Lighter Wheels?
- Thread starter spjoec15
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Sacrilicious
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- Cosmic Blue MS3 of hawtness!
according to this thread, they're 7.7kg = ~17lb each.
http://www.mazdas247.com/forum/showthread.php?t=123667644
the stupid part is that they actually don't cost much more than the stock wheels...it's 480 to replace the cast alloy OEMs and something like just under 600 for a forged one that's a lot nicer (lighter, wider, sexier). mazda sure knows how to make their killing on OEM wheel replacements...
theres sooooooo much more to consider than just vehicle weight - what we're talking about with wheels is rotational inertia, not total vehicle mass. by your reasoning, a lightweight flywheel should make much difference, since you're only removing 5-6 TOTAL from the vehicle, yet they make a HUGE difference in acceleration feel. why? because you're removing rotational mass that the engine has to spin, which takes power - power which could have gone to moving the wheels. extend that down to lighter wheels, and thats even less weight that your engine has to spin, providing more power to move the car.
like i said, you can think what you will, but the actual physics of the matter will win out. why do you think the 3rd gen rx-7 was supplied from the factory with 13lbs wheels? why do you think my protege came from the factory with 16lb wheels? why do you think all 1st gen miata's came with wheels that weighed less than 14lbs? (some even with 12lb wheels) it wasn't totally for weight savings, or else the 3rd gen miata, with all of its "gram strategy" weight saving, would have been supplied with lighter wheels.
like i said, you can think what you will, but the actual physics of the matter will win out. why do you think the 3rd gen rx-7 was supplied from the factory with 13lbs wheels? why do you think my protege came from the factory with 16lb wheels? why do you think all 1st gen miata's came with wheels that weighed less than 14lbs? (some even with 12lb wheels) it wasn't totally for weight savings, or else the 3rd gen miata, with all of its "gram strategy" weight saving, would have been supplied with lighter wheels.
FWIW, My wheels are 6lbs lighter than the stockers. I noticed an immediate difference in acceleration. I've seen time differences in the amount of 1 to 2 10ths at the track when I ran my GTI with 16 inch 15lbs wheels vs. 22lb stocks.
Traction was not an issue really as my GTI didn't spin a whole lot.
Traction was not an issue really as my GTI didn't spin a whole lot.
Sacrilicious
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- Cosmic Blue MS3 of hawtness!
dude, you're missing my point completely. i KNOW that we're talking about rotational mass that needs to be spun up first before we can even apply power to the ground. my point is simply that in the MS3, this power loss is probably a total of no more than 20hp (read my reasoning from before for support). as a result, even if you drop HALF of your wheel + tire weight (24lb), you would still only see a gain of about 10hp.
Swampass...I hear you...and I will concede to Njaremka that we are probably missing the most important factor....mass distribution on the wheels. A wheel that weights 30 lbs could out perform (acceleration) a wheel that weights 20 lbs if most of the mass is at the center of the wheel....
So.....let me say this.... I was ASSUMING that we were talking about wheels of a similar design and mass distribution. Give me a wheel with most of the mass at the center and you will see a performance increase. Again, I thought you were only referring to the weight of the wheel.
So.....let me say this.... I was ASSUMING that we were talking about wheels of a similar design and mass distribution. Give me a wheel with most of the mass at the center and you will see a performance increase. Again, I thought you were only referring to the weight of the wheel.
Sacrilicious
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- Cosmic Blue MS3 of hawtness!
FWIW, My wheels are 6lbs lighter than the stockers. I noticed an immediate difference in acceleration. I've seen time differences in the amount of 1 to 2 10ths at the track when I ran my GTI with 16 inch 15lbs wheels vs. 22lb stocks.
Traction was not an issue really as my GTI didn't spin a whole lot.
i know that you would likely feel something, but tell me this for the sake of the ongoing disagreement: if you had done this drop in weight by going from winter tires to summer tires, would you assume that your gains in acceleration were mostly from weight? for the record, i would be AMAZED if your GTI didn't have traction issues on the track using winter tires...;o
Sacrilicious
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i'm assuming you meant to type "should not make".
if you read what i said, i made no such claim. what i claimed was simply that i can isolate down the theoretical limit of the gains that a wheel + tire on my car can make on the power coming from my engine down to a small portion of the total power. changing the flywheel would be a LOT different, since it doesn't just decrease the power loss i suffered from a small fraction of the 263hp that my engine generated, but increases the total output of my engine from 263hp to something higher. it is here that just a few lbs would make a huge difference, because you're doing something that scales multiplicatively with all 263hp that you started with before...as compared to just reducing the possible loss of up to 20hp of the 263hp.
Young Roids
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Supposedly the RPF1s are manufactured with M.A.T. technology wich forges the rim part while leaving the center portion cast. Looks like a pretty cool tech to me.
I also found another Volk that only weighs 15.5 for the 18.
I'm not sure I am following you. Are you speaking about shaving 6lbs of tire weight vs. 6lbs of wheels weight?
6lbs of tire weight would yield a greater performance advantage due to reducing weight farther from the hub center.
FWIW, My wheels are 6lbs lighter than the stockers. I noticed an immediate difference in acceleration. I've seen time differences in the amount of 1 to 2 10ths at the track when I ran my GTI with 16 inch 15lbs wheels vs. 22lb stocks.
Traction was not an issue really as my GTI didn't spin a whole lot.
that's true, but were you running the same exact tires at same pressures? Granted it won't make a huge difference, running some new, possibly wider tires with good tread on them will hook differently than worn tires. And pressure differences are pretty negligable unless you're running large differences like 20 vs 34 psi.
ps - I <3 RPF1s. i wish i had gotten them for my current car. They will definitely be on my MS3 unless something else comes along (or I come across alot of cash). The mazdaspeed wheels are also very nice.
and FWIW, someone mentioned kosei and other cast wheels being weak. true they might be weaker than some of their forged counterparts, but any wheel si susceptible to damages from potholes if hit just right.
i had a large debate with some people once that were hating on anything cast. 95% of them never tracked their cars anyways. kosei K1's are very popular wheels in autocross and road racing, the price vs weight vs style is very good with them. it will depend on sizing too. sadly, there are far too many people who do not realize the importance of wheel and tire sizes for racing, and think bigger or wider is always better. and then they wonder why they bent their wheel on a pothole in the city, when they have oversized rubberbands for sorry excuses of a tire.
wheels/tires/brakes, some susp components are great to get lighter weights in, unsprung weight is felt alot more than sprung weight (i laugh at people who gut their interiors and trunks and can't feel anything).
but to me, this is a street car. some lighter wheels and tires will help, but there's no need to go all out and spend oodles of money for stuff like that, unless you're really diehard about racing it and getting every last tenth out of it. i usually refer people to spend that money on a driving school and learn to shave time off by driving better before getting super titanium magnesium adamantium strut housings and such. lol
plus, its alot cheaper to turn up the boost
(well cheaper as long as you dont turn it up so far you end up buying yourself a new engine)Sacrilicious
boom boom!
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- Cosmic Blue MS3 of hawtness!
what i meant was that the whole weight issue we're arguing started with njaremka saying that when he took his winter tires + wheels off and put on his summer tires + wheels, he got a large boost in acceleration because he dropped 5lb when he did this. my argument was that he got the huge boost mainly because of the fact that he went from winter->summer tires, whereas he believes it came mainly from the 5lb of reduced rotational weight. my main point was that in the MS3, the rotational weight of the wheels accounts for about 20hp of lost power, so any reasonable savings there would not be able to compare to the gain in acceleration resulting from changing from winter to summer rubbers.
Sacrilicious
boom boom!
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- Cosmic Blue MS3 of hawtness!
ya, ispypsi. i agree that losing the weight in the wheels is definitely useful in more than one way. the only reason i disagreed at all here was how much of an acceleration difference it could possibly give a MS3 when we're measuring 220hp of our 263hp at the wheels on the dyno. if anything, the most important gains we would get from losing the weight would be more handling/suspension related than actual acceleration gains.
also, i understand that even the best forged wheels are still susceptible to dings from potholes, but as i said before, it really does make a difference where you live. for me, potholes are a constant danger, and any appreciable level of protection i can get against them has the potential to save me hundreds of dollars in wheel replacement costs...=D
also, i understand that even the best forged wheels are still susceptible to dings from potholes, but as i said before, it really does make a difference where you live. for me, potholes are a constant danger, and any appreciable level of protection i can get against them has the potential to save me hundreds of dollars in wheel replacement costs...=D
Sacrilicious
boom boom!
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- Cosmic Blue MS3 of hawtness!
ya, i agree that M.A.T. sounds like a really cool technology. unfortunately, i'm not willing to test it out at 275 per wheel just yet...^_^;
true. spending a little more now on a forged wheel might save you alot later in replacement costs. mostly, my comment was directed at people who think cast wheels flat out suck (as if they were made out of sheet metal), when the only reason their wheels failed were because they ran tiny tires with no sidewall or got into an accident.
its also funny when people think forged wheels are more susceptible to any form of danger. forged wheels will scrub and road rash just as easily as cast hehehehehe. except it sucks more when your $700 forged wheel gets curb rash DOH!
and yeah most acceleration feel is all the butt dyno (psychological processes trying to justify the cost or reason for getting something by creating a false feel of results). on paper its cool, but in the world its negligable (but it can be felt sometimes).
just because it doesn't show up on an actual dyno doesn't mean its negligible - you can make a dyno read whatever you want it to.
Lighter wheels can make a big difference, not just in dyno numbers you can slow down faster and cornering gets better with less unsprung weight. Tires have the most change of driving feel of car followed by rims; get too heavy of a rim and car feels like poop. Lighter wells make for more efficiency in driveline. And dynoing a turboed car isnt all the accurate of results because boost spike and other little things on this run that didnt happen on the last run.
