[carrier]

who ride f30 320 with bm3? (stage 1 or stage 2)
do you have comments or suggestion?

[Steakpizza]

I have a 15 320i with BM3. Would really recommend it. If you have or had a JB4, its similar, but the power delivery is smoother. I'm getting a new downpipe to go Stage 2, I'm just debating on getting a highflow cat or a catless one. The highflow cats will let me pass emissions inspections, but Catless downpipes will not for where I am from (Pennsylvania).

With Bm3, your horsepower should sit around ~220 or so, and Stage 2 will probably bring you right around 250ish.

[kobluna]

I'm curious why 320i needs catless or highflow cat for stage 2 (250hp) but 328i makes that amount of power with OEM cat. Downpipe is same for both applications. I know that compression is different but that should't make any difference from a downpipe point of view, should it?

I don't understand that if you make same amount of hp, why the x20i needs aftermarket dp and x28i doesn't. I get it that if one would want to get more hp and/or use a burple map, then aftermarket dp is a must. But there is a tune potential with x28i even with stock dp so with x20i there should be plenty of head room left?

I ask because I'm hesitant to get rid of my cat because then I would not pass emissions inspections.

[rjd_F30]

Originally Posted by kobluna

I'm curious why 320i needs catless or highflow cat for stage 2 (250hp) but 328i makes that amount of power with OEM cat. Downpipe is same for both applications. I know that compression is different but that should't make any difference from a downpipe point of view, should it?

I don't understand that if you make same amount of hp, why the x20i needs aftermarket dp and x28i doesn't. I get it that if one would want to get more hp and/or use a burple map, then aftermarket dp is a must. But there is a tune potential with x28i even with stock dp so with x20i there should be plenty of head room left?

I ask because I'm hesitant to get rid of my cat because then I would not pass emissions inspections.

Because it's more than just different compression ratios. The 320i uses a smaller turbo and different cams so it needs the catless DP to reach stock DP 328i power levels.

[kobluna]

Originally Posted by rjdnyy224

Because it's more than just different compression ratios. The 320i uses a smaller turbo and different cams so it needs the catless DP to reach stock DP 328i power levels.

No, it does not use different turbos! Please also see here:
http://www.realoem.com/bmw/enUS/show...diagId=11_5185 - 20i
http://www.realoem.com/bmw/enUS/show...diagId=11_5185 - 28i

What is different is compression ratio (11:1 vs 10:1), smaller FMIC and smaller diameter midpipe (65mm vs 75mm). I'm going to upgrade my FMIC anyway so it does not matter and I'm not sure yet about midpipe. What I have read about it, it's not the limiting factor really. However, I'm planning to upgrade my muffler to 335i muffler for the looks and sound so it will also flow better than stock 320i muffler with one outlet.

Are you sure about different cams? I haven't heard that earlier? According to realoem they are same for both inlet and outlet side?
http://www.realoem.com/bmw/enUS/show...diagId=11_4776
http://www.realoem.com/bmw/enUS/show...diagId=11_4776

[cpxchewy]

Originally Posted by rjdnyy224

Because it's more than just different compression ratios. The 320i uses a smaller turbo and different cams so it needs the catless DP to reach stock DP 328i power levels.

Originally Posted by kobluna

No, it does not use different turbos! Please also see here:
http://www.realoem.com/bmw/enUS/show...diagId=11_5185 - 20i
http://www.realoem.com/bmw/enUS/show...diagId=11_5185 - 28i

What is different is compression ratio (11:1 vs 10:1), smaller FMIC and smaller diameter midpipe (65mm vs 75mm). I'm going to upgrade my FMIC anyway so it does not matter and I'm not sure yet about midpipe. What I have read about it, it's not the limiting factor really. However, I'm planning to upgrade my muffler to 335i muffler for the looks and sound so it will also flow better than stock 320i muffler with one outlet.

Are you sure about different cams? I haven't heard that earlier? According to realoem they are same for both inlet and outlet side?
http://www.realoem.com/bmw/enUS/show...diagId=11_4776
http://www.realoem.com/bmw/enUS/show...diagId=11_4776

The only difference between the two engine blocks is the piston.
Otherwise, they're the same. The FMIC is shared between the two too.

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

[rjd_F30]

Originally Posted by kobluna

No, it does not use different turbos! Please also see here:
http://www.realoem.com/bmw/enUS/show...diagId=11_5185 - 20i
http://www.realoem.com/bmw/enUS/show...diagId=11_5185 - 28i

What is different is compression ratio (11:1 vs 10:1), smaller FMIC and smaller diameter midpipe (65mm vs 75mm). I'm going to upgrade my FMIC anyway so it does not matter and I'm not sure yet about midpipe. What I have read about it, it's not the limiting factor really. However, I'm planning to upgrade my muffler to 335i muffler for the looks and sound so it will also flow better than stock 320i muffler with one outlet.

Are you sure about different cams? I haven't heard that earlier? According to realoem they are same for both inlet and outlet side?
http://www.realoem.com/bmw/enUS/show...diagId=11_4776
http://www.realoem.com/bmw/enUS/show...diagId=11_4776

Yup you're right, that's what I get for being lazy. But I think the FMICs are the same...

[kobluna]

Thank you both cpxchewy and rjdnyy224 for the additional information and correction. But this makes me actually wonder just even more, not less, why high flow downpipe is needed for 320i. Or is it actually needed for stage 2 with mild burples? I guess I will lose ~20hp with OEM cat but does it actually hurt the engine? Let the investigation continue

[rjd_F30]

Originally Posted by kobluna

Thank you both cpxchewy and rjdnyy224 for the additional information and correction. But this makes me actually wonder just even more, not less, why high flow downpipe is needed for 320i. Or is it actually needed for stage 2 with mild burples? I guess I will lose ~20hp with OEM cat but does it actually hurt the engine? Let the investigation continue

Just to make sure I'm understanding correctly, because now you've got me curious, you're question is: Why does a 320i need a catless DP to get to stock cat stage 1 328i levels of power?

[CntryClub007]

As many others have pointed out, main (really only) difference are the pistons and compression. I've really enjoyed the JB4 with Meth. Car made great power with OEM downpipe and 22lbs of boost.

I know I'm leaving a lot of power on the table with OEM downpipe, but from history of others (2-3 years ago), it appears that the DP on the N20 is the one component that can really throw things into grenading the motor, now I'm not sure why that was though. People running too high of boost? Did the turbo fail? Did they run DP without a tune? Obviously the downpipe wouldn't cause these engines to blow (I'm guessing), but was it an enabler to something else?

Perhaps this has been resolved with BMW3. Does anyone know if I can run BM3 w/ Meth or what is the point of BM3 with a JB4 and such?

I've read a lot of people saying BM3 power delivery is smoother, mine appears to be very smooth and linear, obviously the car just dies in power at 3500rpm (4-pot turbo), but what is so smooth about BM3?

Happy to try and help answer any questions with my Meth experience too...

My numbers: https://f30.bimmerpost.com/forums/sh....php?t=1508531

Personally, I enjoy seeing 320i owners on the forums, we are a small little crew, but there is tremendous value in the car, and I really enjoy driving it.

[rjd_F30]

Originally Posted by CntryClub007

As many others have pointed out, main (really only) difference are the pistons and compression. I've really enjoyed the JB4 with Meth. Car made great power with OEM downpipe and 22lbs of boost.

I know I'm leaving a lot of power on the table with OEM downpipe, but from history of others (2-3 years ago), it appears that the DP on the N20 is the one component that can really throw things into grenading the motor, now I'm not sure why that was though. People running too high of boost? Did the turbo fail? Did they run DP without a tune? Obviously the downpipe wouldn't cause these engines to blow (I'm guessing), but was it an enabler to something else?

Perhaps this has been resolved with BMW3. Does anyone know if I can run BM3 w/ Meth or what is the point of BM3 with a JB4 and such?

I've read a lot of people saying BM3 power delivery is smoother, mine appears to be very smooth and linear, obviously the car just dies in power at 3500rpm (4-pot turbo), but what is so smooth about BM3?

Happy to try and help answer any questions with my Meth experience too...

My numbers: https://f30.bimmerpost.com/forums/sh....php?t=1508531

Personally, I enjoy seeing 320i owners on the forums, we are a small little crew, but there is tremendous value in the car, and I really enjoy driving it.

People were blowing N20's with the JB4 because they were over boosting. It just so happened they had a catless DP. The DP won't blow the motor, bad tuning and over boosting will. I've not heard of any catless cars blow the engine with BM3. Not that it can't happen, but I haven't seen any cases.

You can run BM3 with meth, but you'll need to keep the JB4 as a controller.

I went from a piggyback to BM3, and the biggest difference was the smoothness of BM3 over the piggyback. The piggyback felt peaky and died around 4800rpm, but with BM3 the car still runs out of steam up top, but it pulls deeper into the rev range and doesn't die off as abruptly, if that makes sense. A good flash tune can kind of hide that distinct turbo-car feeling power band. It's just less peaky and well, smoother.

[kobluna]

Originally Posted by rjdnyy224

Just to make sure I'm understanding correctly, because now you've got me curious, you're question is: Why does a 320i need a catless DP to get to stock cat stage 1 328i levels of power?

Yes, that's pretty much my question

Thanks also CntryClub007 for chiming in. I guess I can getaway with my stock downpipe then because I'm not going to use meth anyway. Or try to squeeze the last horsey out of the motor for that matter. It just feels that there would be some potential left but OEM software is limiting it.

I also found a local tuner who actually does a dyno run before and after the re-programming and they are promising 230-250hp with stock everything, no single HW change. They have also listed the differences between 320i and 328i and pistons are pretty much the only difference. Here is a link for reference, but it's unfortunately only in Finnish so it's difficult for you to understand it (even Google has hard time to translate Finnish correctly): https://www.motorbit.fi/bmw-f3x-n20-320i-328i/

The problem with that tuner is that they are using their own tools and I kind of want BM3. But BM3 has no retailer in Finland so it's a bit of a problem. Well, I have a few months to wait anyway as it's winter time now and I couldn't use the additional power anyway. Not to mention the difficulty to test a tune when I have my winter tires on as they are the spiked ones.

[rjd_F30]

Originally Posted by kobluna

Yes, that's pretty much my question

Gotcha. Well, then it must be the pistons and compression if that's the only mechanical difference lol. It can't be the software as a tune makes that completely moot.

Also, I'm sure you know but you don't need a BM3 retailer to go to BM3. You can just buy a license and do it all yourself with a laptop and cable.

[mike@x-ph.com]

Originally Posted by rjdnyy224

Gotcha. Well, then it must be the pistons and compression if that's the only mechanical difference lol. It can't be the software as a tune makes that completely moot.

Also, I'm sure you know but you don't need a BM3 retailer to go to BM3. You can just buy a license and do it all yourself with a laptop and cable.

Correct, you buy the license from PTF or a vendor like us

We send you the cable free of cost to use in order to load your map.
Its a very simple process that can easily be done by anyone

[jkoljo]

I can program it for you in Tampere or Jämsä area. Send me a private msg if interested. You can also try my 320i stage2 if you like.

[kobluna]

Thanks everyone for answers. What I have read some cars needs some modifications to program so that engine runs correctly. It could be also wise to request I-Step update before flashing a new map into ECU?

I PM'd you jkoljo let's see if we can arrange some meeting.

[rjd_F30]

Originally Posted by kobluna

Thanks everyone for answers. What I have read some cars needs some modifications to program so that engine runs correctly. It could be also wise to request I-Step update before flashing a new map into ECU?

I PM'd you jkoljo let's see if we can arrange some meeting.

Yah some cars don't take to OTS maps very well, but that's just the nature of one-size-fits all maps. And some cars, I'd say a majority, run perfectly on the OTS maps. But even if you do have a few tune issues, PTF will work with you to get them fixed and send you new maps if need be.

[combivan]

Basically different part numbers for Pistons, Transmission, Driveshaft, front muffler and Rear exhaust

Piston:
320i - http://www.realoem.com/bmw/enUS/show...diagId=11_4770
328i - http://www.realoem.com/bmw/enUS/show...diagId=11_4770


Rear Exhaust:
320i - http://www.realoem.com/bmw/enUS/show...diagId=18_1105
328i - http://www.realoem.com/bmw/enUS/show...diagId=18_0974


Transmission:
320i - http://www.realoem.com/bmw/enUS/show...diagId=24_1330
328i - http://www.realoem.com/bmw/enUS/show...diagId=24_1330


Driveshaft:
320i - http://www.realoem.com/bmw/enUS/show...diagId=26_0240
328i - http://www.realoem.com/bmw/enUS/show...diagId=26_0240

Front Muffler:
320i - http://www.realoem.com/bmw/enUS/show...diagId=18_0975
328i - http://www.realoem.com/bmw/enUS/show...diagId=18_0975

[combivan]

Originally Posted by rjdnyy224

Yup you're right, that's what I get for being lazy. But I think the FMICs are the same...

FMIC is different from what I can see:
320i - http://www.realoem.com/bmw/enUS/show...diagId=17_0632

328i - http://www.realoem.com/bmw/enUS/show...diagId=17_0632

328i is 30% heavier

[rjd_F30]

Originally Posted by combivan

FMIC is different from what I can see:
320i - http://www.realoem.com/bmw/enUS/show...diagId=17_0632

328i - http://www.realoem.com/bmw/enUS/show...diagId=17_0632

328i is 30% heavier

They are different part numbers, which is interesting... But I'd be curious to know what the real difference is. Where did you see the 328i FMIC was 30% bigger?

[Dulsaf2630]

I have 320i with BM3 and full Fi exhaust (3 inch pipe for N20 320i and 328i). Stage 1 would be about same power as 328i. Stage 2 you would smoke 328i. I work at BMW dealer, so I have driven both stock vehicle many times.

[combivan]

Originally Posted by rjdnyy224

They are different part numbers, which is interesting... But I'd be curious to know what the real difference is. Where did you see the 328i FMIC was 30% bigger?

I only said it was 30% heavier. If you click on each part then you can see the weight of each part