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Why does the 35is speedo stop at 160mph?

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
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sunnydays
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Why does the 35is speedo stop at 160mph?

Post by sunnydays » Wed Jul 19, 2017 10:45 am

Hey all,

So reading around it appears delimited the Z4 35is is drag limited to 178mph. Given that at those speeds the speedo will likely be a out 10% surely it would have made sense to have the speedo go up to 200mph.

I am aware the car is electronically limited to 155mph but this doesnt stop the M cars going to 200 on the speedo despite being limited.....

Thoughts?

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Why does the 35is speedo stop at 160mph?

Post by Bing » Wed Jul 19, 2017 12:38 pm

The Z4 M goes to 180 on the speedo and is allegedly capable of over 170 when delimited. No idea why the 35is stops at 160 though.
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Why does the 35is speedo stop at 160mph?

Post by john-e89 » Wed Jul 19, 2017 1:07 pm

My thought is I'd poop my trollies doing 178 mph in a Zed4, even if it is capable, which surprises me tbh.
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Why does the 35is speedo stop at 160mph?

Post by R.E92 » Wed Jul 19, 2017 2:28 pm

Probably because it's limited to 155.

Without a limiter it should be capable of going over 180mph.

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Why does the 35is speedo stop at 160mph?

Post by mcbutler » Wed Jul 19, 2017 2:43 pm

If you consider the profile of the Z bonnet (E89) it resembles very strongly the upper profile of an aircraft wing.
I am guessing this would create some amount of lift at those sort of speeds, not very nice.
Also in the UK if your stopped speeding over 100mph they can (and will) confiscate your car and arrest you!
I was threatened with this by police in Dorset on the Tolpuddle bypass after passing an unmarked vehicle at 155mph in my C63.
He let me off with a fine and recorded the speed as 98 mph so I could not qualify for the education course. The only reason he did this is because I immediately admitted my guilt, apologised etc which he said was a refreshing change.

So, speed at your own risk, big consequences.
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Why does the 35is speedo stop at 160mph?

Post by sunnydays » Wed Jul 19, 2017 3:36 pm

I understand the speed limits and the car is limited to 155. Yet the M3 Speedo goes up to 200mph.... these are also electronically limited

Really the question is why has BMW selectively chosen to have the speedo top out at 160mph despite it being capable of much more.

The legal speed limit and electronic limiter are not an excuse as many BMW cars have limiters yet still go to 200 on the speedo

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Why does the 35is speedo stop at 160mph?

Post by Ed Doe » Wed Jul 19, 2017 3:59 pm

35is isn't an M car - bmws 'halo' model. Simples, no need for it :)
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Why does the 35is speedo stop at 160mph?

Post by buzyg » Wed Jul 19, 2017 5:08 pm

Because BMW put a speedo on that goes to 160mph :wink: Impressed if an unmodified 35is can reach a higher top speed than an ///M. HP is similar. Any one know the frontal area and cd figures?
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Why does the 35is speedo stop at 160mph?

Post by sunnydays » Wed Jul 19, 2017 5:55 pm

buzyg wrote: Wed Jul 19, 2017 5:08 pm Because BMW put a speedo on that goes to 160mph :wink: Impressed if an unmodified 35is can reach a higher top speed than an ///M. HP is similar. Any one know the frontal area and cd figures?
Frontal area 1.96m squared
Drag coefficient 0.35
CDA 0.69

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Why does the 35is speedo stop at 160mph?

Post by Yorkie Z » Wed Jul 19, 2017 6:14 pm

Because there driven by pensioners who get scared after 60mph :poke: :rofl:
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Why does the 35is speedo stop at 160mph?

Post by buzyg » Wed Jul 19, 2017 6:19 pm

Ok I found some figures.

E85 CD .35, frontal area 1.91 m2, 338bhp @ 7900rpm (Precisely the RPM needed for the E85 to reach it's top speed in 5th gear). :thumbsup:
E89 CD .34, frontal area 1.96 m2, 335bhp @ 5900rpm ( Alas I don't know the power curve or max speed in gears/ratio's)

From these I am struggling to see how a standard 35IS could possibly be several mph faster than a E85/86 ///M. :?

Can any one shed any more light?
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Why does the 35is speedo stop at 160mph?

Post by Smartbear » Wed Jul 19, 2017 6:25 pm

buzyg wrote: Wed Jul 19, 2017 6:19 pm Ok I found some figures.

E85 CD .35, frontal area 1.91 m2, 338bhp @ 7900rpm (Precisely the RPM needed for the E85 to reach it's top speed in 5th gear). :thumbsup:
E89 CD .34, frontal area 1.96 m2, 335bhp @ 5900rpm ( Alas I don't know the power curve or max speed in gears/ratio's)

From these I am struggling to see how a standard 35IS could possibly be several mph faster than a E85/86 ///M. :?

Can any one shed any more light?
How does the torque output compare between the 2 cars?
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Why does the 35is speedo stop at 160mph?

Post by sunnydays » Wed Jul 19, 2017 6:32 pm

buzyg wrote: Wed Jul 19, 2017 6:19 pm Ok I found some figures.

E85 CD .35, frontal area 1.91 m2, 338bhp @ 7900rpm (Precisely the RPM needed for the E85 to reach it's top speed in 5th gear). :thumbsup:
E89 CD .34, frontal area 1.96 m2, 335bhp @ 5900rpm ( Alas I don't know the power curve or max speed in gears/ratio's)

From these I am struggling to see how a standard 35IS could possibly be several mph faster than a E85/86 ///M. :?

Can any one shed any more light?

Torque, weight, gear ratios, tyres, downforce.

Considering the 35is spanks the Z4M from 0-60, 0-100 etc.... its not surpising it has a higher top speed

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Why does the 35is speedo stop at 160mph?

Post by buzyg » Wed Jul 19, 2017 6:38 pm

sunnydays wrote: Wed Jul 19, 2017 6:32 pm
buzyg wrote: Wed Jul 19, 2017 6:19 pm Ok I found some figures.

E85 CD .35, frontal area 1.91 m2, 338bhp @ 7900rpm (Precisely the RPM needed for the E85 to reach it's top speed in 5th gear). :thumbsup:
E89 CD .34, frontal area 1.96 m2, 335bhp @ 5900rpm ( Alas I don't know the power curve or max speed in gears/ratio's)

From these I am struggling to see how a standard 35IS could possibly be several mph faster than a E85/86 ///M. :?

Can any one shed any more light?

Torque, weight, gear ratios, tyres, downforce.

Considering the 35is spanks the Z4M from 0-60, 0-100 etc.... its not surpising it has a higher top speed
Could you kindly show me some physics, or some official proven figures please. The physics I was taught say it's unlikely.
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Why does the 35is speedo stop at 160mph?

Post by buzyg » Wed Jul 19, 2017 6:49 pm

Smartbear wrote: Wed Jul 19, 2017 6:25 pm
buzyg wrote: Wed Jul 19, 2017 6:19 pm Ok I found some figures.

E85 CD .35, frontal area 1.91 m2, 338bhp @ 7900rpm (Precisely the RPM needed for the E85 to reach it's top speed in 5th gear). :thumbsup:
E89 CD .34, frontal area 1.96 m2, 335bhp @ 5900rpm ( Alas I don't know the power curve or max speed in gears/ratio's)

From these I am struggling to see how a standard 35IS could possibly be several mph faster than a E85/86 ///M. :?

Can any one shed any more light?
How does the torque output compare between the 2 cars?
Rob
Rob, the torque affects the acceleration not the top speed.
Relative Top speed is largely governed by. Frontal area, bhp & the cd figure.
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