Flywheel selection
Thread Starter
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
Flywheel selection
My winter project is to replace the 383 in my '79 with a small block 427. My current flywheel is a factory piece ca. 1967. Weighs about 30 lbs. The 383 was externally balanced and I just added the balance weight to the stock internally balanced flywheel. I can use this flywheel on the 427 but I'm thinking a 427 might be too much for a 50 year old cast flywheel. A new piece might be a good idea. My options range from 15 to 36 lbs, cast, steel, or aluminum. Is there any reason to go to a lighter flywheel other than shaving 15 lbs off the car? Any other advice on flywheel selection?
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Get an SFI approved one. And put it in an SFI approved bell housing. Remember where your legs are in relation to the flywheel in the car. May never be a problem. But "remember that one time?"
Weight will be your call. What are you going to do with the car? Drag Race? Road Course/Autocross? Driver?
Heavy=more inertia. Light=less inertia, faster revs.
Weight will be your call. What are you going to do with the car? Drag Race? Road Course/Autocross? Driver?
Heavy=more inertia. Light=less inertia, faster revs.
Thread Starter
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
Get an SFI approved one. And put it in an SFI approved bell housing. Remember where your legs are in relation to the flywheel in the car. May never be a problem. But "remember that one time?"
Weight will be your call. What are you going to do with the car? Drag Race? Road Course/Autocross? Driver?
Heavy=more inertia. Light=less inertia, faster revs.
Weight will be your call. What are you going to do with the car? Drag Race? Road Course/Autocross? Driver?
Heavy=more inertia. Light=less inertia, faster revs.
Anyway, back to the question: Anyone have advice on flywheel selection?
Last edited by drwet; Nov 2, 2017 at 10:12 PM.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
Everyone is so different in what they want it's rather hard for anyone to recommend a weight based on what they liked. One person might really like a lightweight flywheel and clutch combo but the next person hates it. Very generally speaking, if you want quicker rev matching shifts and faster revving then lighter, but you will trade it being more touchy taking off and not being as smooth at low rpm's.
It also depends on the clutch and usage. A clutch that that engages suddenly or won't slip as you take off (think ceramic or carbon pucks) works better combined with a heavier flywheel for street driving. On the other hand, A clutch that will will slip and engage easy works better with a lighter flywheel on the street. Then, for track use a lighter flywheel is better no matter what the clutch is.
It also depends on the clutch and usage. A clutch that that engages suddenly or won't slip as you take off (think ceramic or carbon pucks) works better combined with a heavier flywheel for street driving. On the other hand, A clutch that will will slip and engage easy works better with a lighter flywheel on the street. Then, for track use a lighter flywheel is better no matter what the clutch is.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
but I'm thinking a 427 might be too much for a 50 year old cast flywheel. A new piece might be a good idea.
even an old disc can come apart at idleAs said theres no right answer, always been happy with a little on the heavier side (meaning not lightweight) on the st and a good quality disc no need to go too crazy. Like the manners, stored energy they give on leaving a light, hitting the next gear etc. Road courses you may want to look into "light"
Last edited by cv67; Nov 3, 2017 at 12:39 AM.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
It all depends on first gear ratio and engine tq my 427. With a 4.11 rear end and tko 600 2.87 first gear was easy to take of with a 11.5 pound aluminum 168 tooth. Generally I would advise getting a 22 pound sfi steel
Racer
Joined: Nov 2015
Posts: 319
Likes: 27
We always used to install lightened flywheels in the Porsches. The wind-up and rev control was fantastic. I too am wondering about a lightened steel flywheel for the 327 and look forward to the information that will be posted here. I really want an excuse to use a steel lightened flywheel.
Burning Brakes
Joined: Nov 2014
Posts: 951
Likes: 215
From: Foothills of the Adirondacks.
I have one, and a lightened crankshaft in the old VW. Fast revs are cool.
I will get one for sure when I will rebuild my V8.
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Melting Slicks
Joined: Jul 2006
Posts: 2,291
Likes: 492
From: Salmon Arm, BC
I recently changed out my stock 31 LB for an 18 LB. SFI
You can really notice the lack of inertia at lower RPM's, it doesn't like to chug along at 1500-1800 at a lite load like it did before, and also noticable when slowing down from a spirited run (RPM's drop much faster now.)
I would say that it's very good from a performance perspective, but now it's more work to drive on the street.
Since your goal is to get rid of the cast piece.....Do it, put in a mid weight flywheel, it's a nice performance improvement, I don't think you will be disappointed.
You can really notice the lack of inertia at lower RPM's, it doesn't like to chug along at 1500-1800 at a lite load like it did before, and also noticable when slowing down from a spirited run (RPM's drop much faster now.)
I would say that it's very good from a performance perspective, but now it's more work to drive on the street.
Since your goal is to get rid of the cast piece.....Do it, put in a mid weight flywheel, it's a nice performance improvement, I don't think you will be disappointed.
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 343
From: Allenton Wisconsin
Been running a 11 lb flywheel for 7 years. Nice on the road track, not so nice for street use. For all around the mid weight steel is the right choice. Faster acceleration and still carrying some inertia. T
