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  1. #51
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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    just a gut feeling after looking at your an my dyno's done in mph, and SWAG as to what your bests have been compared to my bests, and how much further this will put you back.

    I have a gut feeling that being "in gear longer" isnt what its cracked up to be. think about it, for ET, dragracers alwas go shorter... for 60-130, i could be off, but dont see how when i revert bac to looking at power over mph.
    I think the key to remember though is he said "street car" so i think it would help for the street both in traction (and hence over all run time from a dig) and in fuel consumption. Drag cars always go down but they also always run fat slicks. So I guess my point is it can't be both. Make it specifically for the street or build it to run its best on the track and know performance will be slightly less on the street when you aren't running your track wheels/tires.
    Never thought I would see the day...
    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Life is so much more fun with a nemesis. I miss Shiv. Click here to enlarge
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  2. #52
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    I was thinking, he ould always go with the taller gearing for fhe street, but maybe optimize drag performance by choosing a different drag wheel setup...? I dont know what combination he would need, but Mr.5 was just discussing this elsewhere, using tires to change effective gearing

  3. #53
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    1 out of 1 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    Let's pretend this is done, what do you guys estimate the ET/trap would be affected by, without wild guesses if possible Click here to enlarge

    60-130 could also improve as it'd be a 2-3 shift not a 3-4 shift...exception being that 2-3 shift is harder to nail fast than a 3-4 (just a straight down pull on the shifter)
    ET should suffer some due to the tq loss per gear going to the drags, but any type of roll racing will benefit from not having to shift as much. I remember when Sledgehammer and I would run in our mustangs. Setups were pretty much the same with me making a little more hp/tq then he did at the tires. Big difference was my 3.73 vs his 3.08 gear. From a slow roll I'd jump him pretty good but I would never be able to hold him off up top and he'd put a good two cars on me.

    If I were to use RB's I'd like to drop down to 2.73 gear, if going with a single I'd keep the stock gearing *provided power shifts to the right with tq dropping off*.

  4. #54
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    Click here to enlarge Originally Posted by Blaizon Click here to enlarge
    Big difference was my 3.73 vs his 3.08 gear. From a slow roll I'd jump him pretty good but I would never be able to hold him off up top and he'd put a good two cars on me.
    Very good example right here.

  5. #55
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    Assuming you're trapping under 130 (which you are obviously) and the first gear will work as well or better on your launch, then this will be good for notable gains at the strip without a doubt. It also will be good driving around town. Though it may not be quite as fun if you like rowing gears around or on track days. Your top gears will also feel much more useless. 6th maybe really hard to ever get into at all, be very hard to cruise in unless you are doing 85+mph. When the season starts coming back around you should get some time at the strip in on your original gears, then swap it out and see what happens with no other changes.

  6. #56
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    that's the plan...hopefully a cheap 2.56 final drive shows up out of a wrecked car in that time...what some vendors are asking price wise for it with the lsd installed is definitely cost prohibitive
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  7. #57
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    Does anyone ever swap in the OEM LSD instead of the Quaife or Wavetrack?

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    i wouldn't do that personally...i'd try to get a customer for my current wavetrac 3.08...if anyone's interested and has a 2.56 let me know...talking to Harold@HPAutowerks who sell these and Quaifes a wavetrac 3.08 unit, like mine, new from them goes for $2995 without core exchange ($1995 with a core return)...i'd do $1495 for my complete final drive with the Wavetrac if anyone's willing to send me their stock 2.56 complete final drive...just throwing it out there...or $2495 for my complete unit, bolt it on, and keep your core

    any DCT takers? I actually think a 3.08 with an LSD would be pretty awesome to have in a DCT car
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  9. #59
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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    I was thinking, he ould always go with the taller gearing for fhe street, but maybe optimize drag performance by choosing a different drag wheel setup...? I dont know what combination he would need, but Mr.5 was just discussing this elsewhere, using tires to change effective gearing
    Very good point. At the very least this is helpful because you could go ahead on the final drive and if it did end up being a little to much you could go slightly shorter overall on the tire and bring back some of the gearing. (May allow you to go wider with tire size or lower with suspension as a side benefit too, since you would have more tire clearance.)
    Never thought I would see the day...
    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Life is so much more fun with a nemesis. I miss Shiv. Click here to enlarge
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  10. #60
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    Alright, moved my 496whp dyno data from March last year over into the spreadsheet i got, added gearing and here's the comparison of 3.08 (current) and what it would turn out to be shift point wise on a 2.56

    Basically i didn't know that given this particular power band i should be shifting 6600rpm 3-4 with the 3.08...i'd short shift it at 6400rpm...really useful spreadsheet, great to visualize changes to gearing..

    First the dyno plot:
    Click here to enlarge

    3.08 acceleration vs. rpm (says that you need to shift at the point acceleration in lower gear is lower than acceleration in the next gear, so best, given this power band is 7k 1-2, 6.9k 2-3, 6.6k 3-4
    Click here to enlarge

    3.08 acceleration vs. mph (according to graph shift into 4th at 104mph)
    Click here to enlarge



    Now here's the same but when final drive is changed to 2.56:
    2.56 accel vs. mph (if required, shift into 4th at 127.8mph, not 130 as i thought, but maybe if we can squeeze more torque up top it might be able to push it out to 129+)
    Click here to enlarge

    2.56 accel vs. rpm (if required, shift into 4th ~6.9k rpm)
    Click here to enlarge

    Not sure if I'm reading it right...attached is the spreadsheet used if anyone else would like to play with it...hopefully black_bnr_32 doesn't mind me sharing it out

    here it is:
    335i - Shift Point Calc.xls - Copy.xlsx.zip
    Click here to enlarge

  11. #61
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    I think this is a bad idea from a "racing" perspective.

    I've also always been against reducing torque multiplication due to tire spin at lower speeds. (That's a driver issue)

    Personally, I'd gear a street car to top out in 4th gear on a 5 speed at the drag strip. If that meant a 4.10 final drive ratio...that's what I'd do. (And I've done that before)

    The only time I'd run a steeper gear ratio is if the car was topping out at the track, or it became a PITA shifting on the street.
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  12. #62
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    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    The only time I'd run a steeper gear ratio is if the car was topping out at the track, or it became a PITA shifting on the street.
    Topping out isn't the only reason though. If you are crossing the traps in 6th because your gears are so short you should look at your final drive. You won't accelerate in 5th and 6th through the traps as hard as you would in 4th.

  13. #63
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    Just to add a bit of input in my past experience with gearing. We all see a lot of cars that perform well due to increase of gearing. These cars are normally very high horsepower cars and in most cases have a lot of lag and narrow power bands. The gearing is used to stretch the short power band to cover more km/h avoiding many gear changes where often the initial challenge on the change is to overcome the lag. Hence we see 2 speed Supras going down the quarter mile very fast.
    With the N54 this isn't a issue and as PEI330ci has also mentioned the torque multiplication drop is more vital than the less gearchanges. We also not suffering with traction at higher speeds therefore there is no need to lower the torque multiplication to the wheels with a longer gear.

  14. #64
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    Click here to enlarge Originally Posted by George Smooth Click here to enlarge
    Just to add a bit of input in my past experience with gearing. We all see a lot of cars that perform well due to increase of gearing. These cars are normally very high horsepower cars and in most cases have a lot of lag and narrow power bands. The gearing is used to stretch the short power band to cover more km/h avoiding many gear changes where often the initial challenge on the change is to overcome the lag. Hence we see 2 speed Supras going down the quarter mile very fast.
    With the N54 this isn't a issue and as PEI330ci has also mentioned the torque multiplication drop is more vital than the less gearchanges. We also not suffering with traction at higher speeds therefore there is no need to lower the torque multiplication to the wheels with a longer gear.
    That's a really good point about using gearing to spread out the torque on narrow power-band applications.
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  15. #65
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    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    That's a really good point about using gearing to spread out the torque on narrow power-band applications.
    It's the reason why diesel cars have longer gearing too: lots of torque and a somewhat narrow power band.

    Personnally I consider going from 3.08 to 2.56 as too much of a gap. It will propably take away alot of the fun from this car, unless you plan to use it for just one specific application.

    2.80 would be better if you want to go longer. It's just not available.

  16. #66
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    I don't mind, I would have attached it if I knew how. Its also useful when comparing what powerband is theoretically faster. Such as, if a guy was exploring different turbo options.

    Nice powerband you have there, congrats. I say 2.56 is crazy. But, both look like they match up real nice with a 130mph trap target. You'd be pulling about the same acceleration at 130 with both options, except one would be in 3rd and the other in 4th.

  17. #67
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    Ya, i've pretty much gave up on the 2.56 swap idea. One extra shift with NLS (no-lift-shifts) module wired in on the car takes next to no time. My 3-4 shift is the fastest of the 3 anyway, takes only 70ms and NLS cuts power to the motor during the shift so its easier on the clutch..

    I was able to launch the car at the beginning of this winter at the strip and get some 1.7x 60' times with 2-step set at 3900rpm and basically a melter burnout on already finished mickey thompsons...in higher ambients that launch might be even better, hoping for a 1.6 or dare i say a 1.5 60' Click here to enlarge

    In any case, i'm staying away from 2.56
    Click here to enlarge

  18. #68
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    Well done Dzenno. The 2.56 could get you +1 or +1.5 Mph. Saving one shift needs to be taken into account as well on top of this.

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    I would not do the swap either because of the cost involved. The swap would benefit you, but putting the same money on adding power could have similar gains.

  20. #70
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    Click here to enlarge Originally Posted by 654 Click here to enlarge
    I would not do the swap either because of the cost involved. The swap would benefit you, but putting the same money on adding power could have similar gains.
    Benefit of it really isn't very obvious and the cost is prohibitive to just play around with it...might be the "last" thing I do Click here to enlarge
    Click here to enlarge

  21. #71
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    Click here to enlarge Originally Posted by Rob@RBTurbo Click here to enlarge
    Does anyone ever swap in the OEM LSD instead of the Quaife or Wavetrack?
    I wouldn't know which one to fit. I got OEM but the complete V8 M3 diff.

  22. #72
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Topping out isn't the only reason though. If you are crossing the traps in 6th because your gears are so short you should look at your final drive. You won't accelerate in 5th and 6th through the traps as hard as you would in 4th.
    hmmm....back when buddies and i built cheaper dedicated drag bikes (usually bought lightly wrecked as a second bike) we would gear for all 6 in the 1/4. Maybe it is a different animal with a bike though.
    Never thought I would see the day...
    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Life is so much more fun with a nemesis. I miss Shiv. Click here to enlarge
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  23. #73
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    Click here to enlarge Originally Posted by Forced Air Click here to enlarge
    hmmm....back when buddies and i built cheaper dedicated drag bikes (usually bought lightly wrecked as a second bike) we would gear for all 6 in the 1/4. Maybe it is a different animal with a bike though.
    A bike is different but still I don't see how shifting that much would help you.

  24. #74
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    Always worked very well. Bikes shift much faster and with the throttle wide open. Especially with a power shifter. Plus this is on bikes that rev to 16,000 rpm mind you. Power is completely top end, makes a V8 M3 look like a diesel. So i guess i can see how it would work out.
    Never thought I would see the day...
    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Life is so much more fun with a nemesis. I miss Shiv. Click here to enlarge
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  25. #75
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    i would wadger that a bike can shift dangerously close to, if not as fast as DCT's...
    I remember clutchless shifting on my R1, $#@! was insane, probably why i love the M so much

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