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Author
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Topic: Flywheels: Alum. Vs. Steel
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johnny 4-speed
Gearhead Posts: 156
From: Larkspur, Ca. USA
Registered: Oct 2004
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posted 11-11-2004 01:43 PM
   
A question about flywheels. I run a 3000lb. 65 Fairlane. I run a top-loader, heavy steel flywheel, 10.5" Ram clutch, a 9 in. w./ 5.13's and a locker, and 10.5 X 27" Hoosier DOT Pro Drag cheaters. I usually drop the hammer @ around 5200, and the car has no bog problem. My question is: with such a heavy clutch, could I run an aluminum flywheel and still have enough inertia stored up in flywheel/clutch to keep RPM's up out of the hole? I figure with the 5.13's, I could afford to give some weight away at the flywheel. Waddaya think? JD
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Ryan Wilke
Gearhead Posts: 2125
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 11-11-2004 02:49 PM
I'm no way an expert, but in my humble opinion, I'd think you should stay with the steel flywheel since it'll maintain more rpms between shifts than you would with the aluminum wheel......... I always thought the aluminum wheels were more for road-racing rigs; where the rpms drop much more and you need it to spin up quicker. In dragracing, you are able to bring the R's up before you 'leave', so you're leaving with the wheel already up to speed. Does that sound about right? Ryan 
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 11-11-2004 03:34 PM
Ryan has the right idea.
Aluminum flywheel is not so much a tool to adjust acceleration, but more for adjusting torque effects. Excess tirespin from torque while accelerating and decelerating, and also entering and exiting turns is more "in control" with a lighter flywheel. Yes the light flywheel will accelerate a little faster, but it will also slow down faster from launches, shifts, braking, and any other little track condition like wind gusts and track bumps, etc...
I have one on my '66 and the only benefit that I can see on the dragstrip is that it works real well in helping me launch consistently with DOT tires. I can control tirespin a whole lot better. ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 268 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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johnny 4-speed
Gearhead Posts: 156
From: Larkspur, Ca. USA
Registered: Oct 2004
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posted 11-11-2004 04:27 PM
Thanks for the input, guys! I guess I'm a little confused about what is ideal on a stick shift set-up. On launch, you want the rotating weight high to carry you out of the hole. On shifting through the gears, I thought it would be advantagous to have a lighter set-up, allowing the engine RPM to drop quicker when RPM goes from 7000 in 1st, to 4500 in 2nd. It seems like it would be easier to accelerate when the weight attached to the crank is less. Keep in mind my 5.13's, it takes less torque to get me moving with a mechanical advantage like that. So, I guess one important question is, do I want RPM's to drop more rapidly between shifts, or is that a bad thing? JD
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Moneymaker
Administrator Posts: 26513
From: Lyons, IL, USA
Registered: May 99
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posted 11-11-2004 05:45 PM
You want to maintain as constant an RPM band as possible.Rule of thumb is light car high RPM engine = light flywheel.
Heavy car lower RPM = heavy flywheel. ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,& '04
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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johnny 4-speed
Gearhead Posts: 156
From: Larkspur, Ca. USA
Registered: Oct 2004
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posted 11-12-2004 01:20 PM
So, is 3000 lbs heavy, or light? Because my motor is definately of the high RPM varity. JD[This message has been edited by johnny 4-speed (edited 11-12-2004).]
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Moneymaker
Administrator Posts: 26513
From: Lyons, IL, USA
Registered: May 99
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posted 11-12-2004 01:23 PM
I would call that heavy.
2800 or less with a 7500 and up RPM band is where I would use an aluminum flywheel.
We tried one in Mark's car and it slowed the car down.
2900 lbs and 8500 RPM.
We have a "lite" steel unit in it now.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,& '04
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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