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      04-17-2008, 07:45 PM   #1
lucid
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Drives: E30 M3; Expedition
Join Date: Apr 2007
Location: USA

Posts: 8,034
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Weight savings cost/benefit benchmarks

I am keen on reducing the weight of my car, and am interested in establishing some cost/benefit benchmarks in that regard. The metrics are clear: lbs saved for benefit, and cost of part for cost, which results in cost/lb. Let's get this started. We can add numbers for different aftermarket components as they become available. The cost figures posted below do not include any installation or paint charges. Also, the focus of this thread is weight reduction only, and rotational inertia reduction or power gain benefits are not documented.

EXHAUST
Stock system: 25 kg (55.06 lbs) (supplied by Gruppe-M and Vorsteiner)
Gruppe-M Titanium catback system: 9.1 kg (20.04 lbs)
Cost: ~$4900
Weight savings: 35.02 lbs
cost/benefit: $140/lb
http://www.gruppem.co.jp/en/home.html

Stock system: 25 kg (55.06 lbs) (supplied by Gruppe-M and Vorsteiner)
Vorsteiner Titanium catback system: 17.33 lbs
Cost: ~$3499
Weight savings: 37.73 lbs
cost/benefit: $92/lb
http://www.jlevistreetwerks.com/p172...duct_info.html
http://www.m3post.com/forums/showthread.php?t=137805

Stock system: 25 kg (55.06 lbs) (supplied by Gruppe-M and Vorsteiner)
Dixis Titanium system including H pipes: 17.18 lbs (supplied by member ArsenalFC)
Cost: ~$5400 (supplied by member ArsenalFC)
Weight savings: 37.73 lbs
cost/benefit: $143/lb

X&CONNECTING PIPES
Stock system: 41 lbs (supplied by encoreinnovation)
Active Autowerke system (just pipes; no cats--don't have weight info on optional race cats): ~25 lbs
Cost: $2000
Weight savings: ~15 lbs
cost/benefit: $133/lb
http://www.m3post.com/forums/showthread.php?t=189185

Stock system: 41 lbs (supplied by encoreinnovation)
Encoreinnovation system (with race cats): 19 lbs
Cost: $4299
Weight savings: 22 lbs
cost/benefit: $195/lb
http://www.encoreinnovation.com/prod...fication/id/14

WHEELS
Stock 19x8.5/19x9.5 Wheels (F/R): 23.4/25.4 lb (GregW's numbers 47/51.5 minus 19" PS2 weights; 23.6/26.1)
19" Volk Racing TE37 Time Attack (F/R): ~21.0/22.0 lb (as stated by Tirerack)
Cost: $3400
Weight savings: 11.6 lbs (over stock 19" wheels)
cost/benefit: $293/lb
http://www.tirerack.com/wheels/Wheel...All&sort=Brand

19x9/19x10 Advan RS (F/R): ~20.4/21.8 lb (Wheels STO)
Cost: ~$2800
Weight savings: 13.2 lbs (over stock 19" wheels)
cost/benefit: $212/lb
http://www.m3post.com/forums/showthread.php?t=265756

18" TRMotorsport MT1 Wheels (F/R): 18.5/19.0 lb (as stated by Tirerack)
Cost: $1236
Weight savings: 22.6 lbs (over stock 19" wheels)
cost/benefit: $55/lb
http://www.tirerack.com/wheels/Wheel...All&sort=Brand

TIRES
Stock 19" Tires; PS2s(F/R): 24/25 lb (Tirerack)
19" PSCs Tires (F/R): 21/24 lb (Tirerack)
Extra Cost: $98 (this is how much more you'd pay over PS2s during tire change; they will wear out faster though)
Weight savings: 8 lbs (over PS2s)
cost/benefit: $12/lb
http://www.tirerack.com/tires/Spec.j...5YR9SPORTCUPXL

EXTERNAL DOOR PANELS
Stock (steel): 18.54 kg (40.84 lbs) /door
http://bmwfans.info/original/E92/Cou...1/ill-41_1700/
Ericsson CF door panels: 3.35 kg (7.38 lbs) / door
Cost: $11466
Weight savings: 66.92 lbs
cost/benefit: $171/lb
http://www.bulletproofautomotive.com...il.php?ID=6547

TRUNK LID
Stock (Steel): 10.625 kg (23.40 lbs) (OC weighed his at 26.0 lbs)
http://bmwfans.info/original/E92/Cou...1/ill-41_1638/
CF Vorsteiner lid: 14.9 lbs (OC Kid weighed it)
Cost: $1362
Weight savings: 11.1 lbs (according to OC's numbers)
cost/benefit: ~$123/lb
http://www.vorsteiner.com/bmw/e92coupe-spoiler.html#
http://www.redline-motorworks.com/product/9306%20BMV

Stock (Steel): 10.625 kg (23.40 lbs)
CF Ericsson lid: 7.04 lbs
Cost: $6400
Weight savings: 16.36 lbs
cost/benefit: $391/lb
http://www.bulletproofautomotive.com...il.php?ID=6423

HOOD
Stock (Al): 10.20 kg (22.47 lbs)
http://bmwfans.info/original/E92/Cou...1/ill-41_1611/
Ericsson CF hood: 12.54 lbs
Cost: $6400
Weight savings: 9.93 lbs
cost/benefit: $645/lb
http://www.bulletproofautomotive.com...il.php?ID=6422

AIRBOX
Stock: 4.95 kg (10.90 lbs)
http://bmwfans.info/original/E92/Cou...1/ill-11_4129/
Unknown German Manufacturer CF Airbox: unknown
Cost: $2700
Weight savings: ~8 lbs (see link below for approximate savings figure, which is realistic)
http://www.ca-automotive.co.uk/produ...faWQ9OA==.html
cost/benefit: ~$340/lb
http://store.bimmerworld.com/shared/...t=products.asp

BRAKES
Stock assembly (F/R): 37.2/30.7 lbs
F caliper assemb: 14.5 lbs with pads and rubber line (Badfish weighed this)
F rotor assemb: 22.7 lbs (Badfish weighed this)
R caliper assemb: 11.0 lbs with pads and rubber line (Badfish weighed this)
R rotor assemb: 19.7 lbs (Badfish weighed this)

Brembo 365x34 (F) 345x28 (R) Kit
Brembo F caliper assemb: 14.0 lb (weighed by sparkyg)
Brembo F rotor assemb: 24.5 lb (weighed by sparkyg)
Brembo R caliper assemb: 9.5 lb (weighed by sparkyg)
Brembo R rotor assemb: 15.0 lb (weighed by sparkyg)
Cost: ~$6100
Weight savings: 9.8 lbs
cost/benefit: $622/lbs
http://www.m3post.com/forums/showthr...15#post5194815

Stoptech 380x35 (F) 355x32 (R) Kit
Stoptech F caliper assemb: 13.11 lbs with pads & bracket (Badfish weighed this)
Stoptech F rotor assemb: 21.01 lbs (Badfish weighed this)
Stoptech R caliper assemb: 11.15 lbs with pads & bracket (Badfish weighed this)
Stoptech R rotor assemb: 19.33 lbs (Badfish weighed this)
Cost: $5890
Weight savings: 4.6 lbs
cost/benefit: $1280/lbs
http://www.**********s.com/product.a...BK_E92_M3_RS10
http://www.m3post.com/forums/showthread.php?t=150944

Performance Friction 371x32 (F) 372x30 (R) Kit (prototype, production will use slightly ligther brackets)
Performance Friction F caliper and rotor assemb: 28 lbs with pads & bracket (James C weighed this)
Performance Friction R caliper and rotor assemb: 34 lbs (James C weighed this)
Cost: $8000
Weight savings: 12 lbs
cost/benefit: $666/lbs
http://www.m3post.com/forums/showthr...=232463&page=3
http://www.nexternal.com/bimmerworl/Product1060

BATTERY
Stock: 27.250 kg (60.02 lbs) -- 90 Amp/Hr
http://bmwfans.info/original/E92/Cou...1/ill-61_2091/
Braille B3121: 21 lbs -- 31 Amp/Hr
Cost: $180
Weight savings: 39 lbs
cost/benefit: $5/lbs
http://braillebattery.com/index.php/batteries/b3121/
DIY: http://www.m3post.com/forums/showthread.php?t=233195
Warning: There are issues with the reserve capacticy of the Braille B3121 when used in the E9X M3; read the DIY for more info.

Stock: 27.250 kg (60.02 lbs) -- 90 Amp/Hr
http://bmwfans.info/original/E92/Cou...1/ill-61_2091/
OEM Mini battery: 34.4 lbs -- 55 Amp/Hr
Cost: $128
Weight savings: 25.6 lbs
cost/benefit: $5/lbs
http://www.trademotion.com/partlocat...&siteid=214672 Part#: 61217571896
DIY: http://www.m3post.com/forums/showthr...=233195&page=7
Note: This is the OEM battery for the MINI and the E46 CSL.

FRONT BUMPER
Stock: 9.91 lbs
http://bmwfans.info/original/E92/Cou...1/ill-51_6244/
Ericsson CF front bumper: 5.28 lbs
Cost: $9800
Weight savings: 4.62 lbs
cost/benefit: $2121/lbs
http://www.bulletproofautomotive.com...il.php?ID=6419

INTERIOR DOOR PANEL
Stock: 3.1 kg
Ericsson CF interior panel: 1.25 kg
Cost: $6600
Weight savings: 4.07 lbs
cost/benefit: $1621/lb
http://www.bulletproofautomotive.com...il.php?ID=6425
http://www.e90post.com/forums/showthread.php?t=168900

FRONT SEATS
Stock: 62.6 lbs each (weighted by Sam@AutoTalent)
BMW performance bucket seats with side airbag: 25.3 kg each (55.7 lbs) (weighed by BMW-M-Mexico)
CF aftermarket bucket seats: ?
Cost: $5000
Weight savings: 13.8 lbs
cost/benefit: $362.3/lb
http://www.turnermotorsport.com/html...FORMANCE-SEATS

REAR SEATS (excluding rear headrests and storage cartridge in fold down seatback)
Stock: ~43 lbs (I weighed these)
Remove them
Cost: $0
Weight savings: 43 lbs
cost/benefit: $0/lb
http://www.m3post.com/forums/showthread.php?t=177061

REAR HEADRESTS
Stock: 783 grams each (1.73 lbs) (I weighed these)
Remove them
Cost: $0
Weight savings: 3.45 lbs
cost/benefit: $0/lb

STORAGE CARTRIDGE (in fold-down rear seatback)
Stock: 738 grams (1.62 lbs) (I weighed this)
Remove it
Cost: $0
Weight savings: 1.62 lbs
cost/benefit: $0/lb

MOBILITY KIT & HOLDER
Stock: 1096 + 275 = 1371 grams (3.02 lbs) (I weighed these)
Remove it
Cost: $0
Weight savings: 3.02 lbs
cost/benefit: $0/lb

PLASTIC BATTERY COVER/TOOL HOLDER
Stock: 1276 grams (2.81 lbs) (I weighed these)
Remove it
Cost: $0
Weight savings: 2.81 lbs
cost/benefit: $0/lb

TRUNK FLOOR COVER/MAT
Stock: 3750 grams (8.26 lbs) (I weighed this)
Remove it
Cost: $0
Weight savings: 8.26 lbs
cost/benefit: $0/lb

TRUNK LID LINING
Stock: 939 grams (2.07 lbs) (I weighed this)
Remove it
Cost: $0
Weight savings: 2.07 lbs
cost/benefit: $0/lb

FRONT LICENCE PLATE & HOLDER
Stock: 378 grams (0.83 lbs) (I weighed these)
Remove it
Cost: $0
Weight savings: 0.83 lbs
cost/benefit: $0/lb

WASHER FLUID
Stock: 3.79 kg (8.35 lbs)
Drain it
Cost: $0
Weight savings: 8.35 lbs
cost/benefit: $0/lb

BODY FAT
Stock: ?
Sculpted body: ?
Cost: ?
Weight savings: ?
cost/benefit: ?

What else?
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Last edited by lucid; 03-06-2009 at 11:53 AM.
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