Engine vs Engine - 320i to 328i - Where is the missing 60HP?

[tim330i]

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.

[phoenix155]

Originally Posted by tim330i

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.

...

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.

If it turns out that all that's needed to match the 328i's power is a software update and piston swap...the 320i might be the poor man's tuner. ;-)

[davidwarren]

Originally Posted by phoenix155

If it turns out that all that's needed to match the 328i's power is a software update and piston swap...the 320i might be the poor man's tuner. ;-)

once you buy new software, and have the entire engine rebuilt, are you really saving anything?

[phoenix155]

Originally Posted by davidwarren

once you buy new software, and have the entire engine rebuilt, are you really saving anything?

Why would you need to rebuild the entire engine? A computer flash (say this and to just replace the pistons (I didn't look at the price) couldn't possibly add up to $3000, could it? If I'm wrong, I'm wrong, but it's just a thought. :-)

[davidwarren]

Originally Posted by phoenix155

Why would you need to rebuild the entire engine? A computer flash (say this and to just replace the pistons (I didn't look at the price) couldn't possibly add up to $3000, could it? If I'm wrong, I'm wrong, but it's just a thought. :-)

you're right, I have no data to back me up, but software + new pistons + all the labor to remove and replace pistons would likely make the $3000 a wash, at best.

[phoenix155]

Well, I'd likely do the mods myself/with friends. But then again, I haven't done the part numbers/prices research. It's all gravy, anyways, since I'll be getting a 328i...when I can afford it, the thought was just very interesting. ;-) The "Dynamic Handling Package" isn't available on the 320i and I really want that option. It's one of my "requirements."

[TerraPhantm]

Probably means the 328 has forged pistons while the 320 doesn't. BMW does overengineer their cars a bit, so you *might* be able to reliably run a stock 328 tune.

The various aftermarket tunes would probably be too much to be reliable however.

[mondo322]

theres no point in getting the 320i if your loading it with options. You might as well get a 328i with much more power and more standard features. the 320i is for someone who doesnt care about all the power and wants a cheaper car with very few options, it is meant to keep under 40k. If you are building it and exceeding 40k you might as well get the 328i

[phoenix155]

Originally Posted by mondo322

theres no point in getting the 320i if your loading it with options. You might as well get a 328i with much more power and more standard features. the 320i is for someone who doesnt care about all the power and wants a cheaper car with very few options, it is meant to keep under 40k. If you are building it and exceeding 40k you might as well get the 328i

I'll agree with this.

[RockLee]

Originally Posted by tim330i

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.

What about the camshafts? I don't see them on the list.

[TerraPhantm]

Originally Posted by RockLee

What about the camshafts? I don't see them on the list.

They're the same according to RealOEM

[tim330i]

Originally Posted by TerraPhantm

They're the same according to RealOEM

I didn't see those on REAL OEM When I put the OP together. Will you link me so I can add the details?

Tim

[mtgswede]

Stop being sissies and just get a 335 already. You'll hardly notice the 2 mpg drop in efficiency while your grinning ear from ear at the 300hp rocketing you to your next speeding ticket.

[AdamIsAdam]

Subscribed. Very interested in a well balanced, best handling BMW at a low price.

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[AdamIsAdam]

Had anyone driven this in a stick yet?

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[AdamIsAdam]

Originally Posted by AdamIsAdam

Had anyone driven this in a stick yet?

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Bueller? Bueller?

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[TerraPhantm]

Originally Posted by tim330i

I didn't see those on REAL OEM When I put the OP together. Will you link me so I can add the details?

Tim

Sure

320

• Intake
• Exhaust
• Valvetronic Cam

328

• Intake
• Exhaust
• Valvetronic Cam

[gonzo08452]

Originally Posted by mondo322

theres no point in getting the 320i if your loading it with options. You might as well get a 328i with much more power and more standard features. the 320i is for someone who doesnt care about all the power and wants a cheaper car with very few options, it is meant to keep under 40k. If you are building it and exceedineg 40k you might as well get the 328i

I agree. I just built one to my specs and ended up just below $35k. White on black leatherette, silver trim, spot pack and lighting pack. Didnt realize it was auto only.

[gt5422md]

Originally Posted by mtgswede

stop being sissies and just get a 335 already. You'll hardly notice the 2 mpg drop in efficiency while your grinning ear from ear at the 300hp rocketing you to your next speeding ticket.

+1

[AdamIsAdam]

Originally Posted by gonzo08452

I agree. I just built one to my specs and ended up just below $35k. White on black leatherette, silver trim, spot pack and lighting pack. Didnt realize it was auto only.

It's available in a stick. Hell, there was one exactly as you described, which is exactly how I would build it, at the NY auto show that I sat in. It was even white over black and it was sweet looking.

But has anyone driven one yet?

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