[Bluenose-2er]

Originally Posted by atomic837

I'm comparing my 6MT 2017 M2 in Sports+ mode to my 6MT 2009 135i.

The most noticeable example I can give is at a steady cruising speed...say the highway at 65MPH somewhere in the vicinity of 3000 RPMs in 6th gear. The initial tip in of the accelerator (i.e. to pass a vehicle) will give me a near instantaneous push back into my seat in the 135i, but will only give me a mild acceleration in my M2 until about a second later when I feel a similar push back into my seat. It's a very distinct sensation where I can clearly feel the engine "waking up" for a brief second before it hits hard at full turbo.

I'm not crazy and I'm not naive. I've been driving for 20 years and have experienced various engine designs (I owned a 2004 WRX and my brother owned a 2009 EVO X, so I know what more substantial lag feels like). I practically drive my 135i and M2 back to back on certain occasions. "My" N54 vehicle is a more responsive and eager car than "my" M2 at lower RPMs. Granted, at higher RPMs the turbo responsiveness improves a bit, and the power blows away the 135i. I'm not disputing that. But the difference is palpable.

In generalities, spec sheets, and marketing propaganda, you would think that my conclusions would have to be mistaken. However, given my daily direct comparisons, I'm confident that the reality, as it pertains to my cars at least, is that I'm not.

Interesting. Seems we have two votes for M2 N55 having less lag than the N54 (myself and doug_999) and one vote for the opposite. Could indeed be individual car characteristics, driving styles, or a combination.

Intuitively, the N54 twin turbo is more oversized (i.e. has more tuning room) than the dual scroll turbo of the M2... which everyone seems to agree is sized for its current tune and not much more. So you would expect that would give the M2 the advantage in the lag department (at factory settings).

Sorry to hear of your experience... I am quite happy with the difference mine has shown. Would really be a bummer to feel that after spending all that money.

[atomic837]

Originally Posted by Bluenose-2er

Interesting. Seems we have two votes for M2 N55 having less lag than the N54 (myself and doug_999) and one vote for the opposite. Could indeed be individual car characteristics, driving styles, or a combination.

Intuitively, the N54 twin turbo is more oversized (i.e. has more tuning room) than the dual scroll turbo of the M2... which everyone seems to agree is sized for its current tune and not much more. So you would expect that would give the M2 the advantage in the lag department (at factory settings).

Sorry to hear of your experience... I am quite happy with the difference mine has shown. Would really be a bummer to feel that after spending all that money.

Don't get me wrong, the M2 is an exhilarating drive, and the turbo and the power it provides is rush. The N54 just feels like a better "around the town" driver" if you're staying in the lower end of the RPMs.

The more I think about this, the more I feel that it might not be "less" lag in the 135i that I'm feeling, but the effect of less boost pressure which would entail less spool up compared to the M2's higher boost.

I'm not certain of the stock boost pressure in an 135i versus an M2, but it's safe to assume that the M2's N55 is a tuned variant with additional boost over the stock engine. More boost equals more time / effort to spin up, right?

In fact, now that I think about it, the response delay in the M2 feels an awful lot like my 135i when I have the JB3 turned on to the high boost setting. The instant response is subordinated to a slightly delayed surge in power as the turbo comes online. For the record, my original comparisons were based on both cars in stock form.

I know I'm oversimplifying, but the M2 engine is in some ways like a chip tuned version of the stock variant. It sort of feels like it at least.

Appreciate the discussion here as it really is helping me to better understand the dynamics of the car. Good stuff.

[Bluenose-2er]

Glad to hear your impression is not affecting your enjoyment of an awesome car.

Good point about the relative boost pressures. I would be curious to know what the factory settings are as well. I am sure some geek on here knows. Anyone? I am not a turbo expert, but your explanation makes some sense. Though again I really did not see it when driving them back to back myself.

I will let the comment slide about the N55B30T0 being a chip-tuned N55B30O0... much more to it than that! Crankshaft main bearings, pistons, oil sump, cooling... etc.

Still think you need to stop driving it like such a granny (kidding!... just kidding)

[atomic837]

Originally Posted by Bluenose-2er

Glad to hear your impression is not affecting your enjoyment of an awesome car.

Good point about the relative boost pressures. I would be curious to know what the factory settings are as well. I am sure some geek on here knows. Anyone? I am not a turbo expert, but your explanation makes some sense. Though again I really did not see it when driving them back to back myself.

I will let the comment slide about the N55B30T0 being a chip-tuned N55B30O0... much more to it than that! Crankshaft main bearings, pistons, oil sump, cooling... etc.

Still think you need to stop driving it like such a granny (kidding!... just kidding)

I'm definitely changing my driving style a bit with the M2. You can't be lazy when you drive it if you want to unleash its full potential. And I'm moving to driving exclusively in Sport + mode (except for the highway).

Totally understand the M2 engine not just being a chip-tuned N55. The mechanical upgrades are legit, but I tend to think they are more of the enablers for a reliable increase in boost pressure.


Curious now. The N54 had a non-turbo inline-6 sibling that was used in the early 128i cars (the N52). Unless I'm mistaken, the N55 didn't have such a compliment.... Aren't the less powerful car models now fitted with completely different 4 cylinder turbo engines? This might explain the NA part of the N55 lacking a bit in comparison.... If BMW engineered the non-turbo N54 sibling to be a strong performer off-boost, it would stand to reason that this behavior would still be present in the more powerful boosted version.

In essence, the N54 just made a good thing even better, whereas the N55 engineers didn't put any focus on tuning off-boost performance (since there isn't a standalone non-turbo variant). This may also explain a piece of the "lag" puzzle.

[Bluenose-2er]

Originally Posted by atomic837

Curious now. The N54 had a non-turbo inline-6 sibling that was used in the early 128i cars (the N52). Unless I'm mistaken, the N55 didn't have such a compliment.... Aren't the less powerful car models now fitted with completely different 4 cylinder turbo engines? This might explain the NA part of the N55 lacking a bit in comparison.... If BMW engineered the non-turbo N54 sibling to be a strong performer off-boost, it would stand to reason that this behavior would still be present in the more powerful boosted version.

In essence, the N54 just made a good thing even better, whereas the N55 engineers didn't put any focus on tuning off-boost performance (since there isn't a standalone non-turbo variant). This may also explain a piece of the "lag" puzzle.

I am pretty sure that M looked at the whole performance curve. Even if it was never released as an NA engine, that doesn't mean they ignore the performance when the turbo isn't fully engaged. If anything, I would think an engine designed from the ground up to be turbocharged would be more seamless than one designed as NA with turbo added later.

[atomic837]

Originally Posted by Bluenose-2er

I am pretty sure that M looked at the whole performance curve. Even if it was never released as an NA engine, that doesn't mean they ignore the performance when the turbo isn't fully engaged. If anything, I would think an engine designed from the ground up to be turbocharged would be more seamless than one designed as NA with turbo added later.

I would still question the degree of engineering spent on the non-turbo performance characteristics of an "off the shelf" engine that is nearly 7 years old. I think it's possible that the M engineers accepted the limitations of the older engine design and focused primarily on the boosted performance, where the engine spends 99% of its operating time. Truly, the perceived lag is quite small no matter how it's sliced.

The two engines seem to have distinctly different behaviors from my experience, even though the specs show them as being very similar. I can appreciate both, as I see them as being necessary tradeoffs for the purposes of the cars they are powering.

I would be curious to drive a M235i for a more apples-to-apples comparison. I truly wonder if the differences really do just boil down to the additional boost on the M2.

[XutvJet]

Originally Posted by atomic837

Curious now. The N54 had a non-turbo inline-6 sibling that was used in the early 128i cars (the N52). Unless I'm mistaken, the N55 didn't have such a compliment.... Aren't the less powerful car models now fitted with completely different 4 cylinder turbo engines? This might explain the NA part of the N55 lacking a bit in comparison.... If BMW engineered the non-turbo N54 sibling to be a strong performer off-boost, it would stand to reason that this behavior would still be present in the more powerful boosted version.

In essence, the N54 just made a good thing even better, whereas the N55 engineers didn't put any focus on tuning off-boost performance (since there isn't a standalone non-turbo variant). This may also explain a piece of the "lag" puzzle.

The N54 and N55 have the same compression ratio, displacement, and architecture. The N54 used a double VANOS, a traditional throttle body, and pneumatic wastegate control. The N55 uses Valvetronic (no throttle body used unless Valvetronic fails) and the 2014+ cars have electronic wastegate control. Arguably, by its design, the N55 should be the better driving motor off boost.

BMW goes to great lengths to deliver smooth power delivery. Thus, for better or worse, they manipulate a ton of parameters to deliver that feel. It's largely why they can deliver so much more snappiness in boost delivery when in the Sport throttle settings. It's not just the throttle becoming more sensitive, it's wastegate, timing, and cam lift manipulation as well.

Also, the nannies in these cars are hyper sensitive and operate quite efficiently in the background to the point that they too influence power and boost delivery. One should drive these cars around in DSC Off for two weeks to see what I'm talking about. I say two weeks because it takes some time to get use to the throttle response, but once you do, the car will become quite lively.

[XutvJet]

Originally Posted by atomic837

I would be curious to drive a M235i for a more apples-to-apples comparison. I truly wonder if the differences really do just boil down to the additional boost on the M2.

The M2 has upgraded pistons, oil squirters, and bearings. Both cars use the same forged crank (other N55 models use a cast crank). Many claim the M2 uses a slightly different turbo though no one has been able to prove this with the exception that the part numbers are different.

The M2 makes around 4psi more than the M235 N55. On the dyno, the M2's power numbers are eerily similar to an M235 running BMS Stage 1 (3.5+ psi) or JB4 Map 1 (4 psi). The only differences being the power curves are slightly smoother with M2. This should be expected since BMW is actually writing code into the DME to deliver more power rather than using piggyback systems to manipulate the boost and timing control data to create power.

Once you start adding mods, there's really no difference between the power numbers and gains. They're basically even.

[atomic837]

Originally Posted by XutvJet

The M2 has upgraded pistons, oil squirters, and bearings. Both cars use the same forged crank (other N55 models use a cast crank). Many claim the M2 uses a slightly different turbo though no one has been able to prove this with the exception that the part numbers are different.

The M2 makes around 4psi more than the M235 N55. On the dyno, the M2's power numbers are eerily similar to an M235 running BMS Stage 1 (3.5+ psi) or JB4 Map 1 (4 psi). The only differences being the power curves are slightly smoother with M2. This should be expected since BMW is actually writing code into the DME to deliver more power rather than using piggyback systems to manipulate the boost and timing control data to create power.

Once you start adding mods, there's really no difference between the power numbers and gains. They're basically even.

Yes. With those things considered, what I'm saying is that I'm curious what my perception would be of the turbo lag in a less aggressively boosted N55, such as in the M235i. My inkling is that it might feel closer to my comparison with a stock N54. As in, less boost = less lag.

[atomic837]

Originally Posted by XutvJet

The N54 and N55 have the same compression ratio, displacement, and architecture. The N54 used a double VANOS, a traditional throttle body, and pneumatic wastegate control. The N55 uses Valvetronic (no throttle body used unless Valvetronic fails) and the 2014+ cars have electronic wastegate control. Arguably, by its design, the N55 should be the better driving motor off boost.

BMW goes to great lengths to deliver smooth power delivery. Thus, for better or worse, they manipulate a ton of parameters to deliver that feel. It's largely why they can deliver so much more snappiness in boost delivery when in the Sport throttle settings. It's not just the throttle becoming more sensitive, it's wastegate, timing, and cam lift manipulation as well.

Also, the nannies in these cars are hyper sensitive and operate quite efficiently in the background to the point that they too influence power and boost delivery. One should drive these cars around in DSC Off for two weeks to see what I'm talking about. I say two weeks because it takes some time to get use to the throttle response, but once you do, the car will become quite lively.

I haven't driven with all the nannies off yet.... Just Sport+. I will give this a shot and see if that makes a difference.

[XutvJet]

Originally Posted by atomic837

Yes. With those things considered, what I'm saying is that I'm curious what my perception would be of the turbo lag in a less aggressively boosted N55, such as in the M235i. My inkling is that it might feel closer to my comparison with a stock N54. As in, less boost = less lag.

I feel the same amount of lag in both. The M2 hits harder though. I actually like my turbo cars to feel a turbocharged. I don't want it lagging like my 2012 WRX or some 1990s turbo car , but I do like it to feel turbocharged. It adds to the character of the car.

I don't know how long you've owned your M2, but if you haven't driven it in cooler conditions (i.e., sub 60s), you'll see reduced lag as well. By nature, there's more turbo lag when the ambient temps are hotter and more humid and less oxygen available.

[nizzo]

Did an Autocross event with the M2, on a hot summer day, was probably high 80s for the ambient temps. We were maybe a dozen guys, across 3 M2's, and they all had HORRENDOUS heat soak-induced turbo lag from a stop. It was atrocious. I'd stomp on the go pedal after each stop at the cones where we're supposed to stop, and it literally would wait a full second before I get going.

Others concurred.

Earlier on at a separate autoX course right near by, at the same racetrack, maybe a half hour earlier, we had M4's (3 of them as well). Those exhibited a lot less throttle lag / heat soak suffering.

I hope BMW in the LCI of the M2 fixed this, because when it's hot out and you're pushing the first gen (2015/2016/2017) M2 as a performance vehicle, that N54 suffers massively from heat soak. Very bad heat management sadly.

It turned me off so much that any chance that I'd consider getting one, was dashed, despite really liking the looks of the car, the brake feel, steering, and just general chassis/handling feel, and the sound/power.

[stefan]

Originally Posted by nizzo

Did an Autocross event with the M2, on a hot summer day, was probably high 80s for the ambient temps. We were maybe a dozen guys, across 3 M2's, and they all had HORRENDOUS heat soak-induced turbo lag from a stop. It was atrocious. I'd stomp on the go pedal after each stop at the cones where we're supposed to stop, and it literally would wait a full second before I get going.

Others concurred.

Earlier on at a separate autoX course right near by, at the same racetrack, maybe a half hour earlier, we had M4's (3 of them as well). Those exhibited a lot less throttle lag / heat soak suffering.

I hope BMW in the LCI of the M2 fixed this, because when it's hot out and you're pushing the first gen (2015/2016/2017) M2 as a performance vehicle, that N54 suffers massively from heat soak. Very bad heat management sadly.

It turned me off so much that any chance that I'd consider getting one, was dashed, despite really liking the looks of the car, the brake feel, steering, and just general chassis/handling feel, and the sound/power.

Some fanatics on here and self proclaimed track stars insist there is no heat soak whatsoever unless tuned. Can't wait for these guys to chime in.

[bobert]

Originally Posted by nizzo

I hope BMW in the LCI of the M2 fixed this, because when it's hot out and you're pushing the first gen (2015/2016/2017) M2 as a performance vehicle, that N54 suffers massively from heat soak. Very bad heat management sadly.

The M2 LCI had no changes to the engine. (There was no 2015 M2. The '16, '17, & '18 models use the N55 - I'm guessing that was just a typo and therefore has no effect on your argument, however. )

[bim2er]

Originally Posted by nizzo

Did an Autocross event with the M2, on a hot summer day, was probably high 80s for the ambient temps. We were maybe a dozen guys, across 3 M2's, and they all had HORRENDOUS heat soak-induced turbo lag from a stop. It was atrocious. I'd stomp on the go pedal after each stop at the cones where we're supposed to stop, and it literally would wait a full second before I get going.

Others concurred.

Earlier on at a separate autoX course right near by, at the same racetrack, maybe a half hour earlier, we had M4's (3 of them as well). Those exhibited a lot less throttle lag / heat soak suffering.

I hope BMW in the LCI of the M2 fixed this, because when it's hot out and you're pushing the first gen (2015/2016/2017) M2 as a performance vehicle, that N54 suffers massively from heat soak. Very bad heat management sadly.

It turned me off so much that any chance that I'd consider getting one, was dashed, despite really liking the looks of the car, the brake feel, steering, and just general chassis/handling feel, and the sound/power.

We hear that starting in July, 2019's won't have the N55 and will have two turbos. We should know at the end of April.

[Isty]

Everytime i upshift from whatever RPM there is a small gap between me giving gas and the car going anywhere. I dont know what kind of lag it is but it ruins the experience every time, regardless of mode.

Its a 2018 manual, really wish I went DCT.. never eperienced loss of boost on dct.

[doug_999]

Originally Posted by Isty

Everytime i upshift from whatever RPM there is a small gap between me giving gas and the car going anywhere. I dont know what kind of lag it is but it ruins the experience every time, regardless of mode.

Its a 2018 manual, really wish I went DCT.. never eperienced loss of boost on dct.

I don’t ever remember that happening with my 2017 manual M2. Maybe take to the dealer?

[Isty]

Originally Posted by doug_999

I don’t ever remember that happening with my 2017 manual M2. Maybe take to the dealer?

I might have to.. it also says I need to make an oilservice, did the breakin service 1000km ago so thats wrong obviously.

I also feel that the bluetooth/spotify integration has problems too, it kinda forgets the phone after 10min of music and shuffle never works properly:S

[akkando]

Originally Posted by doug_999

I don’t ever remember that happening with my 2017 manual M2. Maybe take to the dealer?

I think this has been a common complaint of the Mt.

[stefan]

When you come off throttle you will absolutely come off boost as well in MT unless you are smashing through gears pretty aggressively. Not sure how this wouldn't be possible. But it's there for sure. If you stomp it, you'll feel the lag. Some of that is TC intervention though.

All manual turbo cars are like this.

[boostm3]

I remember doing a bmw event last summer at Limerock. We were doing an autocross for prizes, and we were all driving race prepped M240is, and Ive got to tell you, whenever we had to brake hard going around a cone, after getting hard on the gas pulling out of the turn, it was like an eternity waiting for anything to happen.. Not a lot of fun. These were all equipped with the automatic transmissions.

[SeanWRT]

Best way to feel lag is to do a 3rd or 4th (if you really have 450+whp) full rev range pull. DSC off, you rest assured, in such cases, stock M2 is way too weak to break traction.

Keep in mind, start from OFF THROTTLE cruise speed at below 1500rpm to make sure it's off boost. Floor it, you will know what I mean.

I've done that literally hundreds of times for the past few years, for data logging tuning purpose.

Let me tell you lag is with N54 and S55. You can feel it on the road and see it from log.