Club Cobra GasN Exhaust  

Go Back   Club Cobra > Cobra Talk Areas > ALL COBRA TALK

Keith Craft Racing
Nevada Classics
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
Keith Craft Racing
Keith Craft Racing
Advertise at CC
Banner Ad Rates
MMG Superformance
MMG Superformance
Keith Craft Racing
Keith Craft Racing
March 2024
S M T W T F S
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31            

Kirkham Motorsports

Like Tree17Likes

Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 12-25-2021, 10:12 PM
xb-60's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2009
Location: Adelaide, SA
Cobra Make, Engine: AP 289FIA 'English' spec.
Posts: 13,139
Not Ranked     
Default Flywheel weight?

What weight flywheel should I use?

My car’s total weight should easily be under 1100kg (2400lb)
Gearbox is a Toploader (WR)
Differential ratio is 2.92:1 (my choice)
Engine is a Tickford 302W with 220kW / 300bhp and 435Nm / 320 ft lb
My question…. What weight flywheel should I be using?
A friend who knows his stuff is suggesting a standard weight (28lb) flywheel.
My engine man is suggesting a light weight flywheel, reason being that with the car’s light weight, I'll benefit from a lighter flywheel.
He says that with a light flywheel, the engine will rev “like a Japanese engine”.

Bearing in mind my choice of a high diff. ratio, should I go standard weight flywheel, or light weight? 22lb and 14lb are available.

Cheers!
Glen

Last edited by xb-60; 12-26-2021 at 02:10 PM.. Reason: WR
Reply With Quote
  #2 (permalink)  
Old 12-25-2021, 11:42 PM
CC Member
Visit my Photo Gallery

 
Join Date: Oct 2007
Location: Cape Town, WC
Cobra Make, Engine: Shamrock
Posts: 406
Not Ranked     
Default

With your diff ratio I would stay standard weight especially for road use with lots of stop starts where the lighter the flywheel the more clutch slip you will need to get moving. Light weight flywheels are only of real benefit for serious track racing

To quote Google:
Cons of Lightweight Flywheels

Reduced Off-the-Line Performance. If you want to maximize performance from a standing start, a lightweight flywheel might not move you in the right direction. ...
Rough Engine Feel. With a lightweight flywheel, the engine will feel rougher while running. ...
Gear Rattle.
Tommy likes this.

Last edited by Snake2998; 12-25-2021 at 11:47 PM..
Reply With Quote
  #3 (permalink)  
Old 12-25-2021, 11:52 PM
CC Member
Visit my Photo Gallery

 
Join Date: Oct 2007
Location: Cape Town, WC
Cobra Make, Engine: Shamrock
Posts: 406
Not Ranked     
Default

Read this for more info:
Light flywheels: pros and cons – Infinite-Garage
1795 likes this.
Reply With Quote
  #4 (permalink)  
Old 12-26-2021, 04:55 AM
1795's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2013
Location: Canandaigua, NY
Cobra Make, Engine: SPF MKII Riverside Racer FIA
Posts: 2,471
Not Ranked     
Default

Glen,

The article that Snake2998 provided is pretty much straight to the point. With my lightweight flywheel I have to make sure that I rev match when downshifting. With my street cobra when I had it with a heavier flywheel you did not have to. If you have a 22 lb option, that might be a nice in-between option. A little lighter than the standard, so the engine will rev a little quicker, but not so light weight that the car behaves like a race car.

looking forward to seeing what you decide on.

Cheers,

Jim
__________________
Reply With Quote
  #5 (permalink)  
Old 12-26-2021, 05:24 AM
t walgamuth's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2018
Location: Lafayette, IN
Cobra Make, Engine: Looking to buy
Posts: 1,295
Not Ranked     
Default

My VSE weighs right at 2000#. It has an aluminum block 5.7 chevy taken out to 427 CI. I am running the 19# flywheel from a 67 Nova. Yeah, it feels a bit lumpy but isn''t that what these cars are supposed to be....race car like?
__________________
Cobra loving, autocrossing Grandpa Architect.
Reply With Quote
  #6 (permalink)  
Old 12-26-2021, 08:15 AM
Dwight's Avatar
Senior Club Cobra Member
Visit my Photo Gallery

 
Join Date: May 2001
Location: Florence, AL
Cobra Make, Engine: RCR GT 40 & 1966 Fairlane 390 5 speed
Posts: 4,511
Not Ranked     
Smile

a 302 will rev very quick with a standard flywheel.

I think you will need the weight of the flywheel to move you smoothly down the road.

I vote standard flywheel
__________________
''Life's tough.....it's even tougher if you're stupid.'' ~ John Wayne
"Happiness Is A Belt-Fed Weapon"
life's goal should be; "to be smarter than inanimate objects"
Reply With Quote
  #7 (permalink)  
Old 12-26-2021, 12:18 PM
t walgamuth's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2018
Location: Lafayette, IN
Cobra Make, Engine: Looking to buy
Posts: 1,295
Neutral     
Default

...in a tractor!
__________________
Cobra loving, autocrossing Grandpa Architect.
Reply With Quote
  #8 (permalink)  
Old 12-26-2021, 02:56 PM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 21,888
Not Ranked     
Default

Aluminum flywheel, please. If you do a search, you will find a quote from one of the Kirkham brothers saying you'd be nuts to put anything in a Cobra other than an aluminum flywheel.
sgianino likes this.
Reply With Quote
  #9 (permalink)  
Old 12-26-2021, 07:32 PM
Alfa02's Avatar
CC Member/Contributor
Visit my Photo Gallery
Gold Star Contributor
 
Join Date: Sep 2016
Location: (Beautiful) Sequim, WA
Cobra Make, Engine: Pacific Roadster, 347 cu.in. 5-speed
Posts: 1,922
Not Ranked     
Default

Ok Glen, My $.03 Race car: yes Alum. Flywheel, as Jim said we're at high rpm's, quick shifts, etc. Not having to worry about coming off the line (Stop light) Std. flywheel: you're not gaining anything. Lightened: quicker revs, less internal mass, no slipping of the clutch coming off the line. I went from stock (28lbs) to a lightened (22bs) in the V-8 RX-7, made a HUGH difference without any drivable issues. You know I hate to disagree with patrickt, but sometimes you take your chances Cheers TommyRot.
Reply With Quote
  #10 (permalink)  
Old 12-26-2021, 11:48 PM
Gaz64's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2008
Location: Brisbane, QLD
Cobra Make, Engine:
Posts: 2,773
Not Ranked     
Default

Glen,

I would say aluminium if you went for a 5 speed and lower diff gears.

So a 22lb would be still a nice compromise for street, and occasional track.

Depends on the engine internals, and the whole car in combination.

Gary
__________________
Gary

Gold Certified Holden Technician
Reply With Quote
  #11 (permalink)  
Old 12-27-2021, 12:32 AM
Dominik's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jun 2000
Location: Cape Town, South Africa/Mainz, Germany,
Posts: 1,601
Not Ranked     
Default

If your approach is merely to save total (curb) weight, you may find that your car comes easily under 2.200 lbs (1.000 kg). I had a, to you guys unknown make (LDS), 427 with cast iron 302. It did weigh 1.015 kg. With a single seater racing screen, T5 box and ally differential.

My RAM (from UK) with an all-ally 496 Chevy and Jag suspension & brakes was 2.015 lbs (917 kg)

If you like to reduce rotational weight, which performance-wise counts for much more than total weight, perhaps also consider lighter wheels and tires. I had Hoosiers on the RAM.

Drive a 302 with an aluminium flywheel. I haven't yet.
Get a shatter-proof bellhousing - (which does weigh extra).

I am dying to weigh my latest 427 with leightweight body but cast iron heads on a 427 FE.
Just for reference.
__________________
If I don't respond anymore, that's because I can't log in
Reply With Quote
  #12 (permalink)  
Old 12-27-2021, 03:14 AM
xb-60's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2009
Location: Adelaide, SA
Cobra Make, Engine: AP 289FIA 'English' spec.
Posts: 13,139
Not Ranked     
Default

I'm thinking that the safe option for my application (it's not a race car) is probably a standard weight (28lb) flywheel.
A possible alternative is the 22lb version.

A 14lb steel flywheel or an even lighter version in aluminium sounds like it would be too much of a compromise for my application... even if the Kirkhams would say I'm nuts.

The light weight flywheels would allow quicker 'blipping' of the engine, but I can't see how - apart from a tiny percentage of weight saving relative to the weight of the car - this would result in significantly quicker on-the-road performance.

I'm not too old to learn, so tell me if my logic is wrong

Cheers!
Glen
Tommy and tkb289 like this.
Reply With Quote
  #13 (permalink)  
Old 12-27-2021, 05:19 AM
t walgamuth's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2018
Location: Lafayette, IN
Cobra Make, Engine: Looking to buy
Posts: 1,295
Not Ranked     
Default

Heavy flywheels are for smoothness, like in a Cadillac or truck. Light flywheels will allow quicker acceleration and deceleration. Take your pick. I'll always go for the lightest flywheel I can find in a car planned for high performance.
__________________
Cobra loving, autocrossing Grandpa Architect.
Reply With Quote
  #14 (permalink)  
Old 12-27-2021, 06:41 AM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 21,888
Not Ranked     
Default

An engine with an aluminum flywheel slows down faster as well. In a Cobra, I think that makes it safer. I can't think of any reason to put a heavier flywheel in a Cobra unless all you do is march in a parade line. Now, blipping the throttle when the car is not in gear is fun, especially with a big ol' FE (which you don't have). The engine does not go vroom-vroom, it just goes boom. You can't even tell that it's speeding up, it just sounds like it explodes. 800RPM to 3000RPM instantly, without ever going through 1000, 2000, or 2500. It's the magic of aluminum.
Gaz64 likes this.
Reply With Quote
  #15 (permalink)  
Old 12-27-2021, 07:41 AM
CC Member
Visit my Photo Gallery

 
Join Date: Mar 2009
Location: Mendota, IL
Cobra Make, Engine:
Posts: 692
Not Ranked     
Default

High compression, lots of rear gear , very light flywheel, damp road. You better learn to get smooth on letting up on the loud peddle. If you dont you will be sliding the rear tire without getting o the biners.

They are good for drag strip starts on traction limited cars.
Reply With Quote
  #16 (permalink)  
Old 12-27-2021, 08:13 AM
Average Guy
Visit my Photo Gallery

 
Join Date: Sep 2002
Location: Rushville, IN
Cobra Make, Engine: red Shell Valley, white stripes
Posts: 577
Not Ranked     
Default

If you are a driver who downshifts to slow down, it seems that you would get less slowing by downshifting in a car with a light flywheel.
__________________
When I said I wanted to be somebody, I probably should have been more specific...
Reply With Quote
  #17 (permalink)  
Old 12-27-2021, 08:16 AM
patrickt's Avatar
Half-Ass Member
Visit my Photo Gallery

 
Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 21,888
Not Ranked     
Default

Quote:
Originally Posted by Dirty Harry View Post
If you are a driver who downshifts to slow down, it seems that you would get less slowing by downshifting in a car with a light flywheel.
That is true. But down shifting to slow down in a big block Cobra is asking to be towed home.
Grubby likes this.
Reply With Quote
  #18 (permalink)  
Old 12-27-2021, 09:33 AM
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2017
Location: Frederick, CO
Cobra Make, Engine: ERA FIA 2158, ERA 427SC 649 sold
Posts: 169
Not Ranked     
Default

Heavy flywheels for higher geared cars, heaver cars, street only cars and cars with bigger cams. Lighter flywheel for quicker response and dual purpose cars. Everything being equal, engine with lower torque like a 302, heaver flywheel. big torque engine, lighter flywheel.
Reply With Quote
  #19 (permalink)  
Old 12-27-2021, 10:44 AM
eschaider's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2006
Location: Gilroy, CA
Cobra Make, Engine: SPF 2291, Whipple Blown & Injected 4V ModMotor
Posts: 2,628
Not Ranked     
Default

Most of us regularly drive our cars at 6,000 to 8,000 rpm each time we take them out for a spin. When you combine that with normally shifting at or above 7,500 rpm it is immediately apparent why a light flywheel makes so much sense for our 7,500 rpm daily driving excursions.

I mean if we were just driving around town in third gear or so plodding along with city traffic below 2000 rpm — well obviously there would be no need for the heavier clutch and flywheel assembly. All that would do is make the car more attractive to drive in town and traffic which of course none of us would ever do.

I say dump all those depleted uranium flywheels and lets all move on to a better suited aluminum beryllium alternative, profusely drilled (of course) to eliminate all possible weight.


Ed
1795 and Alfa02 like this.
__________________


Help them do what they would have done if they had known what they could do.

Last edited by eschaider; 12-27-2021 at 10:48 AM.. Reason: Spelling & Grammar
Reply With Quote
  #20 (permalink)  
Old 12-27-2021, 11:50 AM
1985 CCX's Avatar
Senior Club Cobra Member
Visit my Photo Gallery

 
Join Date: Mar 2005
Location: Manchester, NH
Cobra Make, Engine: AK1085 (302), HTM111 (427 Comp), CSX2375R (289 Comp) and Scratch 427 S/C
Posts: 18,750
Not Ranked     
Default

Mine is an alloy unit on the gold car.
Revs fast!
Does limit burnouts however it still breaks the rear loose once Webers open.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 11:01 AM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy
Links monetized by VigLink