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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06-01-2018, 03:54 AM | #113 |
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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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06-01-2018, 05:29 PM | #115 | |
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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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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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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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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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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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09-29-2018, 03:15 PM | #126 | ||
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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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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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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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Btw: i heard ppl saying most of the lag we feel in the higher rpm is the overboost feature. |
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