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I owned two 3 liter Z3s before getting this 3liter Z4. The Z4 seems to have more torque but is 10hp less than the 3 liter Z3. Even my wife said this seems to pull harder. Is there that much difference in the two engines? I was expecting the very same power.:yikes:
 

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Which model Z4 do you have? 3.0i or 3.0si?
 

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More important, what year 3.0i do you have? The '03-'05 3.0i was more powerful than the '06-'08 3.0i as they used different engine series.
 

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I'd like to drive one. I'm sure there is a big difference. Do you know how the 50 extra HP is gained? If the bore and stroke are the same it must be in the cam or valves or injection/headers.
Not sure on those technicalities! Also have sport button and paddle shifters. sport makes a huge difference as it causes gear shifts at higher RPMs.
 

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Discussion Starter #9
Not sure on those technicalities! Also have sport button and paddle shifters. sport makes a huge difference as it causes gear shifts at higher RPMs.
I have the Sport mode transmission and paddle shifter. Sometimes I play with it.
 

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3.0si is 265 HP
265? I think you mean 255? Or is yours tuned?

I'd like to drive one. I'm sure there is a big difference. Do you know how the 50 extra HP is gained? If the bore and stroke are the same it must be in the cam or valves or injection/headers.
It is mostly the induction system. You can upgrade your car to the si's version and get the extra hp. There are many DIY's about the process.
 

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BMW USA lists the car at 255hp in any publication I have seen :dunno:
We all know that BMW's horses are a little different from the rest. They are racing thoroughbreds :rofl:

Car And Driver rates the si as 255 BHP
EVO Magazine has it at 261 BHP
Top Gear: 265 BHP
Autocar: 2651 BHP - not a typo

I'm not going to untangle that mess
 

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David Bilton
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I owned two 3 liter Z3s before getting this 3liter Z4. The Z4 seems to have more torque but is 10hp less than the 3 liter Z3. Even my wife said this seems to pull harder. Is there that much difference in the two engines? I was expecting the very same power.:yikes:
specs for the 2007 3.0i (same as mine) are as follows:

Horsepower = 215 @ 6250

Torque = 185 @ 2750
 

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We all know that BMW's horses are a little different from the rest. They are racing thoroughbreds :rofl:

Car And Driver rates the si as 255 BHP
EVO Magazine has it at 261 BHP
Top Gear: 265 BHP
Autocar: 2651 BHP - not a typo

I'm not going to untangle that mess
EVO and Top Gear are for European models. US models always had 255hp - just as BMW said they did :confused:
 

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Interesting. I thought that the US and European cars were identical powertrain-wise. I thought the difference was due to the usual practice of underrated official power numbers given by German Manufacturers.
 

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Interesting. I thought that the US and European cars were identical powertrain-wise. I thought the difference was due to the usual practice of underrated official power numbers given by German Manufacturers.
They are rated using higher octane fuel in Europe. Have noticed this with a lot of identical vehicles from VW, Audi, MB and BMW sold in both markets... I would assume that they just have more aggressive software/programming taking into consideration the higher quality fuel available. If I recall our 91 octane (which is usually the highest available premium grade here) is the lowest grade of fuel there.
 

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They are rated using higher octane fuel in Europe. Have noticed this with a lot of identical vehicles from VW, Audi, MB and BMW sold in both markets... I would assume that they just have more aggressive software/programming taking into consideration the higher quality fuel available. If I recall our 91 octane (which is usually the highest available premium grade here) is the lowest grade of fuel there.
It's not the higher octane rating of Euro fuel, it's the lack of ethanol being added. Ethanol has less stored energy than gasoline so you get slightly lower power output with our 10% ethanol blend fuel.
 

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Euro octane ratings are not directly comparable to US octane ratings. Europe uses RON. US uses (RON+MON)/2

RON Reaserch Octane Number. (Used in Europe and elswhere in gas stations)
MON Motor Octane Number.
AKI Anti-Knock Index. This is the number that is posted on the gas station in the USA as "Octane". It is derived as (RON + MON)/2

EU ratings of 95/98, are equivalent to US ratings of 91/93.
 
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