel consumption. The ECU programming also differs, with the B-type having more aggressive ignition timing. The most practical difference is in the exhaust note: the B-type produces noticeable pops and crackles on hard acceleration, with the stock exhaust delivering some extra excitement. If you're planning modifications, the B-type has significantly more potential, easily surpassing 300hp with a stage 2 tune. However, be aware that later B-type models come with a GPF particulate filter, which actually limits performance.
My own BMW 5 Series uses the B48B20B engine, while my colleague's identical model has the A-type. The most noticeable difference in daily driving is that the B-type's turbo spools up earlier, delivering maximum torque at just 1500 rpm—it leaps forward with a light tap on the throttle at stoplights. There are subtle adjustments in the engine bay: the B-type has thicker intake piping and a throttle body diameter 5mm larger. During maintenance, I noticed the spark plug specifications differ too; the B-type requires iridium-platinum spark plugs like SILZKGR8B8S. Long-term fuel consumption is similar, but the B-type demands higher-quality oil, specifically 0W-20 low-ash oil.
