BM3 Stage 2 seems slower

[Maseratipapi]

I have a 2020 BMW m4. Ive had BM3 stage 1 93 for a few months and it has been amazing. Recently I installed a catless downpipe and decided to flash stage 2 93. Nothing is wrong with the car it drives fine however i dont know if its in my head or what but i felt like stage 1 might have been faster, or at least spooled faster. Has anyone else experienced this? I took a few datalogs but im not sure what to look for. I will post them below. If anyone spots anything unusual please let me know. First will be data logs of stage 2. Then i flashed it back to stage 1 and took a few more logs. Im still currently stage 1, not sure if i should flash it stage 2 again. Which one seems better in the logs? Thank you

Stage 2 93
https://www.bootmod3.net/log?id=6827...83425ced73500f
https://www.bootmod3.net/log?id=6827...03c76389a033d0
https://www.bootmod3.net/log?id=6827...03c76389a033d1
https://www.bootmod3.net/log?id=6827...1f993776e03b49

Stage 1 93
https://www.bootmod3.net/log?id=6828...83425ced735a24
https://www.bootmod3.net/log?id=6828...83425ced735a25
https://www.bootmod3.net/log?id=6828...1f993776e042de
https://www.bootmod3.net/log?id=6828...1f993776e042df

[808F80]

I noticed the same thing, stage 1 has crazy torque, stage 2 has less torque but crazy top end

[808F80]

I've also noticed some other disadvantages to stage 2

[Maseratipapi]

What other disadvantages? Did you stay stage 2 or go back to stage 1?

[Drewbkm4]

I’m on bm3 stage 2 93 as well,eager to see what’s best. Definitely have to dyno my car soon!!

[M3SQRD]

I don’t have BM3 but the differences in acceleration between BPM GTS, stage 1 and stage 2 ecu tunes is easily noticeable. One post said BM3 stage 1 has more torque and BM3 stage 2 has more top end power. I find this hard to believe because the shape of the torque curve at peak torque (“flat”) is different from the shape of the torque curve at peak power (“negative linearly sloped” due to turbo flow limits). If this is true, why would BM3 even lower the stage 2 peak torque below the stage 1 peak torque when it would’ve been easier from a tuning perspective to keep the “flat” portion of the torque curves the same? However, stage 2 peak torque is higher than stage 1 peak torque. The higher stage 2 “flat” torque curve means as the torque curve transitions to a “negative linearly sloped” torque curve, stage 2 has more torque available than stage 1 and, therefore, more torque at similar rpms means more stage 2 peak power (power is proportional to torque x rpm). Stage 2 tunes typically have 20-25 whp more and 15-20 lbf-ft more than stage 1 tunes.

[Maseratipapi]

Thank you for this detailed response. I need to get it dynoed

[AIJ19]

Hi there,
I also own a 2020 M4 and initially upgraded my stock exhaust with a Valvetronic Equal Length Sport Exhaust—loved the sound and performance. Later, I installed a catless downpipe and tuned the car to Stage 2. Since then, I’ve been experiencing a bad rattling noise during acceleration and a harsh, almost breaking-like sound.

I reached out to Valvetronic for support, and they mentioned that I should’ve opted for a VRSF high-flow catted downpipe instead.

Now I’m considering switching back to the stock downpipe and running a Stage 1 tune. My main question is:
Does Stage 1 still sound aggressive and exciting? I’m trying to strike the right balance between performance and sound quality without the unwanted noise issues.

Any insight or recommendations would be appreciated!

[Mahduece]

AIJ19 IMO nothing makes an S55 sound worse than Catless DP. So I know it’s a pain to do, but take valtronics advice and change that. If you still have your stock dp just save the $ and use those. After all you said you loved the sound prior to the Catless DP install.

As for sound stage 2 vs 1. That won’t matter or change much tbh. Also, why not just take 5 min and flash stage 1 to test?

[tysonjunior]

There is a group on Fb just for BM3 that they can read your data logs. I'm curious as to what you find.

[AIJ19]

Mahduece the reason I upgraded my downpipe because some says that you should not get stage 2 with stock downpiie. It will damage the engine.
Yes I think I have to try the VRSF catted downpipe. My current one is a cheap one. Bad sound could be because of cheap material.

[Mahduece]

Originally Posted by AIJ19

Mahduece the reason I upgraded my downpipe because some says that you should not get stage 2 with stock downpiie. It will damage the engine.
Yes I think I have to try the VRSF catted downpipe. My current one is a cheap one. Bad sound could be because of cheap material.

That’s bad info. Stock DP is fine.

[Jaizero]

Originally Posted by AIJ19

Mahduece the reason I upgraded my downpipe because some says that you should not get stage 2 with stock downpiie. It will damage the engine.
Yes I think I have to try the VRSF catted downpipe. My current one is a cheap one. Bad sound could be because of cheap material.

I have been running BM3 stage 2 Flexfuel Multimap for over a year now with stock cats and exhaust. The stock cats flow just fine, and the tune will not harm the cats or your engine.

I still have the stock plastic charge pipes and J-pipe, too.

No issues whatsoever.

[Maseratipapi]

Originally Posted by AIJ19

Hi there,
I also own a 2020 M4 and initially upgraded my stock exhaust with a Valvetronic Equal Length Sport Exhaust—loved the sound and performance. Later, I installed a catless downpipe and tuned the car to Stage 2. Since then, I’ve been experiencing a bad rattling noise during acceleration and a harsh, almost breaking-like sound.

I reached out to Valvetronic for support, and they mentioned that I should’ve opted for a VRSF high-flow catted downpipe instead.

Now I’m considering switching back to the stock downpipe and running a Stage 1 tune. My main question is:
Does Stage 1 still sound aggressive and exciting? I’m trying to strike the right balance between performance and sound quality without the unwanted noise issues.

Any insight or recommendations would be appreciated!

I have the MAD catless downpipes and my car sounds amazing. However I also have a VRSF single midpipe. If you ever plan on doing catless downpipes it is recommended to do a single midpipe. It’s a nice deep aggressive sound. Not much rasp at alll. Stage 1 and stage 2 are very similar in power

[AIJ19]

Maseratipapi I do have catless downpipe already. Instead of making it better it actually made the sound worst, simetime sounds like broken tone. FYI I got the downpipe from Alibaba, not sure it could be because of cheap material.

[808F80]

Originally Posted by M3SQRD

I don’t have BM3 but the differences in acceleration between BPM GTS, stage 1 and stage 2 ecu tunes is easily noticeable. One post said BM3 stage 1 has more torque and BM3 stage 2 has more top end power. I find this hard to believe because the shape of the torque curve at peak torque (“flat”) is different from the shape of the torque curve at peak power (“negative linearly sloped” due to turbo flow limits). If this is true, why would BM3 even lower the stage 2 peak torque below the stage 1 peak torque when it would’ve been easier from a tuning perspective to keep the “flat” portion of the torque curves the same? However, stage 2 peak torque is higher than stage 1 peak torque. The higher stage 2 “flat” torque curve means as the torque curve transitions to a “negative linearly sloped” torque curve, stage 2 has more torque available than stage 1 and, therefore, more torque at similar rpms means more stage 2 peak power (power is proportional to torque x rpm). Stage 2 tunes typically have 20-25 whp more and 15-20 lbf-ft more than stage 1 tunes.

I don't know why you find it necessary to put all this over complicated speculation. having a hard time trying to figure out what you're saying here. But, most likely stage 1 has a very flat *boost* curve... In the real world that doesn't make the power level usable on a rear wheel drive car, It just makes the torque instantaneous and monstrous. Although this might make the car feel faster/more powerful, in a straight line your quarter mile times will suffer And you'll feel the power die off in the high RPMs, which is exactly what you feel with BM3 stage 1.

BM3 is not a perfect science. The BM3 tuners have done a pretty good job of cracking the code and creating the baseline, That's exactly why it's called "off the shelf" and not "protuned". If you want a refined tune you need to go to a tuning specialist. The stage 1 and stage 2 OTC are not going to be OEM quality.

That being said, in many ways, their stage 2 is closer to being OEM quality, meaning they intentionally made the boost more progressive so that you actually have traction by the time you have HP. That's how a proper tune works. For our purpose, you shouldn't give a turbocharged engine unlimited torque low in the RPM range, just for the power to die off in the high RPMs. It makes you lose traction, makes the power unsusable, and/or makes the power difficult to modulate. BMW deliberately tuned the car with a progressive power level for these reasons.

If you just want to drift the car? Go stage 1: Instant crazy torque and a touchy throttle. If you want a car that's actually faster in a straight line? Go stage two. (Disclaimer I don't recommend drifting these cars unless you have major suspension modification *dangerous)

If you want something that's not "off the shelf"? You might think about getting a custom tune.

You'll notice that the OTS GTS and CS tunes have a progressive boost increase for the reasons that I mentioned.

*I must also make an additional note that the stage 1 tune comes with a more sensitive gas pedal. This is part of the reason why it feels faster, although not all of the reason. Still, if i had to estimate I'd say the stage 1 makes more torque below 4000 rpm, while stage 2 more torque above 5000 (Remember, horsepower is a function of torque. Torque*RPM/5250, so saying there's more torque above 5250 rpm also means there's more power).

Please be safe and don't let these discussions influence anyone to be reckless.

[808F80]

Originally Posted by Maseratipapi

What other disadvantages? Did you stay stage 2 or go back to stage 1?

Stage 2 OTS does not give you total control over the exhaust flap. Currently in discussions with BM3 about it. At first they were very quick to answer my questions and even created a test map that was supposed to solve the problem. But since then they've been silent and I think they need to look deeper into stage 2 on their own.

The other problem I noticed with stage 2 is in 6th gear at about 3,000/3500 RPM on the highway, if you jam the gas you will get jerking and pinging. This is in about 83 degree weather with 91 octane tune on 92 octane gas, close to sea level.

*One other advantage to stage 2: Is you can start and drive the car without switching modes, leave it in econ/sport/sport, full traction control, maybe switch to sport mode if you want, and the car drives 100% civilized as it rips to 100mph like a banshee. Ferrari like acceleration, with full traction control engaged.

[M3SQRD]

Originally Posted by 808F80

I don't know why you find it necessary to put all this over complicated speculation. having a hard time trying to figure out what you're saying here. But, most likely stage 1 has a very flat *boost* curve... In the real world that doesn't make the power level usable on a rear wheel drive car, It just makes the torque instantaneous and monstrous. Although this might make the car feel faster/more powerful, in a straight line your quarter mile times will suffer And you'll feel the power die off in the high RPMs, which is exactly what you feel with BM3 stage 1.

BM3 is not a perfect science. The BM3 tuners have done a pretty good job of cracking the code and creating the baseline, That's exactly why it's called "off the shelf" and not "protuned". If you want a refined tune you need to go to a tuning specialist. The stage 1 and stage 2 OTC are not going to be OEM quality.

That being said, in many ways, their stage 2 is closer to being OEM quality, meaning they intentionally made the boost more progressive to make the power usable in the low rpm. For our purpose, you shouldn't give a turbocharged engine unlimited torque low in the RPM range, just for the power to die off in the high RPMs. It makes you lose traction, makes the power unsusable, and/or makes the power difficult to modulate. BMW deliberately tuned the car with a progressive power level for these reasons.

If you just want to drift the car? Go stage 1: Instant crazy torque and a touchy throttle. If you want a car that's actually faster in a straight line? Go stage two. (Disclaimer I don't recommend drifting [...]

Why is what I wrote speculation? Using the same dyno with the same tech on days with similar ambient conditions (this doesn’t matter for the f8x because the ecu already adjusts for this - check the sae standard for turbo and NA engines) does it or does it not remove “speculation” from different ecu tuning specs? How about different lap times on track when using the different ecu tunes? Based on the average, each tune is ~0.5 sec quicker on a 2.0 mile track. Let’s try this again, the non-BM3 ecu GTS, st1 and st2 tunes I’m using have an increasing higher torque plateau from ~2500-5000 rpm as you step up thru the tunes, torque from ~5000-redline rpm drops off linearly with increasing rpm for all three tunes, and the increasing torque plateau from each tune produces higher peak power because it means the linearly decreasing torque curve starts off from a higher torque value and, therefore, you have more torque as you step thru GTS to st2 when you reach the ~5500-5600 rpm range where peak power occurs. Starting from the GTS tune and stepping thru st1 and st2, you get an additional ~20-25 whp and ~15-20 wheel torque from each stage. So st2 is quicker than st1 and st1 is quicker than GTS. Does this help you comprehend what I wrote as well as remove the “speculation” that you’ve accused me of? If not, it’s not my problem. I don’t believe the BM3 tunes have different trends that makes BM3 st2 slower than BM3 st1.

[808F80]

Originally Posted by M3SQRD

Why is what I wrote speculation? Using the same dyno with the same tech on days with similar ambient conditions (this doesn’t matter for the f8x because the ecu already adjusts for this - check the sae standard for turbo and NA engines) does it or does it not remove “speculation” from different ecu tuning specs? How about different lap times on track when using the different ecu tunes? Based on the average, each tune is ~0.5 sec quicker on a 2.0 mile track. Let’s try this again, the non-BM3 ecu GTS, st1 and st2 tunes I’m using have an increasing higher torque plateau from ~2500-5000 rpm as you step up thru the tunes, torque from ~5000-redline rpm drops off linearly with increasing rpm for all three tunes, and the increasing torque plateau from each tune produces higher peak power because it means the linearly decreasing torque curve starts off from a higher torque value and, therefore, you have more torque as you step thru GTS to st2 when you reach the ~5500-5600 rpm range where peak power occurs. Starting from the GTS tune and stepping thru st1 and st2, you get an additional ~20-25 whp and ~15-20 wheel torque from each stage. So st2 is quicker than st1 and st1 is quicker than GTS. Does this help you comprehend what I wrote as well as remove the “speculation” that you’ve accused me of? If not, it’s not my problem. I don’t believe the BM3 tunes have different trends that makes BM3 st2 slower than BM3 st1.

I think you should have taken more time to read what I wrote. I don't know what's hard to understand about what I said. So I'll summarize::

I very clearly said stage 2 is faster than stage 1 and also that it creates more *power.
Stage 1only *feels* faster, at first, due to its touchy gas pedal and monstrous torque right off the line, which is probably due to it having a flatter boost curve and more torque in the low RPMs. (Stage 2 having a progressive boost curve that gets higher in the higher RPMs)

I'd also like to add that when I first programmed stage 2, I also thought I noticed the same thing," this is not as fast as stage 1" But with a few minutes of experimentation I learned that I was having to slow down a lot more than before, brakes became more of an issue. You don't get the same brutal torque from stage 1, but stage 2 is the more powerful tune. This is especially obvious closer to redline

[M3SQRD]

Originally Posted by 808F80

I think you should have taken more time to read what I wrote. I don't know what's hard to understand about what I said. So I'll summarize::

I very clearly said stage 2 is faster than stage 1 and also that it creates more *power.
Stage 1only *feels* faster, at first, due to its touchy gas pedal and monstrous torque right off the line, which is probably due to it having a flatter boost curve and more torque in the low RPMs. (Stage 2 having a progressive boost curve that gets higher in the higher RPMs)

I'd also like to add that when I first programmed stage 2, I also thought I noticed the same thing," this is not as fast as stage 1" But with a few minutes of experimentation I learned that I was having to slow down a lot more than before, brakes became more of an issue. You don't get the same brutal torque from stage 1, but stage 2 is the more powerful tune. This is especially obvious closer to redline

I was addressing your statement about my “over complicated speculation” and your trouble “comprehending” what I was saying. I can’t tell whether I succeeded but it doesn’t bother me either way. I had no issues ascertaining the differences in acceleration and/or feel between the three different tunes but then again I’m not running BM3 tunes. They each have their own torque hit but to expect a St2 tune to have the same increased torque hit that a St1, or GTS, tune has over the stock torque isn’t realistic; however, once again, IMO there’s enough difference between each tune to feel the increase in torque and power. I don’t find the St1 tune to feel anything like what a NA linear power curve feels like (I can drive back to back to back one of my e92 M3s with the s65, my e46 M3 with the s54 and my f82 with the s55). Nevertheless, I do find the GTS tune has a s55 power curve that feels the closest to a NA linear power curve but it’s still not close to what a s65 or s54 NA pull to redline feels like.

[Maseratipapi]

Originally Posted by 808F80

I don't know why you find it necessary to put all this over complicated speculation. having a hard time trying to figure out what you're saying here. But, most likely stage 1 has a very flat *boost* curve... In the real world that doesn't make the power level usable on a rear wheel drive car, It just makes the torque instantaneous and monstrous. Although this might make the car feel faster/more powerful, in a straight line your quarter mile times will suffer And you'll feel the power die off in the high RPMs, which is exactly what you feel with BM3 stage 1.

BM3 is not a perfect science. The BM3 tuners have done a pretty good job of cracking the code and creating the baseline, That's exactly why it's called "off the shelf" and not "protuned". If you want a refined tune you need to go to a tuning specialist. The stage 1 and stage 2 OTC are not going to be OEM quality.

That being said, in many ways, their stage 2 is closer to being OEM quality, meaning they intentionally made the boost more progressive so that you actually have traction by the time you have HP. That's how a proper tune works. For our purpose, you shouldn't give a turbocharged engine unlimited torque low in the RPM range, just for the power to die off in the high RPMs. It makes you lose traction, makes the power unsusable, and/or makes the power difficult to modulate. BMW deliberately tuned the car with a progressive power level for these reasons.

If you just want to drift the car? Go stage 1: Instant crazy torque and a touchy throttle. If you want a car that's actually faster in a straight line? Go stage two. (Disclaimer I don't recommend drifting these cars unless you have major suspension modification *dangerous)

If you want something that's not "off the shelf"? You might think about getting a custom tune.

You'll notice that the OTS GTS and CS tunes have a progressive boost increase for the reasons that I mentioned.

*I must also make an additional note that the stage 1 tune comes with a more sensitive gas pedal. This is part of the reason why it feels faster, although not all of the reason. Still, if i had to estimate I'd say the stage 1 makes more torque below 4000 rpm, while stage 2 more torque above 5000 (Remember, horsepower is a function of torque. Torque*RPM/5250, so saying there's more torque above 5250 rpm also means there's more power).

Please be safe and don't let these discussions influence anyone to be reckless.

This sums it up perfectly thank you. It was underwhelming initially because of the torque, however after driving with it for a while I can feel how much more power it has in the top end. Definitely an overall better tune for daily driving. Thank you

[Jaizero]

Originally Posted by 808F80

Stage 2 OTS does not give you total control over the exhaust flap. Currently in discussions with BM3 about it. At first they were very quick to answer my questions and even created a test map that was supposed to solve the problem. But since then they've been silent and I think they need to look deeper into stage 2 on their own.

The other problem I noticed with stage 2 is in 6th gear at about 3,000/3500 RPM on the highway, if you jam the gas you will get jerking and pinging. This is in about 83 degree weather with 91 octane tune on 92 octane gas, close to sea level.

*One other advantage to stage 2: Is you can start and drive the car without switching modes, leave it in econ/sport/sport, full traction control, maybe switch to sport mode if you want, and the car drives 100% civilized as it rips to 100mph like a banshee. Ferrari like acceleration, with full traction control engaged.

LMFAO

Efficient throttle does NOT have "Ferrari like acceleration". It definitely doesn't if you're in DL 1 or 2 in 'D' mode.