why is everyone here so hung up on using heavy flywheels?
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,686
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From: NEwhere Ohio
why is everyone here so hung up on using heavy flywheels?
I've read a lot of threads on here about people using heavy steel flywheels.
Why? There is a 12 lb fidanze aluminum flywheel w/ steel replaceable friction surface and steel starter motor teeth.
I am running in on my 93, along w spec stage 3+ sprung hub clutch and it is wonderful.
There is a tiny rattle noise during 1st gear wot, and if you lug it up a hill.
This ain't no cadillac people.
Hot rod did a test in the quarter mile of the same car w a heavy flywheel and a lightweight flywheel.
The results showed that any gains the heavy flywheel had at launch were eclipsed during the big end of the run by less rotating inertia on the motor.
So if you are considering a clutch change, you should also consider lightweight flywheel.
I am very happy w mine.
Why? There is a 12 lb fidanze aluminum flywheel w/ steel replaceable friction surface and steel starter motor teeth.
I am running in on my 93, along w spec stage 3+ sprung hub clutch and it is wonderful.
There is a tiny rattle noise during 1st gear wot, and if you lug it up a hill.
This ain't no cadillac people.
Hot rod did a test in the quarter mile of the same car w a heavy flywheel and a lightweight flywheel.
The results showed that any gains the heavy flywheel had at launch were eclipsed during the big end of the run by less rotating inertia on the motor.
So if you are considering a clutch change, you should also consider lightweight flywheel.
I am very happy w mine.
Safety Car
Joined: Sep 2001
Posts: 4,162
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From: Glenbeulah Wi
Can be hard to drive with a large camed engine. I have a light weight flywheel in my Firebird and you need to be carefull on take off or you can stall it easily. That is the only downside I know of.
Safety Car
Joined: Apr 2005
Posts: 3,624
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From: Dale City VA
I have the same Fidanza FW and a SPEC Stage 3 clutch in my 92.....
With the cam I have - At idle my ZF rattle sounds like a Power Stroke. I constantly have folks ask me "whats wrong" or say "Hey!! somethings broke on your car"....
It's not difficult for ME to drive but I've been driving it for a while.
I had the same FW and clutch in it when it was otherwise stock (for over 20K miles) and it had a slight ZF rattle at idle - but the gear noise under acceleration was very noticeable.
IMO, it's definatly not a mod for everyone with a C4.
Will
With the cam I have - At idle my ZF rattle sounds like a Power Stroke. I constantly have folks ask me "whats wrong" or say "Hey!! somethings broke on your car"....
It's not difficult for ME to drive but I've been driving it for a while.
I had the same FW and clutch in it when it was otherwise stock (for over 20K miles) and it had a slight ZF rattle at idle - but the gear noise under acceleration was very noticeable.
IMO, it's definatly not a mod for everyone with a C4.
Will
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
I prefer them (heavier) as they recover better when shifting, easier to drive on the street, especially with a radical cam.
Driven a few Fidenzas in L98s, modded LT4s and thought they sucked.
Sure you can get used to it but like the stock driving characteristic when it comes to cluches.
Launch a car with a sticky tire on a 12 lber then a 30 or 40 lb.
night and day.
Everyones different
Driven a few Fidenzas in L98s, modded LT4s and thought they sucked.
Sure you can get used to it but like the stock driving characteristic when it comes to cluches.
Launch a car with a sticky tire on a 12 lber then a 30 or 40 lb.
night and day.
Everyones different
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,686
Likes: 753
From: NEwhere Ohio
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,686
Likes: 753
From: NEwhere Ohio
I have the same Fidanza FW and a SPEC Stage 3 clutch in my 92.....
With the cam I have - At idle my ZF rattle sounds like a Power Stroke. I constantly have folks ask me "whats wrong" or say "Hey!! somethings broke on your car"....
It's not difficult for ME to drive but I've been driving it for a while.
I had the same FW and clutch in it when it was otherwise stock (for over 20K miles) and it had a slight ZF rattle at idle - but the gear noise under acceleration was very noticeable.
IMO, it's definatly not a mod for everyone with a C4.
Will
With the cam I have - At idle my ZF rattle sounds like a Power Stroke. I constantly have folks ask me "whats wrong" or say "Hey!! somethings broke on your car"....
It's not difficult for ME to drive but I've been driving it for a while.
I had the same FW and clutch in it when it was otherwise stock (for over 20K miles) and it had a slight ZF rattle at idle - but the gear noise under acceleration was very noticeable.
IMO, it's definatly not a mod for everyone with a C4.
Will
Team Owner
Joined: Sep 2003
Posts: 25,412
Likes: 2,745
I've read a lot of threads on here about people using heavy steel flywheels.
Why? There is a 12 lb fidanze aluminum flywheel w/ steel replaceable friction surface and steel starter motor teeth.
I am running in on my 93, along w spec stage 3+ sprung hub clutch and it is wonderful.
There is a tiny rattle noise during 1st gear wot, and if you lug it up a hill.
This ain't no cadillac people.
Hot rod did a test in the quarter mile of the same car w a heavy flywheel and a lightweight flywheel.
The results showed that any gains the heavy flywheel had at launch were eclipsed during the big end of the run by less rotating inertia on the motor.
So if you are considering a clutch change, you should also consider lightweight flywheel.
I am very happy w mine.
Why? There is a 12 lb fidanze aluminum flywheel w/ steel replaceable friction surface and steel starter motor teeth.
I am running in on my 93, along w spec stage 3+ sprung hub clutch and it is wonderful.
There is a tiny rattle noise during 1st gear wot, and if you lug it up a hill.
This ain't no cadillac people.
Hot rod did a test in the quarter mile of the same car w a heavy flywheel and a lightweight flywheel.
The results showed that any gains the heavy flywheel had at launch were eclipsed during the big end of the run by less rotating inertia on the motor.
So if you are considering a clutch change, you should also consider lightweight flywheel.
I am very happy w mine.
This is a pretty good read and if you care to get more technical there's many good reads out there. There's a place for a light wheel and it's generally not in a 3200 lb car that's street driven or drag raced.
http://www.w8ji.com/rotating_mass_acceleration.htm
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Safety Car
Joined: Apr 2011
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easy rule of thumb...
heavy wheels mean more stored energy. They absorb that energy as they delay the revving of the engine and return it at higher rpm.
Light wheels mean faster revving from less mass, but also mean less energy returned at high rpm..
heavy wheels are also used to maximize the torque thats produced. They keep the crankshaft turning with inertia when the rods are not transfering energy to the shaft...as in a stall situation or low rpm where resistence equals power.
heavy wheels mean more stored energy. They absorb that energy as they delay the revving of the engine and return it at higher rpm.
Light wheels mean faster revving from less mass, but also mean less energy returned at high rpm..
heavy wheels are also used to maximize the torque thats produced. They keep the crankshaft turning with inertia when the rods are not transfering energy to the shaft...as in a stall situation or low rpm where resistence equals power.
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,686
Likes: 753
From: NEwhere Ohio
easy rule of thumb...
heavy wheels mean more stored energy. They absorb that energy as they delay the revving of the engine and return it at higher rpm.
Light wheels mean faster revving from less mass, but also mean less energy returned at high rpm..
heavy wheels are also used to maximize the torque thats produced. They keep the crankshaft turning with inertia when the rods are not transfering energy to the shaft...as in a stall situation or low rpm where resistence equals power.
heavy wheels mean more stored energy. They absorb that energy as they delay the revving of the engine and return it at higher rpm.
Light wheels mean faster revving from less mass, but also mean less energy returned at high rpm..
heavy wheels are also used to maximize the torque thats produced. They keep the crankshaft turning with inertia when the rods are not transfering energy to the shaft...as in a stall situation or low rpm where resistence equals power.
It starts making horsepower exponentially (due to the boost and cam) at high rpm. Im talking > 6000 RPM.
Yes, a lightweight flywheel - to get me up there is what Im going to need.
I shift lightning fast and I have short throw shifter to help me out there.
A heavy flywheel would have me spinning in circles at the line.
I guess I can see your point, if you have a stock intake l98 motor, then the heavy flywheel - to make the best use of what its designed for (low end grunt) is what you need to get you going.
Now, I do think a heavy flywheel is easier to drive in stop-go traffic. But I try to avoid anywhere with stop-go traffic if im in the vette (no fun to be had there).
Safety Car
Joined: Apr 2011
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Ok. lets say I have an insane crazy high rpm solid roller supercharged liter bike beating motor like I plan to have one day in my vette...
It starts making horsepower exponentially (due to the boost and cam) at high rpm. Im talking > 6000 RPM.
Yes, a lightweight flywheel - to get me up there is what Im going to need.
I shift lightning fast and I have short throw shifter to help me out there.
A heavy flywheel would have me spinning in circles at the line.
I guess I can see your point, if you have a stock intake l98 motor, then the heavy flywheel - to make the best use of what its designed for (low end grunt) is what you need to get you going.
Now, I do think a heavy flywheel is easier to drive in stop-go traffic. But I try to avoid anywhere with stop-go traffic if im in the vette (no fun to be had there).
It starts making horsepower exponentially (due to the boost and cam) at high rpm. Im talking > 6000 RPM.
Yes, a lightweight flywheel - to get me up there is what Im going to need.
I shift lightning fast and I have short throw shifter to help me out there.
A heavy flywheel would have me spinning in circles at the line.
I guess I can see your point, if you have a stock intake l98 motor, then the heavy flywheel - to make the best use of what its designed for (low end grunt) is what you need to get you going.
Now, I do think a heavy flywheel is easier to drive in stop-go traffic. But I try to avoid anywhere with stop-go traffic if im in the vette (no fun to be had there).
There is a formula that helps calculate where that point is, when you have enough HP to be better off with less mass on the crank. Must be toward 1000 where its got power to spare...and able to run one gear down a 1/4.
If you ever come across the engine build formulas and the calculations for some of these variables, run thru some...its interesting stuff. Just bring your calculator or slide rule...
Melting Slicks
Joined: Nov 2008
Posts: 2,765
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The brute force , If available when needed,. can overcome the flywheel mass and its inertia torque additions. Real HP is better than "canned" power or stored power when/if you have enough of it to do the job. Thats why there are titanium rods, skirtless pistons, machined cranks...anything to loose weight so it'll spool up faster. If its generating enough HP to overcome the need for torque, then its all good.
There is a formula that helps calculate where that point is, when you have enough HP to be better off with less mass on the crank. Must be toward 1000 where its got power to spare...and able to run one gear down a 1/4.
If you ever come across the engine build formulas and the calculations for some of these variables, run thru some...its interesting stuff. Just bring your calculator or slide rule...
There is a formula that helps calculate where that point is, when you have enough HP to be better off with less mass on the crank. Must be toward 1000 where its got power to spare...and able to run one gear down a 1/4.
If you ever come across the engine build formulas and the calculations for some of these variables, run thru some...its interesting stuff. Just bring your calculator or slide rule...
Need $$$$$ too. LOL
Safety Car
Joined: Sep 2001
Posts: 4,162
Likes: 555
From: Glenbeulah Wi
A heavier "wheel' among other things is good for "parts life", it's more drive-able and will "catch and pass" the car with the "light wheel" if both are of equal weight, power and driven well.
http://www.w8ji.com/rotating_mass_acceleration.htm
http://www.w8ji.com/rotating_mass_acceleration.htm
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,686
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From: NEwhere Ohio
Someone posted a link to it here about 5 years ago.
Of course, those 'power C4 users' that were on here then arent really on here much anymore to remember the article...
Race Director
Joined: Oct 2000
Posts: 14,064
Likes: 1,166
From: N. Alabama
I have the quartermaster clutch (no flywheel) in my C5Z. It is 10mph faster on the back straight at VIR. Top end is better than with the 28# spec that I had before.
I have the OEM DM flywheel in my LT4. I like it for the street. It does hold back acceleration as compared to a lightweight FW but it is so much nicer and quieter as a DD. You cannot have the best of both worlds. It simply does not work that way.
I have the OEM DM flywheel in my LT4. I like it for the street. It does hold back acceleration as compared to a lightweight FW but it is so much nicer and quieter as a DD. You cannot have the best of both worlds. It simply does not work that way.
Safety Car
Joined: Apr 2011
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I have the quartermaster clutch (no flywheel) in my C5Z. It is 10mph faster on the back straight at VIR. Top end is better than with the 28# spec that I had before.
I have the OEM DM flywheel in my LT4. I like it for the street. It does hold back acceleration as compared to a lightweight FW but it is so much nicer and quieter as a DD. You cannot have the best of both worlds. It simply does not work that way.
I have the OEM DM flywheel in my LT4. I like it for the street. It does hold back acceleration as compared to a lightweight FW but it is so much nicer and quieter as a DD. You cannot have the best of both worlds. It simply does not work that way.
Probably the most accurate statement in the whole thread !
Le Mans Master
Joined: Oct 1999
Posts: 6,366
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http://www.vortexbuicks-etc.com/spin_zone.htm
http://www.popularhotrodding.com/tec...e/viewall.html
Is this the article your refering too?
http://www.popularhotrodding.com/tec...e/viewall.html
Is this the article your refering too?
Last edited by bill mcdonald; Sep 2, 2011 at 01:56 PM.
Pro
Joined: Jan 2011
Posts: 633
Likes: 6
easy rule of thumb...
heavy wheels mean more stored energy. They absorb that energy as they delay the revving of the engine and return it at higher rpm.
Light wheels mean faster revving from less mass, but also mean less energy returned at high rpm..
heavy wheels are also used to maximize the torque thats produced. They keep the crankshaft turning with inertia when the rods are not transfering energy to the shaft...as in a stall situation or low rpm where resistence equals power.
heavy wheels mean more stored energy. They absorb that energy as they delay the revving of the engine and return it at higher rpm.
Light wheels mean faster revving from less mass, but also mean less energy returned at high rpm..
heavy wheels are also used to maximize the torque thats produced. They keep the crankshaft turning with inertia when the rods are not transfering energy to the shaft...as in a stall situation or low rpm where resistence equals power.
Someone that understands it!!
In the old days we used to make super heavy flywheels for the drag applications to utilize the stored energy for the launch.
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,686
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From: NEwhere Ohio
whats the flywheel weight on a pro dragster that runs 3.xx second 1/4 miles?
Again, the article I read stated that any gains at the start are eclipsed by the freer reving (it takes rpm to make HP) nature of the lightweight flywheel.
Maybe if you are running a station wagon, heavy flywheel is best.
If you are running a lightweight corvette with a 6000+ rpm redline, then light flywheel is going to give you the best 1/4 mile.
How hard/easy it is to launch it (without spinning the tires or the other extreme bogging it) is a whole different subject.
Assume a perfect launch.
I launch in the 1.8's on drag radials w/ my lightweight flywheel.
Last edited by dizwiz24; Sep 3, 2011 at 09:53 PM.