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46mm vs 48mm throttles

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  • jimmy p.
    replied
    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.

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  • JS154
    replied
    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.

    Leave a comment:


  • proctor750
    replied
    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..

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  • inastrangeland
    replied
    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

    http://www.s14.net/forums/showthread...ght=2.5&page=3

    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.

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  • Az in Oz
    replied
    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.

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  • evommm
    replied
    Yes this GREAT!!!! lots info and i hope people post thier results it will help future builds
    M

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  • mrsha007
    replied
    Great thread. Can someone move it to the Our Best Topics sub-forum?

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  • junkyard_sal
    replied
    +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.

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  • masa
    replied
    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.

    Matti

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  • jimmy p.
    replied
    Nice photos Aropro.
    Thats also the TBs on my 2.0 BTCC motor.
    What is the cost of those these days if you do not mind me asking?
    Thanks
    jimmy

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  • aropro100
    replied
    the gasket come with the tb, part # 1 310 865.1

    the ms 46mm tb show that is was made 1987, which made me believe that 2.3 group A car never use the steet 46mm tb (200/195tb)

    I guess i can do 3 dyno with street 46mm tb ,46mm ms tb, and 48mm tb, (i dont have the evoII tb). Anybody got cheap 46mm cf airbox that they want to sell me?

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  • temple
    replied
    Hmmm. I am not disagreeing, but I am still looking for the proof on these throttle bodies and INASTRANGELAND has not followed up with his dyno sheet. Still waiting for proof!

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  • davem3
    replied
    hi

    do you also have the gasket of the 46 ms rally ttb?
    do you have pm number of it ?
    and have you also the price of the gasket

    greetings dave

    Leave a comment:


  • kevnj
    replied
    This thread is awesome. I wish I had something fruitful to add. Keep up the good work fellas. I've been falling sleep reading the threads on car wax.

    Leave a comment:


  • Brendan
    replied
    I'm running 49.5 TB's based on 48mm housings in my 2.3L now, with matching 49.5mm airbox. Unfortunately, I don't have before/after dyno results where the only change was the TB's (Did Cams, Header at the same time)

    Leave a comment:

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