krazykoncepts

I am doing a auto to five speed swap this weekend and am wondering about flywheels. I can get a stock flywheel for 20cnd with only 75,000k's. So do i pick up that one or buy a performance one?

The car is a n/a with full exhuast, intake...i want some more performance out of it but will is the flywheel worth the money?

truespin88

Usually a lighter flywheel is only good on high-power cars.
A stock flywheel will be fine for your application/budget.

krazykoncepts

how bout the clutch?

Evil Aviator

http://www.mazdatrix.com/f-writng.htm

krazykoncepts

great page....thns evil aviator

Evil Aviator

There is other excellent information on that site. Be sure to check the FAQ, which some people have difficulting finding because the link is near the bottom of the web page. The racing links right below it also has some good pictures and videos.
http://www.mazdatrix.com/index.htm#Home@new

NZConvertible

That's completely untrue. The engine's output has little to do with the benefits a lighter flywheel will give you.

If you can spare the money and the gearbox is out, there's no good reason not to get a lighter flywheel. You won't regret it.

Evil Aviator

1) You do not have the money or do not want to spend the money.
2) You just use your car as a simple daily driver.
3) You live in an area with lots of hills and/or snow and ice, and prefer the stock flywheel.
4) You drag race, and your style of driving works best with the heavier flywheel.
5) Your wife/girlfriend would have trouble driving the car (this may actually be an advantage, lol)
6) Your car is often loaded down with weight (trips, etc.).
7) You are an engineering geek, and prefer a low-inertia flywheel to a light flywheel.

$150FC

you forgot that a heavier flywheel makes more load, which makes a turbo happier.

NZConvertible

Evil,

1) Hey, don't misquote me! You cunningly edited the bit that said "If you can spare the money..."
2) My daily-driven Cosmo had a 10lb flywheel, and while I'd probably now get a 12-15lb one for daily use, I never regretted it.
3) I'll give you that, and I'm glad I don't.
4) True, stock is probably best for dragging, but considering the tiny percentage of drive-time that most people actually spend dragging, it's a tiny sacrifice.
5) I never actually had that complaint, but like you say it could work well for you.
6) Man, it's a 7. It;s primary purpose is not as a long-distance hauler.
7) And the difference is...

krazykoncepts

if a flywheel is helps free power and get faster aceleration than why is the heavier one better for drag?

anobii

A heavier flywheel stores more kinetic energy, ie when the clutch is released, the engine bogs less keeping the engine at an optimal rpm for power through first gear. It improves 60ft times but generally lowers MPH.

-E

MountainTurbo

lol

When I read the title of your thread, I thought you were going to ask whether or not you needed a flywheel

Evil Aviator

Some people like the higher inertia for the launch.

Not all flywheels are made the same, and the weight is not as important as the moment of inertia. Unfortunately, the industry thinks that this concept is too advanced for the general public, so they rate their flywheels by their weight. A well-made flywheel can actually have a lower moment of inertia than a poorly-designed flywheel that is lighter. I attached this picture to show the difference in inertia of two flywheels of the same static weight and diameter.



Also, you may have noticed this quote from the Racing Beat catalog:
"The weight of the stock flywheel is 24 lbs compared to 17 lbs for the Racing Beat Flywheel. The actual reduction in inertia from stock is much greater than the weights suggest, since the stock flywheel is 1 to 2 inches thick at its outside edge."

drft_180sx

Where can I learn about flywheels??? I mean the inertia stuff?

For AutoX wouldn't a slightly lightened steel flywheel by optimal over either stock or aluminum race flywheel?

Kombat_killa

what is better for a stock turbo aplication? a stock 24lb flywheel? or a light steel flywheel?

jon88se

RB's aluminum flywheel is totally streetable...if you have trouble with it for more than a day you can't drive. the comment about high output motors and flywheels is actually completely reversed. very light flywheels work best for low torque applications so an NA rotary is a great application. on a really high output motor a light flywheel is a downside on the street...we've taken light flywheels out of a lot of RWD high powered supras, Z's etc...since 500 lb ft of torque and a very light flywheels meant no traction in at least 3 foward gears with a quick spooling turbo. RB's flywheel for the NA is the best acceleration mod next to the full exhaust system.

Tofuball

That leads me to ask:


If we have a 16lb flywheel and a 24lb flywheel biult to have excatly the same moment of inertia, how would that affect the car?

I'm wondering what behaviors are attributed to the inertia and what to the weight and what to both.

fg0d

How would a 9lb flywheel be in daily street driving?

Where do you usually take the rpms to engage the car with flywheels that light? I just need a guesstimate.

NZConvertible

Okay, I thought it was going to be something new and interesting. I understand the benefits of a lighter flywhwheel are actually from lower inertia. One would also hope that aftermarket flywheel manufacturers also understand this...

There would be no effect, other than the car being 8lb lighter. A flywheel is there to provide the engine with rotational inertia. To make the engine accelerate faster, you need to lower that inertia.

Evil Aviator

See "MOI" in the Quarter Master catalog:
http://www.quartermasterusa.com/qmca...excl-cover.pdf

Physics Geek Links
http://www.mcasco.com/p1rdy.html
http://www.peno.coppe.ufrj.br/ocean/...lecture.ppt#14
http://asia.geocities.com/yklo01

It depends how you drive, and the modifications on your car, but generally most people autocrossing an FC prefer a flywheel with a little less inertia than stock.

I don't think my 12A torqueless wonder would perform very with a low-inertia flywheel at an autocross event.

Since the inertia is the same, you would not notice any difference when driving with either flywheel. I would imagine that the weight would affect the bearing load, but I'm not sure if it would be a significant amount.

It is 100% inertia, but weight (mass) is a factor in inertia, as displayed in the base formula of Inertia = Mass * Radius^2.

drago86

I have a racing beat aluminum flywheel on my car and love it, would never go back to stock. Also I used to live on a very steep hill(scraped starting to going up it if i didnt take it right) and had no problems at all with the flywheel. Infact i ajusted to it in about 2 drives, its really not hard to drive, but it makes a huge differance in accel in first and second gear. Launching the car hard did take more practice though, but it still launches great when you get it right.

Electrikhead

young guns, if you are N/A upgrading your flywheel will gain you your most noticeble performance upgrade in terms of motion, then ANY other upgrade you can do, Period the end, those who care to argue, please provide proof because I will, and those who know, will just agree silently and await the onslaught

andrew lohaus

yes, this is true but only for a uniform mass distribution, which realy isnt the case with either the stock or a typical lightened flywheel. more exactly, INERTIA=integral of mass with respect to radius. or in gheto sybols:inertia=S(mass)d(radius).

this further explains why the stock flywheel has so much inertia, beccause so much of its mass lies at the very edge, where r^2 is so great.

this is why good lightened flywheels will either cast or mashine as much metal out of the lip as possible.


p.s. im not trying to call you out, evil. i just wanted to add a little more to the thread

Evil Aviator

LOL, I know, but I didn't want to get into all that technical stuff. You may have noticed that I used the term "base forumla" instead of "empirical formula" so that the average Joe could understand better. I did post the tech links for those who like math, and those go over what you just stated, and then some.