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Z4 Weight Distribution-- Rather good!

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
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Valor1
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Z4 Weight Distribution-- Rather good!

Post by Valor1 » Mon Sep 11, 2017 4:36 am

I weighed my E89 N54 Z4 with a manual gearbox today on a set of scales typically used for corner balancing. To do a proper corner balancing you need to ensure the pavement is perfectly level. However, as I was not doing a corner balance and as my main goal was to learn the actual real world weight of my car I used a pretty flat surface but one that was not perfect. Of course, when driving rarely is one on a perfectly flat surface anyway so while it may not be the ideal surface for a corner balance it was good enough to determine the exact vehicle weight.

With 19" 255 mm tires in the front and 20" wheels and 285 mm tires in the rear and lightweight forged wheels the manual Z4 weighed in at 3,378. With a lithium battery and a few other tweaks I suspect the weight can be dropped closer to 3,300.

The weight in the front was 1655 and 1723 pounds for the rear.

The weight distribution was actually rather good for a front engine car with 48.9 on the front and 51.1 on the rear.

With a driver in the car (me) the weight distribution improved even further with 48.7 front and 51.3 rear.

I should have checked the balance with the hardtop stowed in the trunk as I'm sure that would have further improved the rear weight bias.

Still, those are pretty good numbers for a car with twin turbo straight six engine!

Car & Driver weighed the C7 Corvette and stated "Although Chevrolet claims a straight-up 50/50 weight distribution, our scales demonstrated a rearward weight bias, with 49.4 percent sitting over the front axle and 50.6 to the rear. That makes it and the C2 the only Corvettes to tip the scales to the stern."

The Corvette Convertible weighs 3,362, basically identical to the Z4 and my car's weight includes active suspension, extended leather, metal roof, etc. The Corvette actually has slightly smaller tires in the front.....245/19 front and the same 285/20" in the rear.

In other words, the manual gearbox N54 Z4 has a better weight distribution than the Corvette which is pretty impressive!

With some simple tuner mods the N54 motor puts out more than 400 hp while the corvette makes 455 hp. Their torque ratings are even closer. Of course, with more mods the N54 can deliver 500 hp :D

Interesting how performance has advanced. The Porsche 993 Turbo S made 425 horsepower and weighed around 3,373 pounds. A convertible E89 with a manual gearbox weighs the same as 993 Twin Turbo S and with easily added tuner parts makes the same power as the legendary Turbo S. Now if only the Z4 had the telepathic steering of the Porsche.

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sunnydays
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Z4 Weight Distribution-- Rather good!

Post by sunnydays » Mon Sep 11, 2017 8:44 am

48.9 front to 51.1 rear
48.7 front to 51.3 rear with driver

dont really know much about weight distrubution OP, can you explain why the second figure is better than the first?

I thought 50:50 or as close to was optimal?
Or is a rear bias preferable for good handling?

Cheers

mcbutler
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Z4 Weight Distribution-- Rather good!

Post by mcbutler » Mon Sep 11, 2017 10:06 am

Valor1 wrote: Mon Sep 11, 2017 4:36 am I weighed my E89 N54 Z4 with a manual gearbox today on a set of scales typically used for corner balancing. To do a proper corner balancing you need to ensure the pavement is perfectly level. However, as I was not doing a corner balance and as my main goal was to learn the actual real world weight of my car I used a pretty flat surface but one that was not perfect. Of course, when driving rarely is one on a perfectly flat surface anyway so while it may not be the ideal surface for a corner balance it was good enough to determine the exact vehicle weight.

With 19" 255 mm tires in the front and 20" wheels and 285 mm tires in the rear and lightweight forged wheels the manual Z4 weighed in at 3,378. With a lithium battery and a few other tweaks I suspect the weight can be dropped closer to 3,300.

The weight in the front was 1655 and 1723 pounds for the rear.

The weight distribution was actually rather good for a front engine car with 48.9 on the front and 51.1 on the rear.

With a driver in the car (me) the weight distribution improved even further with 48.7 front and 51.3 rear.

I should have checked the balance with the hardtop stowed in the trunk as I'm sure that would have further improved the rear weight bias.

Still, those are pretty good numbers for a car with twin turbo straight six engine!

Car & Driver weighed the C7 Corvette and stated "Although Chevrolet claims a straight-up 50/50 weight distribution, our scales demonstrated a rearward weight bias, with 49.4 percent sitting over the front axle and 50.6 to the rear. That makes it and the C2 the only Corvettes to tip the scales to the stern."

The Corvette Convertible weighs 3,362, basically identical to the Z4 and my car's weight includes active suspension, extended leather, metal roof, etc. The Corvette actually has slightly smaller tires in the front.....245/19 front and the same 285/20" in the rear.

In other words, the manual gearbox N54 Z4 has a better weight distribution than the Corvette which is pretty impressive!

With some simple tuner mods the N54 motor puts out more than 400 hp while the corvette makes 455 hp. Their torque ratings are even closer. Of course, with more mods the N54 can deliver 500 hp :D

Interesting how performance has advanced. The Porsche 993 Turbo S made 425 horsepower and weighed around 3,373 pounds. A convertible E89 with a manual gearbox weighs the same as 993 Twin Turbo S and with easily added tuner parts makes the same power as the legendary Turbo S. Now if only the Z4 had the telepathic steering of the Porsche.
And in kilos for the rest of the world (apart from Burma) :poke: :poke:
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Valor1
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Z4 Weight Distribution-- Rather good!

Post by Valor1 » Mon Sep 11, 2017 4:51 pm

sunnydays wrote: Mon Sep 11, 2017 8:44 am 48.9 front to 51.1 rear
48.7 front to 51.3 rear with driver

dont really know much about weight distrubution OP, can you explain why the second figure is better than the first?

I thought 50:50 or as close to was optimal?
Or is a rear bias preferable for good handling?

Cheers
Hello. Yes, a rearward bias is preferred for a number of reasons both in terms of handling, braking and acceleration.

More weight on the rear allows the car to apply its power better and more efficiently.
Less weight on the front allows the car to turn in faster and you can more effectively throttle steer through the turns using both steering and power.
Less weight up front and more in the rear helps braking because when you hit the brakes there is a tremendous weight transfer to the front. This transfer is moderated by having more weigh in the rear.

This is why all top performance cars and race cars are mid-engined. Up to a point, the more weight you can balance to the rear the better. This is also why front engined high performance cars try and move the engine as rearward as possible to shift the weight from the front rearward.

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Z4 Weight Distribution-- Rather good!

Post by buzyg » Mon Sep 11, 2017 8:28 pm

Sounds like some one would love a Corvette. :wink:
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Z4 Weight Distribution-- Rather good!

Post by Mr Tidy » Mon Sep 11, 2017 8:52 pm

buzyg wrote: Mon Sep 11, 2017 8:28 pmSounds like some one would love a Corvette.
:lol:

Actually I was surprised to read that the Corvette is as close in weight to an E89, although of course it doesn't have a metal roof.
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Z4 Weight Distribution-- Rather good!

Post by buzyg » Mon Sep 11, 2017 9:21 pm

Mr Tidy wrote: Mon Sep 11, 2017 8:52 pm
buzyg wrote: Mon Sep 11, 2017 8:28 pmSounds like some one would love a Corvette.
:lol:

Actually I was surprised to read that the Corvette is as close in weight to an E89, although of course it doesn't have a metal roof.
It has a lovely old school V8 though & no turbos. 8) Much better that a folding roof.
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Z4 Weight Distribution-- Rather good!

Post by Valor1 » Tue Sep 12, 2017 2:21 am

buzyg wrote: Mon Sep 11, 2017 9:21 pm
Mr Tidy wrote: Mon Sep 11, 2017 8:52 pm
buzyg wrote: Mon Sep 11, 2017 8:28 pmSounds like some one would love a Corvette.
:lol:

Actually I was surprised to read that the Corvette is as close in weight to an E89, although of course it doesn't have a metal roof.
It has a lovely old school V8 though & no turbos. 8) Much better that a folding roof.
I do like its V8.....but it is nearly a foot longer and 3.5 inches wider than the Z4, it's made of fiberglass and the Vette's interior is really cheap looking by comparison to the Z4. (Although it's miles better than the C6 interior.)

Despite its larger size, at least with tops up, the Z4 actually has a slightly larger trunk / boot.

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