What’s an Aluminum Flywheel Do for Me?
Richard Newton
I just love my aluminum flywheel. The problem is I can’t really document what it does for me. OK – it lowers my lap times and that’s a really big deal. I’m a numbers sort of guy. If you can’t show me numbers then I can’t believe it.
Everyone who runs road courses loves their aluminum flywheel just as much as I do. It just changes the car totally. Hell, I’m starting to sound like on of those puff pieces that the magazines write for the advertisers. Sorry about that.
It all started when I broke the white beast. OK – it probably just wore out. The white monster (also known as an ’85 Corvette coupe) now has over 130,000 miles. Corvettes do wear out – I guess. All of a sudden my '85 no longer had an Overdrive. Every time I would shift to OD I got a whole lot of rpms and no movement. My 4+3 had suddenly become a 4+0. This was something I couldn't ignore.
The real question was if I was going to use this as an opportunity to make any further changes once the transmission came out. Actually the real question was how many more parts could I sneak into the house without having to sleep on the couch. The big engine suddenly became next year's project. The Wilwood big brake project was also moved back on the calendar. Who needs brakes if the car won't move?
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The real question was if I was going to use this as an opportunity to make any further changes once the transmission came out. Actually the real question was how many more parts could I sneak into the house without having to sleep on the couch. The big engine suddenly became next year's project. The Wilwood big brake project was also moved back on the calendar. Who needs brakes if the car won't move?
Aluminum flywheels are the hot ticket for road racers, and wannabe road racers like myself. The idea is to reduce the reciprocating mass so the engine can rev quicker. Keep in mind it’s not going to rev any higher, or with any more power. It’s just going to do it a lot faster. In other words aluminum flywheels let you get to the peak of your power curve a whole lot faster.
None of this is new. What’s new is that I wanted to see if a Corvette with an aluminum flywheel could actually be driven on the street. I’ve been told for years that if I installed an aluminum flywheel I could expect improved times at the track but that I would barely be able to move away from the corner stop sign.
Since my transmission had to come out to repair the OD unit I figured this was as good as a time as any to find out if you could actually drive a Corvette with a lightweight flywheel on the street. The guys at Fidanza said this would be no problem. Then my friend Dennis Lesser at Quality Craft South here in Florida said an aluminum flywheel wouldn’t be a problem if I just spent a little while learning how to drive all over again. Yea, that’s encouraging.
After about thirty seconds of thought I decided to not only replace the flywheel, but the clutch and pressure plate as well. This 4+3 rebuild had suddenly become one of the “Since we’re already doing X why not do Y?”.
This meant I was going to have to acquire any number of parts. Since I hate purchasing parts from a catalog and then having everyone tell me that my problems are really caused by the other guy’s parts. I want one stop shopping. Actually, I want to know who to point the finger at when a project goes bad.
Fidanza put me in contact with the folks at Zoom clutches. Zoom sells the whole package. I can get the flywheel, a new clutch and a new pressure plate from one source. Life is looking better.
What Does It Really Do?
How does this lightweight flywheel really work? More importantly what’s it going to do for me? Remember, they don’t contribute a thing to power output, but they make you faster. How can that be?
If we measure the power output of an engine with the standard GM flywheel and then again with a lightweight aluminum flywheel there won’t be a change in power. This makes it appears that the aluminum flywheel has done nothing and was a total waste of cash. That’s totally wrong. It’s really money well spent.
Remember that the dyno that shows maximum power at constant revolutions. It doesn’t demonstrate what happens to an engine's power output in real life situations - like acceleration.
The reason for this is that when you accelerate the engine not only has to move the total mass of the car but also the internal components of the engine. A considerable amount of power is used to simply move the internal mass of the engine components. Anything you can do to lighten these internal components means more power is available to accelerate the total car. When we lighten the mass of the flywheel, less power is required to accelerate this mass and therefore more power is available to accelerate the car down the track.
It may seem strange that by removing a few pounds from the flywheel you can make a big difference to a 3000lb+ car’s acceleration. In fact the difference is very noticeable.
In turn this means I’m going faster down the track as I approach the next corner. Racers call this carrying more speed into the corner. That means you can pass more cars. That’s a good thing.
This whole aluminum flywheel thing is a good example of using a specialized part for a very specific reason. If all you do is drive on the street then the standard heavy flywheel works just fine. If on the other hand you run a number of track day events then this may be the best thing you can do for your Corvette.
The good news is that my ’85 really isn’t that much different to drive on the street. I get a little shudder when I pull away from the stoplights around town. It’s nothing that I can’ manage though. Remember, GM built your Corvette as a street car.
If GM thought an aluminum flywheel was good for the street they would of installed one in your Corvette in the first place. I just removed one of the GM compromises, and made my Corvette a little more specialized. An aluminum flywheel doesn’t make driving around town all that difficult, just a little different.