[MR.]

Guys, I need your help. Are there any engineers here? I personally have a bit of knowledge on this subject, but I need a few of you to help me out here.

Let's go back to some quotes shared in this forum over the past weeks, which I haven't all been able to find easily, but if our moderator Artemis is able to help then this would be wonderful.

Quote 1: The OPF filter limiting the performance of a 6-in-line engine https://f87.bimmerpost.com/forums/sh...8&postcount=44

Quote 2: There was a member a few weeks back who discussed the strain on the OPF and his tuner discussing with him the fact that the OPF will have impact on the performance and the way the engine is tuned.

Quote 3: The Canadian owner who picked up his car mentioned the following, although I don't consider that an immediate reference: https://f87.bimmerpost.com/forums/sh...&postcount=211

Now let me ask you the following question; what if you swap the N55 for a S55 and add a filter in the exhaust, and (now comes the important part) you change the engine ignition cut off to not over stress the new OPF?

What does that mean for the driving characteristics of a car when you look at the responsiveness of the engine? I am not suggesting anything here yet, but I need more feedback from a specialist to understand the impact of the filter shown below added to the exhaust.



MR

[///M Houbi]

Quote 2, what i was told is that basically US and EU spec cars will have slightly different ECU‘s. The EU models will deliver slightly more power at the motor than the non-OPF equipped cars so both will have the same power at the wheel in the end.

Further i was told that we can expect around 450hp out of the box, not the marketed 410hp. This is an assumption based on dozens of dozens S55 M3/M4‘s my friend has tuned and dynoed in the past years.

I will ask about responsivenes and let you know.

[subliminalaudio]

Originally Posted by ///M Houbi

Quote 2, what i was told is that basically US and EU spec cars will have slightly different ECU‘s. The EU models will deliver slightly more power at the motor than the non-OPF equipped cars so both will have the same power at the wheel in the end.

Further i was told that we can expect around 450hp out of the box, not the marketed 410hp. This is an assumption based on dozens of dozens S55 M3/M4‘s my friend has tuned and dynoed in the past years.

I will ask about responsivenes and let you know.

I always wondered why they down play the HP in their engines

[Veebee]

Hello, as said i think the us and eu versions will come up with different ecu settings.

Opf represents an additional resistance in the exhaust system. We all know that decatted vs catted exhaust cars have different responsivness on the throttle input - the catted one being more laggier. And catalyst is nothing less than additional resistance in exhaust. Logically one can say than the opf will decrease the responsivness.

If that contributes less or more to the responsivness than primary catalyst I would only guess... but for sure it is not a good thing. My technical guess would say it is more resistance than catalyst because it is a gas-solid filtration - the holes are very small. But also the opf is behind the primary cat so i do really not know how much it will affect it. They also could reduce the resitance in the rest of the exhaust (muffler) to make it even but i doubt.

[hellrotm]

No OPF in US...

[MR.]

Originally Posted by hellrotm

No OPF in US...

But does that mean a different tune as well! If so I will load the tune of a U.S. car in my EU car.

MR

[akkando]

Originally Posted by ///M Houbi

Quote 2, what i was told is that basically US and EU spec cars will have slightly different ECU‘s. The EU models will deliver slightly more power at the motor than the non-OPF equipped cars so both will have the same power at the wheel in the end.

Further i was told that we can expect around 450hp out of the box, not the marketed 410hp. This is an assumption based on dozens of dozens S55 M3/M4‘s my friend has tuned and dynoed in the past years.

I will ask about responsivenes and let you know.

"only 40 more hp" they said.

"we'll see when it's on a dyno" I said

[ChrisK]

Originally Posted by MR.

But does that mean a different tune as well! If so I will load the tune of a U.S. car in my EU car.

MR

With the increase in back pressure caused by the OPF I would assume that the EU ECU is tuned differently to compensate, since the goal is similar wheel HP between the US and EU.

My 2 cents

[akkando]

Originally Posted by MR.

But does that mean a different tune as well! If so I will load the tune of a U.S. car in my EU car.

MR

I think the US tune will make less power because it's not trying to make up for the OPF.

[Veebee]

Originally Posted by MR.

But does that mean a different tune as well! If so I will load the tune of a U.S. car in my EU car.
MR

The tune for us will probably not be good for the eu version. But as said nobody knows what is the resistance of the filter in the exhaust...

[AlpsRider]

Originally Posted by Veebee

But does that mean a different tune as well! If so I will load the tune of a U.S. car in my EU car.

MR

The tune for us will probably not be good for the eu version. But as said nobody knows what is the resistance of the filter in the exhaust...

Well if you're going to flash a tune to your ECU you might as well flash a M4 CS tune.

[M-Pilot]

I doubt an emission filter will make 40-50hp difference but even if it does and even if there are two different tunes (i.e US and EU tune), I still don't see the point of getting EU tune on a US car or vice versa. It has no difference than getting a Stage 1 tune or an M4 CS tune in terms of risking your warranty. If I'm willing to risk voiding my drivetrain warranty, I'd rather go for the M4 CS software/tune but it's just me

[M-Pilot]

Originally Posted by AlpsRider

Well if you're going to flash a tune to your ECU you might as well flash a M4 CS tune.

+1

You were 40sec faster than me

[Poochie]

One good thing about Trump, he doesn't give a ish about preserving the environment; so at the moment, vehicle's pollution level or OPF filter is the last thing we have to worry about in the U S or A..

World War 3, maybe..

[GoneIn4Secs]

Originally Posted by ///M Houbi

Quote 2, what i was told is that basically US and EU spec cars will have slightly different ECU‘s. The EU models will deliver slightly more power at the motor than the non-OPF equipped cars so both will have the same power at the wheel in the end.

Further i was told that we can expect around 450hp out of the box, not the marketed 410hp. This is an assumption based on dozens of dozens S55 M3/M4‘s my friend has tuned and dynoed in the past years.

I will ask about responsivenes and let you know.

hmm you say this,

but all the times Ive seen ppl put their stock M2s on dynos, the car is always showing outputting like 30-40 to even 60 hp less???

so whats the real story?

[M-Pilot]

Originally Posted by GoneIn4Secs

hmm you say this,

but all the times Ive seen ppl put their stock M2s on dynos, the car is always showing outputting like 30-40 to even 60 hp less???

so whats the real story?

That's the N55 for you, which is already maxed out from the factory. N55 M2 puts down ~330-335whp stock while being rated at 365hp. I have seen countless dyno runs of M3/M4 ZCP putting down 440-445whp stock while being rated at 444hp on paper. These number will vary depending on the temp, dyno, fuel etc. but this is generally what people refer when they talk about S55 being underrated by BMW. So I wouldn't be surprised if a stock M2C puts down 390-400whp.

[hellrotm]

Originally Posted by MR.

But does that mean a different tune as well! If so I will load the tune of a U.S. car in my EU car.

MR

Ideally remove the OPF’s and get a CS tune(as mentioned above).

[///M Houbi]

Originally Posted by GoneIn4Secs

hmm you say this,

but all the times Ive seen ppl put their stock M2s on dynos, the car is always showing outputting like 30-40 to even 60 hp less???

so whats the real story?

This is about S55 and not N55.

[GoneIn4Secs]

Originally Posted by ///M Houbi

This is about S55 and not N55.

Also u have to know that the car limits power output if the front wheels are not spinning ,

Some ppl dont take this account

[chris719]

Originally Posted by GoneIn4Secs

Also u have to know that the car limits power output if the front wheels are not spinning ,

Some ppl dont take this account

I think you need to do some basic research on chassis dynos and the interpretation of their results...

[Nebelhinten]

Originally Posted by ChrisK

With the increase in back pressure caused by the OPF I would assume that the EU ECU is tuned differently to compensate, since the goal is similar wheel HP between the US and EU.

My 2 cents

That possibility occurred to me since we know that S55 can make enough power to compensate for loss due to the particulate filter. So maybe B58 in Z4 can't be tuned high enough to compensate and bring it to same 382 crank hp as US spec Z4? If the filter alone really accounts for around 50 hp as stated in reviews, B58 would need to be tuned somewhere near 430 hp to compensate. Just found it odd that they would have that big a difference between euro and US version due to filter. In terms of wheel hp, Dynos show stock B58 at around 330, with MPPSK around 370. The cap seems to be at 400whp due to ECU fueling limits.

[chris719]

Originally Posted by Nebelhinten

That possibility occurred to me since we know that S55 can make enough power to compensate for loss due to the particulate filter. So maybe B58 in Z4 can't be tuned high enough to compensate and bring it to same 382 crank hp as US spec Z4? If the filter alone really accounts for around 50 hp as stated in reviews, B58 would need to be tuned somewhere near 430 hp to compensate. Just found it odd that they would have that big a difference between euro and US version due to filter. In terms of wheel hp, Dynos show stock B58 at around 330, with MPPSK around 370. The cap seems to be at 400whp due to ECU fueling limits.

It seems like a big mistake to have designed B58 without accounting for the regulations change if it really reduces power by that much. Your theory makes some sense, but are they really going to produce M4 ZCP and CS with 500 hp equivalent tunes from the factory?