Login


02282011, 11:23 PM  #1 
White and Carbon
7
Rep 163
Posts 
ZCP wheels = .1 second slower in the 1/4 mile?
I see that the ZCP 359M wheels are:
Front: 25.5lb Rear: 28lb Then the other 220M 19's are: Front: 23lb Rear: 26lb I then read that each 1 pound of unsprung weight equals about 10 pounds of sprung weight as far as performance goes. Also, each 100 pounds of sprung weight added to the car equals .1 seconds more in the quarter mile. So, my question is, can you feel this difference? Is it a real world difference? 
02282011, 11:27 PM  #3 
Captain
11
Rep 835
Posts 
Do you mean in a perfect world, with perfect surface traction, in a vacuum, with perfect tire condition, perfect clutch and throttle application, with perfectly straight steering angle, with no head or tailwind, with a 50th percentile male driver, with a full tank of gas and fluid?
/sarcasm. Sorry, I couldn't resist. 
Appreciate
0

02282011, 11:29 PM  #5 
Captain
35
Rep 964
Posts
Drives: E92 M3 SSII/Fox Red ZCP DCT
Join Date: Dec 2008
Location: LA

They are wider. Therefore better grip. Therefore faster.
__________________
E92 M3 SSII/Fox Red, DCT, ZCP past ridesIS350, E92 335i 
Appreciate
0

02282011, 11:41 PM  #7 
Lieutenant Colonel
68
Rep 1,823
Posts 
I found ZCP wheels to be a joke... heavy and cast.. sold them within a month of getting the car... I switched to 18" APEX wheels that weigh around 19lb..

Appreciate
0

02282011, 11:42 PM  #8 
Brigadier General
101
Rep 4,801
Posts
Drives: '08 E92 M3
Join Date: Jul 2008
Location: Los Angeles, Irvine

Well the extra HP in the ZCPs should make up for that extra weight.
__________________
'08 E92 ///M3  AW/BLK/CF, MDCT, 19's
H&R, Vorsteiner, Eisenmann, BMC, BBS More to come... 
Appreciate
0

02282011, 11:43 PM  #9 
Lieutenant Colonel
47
Rep 1,770
Posts
Drives: 2011 E92 M3 ZCP
Join Date: Apr 2010
Location: SoCal

Jesus at this thread
__________________
'12 CLS550 Palladium Silver  loaded
'11 E92 M3 ZCP  SG/BEXT/CF, MDCT, loaded '11 E93 328i, BSM over Saddle Brown, sport, loaded '08 550i MSport, Carbon Black (Gone but not forgotten), '06 W211 E55 AMG (Gone, miss this animal),'01 E39 540i Sport 
Appreciate
0

02282011, 11:52 PM  #10 
Lieutenant
15
Rep 402
Posts 
__________________
2011.5 E92 ///M3 Space Gray; Fox Red & Blk; 6MT; ZCP; ZCV; ZP2; ///M Performance Exhaust (sold)
2012 VW Jetta TDI (sold) 2002 Subaru WRX (sold) The World in 35mm 
Appreciate
0

03012011, 12:05 AM  #11 
Veni Vidi Vici
42
Rep 2,749
Posts
Drives: '11 JB/BBe6spe90
Join Date: Jul 2008
Location: Macungie PA
iTrader: (0)
Garage List 2011 e90 M3Sold [4.25]
2003 RS6  Sold [0.00] 2009 e90 M3  Gone [0.00] 2003 M3 SOLD [0.00] old 2002 [5.00] 
+2
__________________
Dinan compliment of stuff plus PF rotors and RG63s. Enough for now. Why, yes. I am an abrasive bastard. 
Appreciate
0

03012011, 12:27 AM  #12  
Enlisted Member
1
Rep 38
Posts 
Quote:
I'm surprised the weight differences aren't more than they are comparing the forged 220's to the reportedly cast 359's, especially considering the 1/2" added width for the 359's. In fact, if you add 1 to 1.5 pounds for the added 1/2" (there's a 2.5 to 3 lb. difference for the added inch in each set), the difference becomes smaller than I would expect. It makes me wonder if the weights listed above are accurate, and also makes me wonder why there isn't a bigger difference between the forged and cast wheel weights. Clearly I'm no expert here, but I'm curious if anyone has thoughts? 

Appreciate
0

03012011, 12:46 AM  #14 
Captain
11
Rep 835
Posts 
Here's a good primer for those that are not familiar with any of the technologies, but it's by no means definitive and the beall, endall.
One issue is that we don't know with any certainty as to how the 359s are manufactured. If they are indeed flow formed castings, then they can have thinner walls as the composition is more dense due to the forming process, unlike a low pressure (or even gravity) castings. However, take into consideration the size of the spokes of the 220, and I'm led to believe that there's more surface area on the 220 than on the 359. That's just my observation, not fact, so I could be way off. So the 220 is pretty light for an OEM wheel. Yes there are lighter ones, but still impressive. 
Appreciate
0

03012011, 12:55 AM  #15 
PCA, BMWCCA
49
Rep 2,060
Posts 
Not necessarily. X mm more wheel width doesn't = X mm more rubber width as tires have tread with varying "block" widths of rubber, especially when comparing different tire types. Are the tires different sized in OEM applications? Plus, wider rubber could mean more grip at the point of inertia, but it turns into more rolling resistance at speed.
__________________
'08 Carrera S 6MT Guards Red/Black ext leather, Carbon fiber pkg, sport exh, sport chrono +, PASM, Nav, Bose, 19" forged turbos, red tranny tunnel
'07 MV Agusta F4 1000 R 1+1, Corse Red/Silver, RG3 race pipes and factory race ECU 
Appreciate
0

03012011, 12:58 AM  #16 
PCA, BMWCCA
49
Rep 2,060
Posts 
OEM forged wheels are usually no where as light as aftermarket forged wheels, such as 1 piece BBS forged wheels as example. OEM wheels are made to be more stout as opposed to simply the lightest possible, forged or not.
__________________
'08 Carrera S 6MT Guards Red/Black ext leather, Carbon fiber pkg, sport exh, sport chrono +, PASM, Nav, Bose, 19" forged turbos, red tranny tunnel
'07 MV Agusta F4 1000 R 1+1, Corse Red/Silver, RG3 race pipes and factory race ECU 
Appreciate
0

03012011, 01:24 AM  #17  
Captain
17
Rep 918
Posts 
Quote:
__________________
09 e92 SPACE GRAY/// m3 w/ mdct!
06 E46 JET BLACK/// m3 6MT! 

Appreciate
0

03012011, 03:29 AM  #18  
Engineer
2
Rep 18
Posts 
Quote:
After some research, I found the 220M 19" classic M3 twinspoke style to be my primary choice for a number of reasons; in AUS, I actually paid the same price for the EDC/M Drive/220M options compared to the Competition Package (ZCP). The 220M is a true forged rim being light for its size; it is actually more expensive to BMW cost as well as much more expensive to replace at retail. Also, I liked the concept of the classic M3 twinspoke wheel style and the best compromise on ride (for me). Simply 'flick' the narrow spoke of a 220M rim with your fingernail and you can hear the higher pitched ring tone of a lightweight forged wheel. 

Appreciate
0

03012011, 04:44 AM  #19 
Captain
14
Rep 630
Posts 
They also claim that every 10 lbs of extra weight in the car is equivalent to 1 hp. I feverishly on a diet to get back down to my birth weight of 7 lbs. I'll reclaim about 23 hp...he he.
In the real world, it's doubtful the slight difference in wheel weights will matter in acceleration. If it made a considerable difference, people would be going back to the original 18" wheels to save weight. It's all about looking cool. 
Appreciate
0

03012011, 04:57 AM  #20  
Captain
17
Rep 935
Posts 
Quote:
__________________
2011.5 mineral white e92 zcp 6mt m3 

Appreciate
0

03012011, 05:26 AM  #21 
Lieutenant General
295
Rep 10,360
Posts 
In short no, the difference will be much smaller than 0.1 seconds.
Use this formula: ET = 6.1178 x (weight/power)^(1/3) Units are lb and hp. The formula is not exact, however for trends, rough estimates and AB comparisons it is pretty good. You should also note that the 1:10 rule you have heard is not correct. The correct rule is that for every 1 lb saved in a single wheel it is like 8 lbs of total weight saved for the same change made in all 4 wheels (in other words only like a 2 for 1). See my post on this topic here. However for most street carsan M3 the 0.1 seconds per 100 lbs is very close to accurate. You certainly can not apply this rule of thumb across a really wide power to weight ratio though. For your example if I simply round the 2.5 lb to 3. I'll use a total weight change of 24 lb (3*8) and that gives a mere 0.03 second difference. You can also verify the rough power of the formula by looking at some actual test results from Car and Driver with a VW Gold. Article here. Comparing the smallest and largest wheel sizes you should us 8*14 lb difference. The formula for this comparison shows a 0.2 second difference. That is exactly what the testing found! Now the tires were wider and that should give an unaccounted advantage to the larger wheel. Also all inertial effects are not capatured in my rough relationship above and the higher inertia of the wheel would cause a disadvantage for acceleration. Perhaps these effects roughly cancelled. Either way you can see that the formula works pretty well, both for an absolute prediction and even more importantly for this AB comparison. On top of drag racing for autoX and road coarses there are other advantages in handling for having a light wheel and tire combo. The above is just the in a straight line advantage.
__________________
E92 M3  Space Gray on Fox Red  MDCT  CF Roof  RAC RG63 Wheels  Brembo 380mm BBK   Vorsteiner Ti Exhaust  Matte Black Grilles/Side Gills/Rear Emblem/Mirrors   Alekshop Back up Camera  GP Thunders  BMW Aluminum Pedals  Elite Angels   XPEL Full Front Wrap  Hardwired V1  Interior Xenon Light Kit  
Appreciate
0

Post Reply 
Bookmarks 
Thread Tools  Search this Thread 

