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      05-31-2018, 04:58 PM   #111
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What you feel is most likely the overboost coming in. It gives about a +3psi shove. The base car is tuned for about 11-12psi at 70F Ambients at about sea level. With overboost it hits about 13-15psi between 3000-5000rpm. There's usually a delay before it activates and that's what you're feeling.

On a 6MT there is anti-lag between shifts but you have to be "quick" enough. Having overboost also pronounces this if you aren't quick enough.

Many tuners out there because of the burble settings essentially disable this "antilag" feature to keep the turbos spooling. Between shifts without this disabled i can hold roughly 10-12psi and get instantly 12psi as soon as I'm back on the power.
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      05-31-2018, 10:49 PM   #112
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Quote:
Originally Posted by cookiesowns View Post
What you feel is most likely the overboost coming in. It gives about a +3psi shove. The base car is tuned for about 11-12psi at 70F Ambients at about sea level. With overboost it hits about 13-15psi between 3000-5000rpm. There's usually a delay before it activates and that's what you're feeling.

On a 6MT there is anti-lag between shifts but you have to be "quick" enough. Having overboost also pronounces this if you aren't quick enough.

Many tuners out there because of the burble settings essentially disable this "antilag" feature to keep the turbos spooling. Between shifts without this disabled i can hold roughly 10-12psi and get instantly 12psi as soon as I'm back on the power.
Hmmmm I dunno about that. Overboost is activated in third gear only and there's a delay in 2nd as well. I think it's just a reality of the setup.
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      06-01-2018, 03:54 AM   #113
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Originally Posted by stefan View Post
Hmmmm I dunno about that. Overboost is activated in third gear only and there's a delay in 2nd as well. I think it's just a reality of the setup.
Overboost is definitely not activated in 3rd only. Overboost is limited in torque just a smidge in 2nd.. that's probably why you don't feel the pronounced shove. And there's a delay between overboost runs.
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      06-01-2018, 08:59 AM   #114
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Originally Posted by cookiesowns View Post
Overboost is definitely not activated in 3rd only. Overboost is limited in torque just a smidge in 2nd.. that's probably why you don't feel the pronounced shove. And there's a delay between overboost runs.
OK you are right.
Quote:
Originally Posted by Artemis View Post
  • The 1M (N54B30T0 engine) featured a torque of 500 Nm / 369 lb-ft in overboost mode: 450 Nm + 50 Nm in normal operation;
  • The M2 (N55B30T0 engine) features a torque of 500 Nm / 369 lb-ft in overboost mode: 465 Nm + 35 Nm in normal operation.
1M Technical Training (see here):
4.1.2. M Engine dynamics control
As on the BMW Z4 sDrive35is, the maximum torque of 450Nm/295 ft lbs is briefly raised (for five seconds max.) to 500Nm/369 ft lbs by the overboost function. The precondition for the overboost function is a demand for acceleration of more than 80%. The increased torque is available from as low as 1,500 rpm right through to 4,500 rpm. That means that the torque gain can be as much as 100 Nm compared to the BMW 135i . Although in the first two gears the loss of traction limits the amount of power and torque that can be transmitted, more than 450Nm/295 ft lbs can be delivered from third gear on, and 500Nm/369 ft lbs from fourth gear on. When the DSC is active and maximum acceleration is called for, forward thrust is limited in first, second and third gears in favor of handling stability. Configuration is based on the optimum traction.
M2 Technical Training (see here):
4.1.5. Exhaust turbocharging
Overboost

On the N55B30T0 engine, the torque is increased from 465 Nm/343 lb-ft to 500 Nm/369 lb-ft (overboost) by a brief increase in the charging pressure of 0.1 bar above the normal charging pressure.
So then why the lag on shifting? Overboost being electronically controlled should stay pinned during acceleration runs.
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      06-01-2018, 05:29 PM   #115
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Quote:
Originally Posted by stefan View Post
OK you are right.


So then why the lag on shifting? Overboost being electronically controlled should stay pinned during acceleration runs.
No, because there is a delay between runs. Also, you need to shift at redline and in a very assertive way in order to keep antilag active. You get a pretty narrow window, but if done right it's super rewarding.

Newer DME calibrations/software versions seem to have minimized the lag. But since you're LCI you already have the latest.
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      06-01-2018, 05:49 PM   #116
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So would you say this is still a fun car to drive as a daily under realistic traffic conditions?
Fun to drive, absolutely.

I barely got mine past break in service before I had to drop it off for shipment to the states so I never really pushed it. Still, it is fun and spirited even if you don't have the revs up or your foot into the floor - things I have not had the pleasure of really doing yet.

Does it have the torque of an American V8 @ 2,000 rpm, not a chance. If that is what you need look elsewhere.

Do you feel the turbo gain power as you accelerate, you bet. It gains power and delivers it smoothly up to the limits that I have seen so far.

If you are turning low revs do you feel the lag, sure. It is the nature of the design.

Doesn't ever feel under powered to me and it seems to beg to go. I'll be happy when I can truly ask how far.
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      06-02-2018, 08:23 PM   #117
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This thread is timely.

I was just driving back home and hoped on a freeway with no one around, full throttle 1st, 2nd, and with the shift to third gear I experienced a solid second?( felt like forever ) of absolutely nothing... The car felt like it just sat there THEN the boost kicked in and it went like a bat out of hell.

This was in a manual, sport + mode 18 LCI.

- I was shifting fast
- shift from 2nd to 3rd was at 6800+rpm

Comparison with my 11 STI stage 2 is whats going on here?=). Using the STI just as a benchmark there was no discernible wait between shifts, sure the turbo would spool down a bit but there was no pronounced dead spot. I think I understand turbo lag vs throttle response and how that affects drivability and I get that you need to keep the rpm's in a sweet spot with most turbo cars. That meant driving the evo and Subarus at 4k + for the best driving experience.

I've had too many turbo cars actually after my e30 m3, wrx, evo 8, evo 10, then the STI.


Talking with my friend who dailies a 1m and has a similar car past to me suggested that its the nannies getting in the way and he drives when safe only with everything off, no DCT or mdm.

Sorry this is long winded, I love the m2 and want to learn how it works =)

I'm going to try the same pulls with everything off and see if it was traction control stepping in and be mindful of my shifting. Lets see if anything changes.
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      06-03-2018, 04:38 AM   #118
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It could be. I haven’t ran in US spec MDM for awhile. If I shift too hard and chirp 2nd or even 3rd the nanny will kick in. But I usually get a flash.

If people don’t mind the potential warranty void.. ( yes I know. Some dealers now flag you for coding sigh... ) coding in M4GTS EuroMDM is quite possibly the best thing you can do. Really let’s you explore the dynamics of the car with just enough safety room to bring it back if you miss a correction.
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      06-07-2018, 02:58 AM   #119
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Quote:
Originally Posted by Crebain View Post
Using the STI just as a benchmark there was no discernible wait between shifts, sure the turbo would spool down a bit but there was no pronounced dead spot.
This is what kills it for me, you shift -> pedal to the metal -> deeaaaaad for 0.5-1sec -> massive power.

Sureley it can't be ment to be like this?
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      06-07-2018, 10:18 AM   #120
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I'm a former M4 owner and current M2 6MT owner. The only time lag crosses my mind is between shifts - the dethrottling during upshift causes a drop in turbine speed and resulting lag for .2 second or thereabouts. You wouldn't see this in DCT or auto trans. It's fine and reminds me it's a turbocharged car.

Complaining about lag in a modern, high-compression, DI motor is def. a bit of splitting hairs. With a quick shift it's not really noticeable - esp on the racetrack. The M4 has the same characteristic, although slightly less pronounced due to the smaller TT S55 design vs N55
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      06-07-2018, 12:44 PM   #121
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The only big lag I notice on a DCT is at really low RPMs (less than 2000) in second gear then stepping on it, or very very rarely I have had a down shift in low gears then mashing the pedal and just nothing for a second. Not sure if that last one is TC thinking something bad is going to happen at whatever boost level I was at if it gave me everything it had, or what..... but it's very very rare.
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      06-08-2018, 09:57 AM   #122
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Quote:
Originally Posted by Crebain View Post
This thread is timely.

I was just driving back home and hoped on a freeway with no one around, full throttle 1st, 2nd, and with the shift to third gear I experienced a solid second?( felt like forever ) of absolutely nothing... The car felt like it just sat there THEN the boost kicked in and it went like a bat out of hell.

This was in a manual, sport + mode 18 LCI.

- I was shifting fast
- shift from 2nd to 3rd was at 6800+rpm

Comparison with my 11 STI stage 2 is whats going on here?=). Using the STI just as a benchmark there was no discernible wait between shifts, sure the turbo would spool down a bit but there was no pronounced dead spot. I think I understand turbo lag vs throttle response and how that affects drivability and I get that you need to keep the rpm's in a sweet spot with most turbo cars. That meant driving the evo and Subarus at 4k + for the best driving experience.

I've had too many turbo cars actually after my e30 m3, wrx, evo 8, evo 10, then the STI.


Talking with my friend who dailies a 1m and has a similar car past to me suggested that its the nannies getting in the way and he drives when safe only with everything off, no DCT or mdm.

Sorry this is long winded, I love the m2 and want to learn how it works =)

I'm going to try the same pulls with everything off and see if it was traction control stepping in and be mindful of my shifting. Lets see if anything changes.

Been there, done that.. Youll find the lag is still present on MT M2s, nannies or no nannies.
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      06-11-2018, 09:56 PM   #123
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Quote:
Originally Posted by Isty View Post
Quote:
Originally Posted by Crebain View Post
Using the STI just as a benchmark there was no discernible wait between shifts, sure the turbo would spool down a bit but there was no pronounced dead spot.
This is what kills it for me, you shift -> pedal to the metal -> deeaaaaad for 0.5-1sec -> massive power.

Sureley it can't be ment to be like this?
This is what I feel. There was no sense of urgency to the acceleration... Felt like you had to "lead" it a bit to respond accordingly.

I now chalk this up to a weak "base" engine. The N55 was designed as a turbo motor from the start, which completely relies on its boost to make the spec power. Compare this to an older N54, which has a strong NA foundation to its design, and which only ADDS more power with the turbo.

My '09 135i (with the N54) "feels" faster to me, even though it technically makes less power than the M2. Hitting the gas gives you immediate NA power response, with the turbo spooling up just in time to provide and even better kick in the pants. The feel is much smoother and more satisfying to me.
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      09-28-2018, 09:34 PM   #124
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This is a really good thread so I'm gonna dig it back up.
So most people agree there is some lag when going from cruising into boost. That's pretty normal for all turbo engines.
My question is what modification would help minimizing it? I already know that bigger IC is more likely to increase the lag so what could help decrease it? Intake, charge pipe?
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      09-29-2018, 08:33 AM   #125
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Quote:
Originally Posted by mr_lab_rat View Post
This is a really good thread so I'm gonna dig it back up.
So most people agree there is some lag when going from cruising into boost. That's pretty normal for all turbo engines.
My question is what modification would help minimizing it? I already know that bigger IC is more likely to increase the lag so what could help decrease it? Intake, charge pipe?
Go drive a M2C or M3/M4 and then come back and tell me the N55 has lag
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      09-29-2018, 03:15 PM   #126
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Quote:
Originally Posted by doug_999 View Post
Quote:
Originally Posted by mr_lab_rat View Post
This is a really good thread so I'm gonna dig it back up.
So most people agree there is some lag when going from cruising into boost. That's pretty normal for all turbo engines.
My question is what modification would help minimizing it? I already know that bigger IC is more likely to increase the lag so what could help decrease it? Intake, charge pipe?
Go drive a M2C or M3/M4 and then come back and tell me the N55 has lag
Yeah, compared to a m2c (at least with OPF) the n55 in the OGM2 has way less lag
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      09-29-2018, 10:03 PM   #127
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That's all great but the fact that other cars have more lag doesn't really help me.
I'm not unhappy, I love the car but I would like to know if I can make the small lag even smaller.
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      09-29-2018, 11:51 PM   #128
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Quote:
Originally Posted by mr_lab_rat View Post
That's all great but the fact that other cars have more lag doesn't really help me.
I'm not unhappy, I love the car but I would like to know if I can make the small lag even smaller.
That's my point. You don't have any lag. If you think you do, go pick yourself up a nice V8. Like maybe a Mustang or Camaro.
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      09-30-2018, 12:27 AM   #129
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Quote:
Originally Posted by mr_lab_rat View Post
That's all great but the fact that other cars have more lag doesn't really help me.
I'm not unhappy, I love the car but I would like to know if I can make the small lag even smaller.
I think people say a charge pipe and down pipe reduces the lag as the turbo spools quicker, but I'm not an expert on that. I guess ask someone with those mods.
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      09-30-2018, 02:00 AM   #130
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Quote:
Originally Posted by mr_lab_rat View Post
That's all great but the fact that other cars have more lag doesn't really help me.
I'm not unhappy, I love the car but I would like to know if I can make the small lag even smaller.
Downpipe and turbo inlet help a bit

Btw: i heard ppl saying most of the lag we feel in the higher rpm is the overboost feature.
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