[AustinYellowMakesMeHard]

As far as I can make out, everything about these two engines are identical bar hp and torque. So are 420i owners an ECU flash away from unlocking a "428i" or is there something I'm missing?

http://en.wikipedia.org/wiki/BMW_N20

http://www.bmw.com/com/en/newvehicle...i&model_2=428i

[ibimmer954]

Yes, you can tune the less powerful engine to get it up to as much power as the 28i engine. But you will be voiding your engine warranty if you care about that kind of thing. The internals of the engines are different, so they aren't "identical".

[bahasad]

Originally Posted by AustinYellowMakesMeHard

As far as I can make out, everything about these two engines are identical bar hp and torque. So are 420i owners an ECU flash away from unlocking a "428i" or is there something I'm missing?

http://en.wikipedia.org/wiki/BMW_N20

http://www.bmw.com/com/en/newvehicle...i&model_2=428i

They do not sell the 420I in North America. It is only available in 428I form.

Both engines can be modded to produce more HP than their stock numbers. A modded 20i will be at stock 28i numbers (maybe an additional 10-15 HP), and a modded 28i will be at stock 35i numbers (maybe an additional 10-15 HP).

[AustinYellowMakesMeHard]

Originally Posted by ibimmer346

Yes, you can tune the less powerful engine to get it up to as much power as the 28i engine. But you will be voiding your engine warranty if you care about that kind of thing. The internals of the engines are different, so they aren't "identical".

Do you know what exactly is different ? I'm just curious as to how BMW managed to extract 60 more HP and 80 Nm of torque.

[JayRusso]

The 3/420i variants of the N20 have different pistons. I believe that was done to increase the compression ratio (10:1 vs 11:1). In addition, the PSI is much lower (8 vs 18).

It can be tuned to be similar HP, but be careful because the higher compression ratio will not handle the same amount of boost.

- Jason

[AustinYellowMakesMeHard]

Originally Posted by JayRusso

The 3/420i variants of the N20 have different pistons. I believe that was done to increase the compression ratio (10:1 vs 11:1). In addition, the PSI is much lower (8 vs 18).

It can be tuned to be similar HP, but be careful because the higher compression ratio will not handle the same amount of boost.

- Jason

ah that makes sense. Thanks

Btw I don't have a 420i, I've put down an order for a 428i. I was just curious as to how the 428i has so much more HP and Torque.