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  • #16
    I have access to a dyno and I'm doing a relatively mild (284/284) 2.5 build with 46mm TBs. Problem is that I won't be getting to it for a while and I don't have a set of 48s around. I plan to tune it with Megasquirt.
    Several E30 M3's.

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

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    • #17
      Well,,, I will be doing a similar exercise in the future.
      I just received (finally, after a very long time) my fresh engine for my silver race car.
      Its a pretty neat 2.3 litre race motor.
      I am going to put my 46mm throttles on it, tune it and run it like that because thats what I have now.

      At some point if I get a set of "real" 48s or some of John's 49s as a purchase, or if someone has a set to loan me, I'll dyno it again and that will at least tell the tale of if a 46 mm throttle is a restriction to a 2.3 litre race engine.

      It is pretty amazing though, at this juncture in the S14's life that this has never been documented (the max power output possible with 46mm throttles).
      It seems most everyone just marches to bigger throttles as a matter of course without ever seeing what HP they could get out of the 46s.

      Back when I was drag racing American race cars it was pretty well known what size carbs would plateau at what HP, when you had to go up a size, when multiple carbs would be the next step, etc.

      It feels good to know that I'm not the only one who wants to know this...
      Cheers
      jimmy
      Last edited by jimmy p.; 08-22-2009, 09:29 AM.
      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

      Comment


      • #18
        Originally posted by Larsen-Racing View Post
        Don't think Evo2 had 48mm TB's though, but 1990 215hp model did have 48mm.
        And the regular Eur0 2.3L M3 with 215 hp besides the 48mm TB's, what was upgraded to achieve 15 HP more? Hopefully this isn't a so OT question.

        Thanks
        Euro M3'87 NogaroSilver / Euro E34 M5 '93 / Porsche 993 TT 97' Euro / Porsche 993 Carrera 95' Euro / Skyline R33 GT-R

        Comment


        • #19
          Originally posted by diegom6 View Post
          And the regular Eur0 2.3L M3 with 215 hp besides the 48mm TB's, what was upgraded to achieve 15 HP more? Hopefully this isn't a so OT question.

          Thanks
          I think it had to do with the exhaust, software and the cams/timing

          ***
          A special thank you to:
          archie, chutrain, carfantiti, ///M3 Terr, Jake, G2NY, Justin(OKC), Andyman746, dllance, NameIsStanley, JP, Speedvill, blyguy, MTLALEX, ///M0F01SD, Tom64, GK-E30M3, L James, ///CRISS, Das Boots, e30polak, DrWillb, Cactusjacks1, E30terry, S14E30M3 and all the S14 members who have showed support and contacted me.

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          • #20
            Originally posted by Jake View Post
            What's needed is a group of people to share the expense of finding out these answers. But would people really donate to such a cause?

            Jake
            That was my point in my earlier post. If one could do a comparison, with people bringing in their 48mm, 50mm locally, that should be too much of a problem or cost for a day at the dyno.
            Pat

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            • #21
              For bmw to gain 20hp (195hp to 215) they have to change compression 10:5 to 11:0 ,46mm tb to 48mm ,intake port 26mm to 28mm, 248/248 to 248/264 cam. both car have 42/48 header with cat.now this is with AFM . I think if both engine have runs a/n the new enginge will gain more than 20hp over the old engine. It is very hard to know at what point the 46m will stop making power.I think if anyone who thinking about porting the intake port the 48mm tb have to be in the part of the equation.
              Last edited by aropro100; 08-22-2009, 03:46 PM.

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              • #22
                Small OT,,

                i dont know the S14 science so well,, but in EU there are some folks that use the S38B36,,((46 mm)) w/ B38 ITB ((50 mm )) ,, matchport it together,, running Alpha-N or a MAP ,, deletet torque flap
                higher rev lim, and custom airbox,, and estimatet output is 350 hp,, so the gain is 35 hp,, not much, but everything counts
                Sveinbjörn Hrafnsson

                E30 CABRIO S3 8B38
                ALPINA B10 BITURBO 346 @ 507



                http://alpina.123.is/pictures/

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                • #23
                  I don't have any hard facts to provide to this, only some other variables to consider
                  and observations...

                  I believe that there should be 3 options discussed:

                  - 46 US ITB
                  - 46 Large casting ITB
                  - 48mm ITB

                  I recently purchased a set of 49mm ITB (bored out 46mm) and found that the 49mm
                  definitely had a larger plate area vs. 48mm however the area of the throat area near
                  the head was considerably smaller than the 48mm (approx 10% less) and they were
                  bored out. I have never measure a set of stock 46mm US ITB's. I believe the
                  greatest benefit of the 48mm's is the area between the plate and the head. There
                  may not a substantial benefit switching from 46 mm large casting to 48’s if throat areas
                  are similar.

                  Mike
                  sigpic

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                  • #24
                    Jimmy,
                    Check your inbox...
                    MJ

                    Comment


                    • #25
                      Originally posted by aropro100 View Post
                      For bmw to gain 20hp (195hp to 215) they have to change compression 10:5 to 11:0 ,46mm tb to 48mm ,intake port 26mm to 28mm, 248/248 to 248/264 cam. both car have 42/48 header with cat.now this is with AFM . I think if both engine have runs a/n the new enginge will gain more than 20hp over the old engine. It is very hard to know at what point the 46m will stop making power.I think if anyone who thinking about porting the intake port the 48mm tb have to be in the part of the equation.

                      EVO2 has raised compression, all others are 10.5 (except SE)


                      Goodbye M3, you served me well.

                      Comment


                      • #26
                        Originally posted by diegom6 View Post
                        And the regular Eur0 2.3L M3 with 215 hp besides the 48mm TB's, what was upgraded to achieve 15 HP more? Hopefully this isn't a so OT question.

                        Thanks
                        I saw aropro100 mentioned something about intake ports, that I don't know.
                        But 48mm TB's, EVO2 cams, software and bigger exhaust manifold. It shares the manifold with the 320is witch is the biggest BMW M provided for the S14 in stock.
                        1987 BMW M3 E30

                        S50B32 swap thread http://www.s14.net/forums/showthread.php?t=43515

                        Comment


                        • #27
                          my bad, 215hp did have 10.5:1 compression.I don't think the difference of 46mm and 48mm is the point. It is the the headside have a big differentce. I had ported 48mm tb (us.tb) and the intake side was ported to max also. I have just change to real 48mm tb just 2 month ago. my car just run so much better 5000rmp+,and my hot start problem are gone.now my idle ,hot and cold start and drive just perfect.

                          Comment


                          • #28
                            A few worthwhile notes:

                            - The TBs should be thought of as an integral extension of the intake ports. The factory intake port is relatively small, and intended to create good velocity at low engine speeds, not all out peak hp. Installing a set of larger TBs onto a factory head is of limited value, as the port will become restrictive no matter the size of the TBs.

                            - The TBs don't flow as cleanly as a straight port of the same diameter, simply because the throttle plate shaft is an obstruction (and greater in the 46mm TBs).

                            - Airflow through a port becomes restrictive when the speed of the air column approaches about 2/3 mach, and this is not an uncommon problem. The greater the VE and rpm at which peak VE (torque) occurs, the quicker the weakness of the port will be exposed.


                            All these things considered, the larger TBs will yield the greatest benefit when matched to a capable head, valvetrain, and exhaust. TBs are but one piece of a chain that is only as strong as its weakest link. And that being said, a motor equipped with capable head, valvetrain, and exhaust but with 46mm TBs will outperform a relatively stock setup with 48mm TBs.
                            2003 Mitsu EVO VIII - 2.0L / 600+whp
                            1988 BMW M3 turbo - Work in progress. . .
                            1986 SVO Mustang - Work in progress. . .

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                            • #29
                              Hey Ted,
                              I was hoping you would chime in.
                              Everything you posted makes sense withe everything I have learned over the years about race engines.

                              Since this thread seems to be floundering a bit in the new information dept,,, maybe we can switch gears a bit see who has used 46mm throttles on a race engine and what the most hp / tq they have seen from that package.
                              Not very scientific, but will add something to the archives on a question that seemingly has no answer in the S14 community.

                              I'll go first,,, my very modest last 2.3 did 195HP to the wheels on a Mustang dyno with 46 mm throttles (AN, 272s, stock valves, stock header)

                              Since I have posted 195,,, no need to post anything less.
                              Maybe try to keep the trend going upward until we top out???

                              At least then we will have John Doe, 2.?, xxx cams, AN, xx/xx header = XXX RWHP on XXX dyno.

                              We should only try to archive 46mm bog standard street throttles in this thread.
                              cheers
                              jimmy p
                              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

                              Comment


                              • #30
                                Jimmy,

                                I am currently doing this kind of research myself. It will be slow-ish coming, but we will shortly have 2 exact same spec engines with only one difference, this will be the TB's. One car was a 215 car from new, the other was a 195. Both heads have been ported to the exact same specs and running the same valves. Both are running Alpha N style set ups with the Unichip, so both fueling and ignition timing will be optimised for both engines for maximum possible power on full throttle. Also, we are going to play with valve timing also. Both engines have special pocketed pistons to accept any cam, but also it was with varying the valve timing we had in mind.

                                My expectations are that the 46mm car will make the same peak power as the 48mm car, but the 46mm car will have more torque all over untill max power.

                                We are going to record and post up all findings, including the effects on valve timing with each throttle body.

                                This isn't going to ultimately answer a how far can you go with the 46's, but maybe it will show up some myths and remove some wool from peoples eyes?

                                However, I am planning on a 340bhp+ S14 soon and we are planning on using the 46mm TB's. If then the 46's seem restrictive (which we are going to flow bench test and calculate the hp bearing in mind the spec of the engine) we will move on to 48/49 or even 50mm. But, I know of 345bhp+ engines (not s14) which only have 42or less mm Jenvy TB's.
                                E30 M3 Sport Evolution Black
                                E30 M3 Sport Evolution Red
                                E30 M3 Evo II Red
                                E30 M3 Evo II Blue
                                E30 M3 195hp Black
                                E30 318 is White
                                E30 318 is Red

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