Engine & suspension modifications to my BMW 320i

The BMW F30 320i LCI is one of the rarest cars that BMW sold in India. Being a CBU import with 184hp and 270nm, this car never did well in terms of sales in the country due to the existence of the 320d.

BHPian dealer recently shared this with other enthusiasts.

The BMW F30 320i LCI is one of the rarest cars that BMW sold in India. Being a CBU import with 184hp and 270nm, this car never did well in terms of sales in the country due to the existence of the 320d. The 20d had greater torque with the same hp (184hp and 400nm) and in our efficiency centric society, the economy figures of both cars wasn't even comparable. So for the sane-minded the 20d was an obvious pick but for petrol heads, the 20i was still quite alluring (in the absence of the 30i).

Powertrain

In stock form this car is as tame as one can be and while it is decently quick (0-100 in 7.3 seconds), the car was never an enthusiast's delight. The low and midrange had enough oomph to put a smile on the driver's face but the top-end lacked that grunt one's looking for in a fast petrol sedan.
Before purchasing this vehicle, I took time to understand the powertrain and of this vehicle. Knowing that the car came with the B48 engine that was shared with the 330i (*although 20i has higher compression) I knew there was potential to harness the true potential of this engine.

My first step in this journey was installing a bootmod3 stage 1 remap. The experience is highlighted here (BMW 320d & 328i : Official Review). This remap totally transformed the car. Although my cost of ownership skyrocketed due to solely using 99RON or 100RON with the tune, the performance benefits were well worth it. My car was doing a 100-200kmph run in 14.42secs (dragy verified). The 0-100kmph time only came down to a disappointing 5.96secs due to wheelspin and terrible launch conditions (runflats on cement roads).

PS - All runs were/are performed on closed roads.

There was however room for improvement. My goal was to bring 100-200kmph times down to the 12s and to do this, I went ahead and brought a downpipe from MAD-USA and went ahead with a ots stage 2 tune. The ots tune however wasn't well polished and I did not see a performance gain but just an improvement in drivability due to faster turbo spool.

I knew I had to get a custom tune as well as invest in a gearbox tune to reach my target times. Hence last week, I pulled the trigger on a custom stage 2 100 RON tune from Navardi Tuned and a xhp stage 3 gearbox map! While the custom tune is still in progress with 5 revisions already in the past two days, these mods have made turned this docile machine into an absolute rocket ship. Even in the initial stages of the tuning process, my car's pushing out north of 300hp and 450nm of torque. After the tuning process is completed, I intend to get a dyno session at gttunerz, Delhi to actually see the delta created by the custom tune and verify the claimed power figures.

In my opinion even if one chooses not to remap their ECU, the TCU remap is a must for every F30 owner. The car now downshifts lightning fast in manual mode and comfort mode is smoother than stock! The exact benefits of the TCU tune can be looked up here. The TCU tune costed 350USD and the custom Navardi Tune costed an additional 500USD. Both being well worth it in my opinion.

Vehicle Dynamics

As we all know, power is not the only thing required to make a car enjoyable. The F30 exhibited a decent amount of body roll from factory thus taking away from the sports sedan feel of this vehicle. To counteract this, I chose to install a set of Anti Roll Bars. When it came to choosing a set of ARBs, the aftermarket was filled with offerings from eibach, H&R etc. but the endless options only added confusion in the purchase process. This thread on bimmerpost talks about the various options available and highlight the need for balance while installing ARBs as suspension spring rates play a huge roll in their performance. Seeing that I was gonna stick to either stock or a mildly stiffer suspension in the future, I chose to import a set of Front and Rear ARBs from the 440i LCI M Sport as recommended by many in the thread.

The front ARB went from a thin 22.5mm bar to a solid 25.2mm bar and the rear from a 12mm to a 15mm solid bar. These upgraded bars made the car much more direct and my experience with them has been amazing. Little to zero roll in corners with negligible difference in comfort over bumps and rough surfaces. For anyone contemplating the purchase, the part numbers are - Front (6792120) and Rear (6853476).

Fellow 320i owner @PrithwiRay made a video about his experience with ARBs on the 20i that I suggest you watch as It largely resonates with mine.

Boring but much needed mods

The added power of the stage 2 tune called for a much needed brake upgrade thus I chose to order a set of front discs and calipers from the 330i. Although many believe that the F30 generation in India largely share the same brakes, it is not the case for the front brakes but only the rears. The brake packages for the F30 model generation are as follows -

• 320i - 300mm disc upfront with a 54mm single piston caliper.

• 320d - 312mm disc upfront with a 57mm single piston caliper.

• 330i - 330mm disc upfront with a 57mm single piston caliper.

It is interesting to note that the 20d and 30i share calipers but the mounting adapter of the caliper is different thus allowing a larger disc to fit on the 330i. 20d owners looking for an upgrade can simply purchase new discs and the mounting adapter while using the same pads for improved braking performance.

I also performed a basic mod on my intake to improve airflow. More details of which can be found here. (DIY: Intake mod for the BMW 3-Series (F30))

Future Plans

I intend to install a strut brace upfront to make the steering even more direct and add a bit more feel on center. Furthermore, I am in two minds about a bilstein b12 upgrade that might happen if the traffic and road conditions in my city improve (so probably not haha).

Read BHPian comments for more insights and information.