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I guess I'm being insistent

82-T/A said:
You're not understanding the entire principal of what a flywheel does. It's not just a device used for the starter.

Like I said before, General Motors doesn't waste 26 pounds of steel for absolutely no reason at all. There IS a purpose to this. If you want to insist that you know what you're talking about, and that everyone should get one, then go ahead.

Only reason why I'm being adamant about this is because this motor is a 4 cyl. It NEEDs as much low-end torque as it can get. The weight of the flywheel helps the motor build up torque through momentum.
The discussion was about performance gains from lightened flywheels, about which I opined. I think I actually DO understand most of the principles behind the flywheel. For instance, though I did not mention the dampening characteristics of a flywheel, I am not wholly ignorant of that function. I never even mentioned the role of the flywheel as regards the starter. And I'm not even close to "insisting" anything. I have not advocated that anyone get a lightened flywheel, let alone "insisting . . .that everyone should get one."

There, that about covers it.

Now, for the record, here's what I think (not insisting anything)

General Motors put a 26 pound flywheel on the back end of that motor to:
- provide an interface to the clutch
- dampen the operation of the motor (that whole noise/vibration thing)
- have a handy place to put a gear ring for the starter

And I still believe that hp and torque are NOT a function of the flywheel weight.

Let's try to be reasonable and accurate in our replies, shall we? :)
 

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I have a Fidanza flywheel on my current car.
It is a pontiac Vibe.
It has a 1.8 liter motor with an aftermarket turbo kit on it. I run between 200whp and 250whp on a 2700lb fwd car.
I got the lighter flywheel when I decided to put on a beefier clutch.

Here are my takes:
On the bad side, it is easier to stall in 1st gear. I believe there is some truth about loosing low end torque. It takes some getting used to, but everytime someone drives my car, they usually stall in 1st.

The engine feels whispy. In neutrall , it obviously revs quicker. It also drops its revs quicker too. It makes the car feel lighter over all.

Because the revs drop quicker, it just about forces you to shift faster, you feel like you are in a fast forward mode. The good side to this, is that you can shift with your foot on the throttle more, and your clutch will hold the power. This is a big benefit to me as the turbo is making lots of torque and hp, which the stock clutch had trouble with. The lighter flywheel is nicer to your clutch in otherwords.
Also, because the turbo needs load to spool faster, the lighter flywheel caused the turbo to spool at a slightly higher rpm, but because the revs are quicker, the lag time is identical.

Overall, I cant help but think that just as my forged wheel lightened the rotating mass, so did lightening the flywheel, in which the end result is a faster, nimbler car.
In retrospect, I would spend the money elsewhere. The worse drivability in first gear is not worth the gains. I already have a turbo, it makes power enough. I will not do this mod on my Sol when I get it.
 

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js_euler said:
And I still believe that hp and torque are NOT a function of the flywheel weight.

Let's try to be reasonable and accurate in our replies, shall we? :)
I don't want to be mean, but, have you ever installed or replaced a flywheel? And have you ever gone with a lighter flywheel?

It's ok to offer advice, but if you've never actually used what you're talking about, then why are you arguing about it?


By the way, the flywheel is not a dampening device. It CAN be used as a balancing device IF the motor is externally balanced.

The device that gets installed on a car to eliminate noise and vibrations is the harmonic balancer which goes on the front of the crank.

The Ecotec motor has balancing shafts which are installed to help internally balance the motor and reduce the negative torque effects of the rotating assembly. They spin counter to the rotation of the crank and cams.
 

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js_euler said:
And I still believe that hp and torque are NOT a function of the flywheel weight.
You are correct, they are not. But..... but it is a function of how much of the engine's HP and torque is transfered to the rear wheels under acceleration.

HarvesterUT is correct in that a flywheel is an energy storage device. Accelerating a flywheel requires a certain amount of energy. That energy cannot be transfered to the rear wheels. A lighter flywheel absorbs less of the energy and allows more to go though to the rear wheels.

But there is no free lunch. Since the lighter flywheel takes less energy to accelerate it also stores less energy and it requires less resistance to decelerate the flywheel. That is the stalling at takeoff that faultline experiences. And why the engine revs drop faster.

Factory flywheel designs are heavy to smooth out the power pulses especially at lower RPMs and make it easier for the "average" drive to take off from a stop light without stalling the car or having to use excessive revs. With a heaver flywheel the engine decelerates slower allowing smoother shifting (up and down).

Because of gearing (torque multiplication) the effects of a lighter flywheel are much more noticeable in the lower gears.
 

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Every sports car I have ever own has had the factory flywheel removed in place of a lighter one. If you want true heel/toe performance this is the way to go. ECU tuning can greatly benefit after the swap.
 

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Well said.

LBJay said:
Accelerating a flywheel requires a certain amount of energy. That energy cannot be transfered to the rear wheels. A lighter flywheel absorbs less of the energy and allows more to go though to the rear wheels.

But there is no free lunch. Since the lighter flywheel takes less energy to accelerate it also stores less energy and it requires less resistance to decelerate the flywheel. That is the stalling at takeoff that faultline experiences. And why the engine revs drop faster.

Factory flywheel designs are heavy to smooth out the power pulses especially at lower RPMs and make it easier for the "average" drive to take off from a stop light without stalling the car or having to use excessive revs. With a heaver flywheel the engine decelerates slower allowing smoother shifting (up and down).

Because of gearing (torque multiplication) the effects of a lighter flywheel are much more noticeable in the lower gears.
No argument here, LBJay, and well put. :agree:
 

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Having throttle by wire with ECU controls on it could this possibly help the stalling issues with a lighter clutch? Say if the ECU is designed to keep the RPM's from dropping to low to quickly when between gear shifts?
 

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OK. So if you had to choose between only making one of the following 2 mods, which would you choose and why?

1. Lightweight flywheel (stock, 23lbs - lightweight 9.5lbs) = -11.5 lbs rotational weight

vs.

2. Lightweight wheels (stock, 23.6 lbs - BBS RGR, 10 lb) x 4 each = -54.4 lbs unsprung weight

Obviously both these mods can be done, but let's say a guy only wants to spend enough money to do one of these mods. Which one would you do?
 

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I'll take the wheels

Per the preceding discussion, I think the lightened flywheel has fairly serious "driveability" drawbacks - I like smooth and easy. And I think you get a bit of a double bonus w/ the lighter wheels - less unsprung weight and less rotational mass. Just one dork's opinion. :D
 

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jimbo said:
Obviously both these mods can be done, but let's say a guy only wants to spend enough money to do one of these mods. Which one would you do?
Personally I would always do wheels first. But true lightweight 18" wheels are anything but inexpensive. :eek:

But hey what do I know...I'm just a Miata guy, who is used to only paying $100-129 ea for 12-13lb wheels....;)
 

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brentil said:
Having throttle by wire with ECU controls on it could this possibly help the stalling issues with a lighter clutch? Say if the ECU is designed to keep the RPM's from dropping to low to quickly when between gear shifts?
Don't think it would do much for standing starts, but would probably help with shifting. But then again it probably negates part of the reason for the lighter flywheel.

It will be interesting to see what wins that battle. The lighter flywheel or the TBW system.
 

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LBJay said:
Personally I would always do wheels first. But true lightweight 18" wheels are anything but inexpensive. :eek:
The BBS wheels I refered to are $2,500 the set. That is serious money. But cheaper than Fikse's. :D

That's just cash outlay. If I ever trade in the car, I can put the stock wheels back on and still sell the BBS's on ebay for $2,000.
 

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LBJay said:
But hey what do I know...I'm just a Miata guy, who is used to only paying $100-129 ea for 12-13lb wheels....;)
Wow... :eek: those are light! Good job!

What do the stock wheels weigh on the MX-5?
 

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jimbo said:
The BBS wheels I refered to are $2,500 the set. That is serious money. But cheaper than Fikse's. :D

That's just cash outlay. If I ever trade in the car, I can put the stock wheels back on and still sell the BBS's on ebay for $2,000.
I currently have centerline forged wheel on my car, 17's, and they weigh 13#'s. I just checked the site , and there are some 5x110's , 17's for $159 each. It does not say the weight, but being forged, they will be light. That is a great price for forged wheels.
 

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jimbo said:
OK. So if you had to choose between only making one of the following 2 mods, which would you choose and why?

1. Lightweight flywheel (stock, 23lbs - lightweight 9.5lbs) = -11.5 lbs rotational weight

vs.

2. Lightweight wheels (stock, 23.6 lbs - BBS RGR, 10 lb) x 4 each = -54.4 lbs unsprung weight

Obviously both these mods can be done, but let's say a guy only wants to spend enough money to do one of these mods. Which one would you do?

The big difference is that with the flywheel, you have to separate the engine and transmission. So unless you are going to do it yourself, you need to factor in the labor costs as well.
 

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jimbo said:
What do the stock wheels weigh on the MX-5?
Stock on the 06 MX-5 (17x7) are 17 lbs.

A few have switched over to 93-95 RX-7 wheels (16x8) which are in the 14 lbs range. Some the Enkei RP-F1 17x7.5 at 15 lbs and the Kosei K1-TS 17x7 at 13.8 lbs.

Me, I have an NB with Kosei R1 15x7s. Not the lightest at 13 lbs each (about the same as my 15x6 OEM wheels) but I was able to get the 4 wheels with Kumho MXs mounted and delivered to my door for under $900.

I'm ordering a set of Toyo T1Rs ($60 ea) for this summer. That will drop the weight 3 lbs per corner from the MXs.
 

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Very nice, LBJay.:cheers:
 

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Just visiting. It is curious as to the idea of what a flywheel will and will not provide. I offer this information for those who may wish to understand the effects in greater detail.

From my own experience. The average driver will not like a lightened flywheel. You get a small but noticeable performance gain in lower gears at the expense of smooth ideal and possibly increased transmission gear lash or chatter. The clutch can also chatter during slow launch engagement. The engine is much easier to stall at launch. You get a snappier sounding engine. You know, rap, rap, rap, as the RPM quickly goes up and down much more quickly. Fast shifting can be easier and I find heel and tow shifting to be much easier.

This link will explain the effects, as well as provide mathematical calcs for those needing engineering proof. http://www.uucmotorwerks.com/flywheel/how_a_lightweight_flywheel_works.htm
The site is for the BMW engine, but the principals are the same.
 
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