Lighter wheels = much faster? - Page 2 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

rolnslo · 11-13-2008, 01:15 PM

Interesting...

Dan · 11-13-2008, 01:42 PM

The rule I had always heard was 1 lb of rotating mass = 6, not 8, lbs.

Chewy · 11-13-2008, 02:05 PM

depending what the bolt pattern is (5x120), might be able to use BBS which are very popular on BMWs, 22-23lbs

the only downside i find with lightweights, such as magnesium, is that its a soft metal and you can dent your rims very easily.

my input into the off topic section - magnesium blocks disperse heat too quickly to ignite very easily, blow torch a corner for 10minutes it won't work, but u set the entire block in a small (and lower temp) fire place and i guarantee it'll ignite, i've done it twice. So i really wouldn't worry about your wheels igniting unless your brakes, tires, and car are all also on fire. we have magnesium braking components on the aircraft i fly on - brakes and calipers get a LOT hotter than your wheel ever should

Mr Twisty · 11-13-2008, 02:20 PM

Fires are thermite reaction maybe?

andyrew · 11-13-2008, 02:51 PM

Why do you think the Camaro race car concept has such tiny wheels and tires?

Coming from a racer, It makes a BIG difference. I have 3 sets of wheels on my Audi, a set of 18's weighing 55lbs ea, a set of 16's with REo1-R's for racing weighing 51lbs, and a set of 15's with snow tires weighing 43lbs. I can tell a huge difference between the 3. In fact I pick up about 1- 2mpg going from the 18's to the 15's as well.

dieseldave24v · 11-13-2008, 02:53 PM

I was thinking that racers maight use differnt size wheels for a fast gear ration change. If the rim and the tire combo is smaller in diameter you would have a lower final drive ratio "to the pavment" By lower I mean numericaly higher.

Mr Twisty · 11-13-2008, 04:09 PM

Is magnesium too brittle for wheel torque loads?

*GTAHVIT* · 11-13-2008, 04:13 PM

Magnesium is really strong. They use it for aircraft wheels and brakes. Good stuff.

1_2Many · 11-13-2008, 04:18 PM

Quote:

Originally Posted by MisterCamaro69

Is magnesium too brittle for wheel torque loads?

Some C5 Vette's have magnesium wheels and I know last gen Z06 did too. Not sure about current Vette's.

andyrew · 11-13-2008, 04:23 PM

Quote:

Originally Posted by dieseldave24v

I was thinking that racers maight use differnt size wheels for a fast gear ration change. If the rim and the tire combo is smaller in diameter you would have a lower final drive ratio "to the pavment" By lower I mean numericaly higher.

Its a side effect.

The real reason is because the closer the rotating mass is towards the center, the less work the drivetrain has to do to move it. You find this practiced a lot in low HP lightweight cars, such as the Miata.

For example, if you take a weight and attach it to a rope, then swing it while rotating 3 ft from your body. Then swing it 10 feet from your body. How fast are you able to move? How much work is it? Its the same weight right?

Thats the theory behind a smaller wheel/ or even a smaller tire diameter.

Chewy · 11-13-2008, 05:06 PM

Quote:

Originally Posted by MisterCamaro69

Is magnesium too brittle for wheel torque loads?

Magnesium far from brittle, it's much more likely it'll bend/dent

Quote:

Originally Posted by gtahvit

Magnesium is really strong. They use it for aircraft wheels and brakes. Good stuff.

aircrafts such as the big ones flying over jax all the time

*GTAHVIT* · 11-14-2008, 07:41 AM

Quote:

Originally Posted by Chewy

Magnesium far from brittle, it's much more likely it'll bend/dent

aircrafts such as the big ones flying over jax all the time

Dont forget the helos. we have em too

Rallyman6 · 11-14-2008, 11:47 AM

Back to Rotating mass:
I'm not an expert in determining how much more rotational mass there is in a 18" wheel than a 20". However, the TV show Sports Car Revolution (SCR) took a Acura RSX and changed the tires/wheels from 15" to 17" and did a dyno comparison. Both sets of tires and wheels weighted about the same, so no change in unsprung weight. The end result was that with the 17" wheels the dyno measured 7 less horsepower at the drive wheels when compared to the 15" package. That's a big difference due to just tires/wheels.

On my rallycar we went from a 15" Wheel to a 13" inch wheel, which made a HUGE difference in straight line acceleration.

swifttal · 11-14-2008, 12:11 PM

Quote:

Originally Posted by Dan

The rule I had always heard was 1 lb of rotating mass = 6, not 8, lbs.

Ditto, I've always heard the same

1lb unsprung weight = 6lbs sprung weight

and for each 8lbs sprung weight lost = 1 hp (not hp gain, but the same effect as you would get adding 1 hp)

Just what I've been taught - I'll dig through some of my books tonight for references

11-13-2008, 02:05 PM	#17
Chewy My boredom isn't safe Drives: 2010 SS Camaro Join Date: Sep 2008 Location: Jacksonville, FL Posts: 1,224 View My Garage	depending what the bolt pattern is (5x120), might be able to use BBS which are very popular on BMWs, 22-23lbs the only downside i find with lightweights, such as magnesium, is that its a soft metal and you can dent your rims very easily. my input into the off topic section - magnesium blocks disperse heat too quickly to ignite very easily, blow torch a corner for 10minutes it won't work, but u set the entire block in a small (and lower temp) fire place and i guarantee it'll ignite, i've done it twice. So i really wouldn't worry about your wheels igniting unless your brakes, tires, and car are all also on fire. we have magnesium braking components on the aircraft i fly on - brakes and calipers get a LOT hotter than your wheel ever should __________________

11-13-2008, 02:20 PM	#18
Mr Twisty Drives: the 2nd amendment home Join Date: May 2008 Location: OK Posts: 14,765	Fires are thermite reaction maybe? __________________ "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -- Benjamin Franklin lib·er·ty /ˈlibərdē/ noun 1. the state of being free within society from oppressive restrictions imposed by authority on one's way of life, behavior, or political views

11-13-2008, 04:09 PM	#21
Mr Twisty Drives: the 2nd amendment home Join Date: May 2008 Location: OK Posts: 14,765	Is magnesium too brittle for wheel torque loads? __________________ "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -- Benjamin Franklin lib·er·ty /ˈlibərdē/ noun 1. the state of being free within society from oppressive restrictions imposed by authority on one's way of life, behavior, or political views

11-13-2008, 04:13 PM	#22
GTAHVIT Blessed Drives: 2013 Sonic RS MT Join Date: Dec 2007 Location: Saint Augustine FL Posts: 28,444 View My Garage	Magnesium is really strong. They use it for aircraft wheels and brakes. Good stuff. __________________ Click image to see build thread. PQ - "the love of cars. It's a boys first step toward manhood and a mans last hold on boyhood." Fbodfather - "We do not want to use the Z28 moniker on a car that does not deserve this hallowed name." The_Blur - "Let's not confuse competitors with equals."

11-14-2008, 11:47 AM	#27
Rallyman6 Member Drives: '10 2SS/RS IOM, Wht Stripes, Roof Join Date: Oct 2008 Location: Wellesley Hills, MA Posts: 850 View My Garage	Back to Rotating mass: I'm not an expert in determining how much more rotational mass there is in a 18" wheel than a 20". However, the TV show Sports Car Revolution (SCR) took a Acura RSX and changed the tires/wheels from 15" to 17" and did a dyno comparison. Both sets of tires and wheels weighted about the same, so no change in unsprung weight. The end result was that with the 17" wheels the dyno measured 7 less horsepower at the drive wheels when compared to the 15" package. That's a big difference due to just tires/wheels. On my rallycar we went from a 15" Wheel to a 13" inch wheel, which made a HUGE difference in straight line acceleration. __________________ 2SS/RS IOM, Wht Stripes, 6MT, IO Interior, Roof, Eibach Sways, BC Coilovers, BMR Swing arms,Barton Short Shift, BBK LT's, GMPP exhaust, Hi-Flow Cats, MAST Stage 2 Cam, CAI = 470RWHP

11-13-2008, 01:15 PM	#15
rolnslo Rolling along... Drives: 2011 2SS/RS SGM Join Date: Mar 2008 Location: Houston, TX Posts: 4,380 View My Garage	Interesting...

11-13-2008, 01:42 PM	#16
Dan Drives: 2004 GTO Join Date: Jul 2007 Location: Montgomery, AL Posts: 448	The rule I had always heard was 1 lb of rotating mass = 6, not 8, lbs.

11-13-2008, 02:51 PM	#19
andyrew Drives: Audi A4 STG3, Porsche 914 v8 Join Date: Oct 2008 Location: Modesto, ca Posts: 126 View My Garage	Why do you think the Camaro race car concept has such tiny wheels and tires? Coming from a racer, It makes a BIG difference. I have 3 sets of wheels on my Audi, a set of 18's weighing 55lbs ea, a set of 16's with REo1-R's for racing weighing 51lbs, and a set of 15's with snow tires weighing 43lbs. I can tell a huge difference between the 3. In fact I pick up about 1- 2mpg going from the 18's to the 15's as well.

11-13-2008, 02:53 PM	#20
dieseldave24v PowerStroke this Ford boy Drives: Like Don Garlits "Big Daddy" Join Date: Sep 2008 Location: Richlands/Camp Lejeune NC Posts: 462	I was thinking that racers maight use differnt size wheels for a fast gear ration change. If the rim and the tire combo is smaller in diameter you would have a lower final drive ratio "to the pavment" By lower I mean numericaly higher.

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