How much power am I losing....?

mrubino83 · 03-25-2004, 04:48 PM

With my heavy @$$ rims? Weight:28lbs w/o tire. I have heard that it is upwards of 20whp. Is that true? I can feel it when braking thats for sure. Needless to say, my next mod will be lighter rims

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cronic · 03-25-2004, 04:53 PM

Holy crap what do you have on there 22" chrome spinnaz?

Uncle Scotty · 03-25-2004, 04:57 PM

28 POUNDS?????

DooD....uuuummmmm.....I think you should find something a bit....no...a LOT lighter.....

Jeez....I start thinking 'too heavy' at 16 pounds.

StarDogChampion · 03-25-2004, 04:58 PM

blingBLING

Subie2 · 03-25-2004, 05:07 PM

Technically your not losing power. Just not getting it to the ground like you should.. plus power to weight ratio is being thrown off.

mrubino83 · 03-25-2004, 05:18 PM

18x7.5 motegi mr-7. Pretty sure that 28lbs is how much they weigh. Anyone?

vile · 03-25-2004, 05:22 PM

yup, 27.5 lb

overdose · 03-25-2004, 05:43 PM

mine are 24 and i'm switching to subzeros, they hurt

Unabomber · 03-25-2004, 05:46 PM

Ouch!

Heavier weight wheels, through rotation mass can multiply their weight which will result in decreased performance. For example, an additional 5 lbs per corner of wheel weight (20 lbs total) has an equivalent effect on acceleration of 50-80lbs of weight in the car. Also, as you increase wheel size, realize that you are increasing the wheel's distance from the center of rotation. Due to wheels having rotational mass, larger wheels have a larger rotational mass. For example, spinning a 1lb weight 8 inches from the center of a wheel requires less work than spinning that same weight 9 inches from the center. Unsprung weight: "Unsprung weight is the total weight of components not supported by the springs. This includes control arms, brake components, spindles, wheels and tires. Reducing unsprung weight is a key factor to improving a vehicle's handling." Among other things, it allows the suspension to react faster and improves the tires' contact with the road, producing more grip on rougher road surfaces.

fliz · 03-25-2004, 07:27 PM

27.5-16.5 * 4 = 44 lbs

When you add in the rotational inertia, you're looking at the same straight line performance as adding at least 100lbs to your car.

The good news is you've lowered the CG of your car.

Luke (from Tirerack) gave the estimate of 5lbs unsprung weight = 1 hp the other day.

9 hp is definitely something you can feel on the butt dyno.

rottenspam · 03-26-2004, 11:19 AM

According to the rotational worksheet I have.....

Comparing stock rims to your upgraded 18" rims stock weigh ~16.5lbs, and the RE92's weight 22lbs, and with your 18"'s at 27.5 lbs, and just guestimating your running 225/40's since they would have about the same revolutions per mile as stock. not that the size matters for the calculations much, but I'm guessing the tires weigh in at about ~23 lbs, for a set of AVS 100's....

Then the increase in rotational intertia is the equivlent of adding about 268lbs of chassis weight. Or sticking two people in your car.

or chopping 15lb-ft of torque from the engine.

mouserWRX · 03-26-2004, 11:23 AM

Hmm...wonder if my 20.5lbs Rota Formels are too heavy w/ my ES100s then

Then again, do I wanna drop over $1k on wheels? hmm....

mbiker97 · 03-26-2004, 12:23 PM

You don't need to drop that much money. Rota makes some much lighter wheels than those. The Subzero is only 16.5# and the Slipstreams are only 13.5#.

mouserWRX · 03-26-2004, 12:27 PM

But they are not very visually pleasing to my eye

If I want lighter wheels, I'd probably go w/ Superleggeras or some BBS wheels.

UncleMeat · 03-26-2004, 03:23 PM

Hey guys, I didn't make this, but I found it... good way to see how much power your big chrome dubs are robbin you of.

http://www.jayratkowski.com/cars/wrx/rotational.xls

I don't have the stock RE92 weight, so it's not 100% perfect.

WrXsTeel · 03-26-2004, 04:01 PM

Jez.. and I thought my 18lb Tarmac 2's were on the heavy side.

mbiker97 · 03-26-2004, 04:38 PM

Quote:

Originally posted by UncleMeat
Hey guys, I didn't make this, but I found it... good way to see how much power your big chrome dubs are robbin you of.

http://www.jayratkowski.com/cars/wrx/rotational.xls

I don't have the stock RE92 weight, so it's not 100% perfect.

That's a neat little spreadsheet. I'll have to save that when I get back to work on Monday.

p.s. Stock RE92s are 21#.

cwingo · 03-26-2004, 11:00 PM

how much do the stock wheels weight?

vsboxerboy · 03-26-2004, 11:19 PM

hey if my wallet were as plump as id like it to be id go for some of those volk/rays engineering TE-37's on my black STi but for right now i have to deal with stock rims on my 02 rex

Rocketcar · 03-26-2004, 11:43 PM

Horaay for my slipstreams!!! The only problem is the fender gap which is the same as stock since the wheels are the same size but wow i notice it. Someday I'll get those new springs!!

WRXedUSA · 03-27-2004, 01:09 PM

I was caught running into a 24hr supermarket with one of my 17" Yokohama/Tarmac setup looking for a Produce scale...

mbiker97 · 03-29-2004, 11:14 AM

Quote:

Originally posted by cwingo
how much do the stock wheels weight?

16.5#

abqkid · 04-13-2004, 11:21 PM

the estimate that me and my friend came up with was that per every pound added in the rims/wheels it comes out to be double the weight if you were to actually put it in the trunk of the car.
this is because you not only have to spin the extra weight but you have to move it forward aswell.
4 lbs extra per wheels=8lbs in the trunk x 4 =32lbs
15lbs extra per wheel = 30 in the trunk x 4 = 120lbs

03-25-2004, 04:48 PM	#1
mrubino83 Scooby Specialist Member#: 22987 Join Date: Aug 2002 Chapter/Region: SCIC Location: Sunny So. Cal. Vehicle: 2010 PB EVO X GSR... .. It's All Stock Officer	How much power am I losing....? With my heavy @$$ rims? Weight:28lbs w/o tire. I have heard that it is upwards of 20whp. Is that true? I can feel it when braking thats for sure. Needless to say, my next mod will be lighter rims * Registered users of the site do not see these ads.

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03-25-2004, 04:53 PM	#2
cronic Scooby Guru Member#: 9749 Join Date: Aug 2001 Chapter/Region: SWIC Vehicle: -	Holy crap what do you have on there 22" chrome spinnaz?

03-25-2004, 04:57 PM	#3
Uncle Scotty * Banned * Member#: 16200 Join Date: Mar 2002 Vehicle: OK buy Nates beans westcoastroasting.com	28 POUNDS????? DooD....uuuummmmm.....I think you should find something a bit....no...a LOT lighter..... Jeez....I start thinking 'too heavy' at 16 pounds.

03-25-2004, 04:58 PM	#4
StarDogChampion Scooby Specialist Member#: 10276 Join Date: Sep 2001 Vehicle: 2001 Impreza RS 2002 WRX, 2012 535i	blingBLING

03-25-2004, 05:07 PM	#5
Subie2 Scooby Specialist Member#: 14750 Join Date: Jan 2002 Location: Anywhere but here. Vehicle: 2007 Element SC Root Beer Metallic	Technically your not losing power. Just not getting it to the ground like you should.. plus power to weight ratio is being thrown off.

03-25-2004, 05:18 PM	#6
mrubino83 Scooby Specialist Member#: 22987 Join Date: Aug 2002 Chapter/Region: SCIC Location: Sunny So. Cal. Vehicle: 2010 PB EVO X GSR... .. It's All Stock Officer	18x7.5 motegi mr-7. Pretty sure that 28lbs is how much they weigh. Anyone?

03-25-2004, 05:22 PM	#7
vile Scooby Specialist Member#: 32371 Join Date: Jan 2003 Location: formerly known as mem. # 10615 Vehicle: '02 t-rex wagon platinum	yup, 27.5 lb

03-25-2004, 05:43 PM	#8
overdose Scooby Specialist Member#: 46399 Join Date: Oct 2003 Chapter/Region: MWSOC Location: Grand Rapids, MI Vehicle: 0000 Knows nothing, about nothing.	mine are 24 and i'm switching to subzeros, they hurt

03-25-2004, 05:46 PM	#9
Unabomber Big Ron Super Moderator Member#: 18062 Join Date: Apr 2002 Chapter/Region: MWSOC Location: Muncie, IN Vehicle: 2004 WRX Sport Wagon Platinum Silver Metallic	Ouch! Heavier weight wheels, through rotation mass can multiply their weight which will result in decreased performance. For example, an additional 5 lbs per corner of wheel weight (20 lbs total) has an equivalent effect on acceleration of 50-80lbs of weight in the car. Also, as you increase wheel size, realize that you are increasing the wheel's distance from the center of rotation. Due to wheels having rotational mass, larger wheels have a larger rotational mass. For example, spinning a 1lb weight 8 inches from the center of a wheel requires less work than spinning that same weight 9 inches from the center. Unsprung weight: "Unsprung weight is the total weight of components not supported by the springs. This includes control arms, brake components, spindles, wheels and tires. Reducing unsprung weight is a key factor to improving a vehicle's handling." Among other things, it allows the suspension to react faster and improves the tires' contact with the road, producing more grip on rougher road surfaces.

03-25-2004, 07:27 PM	#10
fliz Scooby Guru Member#: 30342 Join Date: Nov 2002 Location: #blp	27.5-16.5 * 4 = 44 lbs When you add in the rotational inertia, you're looking at the same straight line performance as adding at least 100lbs to your car. The good news is you've lowered the CG of your car. Luke (from Tirerack) gave the estimate of 5lbs unsprung weight = 1 hp the other day. 9 hp is definitely something you can feel on the butt dyno.

03-26-2004, 11:19 AM	#11
rottenspam Scooby Newbie Member#: 21297 Join Date: Jul 2002 Location: League City, TX Vehicle: 2005 Legacy GT LT Atlantic Blue Pearl	According to the rotational worksheet I have..... Comparing stock rims to your upgraded 18" rims stock weigh ~16.5lbs, and the RE92's weight 22lbs, and with your 18"'s at 27.5 lbs, and just guestimating your running 225/40's since they would have about the same revolutions per mile as stock. not that the size matters for the calculations much, but I'm guessing the tires weigh in at about ~23 lbs, for a set of AVS 100's.... Then the increase in rotational intertia is the equivlent of adding about 268lbs of chassis weight. Or sticking two people in your car. or chopping 15lb-ft of torque from the engine.

03-26-2004, 11:23 AM	#12
mouserWRX Scooby Specialist Member#: 48960 Join Date: Nov 2003 Location: Austin Vehicle: 2006 TL Anthracite	Hmm...wonder if my 20.5lbs Rota Formels are too heavy w/ my ES100s then Then again, do I wanna drop over $1k on wheels? hmm....

03-26-2004, 12:23 PM	#13
mbiker97 Scooby Guru Member#: 7922 Join Date: Jun 2001 Chapter/Region: MWSOC Location: Tucson Vehicle: 04 CTS-V b/b/b 99 GMC Highrider	You don't need to drop that much money. Rota makes some much lighter wheels than those. The Subzero is only 16.5# and the Slipstreams are only 13.5#.

03-26-2004, 12:27 PM	#14
mouserWRX Scooby Specialist Member#: 48960 Join Date: Nov 2003 Location: Austin Vehicle: 2006 TL Anthracite	But they are not very visually pleasing to my eye If I want lighter wheels, I'd probably go w/ Superleggeras or some BBS wheels.

03-26-2004, 03:23 PM	#15
UncleMeat Scooby Specialist Member#: 33256 Join Date: Feb 2003 Chapter/Region: MWSOC Location: Milwaukee, WI Vehicle: 2010 subasuckbox vomit	Hey guys, I didn't make this, but I found it... good way to see how much power your big chrome dubs are robbin you of. http://www.jayratkowski.com/cars/wrx/rotational.xls I don't have the stock RE92 weight, so it's not 100% perfect.

03-26-2004, 04:01 PM	#16
WrXsTeel Scooby Newbie Member#: 19092 Join Date: May 2002	Jez.. and I thought my 18lb Tarmac 2's were on the heavy side.

03-26-2004, 11:00 PM	#18
cwingo Scooby Newbie Member#: 33846 Join Date: Mar 2003 Location: Maryland	how much do the stock wheels weight?

03-26-2004, 11:19 PM	#19
vsboxerboy Scooby Newbie Member#: 38534 Join Date: Jun 2003 Location: Southern California Vehicle: 2002 WRX Sedan Silver	hey if my wallet were as plump as id like it to be id go for some of those volk/rays engineering TE-37's on my black STi but for right now i have to deal with stock rims on my 02 rex

03-26-2004, 11:43 PM	#20
Rocketcar Scooby Newbie Member#: 12294 Join Date: Nov 2001 Chapter/Region: SCIC Location: Fullerton Vehicle: 06 WRX Sea dan Black	Horaay for my slipstreams!!! The only problem is the fender gap which is the same as stock since the wheels are the same size but wow i notice it. Someday I'll get those new springs!!

03-27-2004, 01:09 PM	#21
WRXedUSA Scooby Specialist Member#: 26833 Join Date: Oct 2002 Chapter/Region: SWIC Location: Seal Beach, CA Vehicle: '07 Bugatti Veyron '03 Chevy Silverado	I was caught running into a 24hr supermarket with one of my 17" Yokohama/Tarmac setup looking for a Produce scale...

04-13-2004, 11:21 PM	#23
abqkid Scooby Specialist Member#: 52295 Join Date: Jan 2004 Chapter/Region: SWIC Location: Albuquerque Vehicle: 2003 WRX Wagon PSM	the estimate that me and my friend came up with was that per every pound added in the rims/wheels it comes out to be double the weight if you were to actually put it in the trunk of the car. this is because you not only have to spin the extra weight but you have to move it forward aswell. 4 lbs extra per wheels=8lbs in the trunk x 4 =32lbs 15lbs extra per wheel = 30 in the trunk x 4 = 120lbs