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  #21  
Old 18-08-2014, 08:34 AM
btz461 btz461 is offline
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The DME software has a slightly different profile hence the lower bhp figures for the S54 engine cars.Otherwise identical to the M3 engines.
Nothing to do with the rev limiter.
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  #22  
Old 18-08-2014, 08:28 PM
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The profile is quite different, I had my S54 Z3M remapped by the guys at Evolve.
They loaded on a M3 S54 profile and it wasn't good at all.

The guys spent about 4-5 hours on a map for my S54 which resulted in 347bhp and I decided to keep the rev limiter as standard due to the reported bearing issues.
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  #23  
Old 18-08-2014, 09:20 PM
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Quote:
Originally Posted by btz461 View Post
The DME software has a slightly different profile hence the lower bhp figures for the S54 engine cars.Otherwise identical to the M3 engines.
Nothing to do with the rev limiter.
The formula for calculating Horsepower is:

HP = (RPM * Torque in ft/ lbs) / 5252

Therefore, if torque is the same, then the engine revving to 8000rpm will produce a higher HP figure than the engine revving to 7,400rpm. I realise the E46 M3 has a higher torque output, but the higher rev limit accounts, in part, for the higher HP, as per the maths.

I have it in correspondence with BMW UK that the S54 engine in the Z3MC has a lower redline than the same S54 engine in the E46 M3, in order to keep the under-bonnet temperature down because there is less cooling in the smaller engine bay of the Z3MC.

The shorter length of the MC's exhaust system is also supposedly responsible for lesser performance from the same S54 engine than in the E46 M3, because it is slightly more restrictive.
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Last edited by exdos; 18-08-2014 at 09:31 PM.
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  #24  
Old 19-08-2014, 07:23 AM
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I can't comment on the reduced BHP question but can on the driving experience since I've owned 2 x S54 Z4M's and now own an S50 MC. The difference is like night and day out on the road and immediately felt through the throttle. It's more visceral in an S50 and feels like an older more ragged driving experience.

There's a rawness to it, still ///M in feel but not as measured as an S54. When I first drove my MC it definitely felt like a step backwards but after a few drives I now adore the sort of heavier sensation if that makes any sense. The gearing will of course have a lot to do with that and I'd personally be interested to feel what the S54 MC feels like in comparison.

I loved the Z4MCs I owned and have nothing but good things to say about them but with the S50 I've essentially got myself a car that inspires me to drive and feels like slightly more of an event each time I turn the key.

Could all be in my head of course!

Good luck with your search
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  #25  
Old 19-08-2014, 03:13 PM
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The size of the Z4 would also be a factor, Z3 with S54 best of both worlds and rarity of an already rare car you have to pay for ;-)
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Old 19-08-2014, 03:58 PM
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Maybe but physical length aside there's only 50kg in it curb weight wise.

Z4MC: 1,470 kg
Z3MC: 1,420 kg

I guess I was also commenting more from a pure mechanics-of-driving perspective.
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  #27  
Old 19-08-2014, 04:11 PM
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The air-intakes of the Z4MC and E46 M3 are also better (and bigger due to more space under the larger bonnets) than that of the Z3MC, which also assists in producing more torque/power.
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  #28  
Old 19-08-2014, 07:58 PM
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Quote:
Originally Posted by inkey$ View Post
Maybe but physical length aside there's only 50kg in it curb weight wise.

Z4MC: 1,470 kg
Z3MC: 1,420 kg

I guess I was also commenting more from a pure mechanics-of-driving perspective.
I was referring to the size not the weight, the Z4 feel much bigger than a Z3 and feels so different to drive even in S54 to S54 form.
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  #29  
Old 19-08-2014, 09:01 PM
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Fair point. I can see how some people might struggle with the difference.
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  #30  
Old 20-08-2014, 10:05 PM
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Nice footer pic
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