Close

    • Stock dual clutch E92 M3 takes on a stock E92 6-speed M3

      This is a debate that ranges all the time on the forums. What is faster, DCT or manual? Well, the dual clutch simply does shift faster and we see time and time again that the manual can not match it. This is a constant on every platform with a dual clutch and manual option (Porsche PDK versus manual direct comparison was posted earlier this year). The more shifts involved the bigger the advantage a dual clutch will have.

      On the M3 the DCT is geared much tighter in 1st, 2nd, and 3rd gears. The manual is geared better for the top end as it can stay in third longer (up to 113 miles per hour) than the dual clutch which has to shift to fourth much earlier. That is why you see the manual creep up in third gear in the video below but it still can not overcome the DCT shift speed advantage despite having lower drivetrain losses.




      This article was originally published in forum thread: DCT M3 VS 6 speed manual M3 started by LostMarine View original post
      Comments 121 Comments
      1. M3GTtt's Avatar
        M3GTtt -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        shift speed is faster. your assuming ll else is equal
        Hp advantage to MT, weight advantage to MT, gearing advantage to MT= negating the shift speed advantage given a competent MT pilot
        Actually I think the gearing advantage is to the DTC, the S65 (like the big brother S85) likes the high revs, the 7 gears make it possible to be more in the prime rev range.

        I highly doubt that there is a driver out there (unless some super pro) that can shift faster and more consistantly than a the M-TDC can every time.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by M3GTtt Click here to enlarge
        Actually I think the gearing advantage is to the DTC, the S65 (like the big brother S85) likes the high revs, the 7 gears make it possible to be more in the prime rev range.
        No, the advantage is only in the first 3 gears. After that, manual has the advantage.
      1. M3GTtt's Avatar
        M3GTtt -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        No, the advantage is only in the first 3 gears. After that, manual has the advantage.
        So M-DTC has the advantage on 1, 2 and 3rd and the Manual on 4th 6th and 7th, then the M-DTC has the advantage having 7th gear (or it might be a dissadvantage).

        Well, how many races go beound the 120mp barrier? 1/4 mile barely touches the 4th gear I would think, so then the M-DTC has the win, faster shifts and better ratios in 1-2-3 should win out the loss of power. Talking about loss of power, the time it takes a manual clutch to engage is also loss of power while the double clutch unit has already engaged the next gear so there is no delay time.
        I dont believe the added weight of the M-DTC is that much. I remember the SMG-3 Unit in my E60M5 was tiny (failed after 1.5km of driving Click here to enlarge) compared to a manual box, maybe the Double clutch unit is more bulky.

        In any case the shift speed (mistake factor) is going to be more crytical in the first 2 shifts (1-2 and 2-3) because the rev's come in faster.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by M3GTtt Click here to enlarge
        then the M-DTC has the advantage having 7th gear
        For mileage, sure. It won't accelerate faster in 7th than the manual will in 6th.

        Click here to enlarge Originally Posted by M3GTtt Click here to enlarge
        In any case the shift speed (mistake factor) is going to be more crytical in the first 2 shifts (1-2 and 2-3) because the rev's come in faster.
        Yes, the main advantage is at lower speeds. When you are in higher gears spending more time in gear it does not matter quite as much.
      1. LostMarine's Avatar
        LostMarine -
        consider 2 equal hp E92's, A+B. everything equal, weight ect. 3300 lbs/ 414 hp

        they run equal

        now, add a manual transmission and gears to car A. whats the net hp now with DT loss? figure-15%
        414-62 hp=352 RWHP (DJ)pretty close eh..

        no add 300 lbs for trans (figurativley), now 3600 lbs

        car B gets DCT add 400 lbs (figuratively) now 3700 lbs
        assume 18% DT loss (74), 414-74= 340, (damn pretty close again!)

        If accepted norm is 100lbs =1mph/,1 seconds in the 1/4 mile
        and 10 hp is 1mph and .1 sec in the 1/4 mile

        that means the 6 MT has a .2 and 2 mph advantage over a normal automatic, and on paper vs DCT.

        so, someone show me how much ACTUAL time is saved through a 1/4 mile run Click here to enlarge

        you guys are so caught up in the fact is DCT, OMG DCT!! but regardless real automatics have always had a shift speed advantage over MT, but as mentioned above, its not real, its only more consistent, and thast the advantage..
      1. ERM324's Avatar
        ERM324 -
        DCT compensates by tighter gear ratios and faster shifts. On the supercharged platform the tighter gear ratios will leave you at more power after shifts than the 6mt. I will argue this until neither of us give a $#@! to bother anymore but DCT does have the advantage and its proven over and over again lol
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by ERM324 Click here to enlarge
        DCT compensates by tighter gear ratios and faster shifts. On the supercharged platform the tighter gear ratios will leave you at more power after shifts than the 6mt. I will argue this until neither of us give a $#@! to bother anymore but DCT does have the advantage and its proven over and over again lol
        lol, i knew youd be sucked back in here Click here to enlarge

        It doesnt ACTUALY matter to either of us, we all drive DCT, im, just sayin Click here to enlarge

        but we shall see. ive run an e92 M3 N/A, and im gonna hunt for that 6MT M3 535, as well as the rest of the s/c 6MT's Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        but regardless real automatics have always had a shift speed advantage over MT
        Not always, that is a recent development. After the E46 the autos were faster than the manuals. Prior, the manuals were the performance choice.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by ERM324 Click here to enlarge
        DCT compensates by tighter gear ratios and faster shifts. On the supercharged platform the tighter gear ratios will leave you at more power after shifts than the 6mt. I will argue this until neither of us give a $#@! to bother anymore but DCT does have the advantage and its proven over and over again lol
        Only until you shift out of third. Take an actual look at the gearing between the two.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Not always, that is a recent development. After the E46 the autos were faster than the manuals. Prior, the manuals were the performance choice.
        please show me the last automatic, of any car, that shifts slower than a MT
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        please show me the last automatic, of any car, that shifts slower than a MT
        E36 M3, E46 330i, E46 323i, etc. This is partially why the 1/4 mile numbers for the manuals on these models were always faster.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        E36 M3, E46 330i, E46 323i, etc. This is partially why the 1/4 mile numbers for the manuals on these models were always faster.
        your telling me all of those automatics shifted slower than a manual, GTFO here.. show some data i meant
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        your telling me all of those automatics shifted slower than a manual, GTFO here.. show some data i meant
        I can't believe you don't know this but you are relatively new to BMW's it seems.

        If you don't believe me just search for E36 M3 automatic versus manual. Do the same for any E46. You can do it for E39's as well. Automatics were slower previously.

        Oh, even the 996 911's are a good example as well although in the turbos case brake boosting at the line helped but from a roll the manual was still faster.
      1. LostMarine's Avatar
        LostMarine -
        im talkin specifically about the shift speed, not the cars themselves. I agree that manual are faster, because of everything that i stated above. what im getting at, is i dont recall any "performance" automatic car from the 90's on, being slower shifting than MT. in .xyz ms terms
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        im talkin specifically about the shift speed, not the cars themselves.
        Yes, I believe the manuals were the faster shifting option as the autos back then were nowhere near where they are now.

        And I just mentioned a bunch of cars with automatics slower than their manual counterparts.
      1. LostMarine's Avatar
        LostMarine -
        I dont think your pickin up what im puttin down.. ill do my own research later
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        I dont think your pickin up what im puttin down.. ill do my own research later
        I don't think you are understanding me. The manuals were the faster option until the automatic shifting speed improved to make up for the drivetrain loss.

        The old steptronics didn't shift fast. I guess you had to experience it.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I don't think you are understanding me. The manuals were the faster option until the automatic shifting speed improved to make up for the drivetrain loss.

        The old steptronics didn't shift fast. I guess you had to experience it.
        i had a 330ci, no idea what trans is in them. im just saying, even not smg. Ill have to go back and see what recorded MT shift times are vs posted AT time to continue my point
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        i had a 330ci, no idea what trans is in them. im just saying, even not smg. Ill have to go back and see what recorded MT shift times are vs posted AT time to continue my point
        I had a 330i and the manuals were faster. The E36 M3 is the perfect example as well.
      1. akh23456's Avatar
        akh23456 -
        People also forgot it is very easy for us dct guys to hit the limiter and lose power for a second. ( in manual mode)