Aliviar peso do volante do motor
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gaucho, nao lembro exatamente quanto tirei do meu.
mas foi na faixa de 1,5kg e posso lhe afirmar 2 coisas.
o carro ficou bemmm arisco, ainda mais se tratando de um aspirado com comando alto e 2 dcoe 45mm mas ainda assim totalmente dirigivel ( meu pai que o diga )
senti o motor subindo giro com mais forca nas arrancadas, e nas retomadas.
pra balancear o conjunto inteiro o certo e fazer o seguinte.
pistoes, pinos e bielas devera ser feito o balanceamento estatico com balanca de precisao.
primeiro pesa-se os 4 pistoes com seus respectivos pinos, ai voce acerta os 3 pistoes deixando todos com o mesmo peso do pistao mais leve, o material devera ser retirado cuidadosamente pelo lado inferior ( interno ) da cabeca do pistao.
depois voce balanceia as 4 bielas seguindo o mesmo procedimento dos pistoes ( o ideal e usar pesar ela suspenca horizontalmente pelo furo do pino, pesando apenas a parte inferior dela ). se nescessario tirar material, devera ser feito na capa da biela, tambem tomando cuidado para nao afinar ela ( geralmente tira-se pouco material, principalmente se for bielas forjadas, pois elas ja vem quase com o mesmo peso )
ai vem o balanceamento dinamico, onde vai ser balanceado o plato+disco+volante primeiro, depois faz o balanceamento do vira + polia dianteira, e depois balanceia o conjunto inteiro. lembre que a empresa devera marcar a posicao correta de montagem do conjunto, pois se montar invertido ja perde o balanceamento.
e um pouco complicado de explicar, mas nao e um bixo de 7 cabecas pra fazer nao, basta achar um local de qualidade para efetuar o servico de balanceamento dinamico ( o estatico voce mesmo pode fazer ). geralmente quem faz esse servico e empresas que fazem balanceamento de cardan.
bom, espero ter ajudado.
abracao
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aproveitando , e pra turbo , fica bom galera ?
um amigo aqui montou 8 bicos.
só que enão entendi , ele aliviou o vira e colocou o volante do m.i
certo seria aliviar vira e volante não é só que ai ele me disse que é o volante que embala o motor.
por isso ele lanõ o volante mais grosso. o que ele tiro do vira diz que compensou um pouco no volante do m.i
pra mim fico quase na mesma. to vendo que vo te que abri o meu , ai ja alivio se marca.
valeu gaucho , vai ajuda bastante gente isso aqui. abraços :ppeam:
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pra que fizestes isso? melhorar a disperção do calor?
dizem q melhora (tomara)
, pois preciso demais de freios.a maioria dos discos de performance lá de fora são vendidos desse jeito slotados
aqui a powerbrakes e até a fremax já vendem desse jeito
ouví dizer q o freio melhora bastante , mas as pastilhas comem + rápido tb
gastei 40 reais de serviço em cada disco
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por falar em fremax, eu acho que vou pegar discos deles, vou pegar quatro dianteiros de marea turbo na versão tuning que vem slotados, o que acham? são ventilados, 284mmx26mm, slotados. as pinças devo usar de marea/golf também, quem sabe uma melhor que caiba dentro de aro 15.
quero que caiba em aro 15 replica da empi que vou colocar no fuque.
p.s: dai eu usaria uma valvula reguladora de pressão no freio porque no caso serão discos de mesmo tamanho nas quatro rodas.
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p.s: dai eu usaria uma valvula reguladora de pressão no freio porque no caso serão discos de mesmo tamanho nas quatro rodas.
e o freio de mão não existirá ?
vá no ferro velho compre os discos e pinças dianteiras dos citroens bx, xm, xantia….........e adapte na traseira do seu fusca (essas pinças são enormes e vem c o freio de mão)
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gaucho, tem uma matéria na auto power e na fullpower que fala bem um teste feito num focus. tiraram um volante original de 9kg e colocaram um de 5kg, a 6000rpm de 2º marcha equivale a 170kg de peso morto (bancos, painel, lata), em 3º marcha a 6000rpm equivale a uns 60kg de peso morto, por isso é interessante um alívio de peso inercial inteligente.
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segue a explicação abaixo pra quem quiser entender
torque is simply force with a rotational component. for simplicity s sake let s ignore the rotational component for the moment. force = mass(m) * acceleration(a). so if you decrease m and leave a constant then you would lose torque. but a lightened flywheel will accelerate faster than the stock unit so if you should see the same amount of torque maybe a little more.
where people are coming from when they say you lose torque with a lightened flywheel is a lightened flywheel has less momentum than the stock unit so it can transfer less torque to the drive train in the moment when the clutch engages the flywheel. so you have to give an engine with a lightened flywheel more gas to prevent it from bogging as you let the clutch out than you would an engine with a stock flywheel.
ok, let s break it down to basics…
mass = inertia
inertia = resistance to motion change
if you have more mass, you have more inertia... and therefore more resistance to change in motion. objects with more inertia require more force to change their direction/speed/motion than objects of lower inertia.
in the case of the heavy flywheel, that s more resistance to acceleration as well as deceleration. when your engine is spinning in neutral and you engage the clutch to start moving, the flywheel helps your engine overcome the added load of the car s mass... effectively, the inertia of the flywheel (spinning) helps to overcome the inertia of the car (sitting still, not wanting to move). if your flywheel weighs 20 pounds and your car weighs 2000 pounds, you can see that a 20 pound flywheel will help to move the car better than a 10 pound flywheel will. it resists the change in motion that the car is imparting upon it more than the lighter flywheel, so it will require less input from the engine, and start the car moving along a bit smoother.
analogy:
ever go bowling? compare an 8 pound bowling ball to a 16 pound bowling ball. the 8 pounder is easier to accelerate (from the stopped position to you throwing the ball at higher speed) and easier to direct (aim). your arm also gets less tired with the 8 pound ball. the drawback is that the ball loses more speed toward the end of the bowling lane, and may not knock down as many pins as you want. you also have to be more careful with controlling the direction of the ball, since it s easier to fling out the wrong way if your arm twitches or something the 16 pound bowling ball is harder to accelerate and harder to direct, but it carries more speed at the end of the bowling lane because of its higher mass (and resulting higher inertia). it knocks more pins down. it s also harder to send the ball careening into someone else s bowling lane, because it s harder for your arm to suddenly jerk it to the side.
now relate this analogy to a car... the pins at the end represent your car s weight/mass, the bowling ball is the flywheel, and your arm is the engine. the lighter flywheel will be easier to accelerate and decelerate- so you ll have quicker starts, faster acceleration because the flywheel has less inertia to overcome, and quicker shifts because the revs drop faster when you let off the throttle. the downside is that you have to control the flywheel more, since the direction (speed of rotation) varies that much more. this is why people say that an 8 pound flywheel isn t good for a daily driver . i don t have any problem driving with mine. the heavier flywheel has higher inertia than the lighter one, so it will start your car from a stop more easily (knock down more pins), but it will hurt you everywhere else. it takes more force/power to accelerate (overcoming more inertia), doesn t allow you to shift as quickly (revs don t drop fast enough), but it is easier to drive because the speed of rotation doesn t change as rapidly as the lighter flywheel. small changes in your throttle position don t change the revs as much, because the power blips are just soaked up in the heavier flywheel. this is why people might think that a lighter flywheel takes more gas while cruising , because that lighter flywheel takes more attention at the gas pedal than the heavier one to maintain speed. the lighter flywheel will give you better gas mileage.. ever push that 8 pound bowling ball on the ground at a constant speedá now try the 16 pounder- which one takes more energy to push? the 16 pounder. it s the same as the flywheel.
do you lose torque with the lighter flywheel? yes and no. you lose torque to start the car moving, since less energy is stored in the flywheel- so you have to apply more torque from the engine. on the other hand, you use less torque to overcome the inertia of the flywheel while accelerating and decelerating, so you can use the torque from your engine more effectively. you don t lose any torque when going to a lighter flywheel- you just change the source and application of torque in your car s drivetrain.
so...
light flywheel: better acceleration, better mileage, takes more skill to drive
heavy flywheel: worse acceleration, lower mileage, takes less skill to drive
it s that simple.
thanks calesta, you cleared up a lot of questions that i didn t even think to ask. however, i now have 2 things that i d like you to look at for me:
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i see how a light flywheel can increase power through the loss of weight, but how much power are we talking here? i mean, assuming you re accelerating, you ve got to rotate the pistons, rods, crank, valvetrain, flywheel, clutch, transmission, axles, brakes, hubs, wheels, tires, etc. now i know that the pre-transmission components move faster so their weight counts more, but it still seems insignificant.
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a lot of people use dyno tests to prove the horsepower/torque gains from their flywheel, but i think i see a flaw in this: while on the dyno, the engine doesn t have to move the car, just the dyno drum. if you lighten your rotational mass, won t this increase effective torque/horsepower on the dyno for the sole reason that the engine has to rotate less mass, and won t this effect be greatly lessened when the car has to be moved by the engine? after all, rotating or not, the engine still has to move 2300lbs of car.
i will subscribe to the fact that you ll go faster with a lightened flywheel, but is it enough to spend a few hundred on?
sorry if any of this sounds stupid, i think i ve just confused myself by thinking about it too much.
1. yes, you still have to move the rest of the rotating parts in the car... that s why we try to buy things like lighter pistons, lighter rods, lower loss transmission components, and lighter wheels/tires/brakes. you try to gain every little bit where you can. i really don t know how much more power a lighter flywheel would free up, but you could do the math figuring in a reduction in rotational intertia from the loss of a few pounds on a rotating disc. i don t really want to sit down and do the calculations right now, not for this thread. the main advantage i get isn t in faster acceleration of the car- it s drivability on the track. my engine revs up and down faster now, so i can rev it up faster when i m at the line waiting for an instant green at the track, or i can shift faster on the road course without worrying about the heavy flywheel jerking me around when i engage the clutch. i personally couldn t tell much when i put my new flywheel in, but i get used to changes in driving dynamics so quickly that it doesn t matter. i also changed a lot more than just the flywheel when it went in, so it was hard for me to judge what stemmed from the flywheel change and what didn t. by the way- lighter components don t really add power- they just reduce the amount of losses through your drivetrain. your engine isn t making any more power than before... more power is just making it to the wheels than before. you re not making more power- you re just losing less of it. just a technicality...
2. the drums on a standard dynojet dynamometer are set to simulate a 3000 pound car at default, i think... so when your honda is tied down onto one, it s actually trying to move more mass than it does on the street. i could be wrong on the preset mass simulation with the rollers, but i think that s the right number. you re not moving 2300 pounds of car anymore- when you re on the dyno, the engine is trying to move 3000 pounds of simulated car. the power increase at the wheels that you measure are pretty close to what you would feel in the car.
as a side note, it s hard to correctly tune a car to 100% on a chassis dyno with fixed rotational inertia on the rollers. if you re not simulating the proper mass with the rollers, you end up tuning for the wrong air/fuel ratio. rollers set to a simulate a weight/mass heavier than the car strapped onto them will make the engine pull a higher load than it would on the street, and lighter rollers will do the same thing- just in the opposite direction. the best way to dyno tune a car is to use a dyno with adjustable roller mass or adjustable weight placement in those rollers to change the rotational inertia and simulate the proper weight of the car for the engine to pull against. if this isn t available, you can tune to the best power on a fixed weight roller dyno, find out what air/fuel ratios your engine makes the best power at for each given rev band, then take it out on the street with a wideband sensor and tune it again to the max power a/f ratios. this way you re tuned for max power pulling against the exact right load, and you ll get the best performance. on the other hand, tuning against 3000 pounds of simulated resistance really wouldn t be that bad in our hondas anyway, since you probably weigh about 2700 pounds total on the street, and then you have to deal with wind resistance too, and maybe a few heavy things in your trunk. 3000 pounds is close enough for me.
but just one question, if a lightened flywheel allows the car to accelerate quicker wouldn t that free up torque (since torque is what makes you move from a standstill and horsepower is what keeps you there as i understand it) not horspower as stated earlier? if anything, wouldnt you lose horsepower (by my definition) because the freed horsepower by the heavy stock flywheel (because a heavier flywheel has more momentum thus making it easier to keep it spinning at the same pace) is now locked down because the lightened flywheel is harder to keep turning at the same pace (but at the same time your freeing torque, its a trade off). sorry if that was confusing, am i confusedá i m trying to keep this as simple as possible.
2. yes and no. think of it this way. your flywheel is a giant capacitor for your engine- effectively an energy storage medium for your drivetrain. you have fill up the flywheel with energy before you can apply it somewhere else... so larger flywheels induce a lag to your acceleration. once you have the flywheel filled up with energy, you can start to move power through it to the rest of your drivetrain. on the same note, you have to drain the flywheel of energy before you can start slowing down your engine and car. with a heavier flywheel, you have more energy in the system at maximum so you will be able to maintain a high speed more easily (more momentum) but you re not transferring any additional power through the drivetrain to make you go faster.
visualize this:
water input ----------_____---------- water output
you have a water dumping out on the ground. it s going down a hill. halfway through that ramp, you have a ditch. the ramp continues on to bottom of the hill where measure the water flow.
when you have a heavy flywheel, your water goes down the hill, flows into the ditch until the ditch is full, then continues on down the ramp. you have to fill the ditch for water to flow over it, and you have to empty the ditch of water before you consider the flow finished. when you have to fill the ditch and empty it, it takes more time for the water flow to travel the distance- but then again, if you shut off the water at the top of the hill, you still have water in the ditch to supply the bottom of the hill. your flywheel does this same thing with stored energy- it makes sure your drivetrain still has energy to operate with, so it makes the car easier to drive.
when you have a light flywheel, the ditch is smaller, or gone altogether. ----------__----------
you have less to fill, and less to empty. your water flow at the bottom of the hill (your wheels) is still the same, but your response time is much better. you don t have to wait as long for the ditch to fill with water before you start getting water at the bottom of the hill. at the same time, you don t have to wait for the ditch to empty as long when you shut the water off. this is good for quick engine response in racing, but not good if you don t like paying attention to the gas pedal while you re driving. your speeds will drop much faster when you let off the gas on a lighter flywheel car, because you have less water in the ditch left to power the bottom of the hill.
with either size ditch (or weight of flywheel)- you re still getting the same amount of flow at the bottom of the hill, so the same amount of force is ultimately transferred to your wheels. the time (and speed with which) you re able to apply it over is just changed.
quick note:
torque = force
horsepower = power
power = application of force over time
so... the faster you apply your force, the more power you have. the lighter flywheel gives you more horsepower (actually makes you lose less) because you re able to apply your torque at a faster rate.
does that analogy help any?
but the lighter flywheel would store less energy, so when trying to cruise youll use up more fuel b/c engine has to keep the car moving.
you store less energy, but you still use the same amount of energy to run the car at a constant speed. the energy stored in the flywheel doesn t mean you need less power from the engine to maintain speed- it just means that you ll have less power loss when you get off the gas. that s it. your mileage will be the same. i didn t have any change in mileage when i went from stock to an 8 pound flywheel, at least not on the highway.
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ja tinha lido algo parecido com isso…mas este texto está muito bom para quem nunca tinha parado para pensar por este lado (muita gente).
[] s
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não li tudo mas o que deu pra tirar foi o seguinte:
um volante aliviado tem menos inércia por, ou seja, é mais fácil de ser girado e faz as acelerações e reduzidas serem mais rápidas. pura física.
e menos inércia = menos esforço.
até o desgaste e consumo diminem alguma coisa, principalmente se balancear pistões, virabrequim, etc.
o lado ruim é que o carro ficará mais arisco e se terá de dosar mais o acelerador justamente pelo motor subir e descer mais fácil os giros, então tem que dosar mais o pé.
o west me explicou alguma coisa uma vez e ainda disse que se for fazer alguma alteração pequena num motor original que seja alívio de volante. era o que tinha no falecido corsa 2.0 dele.
se falei alguma besteira alguém me corrija.
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me senti mais burro ainda
o joel deu uma resumida ai em cima.
concordo contigo, nosso idioma é o português, legal quando as pessoas expoem seus conhecimentos, de forma clara e de facil compreensão.
respostas baseadas em ctrl+v e ainda por cima em outro idioma realmente poderiam ser de melhor serventia caso ao menos tivessem sido explanadas (em nosso idioma) pelo autor do post.
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o joel deu uma resumida ai em cima.
concordo contigo, nosso idioma é o português, legal quando as pessoas expoem seus conhecimentos, de forma clara e de facil compreensão.
respostas baseadas em ctrl+v e ainda por cima em outro idioma realmente poderiam ser de melhor serventia caso ao menos tivessem sido explanadas (em nosso idioma) pelo autor do post.
e não citou nem a fonte…
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_nada mais revoltante do que um motor lerdo, sem reposta você pisa no acelerador e parece que o virabrequim está recolhendo uma âncora… na verdade um volante pesado.
ultimamente as montadoras vêm fazendo muitos motores deste tipo: eles são ótimos para dobrar esquinas confortavelmente, ou facilitar o controle de embreagem na rampa do estacionamento do supermercado, mas pra que quer ver o oco, volantes pesados são como bigornas rotativas.
volantes existem para armazenar energia, assim disponibilizando força suficiente para o motor manter-se em marcha lenta e também para recolher e entregar individualmente a força de cada cilindro.
existe uma regra dentre os preparadores que adicionar peso a algo que gira, é muito mais prejudicial à performance, do que acrescentar peso a carroceria.
isso e a mais pura verdade objetos que rotacionam, sofrem influencia do fenômeno físico chamado de inércia assunto supreedentemente complexo, mas incrivelmente capaz de melhorar o desempenho do seu carro.
qualquer corpo em movimento tem energia cinética que e´o trabalho necessário para tirar aquela massa do repouso e colocá-la a uma determinada velocidade
quanto menos trabalho for empregado para girar o volante (poderia ser também uma roda) maior será a disposição de força para gerar cavalos a pergunta e quanta força será necessária para girar o seu volante
momento de inércia
a força necessária não depende apenas da massa do volante, mas principalmente de como essa massa esta distribuída no corpo. por cálculos complexo e possível descobrir exatamente a ação do peso do volante sobre o carro, mas para tanto é preciso conhecer o momento de inércia do volante como e virtualmente impossível para entusiastas medir esse momento o importante e saber que ele cresce ao quadrado do raio. quanto menor o momento inércia mais leve será seu carro .por exemplo mun. dinamômetro honesto de volante o acréscimo de 500 gramas próximo ao diâmetro externo tem mais peso que um quilo na carroceria do carro.
na medida em que caminhamos em direção ao centro do volante, o efeito cinético rotacional diminui ate que 500 gramas valem realmente 500 gramas.
motores com volantes pesados a altos momentos de inércia consomem grande parte da potencia do motor, ao invés de libertarem os preciosos cavalos para rodas. outro ponto negativo é na troca de marchas, de primeira para segunda, por exemplo, o motor tende a demorar a perder rotação, ao invés de diminuí-la rapidamente até onde possa casar com a velocidade da próxima marcha. a formula abaixo e capaz de estimar a ação do peso do volante o carro mas este valor pode variar com o momento de inércia da peça.
peso = _____ 1______ peso do ( raio do volante x relação da marcha x relação final)
efeito 2 volante raio do pneu
estudos realizados em um ford focus pelo engenheiro americano dave coleman, cientista de foguetes da revista americana sport compact car, quantifica o poder dessa formula.
dave trocou um volante de 9,7kg por um de 4 kg, mantendo o restante do carro intocado fazendo as contas com a relação de primeira marcha 3.667:1 e final 3,82: 1,chegou se a conclusão de que o carro fica 118 kg “mais leve” nessa marcha.na segunda foram 43,1kg a “menos” ,de terceira “pouco mais de 22 kg mas o grande beneficio segundo dave ,foi à melhoria da dirigibilidade .
‘basta relar no acelerador e o giro realmente sobe, alem das marchas entrarem na veia sem aquele lag insuportável “relata o cientista de foguetes sobre rodas.
durabilidade
como o volante e responsável por receber o atrito da embreagem, a carga de esforços
sobre a peça é enorme. os materiais de construção mais resistente e duráveis são :
alumínio fortal, cromo-molibdenio e aço forjado as peças extremamente leves feitas a partir de modelos originais em ferro fundido, merecem acompanhamento periódico._
reportagem tirada da revista autopower nº 59
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gaucho, tem uma matéria na auto power e na fullpower que fala bem um teste feito num focus. tiraram um volante original de 9kg e colocaram um de 5kg, a 6000rpm de 2º marcha equivale a 170kg de peso morto (bancos, painel, lata), em 3º marcha a 6000rpm equivale a uns 60kg de peso morto, por isso é interessante um alívio de peso inercial inteligente.
na prática não funciona bem assim, fizemos esse teste em um focus sedan trocando o volante original (9,8kg) por um de alumínio (3,8kg), no teste de arrancada contra outro carro de parâmetro o ganho foi muito pequeno, retomada idem.
