05-28-2021, 03:30 PM | #1 |
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2020 M5C no power gains after tune
Hi everyone,
So been trying to run stage 2 map on my M5C. Installed the Supersprint catless Downpipes and Eventuri Intake. Tried running a DME Tune and found absolutely no difference in drag times. So I thought it was only DME, then tried out with Superchips UK still no luck. Also neither of them are able to tune the TCU. So long story short I'm getting consistent 10.8 sec quarter mile times running both the maps and on stock tune as well. Before installing the Downpipes and Intakes was consistently running 11.2 (bone stock). So clearly the intakes and Downpipes have made a difference but the tunes haven't. All data logging is done on dragy and racebox. My questions: Since it's a 2020 M5C and the TCU isn't tuneable for the moment is it causing restrictions to the power being put to the ground? Looking forward to getting into the low 10s. Any suggestions would be extremely helpful. Cheers!
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05-28-2021, 06:05 PM | #2 |
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I don’t think you would have got a .4 sec improvement from just dp and an intake, so the tune might be on there, maybe you’re have trouble flashing back to stock? It’s definitely not a tcu tune issue as there are tons of folks running good times (even 9’s) without it
A lot of people manage to run 10.8-10.9 stock (good DA, warm tires with correct pressures, good gas) and then move down to 10.4 with a tune intake and dp - so your gains of .4 seem consistent with everyone else’s. People running under 10.3 have put in some more effort to get there (custom tunes, lighter wheels, lighter exhaust, etc) Sorry if you already know some of this info but check your DA and compare it to others on here (there is a calculator for adjusting times for higher DA on google) if it’s over 3500 usually it might be hard to get the lower times you want consistently TCU tune seems to be good for .01 sec max but the 2020 transmission is better the older ones so not sure if that is your hold up It might be your pressures? Try dropping them down to 28 psi in the rear (when warm) and make sure to get some heat in them before launching (no need for a burnout, spirited driving usually does the trick) It might be your launch technique? Try to launch right when the flag pops up - no need to build any excess boost when it’s tuned, seems to just cause wheel spin Good luck in your quest for low 10’s! |
06-08-2021, 08:45 AM | #3 | |
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Here's some stock ET's and trap speed for reference on a 2021 M5C |
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06-08-2021, 08:48 AM | #4 |
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Post before and after datalogs from the tune to compare boost and ignition timing
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06-11-2021, 04:18 PM | #7 | |
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06-11-2021, 05:21 PM | #8 |
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What fuel are you running? All tunes add power by upping the timing and boost, both require higher octane fuel or the DME will just pull the timing when it senses knock and your performance can actually be worse or no improvement at all over stock.
To see if this is your issue, get some data logs of your timing and boost or just run a 50/50 mix of race 100 octane and 91 or 93 and see if your draggy times improve. Alternatively you can mix a boostane or other high quality octane booster with 91/93 gas. Shoot for a minimum octane of 96 ((R+M)/2, not RON). |
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06-11-2021, 07:47 PM | #9 | ||
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What i have seen you should be around 219 km/h /136mph with stage 2 but of course it depends on conditions and fuel but it should definitely be higher than with stock tune. What are your tunes? Have you talked to the tuners? |
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06-12-2021, 02:54 PM | #11 | |||
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Have a JB4 on the way, fingers crossed I have better luck with that.
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06-12-2021, 03:06 PM | #12 | ||||
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06-12-2021, 03:07 PM | #13 | |
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this is messed up. im stage 2, 2019 non comp and i got 2.95 (not on the drag strip tho). Im thinking of tcu tune since im 2019, seems very restricted in first 2 gears, and it wont launch at 3k rpm just 2.5 |
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06-12-2021, 03:18 PM | #14 | ||
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06-12-2021, 03:32 PM | #15 | |
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Even stock i felt like 1-2 was meh then 3rd onwards was fast. my car was producted 10/2018 so i should be good. Im just afraid bmw restricts the power for a good reason lol, dont want my tranny to die Last edited by dcali; 06-12-2021 at 03:38 PM.. |
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06-12-2021, 03:51 PM | #16 | ||
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06-14-2021, 12:11 PM | #18 |
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https://www.n54tech.com/forums/showthread.php?t=65639
here's my thread on other forum check if interested , no gains after JB4 installation.
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07-02-2021, 11:44 AM | #19 | |
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07-02-2021, 12:20 PM | #20 |
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Wow, that is quick !. Is this on an LCI car, and from standing start, no roll out ?.
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07-02-2021, 12:22 PM | #21 | |
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07-15-2021, 10:21 AM | #22 |
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You'd have to record logs of your 1/4 mile runs to see how boost, timing, AFR, and throttle use. Having a JB4 might be handy so you could tweak the tuning yourself on the fly for maximum gains.
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