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Why is the S54 only 325bhp in the ZM?

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  • Why is the S54 only 325bhp in the ZM?

    Hi all,

    First post and its a question!

    I've owned many M3's (5x E46, 1x E36 & 1 E30) but now have a family friendly estate and now have the need for a toy, and having been a long term lover of the Z3MC, the time is right. I've read this forum (a lot) and is a credit to you all.

    But there is one question I haven't been able to answer, I've done a search on here and elsewhere, but cannot find the answer:

    Why is the S54 'only' 325bhp in the Z3M when it is 343bhp in the M3 & Z4M?

    Is it something to do with the exhaust?

    I would be interested to know form any owners who have experience of the S54 in both the Z3M & M3 to know what the difference is. Also, what is the 'real difference between the S50 & S54? I don't mean the DSC/grils etc, I mean out on the road, what is the difference?

    I wasn't that impressed by the E36 M3, but loved the S54 (hence owning 5!), so I am keen to know to assist in my search. There aren't exactly loads around for sale to go and test drive!

    Thanks in advance

  • #2
    I think I've read that they reduced the rev limit for the S54 M Coupe (Z3M)
    Not actually in the least bit fat

    2000 S50 Titanium Silver / Black
    ACS Suspension, Exhaust & Type III Wheels
    Simota carbon air intake | Strong Strut Front Brace

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    • #3
      I read in a magazine it was something to do with the exhaust manifold and space issues , could be bollocks mind , I also read that Adolf hiltler flew to the moon in a b52 bomber in the Sunday sport

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      • #4
        Originally posted by paulwirral View Post
        I read in a magazine it was something to do with the exhaust manifold and space issues , could be bollocks mind ,
        I thought it might be this, but according to another source today, the manifolds are the same.

        Originally posted by paulwirral View Post
        I also read that Adolf hiltler flew to the moon in a b52 bomber in the Sunday sport
        This is true

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        • #5
          Lower rev limit on the M Coupe compared to the E46M3/Z4M etc

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          • #6
            Originally posted by Fat Tony View Post
            I think I've read that they reduced the rev limit for the S54 M Coupe (Z3M)
            In the M3 its 8250 (iirc), is the Z3M 7400? Would that account for the 28bhp difference? Surely raising the rev limiter would restore the difference then?

            Although this leads me along another thought process; if the S54 engine is the same, is it the limitations of the gearbox that meant the engine had to be de-tuned (by the ECU mapping) so as not to put too much through the gearbox? Is the gearbox from the 3.0 E36 M3? (I could be talking total bollocks at this point)

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            • #7
              Originally posted by E46ACS View Post
              I thought it might be this, but according to another source today, the manifolds are the same.



              This is true
              I see your from Durham , I'm from Gilesgate originally , and I knew there was reason to doubt that headline all those years ago it must be true if another daft Geordie says it is
              I can remember reading z coupes were held back a little so as not to embarrass the m3 flagship , could make sense I suppose ?

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              • #8
                Originally posted by paulwirral View Post
                I see your from Durham , I'm from Gilesgate originally , and I knew there was reason to doubt that headline all those years ago it must be true if another daft Geordie says it is
                I'm no Geordie (not a Mackem either! )

                It looks like the lower rev limiter is definitely the cause of the lower power, but no closer as to why?

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                • #9
                  One consideration is the rod bearings (see other threads).
                  The story I've heard is that the early (pre-December '02) S54 engines had issues with spinning or running rod bearings at sustained high revs. This would apply to all S54-engined Z3Ms as they were built before that date.
                  As a result, BMW recalled all E46 M3s and did a bearing-change on them FoC. For some reason, they didn't offer a recall for the Z3MCs with the same motor, so these didn't get done. Instead, a lower rev limit was imposed (change to ECU?). Later S54 engines had a different rod design with different rod bolts which presumably eliminated the problem.
                  I'm old skool, with a garage full of cast iron pushrod V8s, so am not used to revving anything over 5K. However for peace of mind I'm thinking of changing the rod bearings in my S54, but haven't taken the plunge just yet.

                  Roger

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                  • #10
                    S54 Z3M power was pegged back as not to overhaul the E46 M3 (even though it did in acceleration figures as it was lighter), mainly with the lower rev limit. But there is all kinds of rubbish about the intake and exhaust space being the main reason.

                    Problem of raising the rev limit then risks bearing issues, which were not officially recalled on the Z3M...because of the lower rev limit. As it's the same engine built with the same bearings as the early E46, but BMW reckon the lower rev limit didn't warrant recalling the S54 Coupe.

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                    • #11
                      Originally posted by E46ACS View Post
                      I thought it might be this, but according to another source today, the manifolds are the same.



                      This is true
                      Originally posted by E46ACS View Post
                      I'm no Geordie (not a Mackem either! )

                      It looks like the lower rev limiter is definitely the cause of the lower power, but no closer as to why?
                      I just get called a Geordie because I stick out like a sore thumb down here when I speak among the scousers !
                      Good luck with your car search , I had one for a couple of years and enjoyed the experience , don't discount a modded one , they are a lot better than standard ones if your precious about originality .

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                      • #12
                        Our power decrease comes as a result of the lower limiter - as has been mentioned already.

                        The S54 cars in the US and Canada have cats in the exhaust manifold, which further reduces power compared to the EU/UK/SA/AU cars.

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                        • #13
                          Originally posted by c_w View Post
                          S54 Z3M power was pegged back as not to overhaul the E46 M3 (even though it did in acceleration figures as it was lighter), mainly with the lower rev limit. But there is all kinds of rubbish about the intake and exhaust space being the main reason.

                          Problem of raising the rev limit then risks bearing issues, which were not officially recalled on the Z3M...because of the lower rev limit. As it's the same engine built with the same bearings as the early E46, but BMW reckon the lower rev limit didn't warrant recalling the S54 Coupe.
                          This ^

                          Although I believe there is some effect due to exhaust ie I have a remapped and raised red line of 8k (the retro fit bearing work was done on mine under warranty as a goodwill when the car was in for a failed fan unit and associated damage and yet does not make stock S54 M3 figures therefore there must be other factors ie induction / exhaust. I can't remember my exact dyno but from memory it's around 335bhp.

                          Re difference between s50 v s54 stock real world is about 20-25bhp the S50 running 290-300 the S54 a lot closer to the published 325bhp.

                          In terms of driving the S54 does feel torquer above 5k rpm, the fly by wire feels more responsive but you get a disco traction control lightshow on the dash
                          VIDEO or Journal

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                          • #14
                            Originally posted by paulwirral View Post
                            I had one for a couple of years and enjoyed the experience , don't discount a modded one , they are a lot better than standard ones if your precious about originality .
                            I've got Paul's old one and sympatheticly modded ones are the ones to go for. Most people eventually put up a post asking if h&r rollbars etc are all that. Only for the response to be 'yes do it!'. Like this it's far more fun than the m3 albeit rear tyres don't last long.

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                            • #15
                              Originally posted by Jonttt View Post
                              Although I believe there is some effect due to exhaust ie I have a remapped and raised red line of 8k (the retro fit bearing work was done on mine under warranty as a goodwill when the car was in for a failed fan unit and associated damage and yet does not make stock S54 M3 figures therefore there must be other factors ie induction / exhaust. I can't remember my exact dyno but from memory it's around 335bhp.

                              Re difference between s50 v s54 stock real world is about 20-25bhp the S50 running 290-300 the S54 a lot closer to the published 325bhp.
                              I'm pretty sure I've read the E46 M3s don't always make the 343bhp figure, so might be closer than you think to yours?

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