Aluminum Flywheel
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Joined: Feb 2004
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From: Park City Utah
Aluminum Flywheel
Looking to switch the stock steel flywheel to an aluminum flywheel and keep everything else stock what brand should I get? and how would I make sure it is zero balanced with the rest of the clutch assembly so I do not have any vibration issues.
Former Vendor
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From: Portland OR
St. Jude Donor '10-'11-'12
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Chris, just sharing my experiences here.
I think the rumor persists because most people who get an Alum flywheel only do so with a new aftermarket clutch. The new clutch is almost always more agressive and IMO is why its harder to get going. People blame the flywheel when its there new XYZ stage 5+ clutch thats a bear to get going.
The weight difference from a stock LS2/flywheel to just about any aftermarket clutch is greater than the change in weight to a fidanza flywheel. I ran my car for 12k miles with a LS7 clutch and fidanza aluminum flywheel and there was zero harder driving with it. The rumor says you have to rev the car to the moon to get going (inertia) but I didnt even have to touch the gas pedal to get going in first gear (900rpm idle).
The fidanza flywheel is a great mod to counter the insane 15+ pound difference in weight to just about any aftermarket clutch out there. My Spec twin disc in my car now is 39 pounds. Thats 10 less than a LS7 and fidanza combo and like 30 less than the boat anchor stock flywheel. Since the spec twin is fine at the track on launches, I dont see how a heavier LS+fidanza clutch is a detriment.
Its a great mod on a vette because the stock clutch is waaaay heavier than the f-car clutches pre-2002. C6's have far more dead weight than in needs. If you needed more weight to get going then why didnt the heavier f-car have more flywheel weight? The C6 is 400 lbs lghter and thus needs even less weight than a F-body.
This is one mod people should only take opinions on from people who factually had/have it. It was a no brainer for me. Revs were far quicker and the car dyno'ed 11rwhp more. I ran one on my C5 with a Spec 3 and loved that too. It was easy getting into gear and I didnt see any harder to drive characteristics.
Findanza rocks.
Note*** Aluminum flywheels can warp with big slipping at a drag track. They are a street and road coarse deal.
I think the rumor persists because most people who get an Alum flywheel only do so with a new aftermarket clutch. The new clutch is almost always more agressive and IMO is why its harder to get going. People blame the flywheel when its there new XYZ stage 5+ clutch thats a bear to get going.
The weight difference from a stock LS2/flywheel to just about any aftermarket clutch is greater than the change in weight to a fidanza flywheel. I ran my car for 12k miles with a LS7 clutch and fidanza aluminum flywheel and there was zero harder driving with it. The rumor says you have to rev the car to the moon to get going (inertia) but I didnt even have to touch the gas pedal to get going in first gear (900rpm idle).
The fidanza flywheel is a great mod to counter the insane 15+ pound difference in weight to just about any aftermarket clutch out there. My Spec twin disc in my car now is 39 pounds. Thats 10 less than a LS7 and fidanza combo and like 30 less than the boat anchor stock flywheel. Since the spec twin is fine at the track on launches, I dont see how a heavier LS+fidanza clutch is a detriment.
Its a great mod on a vette because the stock clutch is waaaay heavier than the f-car clutches pre-2002. C6's have far more dead weight than in needs. If you needed more weight to get going then why didnt the heavier f-car have more flywheel weight? The C6 is 400 lbs lghter and thus needs even less weight than a F-body.
This is one mod people should only take opinions on from people who factually had/have it. It was a no brainer for me. Revs were far quicker and the car dyno'ed 11rwhp more. I ran one on my C5 with a Spec 3 and loved that too. It was easy getting into gear and I didnt see any harder to drive characteristics.
Findanza rocks.
Note*** Aluminum flywheels can warp with big slipping at a drag track. They are a street and road coarse deal.
Last edited by SpinMonster; Mar 24, 2011 at 02:11 AM.
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Tech Contributor
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
The LS7 orients in 6 positions to the flywheel. When you buy a LS7/stock flywheel, they are shipped separate and thus they are not balanced from the factory.
Spend the extra money and get it checked. You will appreciate this if you have a vibration and have to do the job twice because you wanted to save 75-100 bucks on the balancing.
Tech Contributor
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
This is another thread that will show everyone with the fidanza on their C6 loves it and everyone saying its bad never had one personally on a C6.
Last edited by SpinMonster; Mar 24, 2011 at 02:14 AM.
Le Mans Master
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From: Cumming, GA
Race Director
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From: Saint Albans, WV
Oddly enough for me since I had my Spec Super Twin Carbon w/lightweight flywheel installed two years ago my revs seem to stay up more between shifts compared to the stock setup. Odd but true.
Melting Slicks
Joined: Dec 2006
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From: Woodinville WA
Chris, just sharing my experiences here.
I think the rumor persists because most people who get an Alum flywheel only do so with a new aftermarket clutch. The new clutch is almost always more agressive and IMO is why its harder to get going. People blame the flywheel when its there new XYZ stage 5+ clutch thats a bear to get going.
.
I think the rumor persists because most people who get an Alum flywheel only do so with a new aftermarket clutch. The new clutch is almost always more agressive and IMO is why its harder to get going. People blame the flywheel when its there new XYZ stage 5+ clutch thats a bear to get going.
.
Former Vendor
Joined: Apr 2006
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From: Portland OR
St. Jude Donor '10-'11-'12
No doubt the fidenza has lot and lot of happy customers and you have some good points spin, in fact if and when I replace the Mcleod I might go in that direction.
Safety Car
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From: Miami FL
2020 C6 of the Year Finalist - Unmodified
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16,'17,'18-'19-'20-'21-'22
+1 for the LS7 - Fidanza aluminum combination. Engine is LS2 with heads and cam, etc, 504 flywheel horsepower. Drives like stock. 
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From: Lakewood Ranch, FL
Moderator
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From: Lakewood Ranch, FL
Le Mans Master
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From a similar thread in Oct 2008:
Everything SpinMonster has said is true not only in the real world where he has experience, but also technically and can be proven by the math. The e-mails from the clutch companies were pretty sad quite frankly, they show a distinct lack of knowledge. A lightweight flywheel is king on the dragstrip...look what the fastest dragracers run.
When considering the launch, the inertia of the flywheel is not even half of the inertia in the whole "system". (Spin referred to this in an earlier post.) Of the two variables RPM and mass, RPM has the far greater impact on the kinetic energy stored by the "system". Let me run through a sample HP calculation on a lightweight flywheel vs a heavy flywheel.
To illustrate the effects of a lighter flywheel, let's take the acceleration of the Z06 from 5-60 MPH where the engine goes from 600-7000 RPM in 3.7 seconds (clutch engaged from a roll). Work is done ON the flywheel by the engine to increase its' kinetic energy (KE) with the amount of work done (KE added) given by the KE (after) minus the KE (before). KE=1/2Iw^2 (where I is rotational inertia and w is the angular velocity) from this link: http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html
The rate at which work is being done on the flywheel is equal to the rate at which the KE is increasing. HP is the rate at which work is being done so we're left with finding the KE added and dividing by the time it took to add the KE to the flywheel to find the average HP required to accelerate it from one RPM to another.
flywheel/clutch: 60 LBs (~27.3 KG) and 13" diameter (~.33m). These are my estimates...close enough to get a good number but they are not 100% accurate. If you have the correct numbers, there's enough here to get the exact answer...I think I'm low on the diameter and high on the mass.
From the link above, I for the flywheel is I=1/2MR^2 where M is the mass and R is the radius of the flywheel/clutch.
I=1/2(27.3KG)(.165m)^2=.372 kg-m^2
600 RPM=(600/60)(2)(pi)=62.8 rad/sec
KE (before)=1/2(.372)(62.8)^2=733.7 Joules
7000 RPM=(7000/60)(2)(pi)=733 rad/sec
KE (after)=1/2(.372)(733)^2=99866 Joules
KE (after)-KE (before)=99866-733.7=99132 Joules
1 Joule=.738 ft-lb
99132(.738)=73159 ft-lb which is the total work done to increase the RPM from 600 to 7000.
To get the rate at which work was done, divide by the 3.7 sec run giving: 73159 ft-lb/3.7 sec= 19773 ft-lb/sec
1 HP=550 ft-lb/sec, so we have 19773/550=36 HP to accelerate the flywheel. If the weight of the flywheel/clutch is reduced to 30 LBs, it will only take 18 HP for the same acceleration...that's a free 18 HP! Of course the rate at which the RPM is sweeping is ~1730 RPM/sec which is much more than on a dyno, but you will see an increase on a dyno with a lighter flywheel. As you can see, the effect is dependant upon the rate of RPM increase. Therefore as you go up in speed/gears, the RPM rate decreases requiring less HP to accelerate the flywheel. By the time you get in 3rd and certainly 4th, the effect is so small (in comparison to the LS7's rated engine HP) it's considered negligible.
As you can see, mass is a first order determinant (linear) and RPM is a second order determinant (exponential). So while doubling the mass will double the KE, doubling the RPM will increase KE by four times. Now to tie things together using a flywheel/clutch at 60 lbs and rotating at 1000 RPM and analyze KE using 1/2Iw^2. Using only the M portion of "I", we have 60*(1000^2)= 60,000,000 units. The rest of the "system" consists of the crankshaft, rotating portion of the connecting rods (rods have rotating and reciprocating portions), timing gears, timing chain, cam, harmonic dampner, and all pulleys (most engines would include the alternator, but not here). Let's say the KE of the rest of the system is 1/2 of the flywheel/clutch giving it 30,000,000 units (giving a total of 30 lbs of mass equivalent to the rest of the system) making the total 90,000,000 units or 90*1,000,000. If we reduce the mass of the flywheel by 20 lbs, we now have a total of 70 lbs of mass leaving us with the equation 70*(x^2)=90,000,000 where x=RPM with the lightweight flywheel required to equal the KE of the system with the heavy flywheel at 1000 RPM. Grinding through the math gives us x=1134 RPM to equal the same KE...not a very significant increase. Most people tend to use more RPM than needed when driving on the street and would never notice a difference in drivability. At the dragstrip, a 3000 RPM launch with a heavy flywheel would require a 3400 RPM launch with a lightweight flywheel. The launch in the post above at 4000 RPM w/lightweight FW is the equivalent to 3530 RPM with a heavy FW. Again Spin is correct where he said in several posts that a bog after a lightweight FW installation has more to do with the new clutch grabbing better/quicker and requires the driver to use a little skill to slip it. My ZR-1 has trouble with wheelspin off the line so I launch at 2500-3000 RPM and slip the clutch up to 40-45 MPH.
The mantra of a lightweight FW requires more RPM is true but usually grossly overstated. Its' largest benefit is in 1st gear on the dragstrip. Road racing at courses that use mainly 3rd and 4th don't see much benefit in acceleration but rev matching on downshifts are made easier by the quicker revving. Smaller engines will see larger performance gains with a lightweight FW because it's a larger % of the "system"...but you may only need 1200 RPM instead of 1000 RPM on the street to leave a stoplight.
When considering the launch, the inertia of the flywheel is not even half of the inertia in the whole "system". (Spin referred to this in an earlier post.) Of the two variables RPM and mass, RPM has the far greater impact on the kinetic energy stored by the "system". Let me run through a sample HP calculation on a lightweight flywheel vs a heavy flywheel.
To illustrate the effects of a lighter flywheel, let's take the acceleration of the Z06 from 5-60 MPH where the engine goes from 600-7000 RPM in 3.7 seconds (clutch engaged from a roll). Work is done ON the flywheel by the engine to increase its' kinetic energy (KE) with the amount of work done (KE added) given by the KE (after) minus the KE (before). KE=1/2Iw^2 (where I is rotational inertia and w is the angular velocity) from this link: http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html
The rate at which work is being done on the flywheel is equal to the rate at which the KE is increasing. HP is the rate at which work is being done so we're left with finding the KE added and dividing by the time it took to add the KE to the flywheel to find the average HP required to accelerate it from one RPM to another.
flywheel/clutch: 60 LBs (~27.3 KG) and 13" diameter (~.33m). These are my estimates...close enough to get a good number but they are not 100% accurate. If you have the correct numbers, there's enough here to get the exact answer...I think I'm low on the diameter and high on the mass.
From the link above, I for the flywheel is I=1/2MR^2 where M is the mass and R is the radius of the flywheel/clutch.
I=1/2(27.3KG)(.165m)^2=.372 kg-m^2
600 RPM=(600/60)(2)(pi)=62.8 rad/sec
KE (before)=1/2(.372)(62.8)^2=733.7 Joules
7000 RPM=(7000/60)(2)(pi)=733 rad/sec
KE (after)=1/2(.372)(733)^2=99866 Joules
KE (after)-KE (before)=99866-733.7=99132 Joules
1 Joule=.738 ft-lb
99132(.738)=73159 ft-lb which is the total work done to increase the RPM from 600 to 7000.
To get the rate at which work was done, divide by the 3.7 sec run giving: 73159 ft-lb/3.7 sec= 19773 ft-lb/sec
1 HP=550 ft-lb/sec, so we have 19773/550=36 HP to accelerate the flywheel. If the weight of the flywheel/clutch is reduced to 30 LBs, it will only take 18 HP for the same acceleration...that's a free 18 HP! Of course the rate at which the RPM is sweeping is ~1730 RPM/sec which is much more than on a dyno, but you will see an increase on a dyno with a lighter flywheel. As you can see, the effect is dependant upon the rate of RPM increase. Therefore as you go up in speed/gears, the RPM rate decreases requiring less HP to accelerate the flywheel. By the time you get in 3rd and certainly 4th, the effect is so small (in comparison to the LS7's rated engine HP) it's considered negligible.
As you can see, mass is a first order determinant (linear) and RPM is a second order determinant (exponential). So while doubling the mass will double the KE, doubling the RPM will increase KE by four times. Now to tie things together using a flywheel/clutch at 60 lbs and rotating at 1000 RPM and analyze KE using 1/2Iw^2. Using only the M portion of "I", we have 60*(1000^2)= 60,000,000 units. The rest of the "system" consists of the crankshaft, rotating portion of the connecting rods (rods have rotating and reciprocating portions), timing gears, timing chain, cam, harmonic dampner, and all pulleys (most engines would include the alternator, but not here). Let's say the KE of the rest of the system is 1/2 of the flywheel/clutch giving it 30,000,000 units (giving a total of 30 lbs of mass equivalent to the rest of the system) making the total 90,000,000 units or 90*1,000,000. If we reduce the mass of the flywheel by 20 lbs, we now have a total of 70 lbs of mass leaving us with the equation 70*(x^2)=90,000,000 where x=RPM with the lightweight flywheel required to equal the KE of the system with the heavy flywheel at 1000 RPM. Grinding through the math gives us x=1134 RPM to equal the same KE...not a very significant increase. Most people tend to use more RPM than needed when driving on the street and would never notice a difference in drivability. At the dragstrip, a 3000 RPM launch with a heavy flywheel would require a 3400 RPM launch with a lightweight flywheel. The launch in the post above at 4000 RPM w/lightweight FW is the equivalent to 3530 RPM with a heavy FW. Again Spin is correct where he said in several posts that a bog after a lightweight FW installation has more to do with the new clutch grabbing better/quicker and requires the driver to use a little skill to slip it. My ZR-1 has trouble with wheelspin off the line so I launch at 2500-3000 RPM and slip the clutch up to 40-45 MPH.
The mantra of a lightweight FW requires more RPM is true but usually grossly overstated. Its' largest benefit is in 1st gear on the dragstrip. Road racing at courses that use mainly 3rd and 4th don't see much benefit in acceleration but rev matching on downshifts are made easier by the quicker revving. Smaller engines will see larger performance gains with a lightweight FW because it's a larger % of the "system"...but you may only need 1200 RPM instead of 1000 RPM on the street to leave a stoplight.
Race Director
Joined: Dec 2006
Posts: 12,362
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From: Fort Worth, Texas
Our SFI certified billet 18lb flywheel will work with ls1/6 style clutches and will not warp like the insert on an aluminum flywheel can. It costs $349.99 if anyone is interested. Feel free to call the shop at 817-750-2000, Chris