With the roll out of the new entry level F30 320i BMW has kicked off a wave of discussion. Most interestingly the 320i and 328i both use the award winning N20; TwinPower single turbo, twin scroll, 2.0 liter inline 4 cylinder engine as the 328i. However the 320i is factory rated at 180 hp at 5,000 RPMs and 200 lb-ft of torque from 1,250 RPMs. On the other hand the 328i comes with 240hp at 5000 RPMs and 255 lb-ft of torque from 1250 RPMs. What happened to the missing 60 horses and 50 lf-ft of power if both cars are N20 powered?
The first obvious answer is something in BMW's DME control software that limits the power, most likely by limiting boost pressure, on the 320i. That appears to be true as both the 320 and the 328 use the same DME hardware (PN - 12148604210) and the same engine control system MEVD 17.2.9. With confirmation their is a software tweak to limit power on the 320i we go in search of other changes that might limit the 320is ability to make the same power the 328i N20 puts down.
Read more about the 2013 BMW 320i entry level 3 series
The next easy target is the intake, exhaust manifold and turbo. Surprisingly they turned out to be the same part number. In fact the 320i and the 328i share almost the exact same part numbers for all the major engine components.
Shared engine components between F30 320i and 328i
- Cylinder head - PN 11127624778
- Connecting rods - PN 11247624616
- Crankshaft - PN 11212212762
- Intake manifold - PN 11617588126
- Air box - PN 13717597589
- Air filter - PN 13718507320
- Intercooler - PN 17517618809
- Radiator - PN 17117600520
- Throttle body - PN 13547588625
- HPFP - PN 13517584461
- MAF - PN 13627602038
- DME/ECU - PN 12148604210
- Exhaust manifold/turbo - PN 11657642469
See what is missing in the above list? The difference in the 320i and the 328i is the pistons. While both have a 10:1 compression ratio the 320i has a different part numbers for the pistons then the 328i. What that exactly means in terms of the ability to boost the turbo pressure and get 328 power from your 320 is not yet known.
Stay tuned as we continue to sift through BMW's technical documents searching for an answer.