Bootmod3 - Boost by gear reduction M3/ M4

Discussion in 'F80 M3 Saloon / F82 M4 Coupe / F83 M4 Convertible (2014-present)' started by Jim996, Mar 26, 2020.

  1. 26 Mar 2020 at 6:56 PM #1
    Jim996

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    Assuming the apocalypse gets sorted in the next few weeks......

    Just updating my Stage 1 93 map and noticed I can add Boost by gear reduction.....

    Has anyone tested this feature and can give me numbers that work? I'm thinking of trying 30 percent in 1st, 20 percent in 2nd and 10 percent in 3rd?

    Cheers
     
  2. 26 Mar 2020 at 6:58 PM #2
    Steveo

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    Trial and error, until she cannay take it anymore captain! :muttley:
     
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  3. 26 Mar 2020 at 8:16 PM #3
    swissfra

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    Doubtful you'll need a drop in 3rd gear, but a reduction in first and second definitely helps. Someone will be along presently to contradict that though, so best bet is to try it for yourself.

    Now if only you had somewhere to go...
     
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  4. 26 Mar 2020 at 8:21 PM #4
    api330

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    I dropped mine to what you suggested but I still decided to use the GTS map as it really suits the car,
     
  5. 26 Mar 2020 at 8:26 PM #5
    marrow

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    What’s different on the gts ?
    Is it less power and torque
     
  6. 26 Mar 2020 at 8:46 PM #6
    api330

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    Yes I think its about 475, A genuine GTS has 495 with the water injection so as our car don't have that the power is around the 475 mark but the way its delivered is so nice no massive slug of torque the second you go with in an inch of the throttle pedal, It just builds as the revs rise giving most of its torque and power at the top end a really nice map, These are just my thoughts,
     
  7. 26 Mar 2020 at 8:51 PM #7
    TerryLloyd

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    I have 30% reduced in 1st 20% in 2nd using stage 2 with oem downpipes - depends on tyres really using 295 Cup 2 on the rear with LC it puts the power down well, just flooring it not so good in first and second
     
    Last edited: Mar 27, 2020
  8. 26 Mar 2020 at 9:01 PM #8
    Jim996

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    I'm on Cup2s but just wanted to smooth out the 1st and 2nd gears
     
  9. 27 Mar 2020 at 10:51 AM #9
    T5Pilot

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    You're not "smoothing" anything by simply reducing torque. Use your right foot correctly & you have all the "smoothing" you need.
     
  10. 27 Mar 2020 at 12:27 PM #10
    TigMik

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    So are you saying that there’s no point reducing the boost on first and second gears if you have BM3 @T5Pilot? Or does reducing boost actually make a difference on launch/setting off??
     
  11. 28 Mar 2020 at 1:10 AM #11
    T5Pilot

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    I suppose it depends on how you drive. If you’re wanting to be able to just floor the throttle, then reducing the talk would no doubt help as regards traction & takeoff. To me, it sort of doesn’t make sense, having a tune for more power then just turning it down. I kinda see why some might want to just for launching, but I personally like to have it all available & control the delivery myself with the pedal.
    ETTO, that’s just my take on it.
     
  12. 28 Mar 2020 at 9:05 AM #12
    Conor wood

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    Recently put stage 1 bm3 on my m4 and reduced the boost by 20% in 1st gear only just think it helps get off the line smoother and not as jerky
     
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  13. 28 Mar 2020 at 12:53 PM #13
    Jim996

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    Yes thanks for that. Here's me wondering how I ride my race bike so quickly just slamming the throttle wide open in the low gears.......
     
  14. 28 Mar 2020 at 2:05 PM #14
    cossie1

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    Honestly I haven't felt the need to mess with torque reduction per gear, even in the winter with Stage 2.

    I am one of those that needs the car to be lively though, so that A) I stay alert when driving it and B) I don't get bored of the car.
     
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  15. 29 Mar 2020 at 11:42 AM #15
    T5Pilot

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    Completely different scenario - As well you know
     
  16. 29 Mar 2020 at 1:23 PM #16
    Jim996

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    My point is that first and second gears are so powerful on the car that I tend to avoid using them and usually just short shift through them quite quickly. Second gear feels overpowered for the kind of tight 90 degree country road corners so the aim is to make it a useable gear rather than one you have to be really careful with and avoid the on/off power delivery with them. My throttle control is very good but the lower gears still can feel a bit light switch hence feathering the throttle and quickly short shifting through them.

    Race bikes are exactly the same and the big 1000s have exceptionally tall first and second gears to accommodate the power and make them useable, 1st will go to 85 and second to about 115 on a typical 1000cc. I can't alter the gearing on the M4 but if the facility is there to reduce torque then I'm going to fiddle with it.

    Chances are I will end up removing the reduction anyway but it's nice to have the option.
     
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  17. 29 Mar 2020 at 2:53 PM #17
    TerryLloyd

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    I find myself using 3rd to come out of tight bends with the stage 1-2 tunes - with the CS map you can use second - so less power in the lower gears makes sense ,I have a turbo charged Yamaha r1 engine in a seven kit car the low torque of the bike engines makes them v/good on traction
     
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  18. 29 Mar 2020 at 5:56 PM #18
    glynharper

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    I think I have my boost limited by 50% in 1st and 30% in 2nd. Makes it a lot better for traction.
     
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  19. 29 Mar 2020 at 10:00 PM #19
    T5Pilot

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    I have to say, I like this reply & the sensible logic applied. To the extent that I'm actually going to have an experiment & try it myself. So, I'm going to try a 40% reduction in 1st & 25% reduction in 2nd. Will see how it goes (when I can actually go out & drive the car anyway.....).
    For the purposes of experimentation, I'm trying these figures with an expectation that the difference will be very noticeable? I can't see any point in trying a 'subtle" change initially, as I want to feel the difference & maybe progress from there...
     
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  20. 29 Mar 2020 at 10:13 PM #20
    Plastic B

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    I’d be interested in how this goes as even in my standard car I find that unless the tyres are very hot and it’s bone dry first gear is almost unusable so I dread to think what it’s like on stage 1 or 2. I’m toying with the idea of BM3 (mainly for the burbles as mine doesn’t have any really) so this would be another positive if it’s worthwhile.
     

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