F30 320i vs 328i engines - Part number comparison

by Tim Jones on January 17, 2013, 12:35 pm

BMW has just announced a new entry level F30 3 series, the 320i. The 320i shares the same N20; TwinPower single turbo, twin scroll, 2.0 liter inline 4 cylinder engine as the 328i. The 320i is factory rated at 180 hp at 5,000 RPMs and 200 lb-ft of torque from 1,250 RPMs. Stacked next to the 328i with 240hp at 5000 RPMs and 255 lb-ft of torque from 1250 RPMs and the obvious question is what is the difference in the two engines.

The first obvious answer is there 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 a software tweak the likely difference between the 320i and the 328i 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 the exact same part numbers for a majority of the 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 horsepower from your 320 is not yet known.

Stay tuned as we continue to sift through BMW's technical documents searching for an answer.

BMW at the 2013 North American International Auto Show - Click here to see all 524 images

Leave a Comment

54 responses to F30 320i vs 328i engines - Part number comparison

SteVTEC commented:
January 17, 2013, 6:18 pm

WOW! So there's some serious potential to turn things back up in this car then!

If you could get to 210-220hp with a similar boost in torque with a Stage 1 upgrade, this car just got a whole lot more interesting to me.

namelessman commented:
January 17, 2013, 8:33 pm

Quote:

Originally Posted by tim330i

This effectively says that the 328i is a $2-3k engine tune over 320i from the factory. Is N20 just for US spec 320i or for Euro/Canadian 320i as well? I wonder if non-US folks have already figured out how to boost the 320i.

av98 commented:
January 17, 2013, 8:34 pm

What's the bore & stroke between the engines?

From your list there are lots of areas for lost power & response from these:

-smaller diameter throttle body
-smaller or non straight intake manifold runners
-smaller diameter airbox
-lower flow CFM air filter
-smaller intercooler
-non dished pistons
-crankshaft with a lower stroke
-smaller exhaust manifold/turbo
-non polished or ported cylinder head

Seems like they are limiting power via less air & a controlled less powerful combustion. Plus the turbo recovery and cooling are more crippled.

Ronin951 commented:
January 17, 2013, 9:15 pm

Are we sure it's 10:1. Here's the difference in the short block description

328i
Short Engine N20B20A 1 11002297079
only in conjunction with

320i
For vehicles with
Low compression engine
S858A=Yes <== what is this?
01 Short Engine N20B20A 1 11002297079

m8o commented:
January 17, 2013, 11:20 pm

isn't starting w/a lower compression engine better for swapping in a big honk'n turbo?

(of course that would only be coupled with greatly increasing for the airflow both in and out ; just wanted to frame it with that)

Ronin951 commented:
January 18, 2013, 12:52 am

Quote:

Originally Posted by m8o

isn't starting w/a lower compression engine better for swapping in a big honk'n turbo?

Unfortunately, I'm not sure how much turbo swapping is going to happen. The turbo and exhaust manifold are a single component. The engineers have their reasons (hot-side performance), but from a mod perspective it sucks. It's not like the traditional way where it's just a matter of matching the housings to the flanges.

Basically we'll have to rely on a vendor to engineer an exhaust manifold and plumbing, or swap in from another engine/year like they do on the Audi's A4's, which have a similar setup. I checked the 745Li (IIRC), which is a turbo'd v8, but the header flanges are different and it may not even be an "upgrade". Intra-make part upgrade/swapping is not a new concept, but in the case of turbo's it requires knowing the subtle differences between the parts.

Back on-topic, I think the OP was incorrect, but I'm open to be proven wrong. I hope I'm right though cuz I'll be pretty pissed if it's just a tune

JoeFromPA commented:
January 18, 2013, 8:30 am

So I'm really curious about the pistons. That could either be no big deal or big freaking deal when it comes to turning the power up. Why swap them? The biggest reason I can think of is cost-savings OR greater rotating mass efficiency through a different crown design or ring pack design. But it's not like the regular n20 is some inefficient beast - so neither of those really makes sense to me except perhaps cost-savings achievable by using a lower quality piston because you are running so much less dynamic compression against them with the detuned engine.

If I'm totally off base then the 320i is going to be the entry-euro-tuner's delight. No forced "lines", cheaper, and an engine ready to play in the ~260whp range on pump gas.

vitchie commented:
January 18, 2013, 9:13 am

There is defnitely a difference in compression ratio. The 328 is 10:1 and the 320 is 11:1. Thus, the higher compression 320 will knock a lot sooner than the 328, so less tunable. I've also heard that the 320 has thinner drive shafts.

tim330i commented:
January 18, 2013, 11:15 am

Quote:

Originally Posted by vitchie

There is defnitely a difference in compression ratio. The 328 is 10:1 and the 320 is 11:1. Thus, the higher compression 320 will knock a lot sooner than the 328, so less tunable. I've also heard that the 320 has thinner drive shafts.

Where did you get your info on the compression ratio? BMWUSA.com (i know, not the best source of info) lists it as 10:1 -

http://www.bmwusa.com/Standard/Conte...fications.aspx

The 320i gets different part numbers for the rear half shafts, but it doesn't look like the 328 shares half shafts with the 335i either. So you could say the 328i shafts are thinner then the 335i. I have no idea if that is true or not, but you see my point.

Tim

tim330i commented:
January 18, 2013, 11:17 am

Quote:

Originally Posted by av98

What's the bore & stroke between the engines?

From your list there are lots of areas for lost power & response from these:

-smaller diameter throttle body
-smaller or non straight intake manifold runners
-smaller diameter airbox
-lower flow CFM air filter
-smaller intercooler
-non dished pistons
-crankshaft with a lower stroke
-smaller exhaust manifold/turbo
-non polished or ported cylinder head

Seems like they are limiting power via less air & a controlled less powerful combustion. Plus the turbo recovery and cooling are more crippled.

I think you misread my post. All the things you listed besides the pistons are the same. They share the same BMW part number for the 328 and 320.

Tim

tim330i commented:
January 18, 2013, 11:26 am

Quote:

Originally Posted by Ronin951

Are we sure it's 10:1. Here's the difference in the short block description

328i
Short Engine N20B20A 1 11002297079
only in conjunction with

320i
For vehicles with
Low compression engine
S858A=Yes <== what is this?
01 Short Engine N20B20A 1 11002297079

Quote:

Originally Posted by vitchie

These seem to be in direct contradiction to each other. I seem to remember reading about the 320 in Europe having a 11:1 compression ration but the description of the short block above seems to say otherwise.

Tim

vitchie commented:
January 18, 2013, 11:32 am

Check post #6 here: No official quote from BMW, but rather a BMW tuning company in SA.

http://www.bmwfanatics.co.za/showthread.php?tid=39504

tim330i commented:
January 18, 2013, 11:35 am

Makes sense I guess. That means that you'd need a thicker head gasket or something to decrease the compression ratio to really be able to turn up the boost. Not the end of the world but not as simple as a software flash.

Tim

Ronin951 commented:
January 18, 2013, 12:05 pm

According to RealOEM the 328i N20 piston (11257618811) is no longer manufactured http://www.realoem.com/bmw/showparts...70&hg=11&fg=20

namelessman commented:
January 18, 2013, 12:22 pm

The bmwusa configurator says the 320i base weight is 3295lb, so with the same N20 engine as 328i(3410lb, 8AT), where is the weight reduction coming from? Also, detuned N26 is not available on 320i, which is odd since N26 should benefit BMWNA on the PZEV footprint. This may mean N26 is either too expensive, or, N26 cannot be tuned(disappointing!).

av98 commented:
January 18, 2013, 1:40 pm

Quote:

Originally Posted by tim330i

I think you misread my post. All the things you listed besides the pistons are the same. They share the same BMW part number for the 328 and 320.

Tim

Yep I did your statement wasn't very clear. Which still makes the important specs on the engine valid- bore, stroke, compression- what are they?

av98 commented:
January 18, 2013, 1:42 pm

Quote:

Originally Posted by namelessman

The bmwusa configurator says the 320i base weight is 3295lb, so with the same N20 engine as 328i(3410lb, 8AT), where is the weight reduction coming from? Also, detuned N26 is not available on 320i, which is odd since N26 should benefit BMWNA on the PZEV footprint. This may mean N26 is either too expensive, or, N26 cannot be tuned(disappointing!).

Wow that's a huge savings, great to know. If a BMS software tune gets the 320i to 215 whp/trq you have yourself a 328i equivalent.

namelessman commented:
January 18, 2013, 2:08 pm

Quote:

Originally Posted by av98

Yep I did your statement wasn't very clear. Which still makes the important specs on the engine valid- bore, stroke, compression- what are they?

Data from bmwusa configurator shows that bore, stroke, compression are the same on both cars.

328i:
Engine
Type/cylinders/valves per cylinder
TwinPower Turbo/Inline 4/4
Displacement
1997 cc
Bore/stroke
3.3/3.5 inch
Nominal output hp/rpm
240/5000-6000
Max. torque lb-ft/rpm
255/1250-4800
Compression ratio
10 :1

320i:
Engine
Type/cylinders/valves per cylinder
TwinPower Turbo/Inline 4/4
Displacement
1997 cc
Bore/stroke
3.3/3.5 inch
Nominal output hp/rpm
181/5000
Max. torque lb-ft/rpm
184(250) / 1250-4500
Compression ratio
10 :1

tim330i commented:
January 18, 2013, 2:14 pm

I have feeling the data on BMWUSA.com is wrong.

elistan commented:
January 18, 2013, 2:15 pm

Quote:

Originally Posted by namelessman

Data from bmwusa configurator shows that bore, stroke, compression are the same on both cars.

328i:
Engine
Type/cylinders/valves per cylinder
TwinPower Turbo/Inline 4/4
Displacement
1997 cc
Bore/stroke
3.3/3.5 inch
Nominal output hp/rpm
181/5000
Max. torque lb-ft/rpm
184(250) / 1250-4500
Compression ratio
10 :1

320i:
Engine
Type/cylinders/valves per cylinder
TwinPower Turbo/Inline 4/4
Displacement
1997 cc
Bore/stroke
3.3/3.5 inch
Nominal output hp/rpm
181/5000
Max. torque lb-ft/rpm
184(250) / 1250-4500
Compression ratio
10 :1

I'm not sure if the source data from BMW was messed up, or if you accidentally did a copy-paste error, but the 328i certainly doesn't have only 181 hp...

namelessman commented:
January 18, 2013, 2:22 pm

Quote:

Originally Posted by elistan

I'm not sure if the source data from BMW was messed up, or if you accidentally did a copy-paste error, but the 328i certainly doesn't have only 181 hp...

Fixed copy-paste error in previous post, thxs. Bore/stroke/compression ratio still the same on both data sheets.

namelessman commented:
January 18, 2013, 2:38 pm

The datasheet also says 320i 8AT has 250 lb-ft, which is almost the same as the 328i. So it seems the only difference is really 60+HP.

Footnote
Figures in ( ) apply to vehicles with 8-speed automatic transmission.

Nominal output hp/rpm
181/5000
Max. torque lb-ft/rpm
184(250) / 1250-4500

Ronin951 commented:
January 18, 2013, 2:57 pm

Unfortunately, here's what I *think* happened. I have an email out to BMW to comment.

2012 MY 328's have 10:1 N20's tuned low

2013 MY 320's have 11:1 N20's boosted low
~2013 MY 328's have 11:1 N20's boosted high (see my post about piston being discontinued)

This would mean that BMW would put the same engine with the same CR in both 320 and 328. Makes sense for simplicity sake. The bad thing (for 328 owners) is they will already be tuned high (most likely more boost from factory). So, from BMW's perspective 328 owners can no longer piggy back to ~335i power, but 320 owners can piggy back to 328 power. This is oversimplified, but hopefully you get the idea.

If a "legacy" 328 needs a new piston all 4 will be replaced with the 11:1 CR ones and a software update. This whole setup means that BMW has to only maintain 1 set of pistons and two tunes. Not 2 sets of pistons and two tunes. One way to confirm without digging into the engine is to check new vs old 328 boost pressures, which is probably where they would make the adjustment (like a piggyback).

This is all speculation, but might be worth looking into deeper.

EDIT: This jives with namelessman's post. Power increase from boost would primarily be seen in the HP range.

namelessman commented:
January 18, 2013, 3:41 pm

Is HP = torque x rpm? Since the torque specs on both are similar(at least for 8AT), so maybe the difference is to taper the engine rev on 320i N20 at 5000rpm to throttle at 181hp, but allows 328i N20 to keep pushing to 6000rpm and 240hp. I guess we would see dyno charts soon enough on this. For now, 328i does appear to be a $2k-3k(expensive) factory tune versus 320i.

As tim330i noted, the bmwusa data can be incorrect too, or else it would really be odd that 320i N20 MT only get 184 lb-ft@1250-4500rpm ....

Ronin951 commented:
January 18, 2013, 4:12 pm

Quote:

Originally Posted by namelessman

Is HP = torque x rpm? Since the torque specs on both are similar(at least for 8AT), so maybe the difference is to taper the engine rev on 320i N20 at 5000rpm to throttle at 181hp, but allows 328i N20 to keep pushing to 6000rpm and 240hp. I guess we would see dyno charts soon enough on this. For now, 328i does appear to be a $2k-3k(expensive) factory tune versus 320i.

As tim330i noted, the bmwusa data can be incorrect too, or else it would really be odd that 320i N20 MT only get 184 lb-ft@1250-4500rpm ....

Yeah, so much for being excited for my car to arrive. For me, the whole point in getting a 328 was its unrealized power. Now it seems the goal post has moved.

Itgb commented:
January 18, 2013, 6:00 pm

Quote:

Originally Posted by tim330i

I have feeling the data on BMWUSA.com is wrong.

+1

Taking a look at the UK 320i engine specs, this is what I would expect:

Engine Cylinders/valves 4/4

Capacity (cc) 1997

Stroke/Bore (mm) 90.1/84.0
Stroke/Bore (inch) 3.50/3.30

Max output (kW/hp/rpm) 135 (184)/5000

Max torque (Nm/rpm) 270/1250-4500 (270Nm = ~200lb-ft)

Compression ratio : 11.0:1

namelessman commented:
January 18, 2013, 6:14 pm

Quote:

Originally Posted by Ronin951

Yeah, so much for being excited for my car to arrive. For me, the whole point in getting a 328 was its unrealized power. Now it seems the goal post has moved.

Not really an expert on this, but I would think as long as newly built 328i still has the same N20 engine part number, it probably still has unrealized power to unleash(same as 2012 built ones). If the numbers are correct, the observation would be that BMW AG simply dial down the same US-spec N20 performance further for 320i. It would be a very smart move(no new parts, incremental emission qualification, just-in-time shift of production slots from troubled Europe to US/Asia, etc, etc). It is just that 320i owners would have even more headroom for unrealized power than 328i, given nearly all engine parts are identical as OP stated(even brakes are same part# in realoem).

What is unclear now is how to get the 120-lb weight reduction. Does the factory take out all the noise-insulation material to save weight and 320i is noisy as hell?

Ronin951 commented:
January 18, 2013, 9:40 pm

Quote:

Originally Posted by namelessman

What is unclear now is how to get the 120-lb weight reduction. Does the factory take out all the noise-insulation material to save weight and 320i is noisy as hell?

No:

electric seats
rear fold-downs

Different:

Exhaust
Drive and axle shafts
Tranny

Here and there you could probably pick away 120-lb

smashhell commented:
January 18, 2013, 9:55 pm

Quote:

Originally Posted by Ronin951

No:

electric seats
rear fold-downs

Different:

Exhaust
Drive and axle shafts
Tranny

Here and there you could probably pick away 120-lb

You could probably take away 100 lb from changing seats alone.

namelessman commented:
January 19, 2013, 2:01 am

Quote:

Originally Posted by Ronin951

No:
electric seats
rear fold-downs
Different:
Exhaust
Drive and axle shafts
Tranny
Here and there you could probably pick away 120-lb

That makes sense, $2-3k for a ECU tune plus additional beefed up drive+output shafts and such from the factory(with OEM warranty) is not bad.

justinnum1 commented:
January 19, 2013, 2:34 am

its a different transmission?

Jamesonsviggen commented:
January 19, 2013, 9:24 am

Quote:

Originally Posted by namelessman

That makes sense, $2-3k for a ECU tune plus additional beefed up drive+output shafts and such from the factory(with OEM warranty) is not bad.

So far the best ecu tunes for the n20 are below $500.

namelessman commented:
January 19, 2013, 11:56 am

Quote:

Originally Posted by justinnum1

its a different transmission?

From realoem the AT/MT replacement part numbers are different, can it be just different fitment into the engine bays, or different HP ratings do require reinforced components on the high HP engines?

(copy-paste data disclaimer

)
rear axle output shafts -- 320i: 28mm; 328i: 31mm; 335i: 35mm
drive shafts for AT -- 320i: 1563mm; 328i: 1539mm; 335i:1508.5mm

335i AT:
Rmfd automatic transmission EH GA8HP45Z 1 09/2012 24008601194
328i AT:
Rmfd automatic transmission EH GA8HP45Z 1 09/2012 24008609706
320i AT:
Rmfd automatic transmission EH GA8HP45Z 1 09/2012 24008609707

335i MT:
Rmfd-6 speed gearbox GS6-45BZ - THY8 1 23007617492
328i MT:
Rmfd-6 speed gearbox GS6-17BG - TAU0 1 23007633990
328i MT:
Rmfd-6 speed gearbox GS6-17BG - TAY9 1 23007633989

justinnum1 commented:
January 19, 2013, 11:58 am

Quote:

Originally Posted by namelessman

From realoem the AT/MT replacement part numbers are different, can it be just different fitment into the engine bays, or different HP ratings do require reinforced components on the high HP engines?

(copy-paste data disclaimer

the 335 and 328 share the same auto and the numbers are different on what you postes...

namelessman commented:
January 19, 2013, 12:06 pm

Quote:

Originally Posted by justinnum1

the 335 and 328 share the same auto and the numbers are different on what you postes...

The numbers are the ones for 10/2012 production month(or from 9/2012?), it does look like different production months have different PN#s(e.g. 2/2012). This is complicated stuff.

Ronin951 commented:
January 19, 2013, 8:16 pm

Quote:

Originally Posted by Jamesonsviggen

So far the best ecu tunes for the n20 are below $500.

I talked with one of the piggyback vendors about the impact of 11:1. Response was there will be lower boost with "similar" power compared to the 10:1's. Pretty much as expected.

namelessman commented:
January 21, 2013, 1:08 am

Quote:

Originally Posted by Ronin951

Are we sure it's 10:1. Here's the difference in the short block description
328i
Short Engine N20B20A 1 11002297079
only in conjunction with
320i
For vehicles with
Low compression engine
S858A=Yes <== what is this?
01 Short Engine N20B20A 1 11002297079

Some discussions on other forums mentioned that 320i in other countries can come with a low compression option S858A and 10:1 and same 7079 part# as above, or without option S8585A and 11:1(and a different engine part #). One possibility is that the bmwusa data sheets are correct, and US spec 320i N20 is with S8585A option.

namelessman commented:
January 21, 2013, 1:22 am

Quote:

Originally Posted by Ronin951

I talked with one of the piggyback vendors about the impact of 11:1. Response was there will be lower boost with "similar" power compared to the 10:1's. Pretty much as expected.

So does it mean piggyback solutions can do 240HP-ish, but not 300HP? I wonder how well the piggyback ones "compliment" the factory ECU, if the ECU does not like the modified readings, would it throw a fault code or CEL?

3284me commented:
January 21, 2013, 5:21 am

Anyone have the 0-60 time on the 320?

Sorry just saw the answer in the other thread.

Ronin951 commented:
January 21, 2013, 10:53 pm

Quote:

Originally Posted by namelessman

My question was specifically 10:1 vs 11:1 on a 328 and I was told the gains would be similar and that there were 320 specific settings, which presumably just lowers boost. There is a different P/N for the exhaust on a 320, so an 11:1 328 vs 320 would probably have different dyno results. How much different I can only speculate.

I can't speak to CEL's, etc. That's probably better asked in a separate thread. I will say if the 2013+ 328's do have a different CR, the vendors will probably have to start asking customers the MY of their 328's.

tim330i commented:
February 1, 2013, 11:00 am

I can 100% confirm that the compression ratio on the F30 320i is 10:1. That is the same 10:1 that the 328i has.

Tim

Ronin951 commented:
February 1, 2013, 8:38 pm

Quote:

Originally Posted by tim330i

I can 100% confirm that the compression ratio on the F30 320i is 10:1. That is the same 10:1 that the 328i has.

Tim

Compression measured?

tim330i commented:
February 2, 2013, 9:11 am

Quote:

Originally Posted by Ronin951

Compression measured?

No, direct from BMW NA.

Tim

SteVTEC commented:
February 2, 2013, 9:01 pm

Sweet!

Ronin951 commented:
February 3, 2013, 4:23 pm

^

namelessman commented:
February 12, 2013, 12:52 pm

Any updates on the engine comparisons?

tim330i commented:
February 12, 2013, 1:36 pm

Quote:

Originally Posted by namelessman

Any updates on the engine comparisons?

What other info are you looking for?

Tim

Terry @ BMS commented:
February 12, 2013, 2:06 pm

Quote:

Originally Posted by tim330i

I can 100% confirm that the compression ratio on the F30 320i is 10:1. That is the same 10:1 that the 328i has.

Tim

Interesting I was told the 320 was 11:1 rather than 10:1. I've yet to see one at the office but we've tuned a few remotely using the Stage1.

N20 Stage2 tune development is underway now.

tim330i commented:
February 12, 2013, 2:26 pm

Quote:

Originally Posted by Terry @ BMS

Interesting I was told the 320 was 11:1 rather than 10:1. I've yet to see one at the office but we've tuned a few remotely using the Stage1.

N20 Stage2 tune development is underway now.

There was a lot of conflicting reports. That's why I confirmed it directly with my contacts.

Tim

namelessman commented:
February 12, 2013, 2:42 pm

Quote:

Originally Posted by tim330i

There was a lot of conflicting reports. That's why I confirmed it directly with my contacts.

Tim

So is it confirmed that 320i is purely an electronic detune of 328i engine-wise(and the two versions use exactly the same engine and associated engine parts)?

tim330i commented:
February 12, 2013, 3:13 pm

Quote:

Originally Posted by namelessman

So is it confirmed that 320i is purely an electronic detune of 328i engine-wise(and the two versions use exactly the same engine and associated engine parts)?

Nope. Read the first post.

Sent from my iPhone using BimmerApp

stom_m3 commented:
February 13, 2013, 10:44 am

Quote:

Originally Posted by tim330i

Nope. Read the first post.

Sent from my iPhone using BimmerApp

If you look at RealOEM, the 328 N20 and N26 pistons are "ended." The 320 N20 has the only current part number listed. Is there other information showing that the current 320 pistons are any different than the current 328 pistons?

3ismagic# commented:
February 28, 2013, 9:21 am

Quote:

Originally Posted by Terry @ BMS

Interesting I was told the 320 was 11:1 rather than 10:1. I've yet to see one at the office but we've tuned a few remotely using the Stage1.

N20 Stage2 tune development is underway now.

Terry,
Care to speculate on what stage 1 adds in the 320i? By my guesstimates it should put out 210-220 bhp?

Jack in Jax commented:
May 20, 2013, 2:59 pm

Let me bump this to catch Terry's attention as I too would appreciate hearing his answer.

Jack