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46mm vs 48mm throttles

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  • #46
    Incase you want to buy new ones i might have one set of housings.

    Just bare housings for use groupA head.

    Btw these are still available at bmw ms, also+ throttle plates+ shafts+poti.



    • #47
      +1 on price and part number for the various 46mm TBs.

      I would love to see the dynos for these parts. I agree with Jimmy, that I don't think you need to the 48mm+ TBs or monster money to build strong and fun 2.3L S14 motors.

      I just built an M3T spec motor for less than 10k including my purchase of a core motor, Schrick cams (Roughly $1K), and the MS cam timing gears ($500+ by themselves). I am running the stock 46mm TBs. After break-in I will pull some dyno runs.
      1989 e30 m3 Zinnoberrot/Grey 256k Track/M3T
      1991 e30 m3 Alpinweiß/Schwartz 81k Garage Queen
      1991 325iX Diamantschwarz/M-Tech 110k Snowmobile (For Sale)
      1991 325ic Macau Blau/M-Tech 178k M-Tech Cabrio 5spd (For Sale)
      2002 Chevy 2500HD 8.1 Vortec, Alison Tranny, 4.10 gears


      • #48
        Great thread. Can someone move it to the Our Best Topics sub-forum?
        "Just road, seat, ASS; THE END!" - Jeremy Clarkson
        "If you had a choice between a million dollars and world peace, what would you get for your E30 M3?" - ItsNotTheNissan


        • #49
          Yes this GREAT!!!! lots info and i hope people post thier results it will help future builds


          • #50
            I am very interested in this thread. You would have to think that all things being equal the 48mm units have roughly a 9% increase in volume flow capability and so would make more power, but that's only a small part of the overall process. I have access to both for my build but will be using 46mm but I might see if a dyno run can be done once tuned, with the 48mm units.

            "But most of all...
            ... I like the way you move......"


            • #51
              I just noticed that I forgot to update this thread with the results of the 46 vs. 49 TBs.

              Here is the link, post 38


              On another note, as it turns out, the motor was slowly tearing itself apart due to a poorly machined head. Even with the head and cam issues casued by it, the motor still made more power above 7K rpm. I think if the motor had been in the same condition as it was when tuned for the 46s, it would have made the same or more power under the curve.

              I now have a local shop doing all my machine work and am building 2 more 2.5 motors. Just rebuilt a stock 2.3 and am testing the miller MAF setup. Will have more info as the builds progress.
              Several E30 M3's.

              More than I need but not as many as I want....


              • #52
                Man I'm glad I found this thread. I was contemplating bumping up from the stock 46's but definitely not anymore. I assume there is a bit more comparative data a decade on?

                The homoligation theory makes total sense - The larger tb's are useless on the street car but gave an excuse to use them on the race car. Wonder what a bone stock late evo would do with the 46's retrofitted..


                • #53
                  I can confirm that 46mm street TBS with stock (not oversized) valves with a proper combination of cams, compression, fuel, map, head port and header choice can make greater than 300BHP on a 2.3LS14.
                  2010 BMW Club Racing E30 M3 Touring Car Champion
                  2011, 2013 SCCA Runoffs Super Touring Under 3.0L Bronze Medalist
                  2011 SCCA Jim Fitzgerald Rookie of the Year
                  2012 SCCA Northeast Divisional STU Champion
                  2015 SCCA Runoffs STU Polesitter


                  • #54
                    Originally posted by JS154 View Post
                    I can confirm that 46mm street TBS with stock (not oversized) valves with a proper combination of cams, compression, fuel, map, head port and header choice can make greater than 300BHP on a 2.3LS14.
                    Which confirms what I had theorized in the beginning of the thread what seems like forever ago (well it was what 9 years ago), the larger TBs were a homologation for the next evolutions of the larger, more powerful 2.5 litre DTM engines that were 360HP and above.
                    The original 2.3 litre Gruppe A iterations made 300+ HP on 46mm TBs.
                    jimmy p.
                    87 E30 M3 Prodrive British Touring Car
                    88 E30 M3 Zinnoberot - Street
                    88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
                    92 E30 M Technic Cabrio - S14 POWERED!
                    98 318Ti M44, Base - Morea Green
                    04 Ford F350 - V10