I have not changed my story one bit. it's your understanding that's in question. If there WAS a misunderstanding on your part, I just clarified it.

Whether or not I believe the flywheel is a source of MORE vibrations vs the pulley is not revelant to the basic argument I made from the beginning.

The contention is the same and Spec-01's comments basicly mirror mine. Feel free to reply to his posts if you like.

 

 

I assume you would take the same stance on lightened pullies also? (if my understanding of your replies are correct).

 

SPEC - What I have installed is the Carbonetic (which is ATS/Across) lightweight flywheel. It supposedly weighs 9.9 lbs approximately, along with their carbon twin-disc clutch.

Do you know much about Carbonetic (ATS/Across) and their lightweight flywheels? It cost a fortune and came highly, highly recommended.

 

Carbonetic are great quality parts, but they've been known to have some reliability issues on other cars. I don't know if it's because of a poor install, or if it's the part itself or if it was just over abused.

 

If you're concerned with 1/4 mile especially 60ft times a heavier flywheel would be better. It's a bitch to get consistent launches with my lightweight flywheel! of all the mods I've done the flywheel is the only one I am having second thoughts on.

 

Yup. As the flywheel gets lighter, less kinetic energy is stored. Results in a harder to launch car in the 1/4.

 

Lekker: I want to provide you with two sets of answers, one relative to the weight of the flywheel used and one relative to the use of carbon/steel and carbon/carbon clutch assemblies.

Part 1 (MOI and other Lightweight Flywheel Info)
On the flywheel side of things it is paramount for you to understand that reduced weight affects MOI (moment of inertia). When people reference that lightened flywheels make their car "feel" slower or affects their ET and Trap Speeds at the drag strip they are experiencing the results of reduced MOI. The significance of MOI is relative to two separate but tightly related factors these are: Weight and the Radius at which said weight operates. These two things can greatly affect the delivery of power to the wheels...but it is significant to note that though there will be a change in the delivery of power at low RPM (because of the affects of reduce rotating mass/MOI), reduced MOI will actually allow more power to transmit to the wheels in the mid to upper RPM range.

Selection of a flywheel that best suits you can be based on a number of factors like vehicle weight, gearing, tire size and type and planned RPM usage (or driving style and requirements of vehicle use). I will provide a general example to help better illustrate these factors. Let’s imagine a G35 that is built for drag racing and street use (using a Steel Flywheel). It produces 450lb.-ft at the wheels and runs on Street Tires. The customer launches at 3500 RPM and with this configuration he commonly experiences massive amounts of wheels spin. In hopes of attaining a better launch he can do several things (Realize that these are general explanations and as such intended as an example only):

1) He can always run a stickier tire, which will help reduce wheel spin and allow him to get out of the hole faster (but he really wants to continue to use the car for street use and likes the mileage that he gets from his current tire choice).
2) He could dial back the power in an attempt to save the tires, but he loves the power he makes with the current set-up.
3) He could change the gearing of the car to lead to a more progressive power delivery.
4) He could move to a lightened flywheel which will dampen the hit of power, as a result of its reduced MOI, and allow the car to get out of the hole without as much tire spin.

Remember, the flywheel is only part of the equation. If you have any questions about what is right for you please let me know and I will be happy to provide more specifics on a case by case basis.

Part 2 (Carbon/Steel vs. Carbon/Carbon)
I am relatively familiar with the product offerings provided by other manufactures and we are actually in the process of developing/testing our own carbon-carbon assemblies as we speak. Though I am not sure of the specifics of the assembly that you are using I do have some insight relative to our experience and understanding of clutches of this type. In order for carbon based clutch kits to perform as efficiently as possible, and in hopes of attaining the greatest life from the materials, it is ideal for all friction surfaces to be made of carbon.

Use of a Carbon-Steel clutch kit, that requires the carbon to interface with a steel friction surface, has some inherent down sides. Clutch capacity and overall functionality is relative to several factors: friction surface area, coefficient of friction (of the materials used), and clamp load are part of this equation...but the window of operation is also affected by temperature. As you all likely know, carbon has a wonderful ability to dissipate heat. Steel on the other hand is not as capable in this regard.

Carbon based clutch discs that rely on steel surfaces will always be limited by the steel's inability to shed heat fast enough. Though a certain amount of heat is required for carbon to effectively work, if the temperatures get to high you can actually cause a breakdown of the carbon compound and a subsequent dusting (or obliteration) of the disc material.

That being said, as we have worked to develop our technology and materials relative to true carbon-carbon clutch kits we have found that use of complete carbon assemblies is a far better route. This is all the info I can provide at this time but I will keep you all up do date as we continue to consider these materials.

Again, I hope this info helps. Please let me know if you have any further questions. Thanks!

 

SPEC-01-

I must admit you're one of the few vendors that seems well-versed in automotive principles. You also debate in a friendly manner and provide a bunch of great information.

With that said, I disagree you regarding the OEM crank pulley dimples Maybe I should have elaborated more on what the intended purpose of the dimples are. From what I've researched, the dimples balance the crank during high load and rpms, much the same way the elastomer rings quells vibrations. The dimples may very well balance the pulley to a degree as well, but the overall number of dimples on a 6" pulley are suspect when the claim is simply to balance the pulley. I had a modified 94 Z28 (LT1 duh) and I spent A LOT of time wrenching, driving, and racing my friend's 5.0's back in college. Neither the LT1 or 5.0 had as fancy OEM pulley/damper as my 96 Maxima (VQ30) or my G35 have. I ran a UDP on my LT1, and as you know, the LT1's require that you install the UDP and then piggyback the OEM pulley to the front of UDP. So yes, you're right about the LT1 pulley. It was indeed balanced to the crank.

 

mathematic racing... for the lose.

I always prefer real world experience over "hypothetical" experience. *cough* Jeff *cough*

 

I don't see how a few drilled holes in a crank pulley could effective balance the crank. Most cranks also feature these drilled holes. As do flywheels.

IBP, Which real life experiences are you referring to? I've run/installed both UDPs and light flywheels on my previous cars.

 

I think you've misunderstood my meaning......

Did you race them repeatedly? Did you inspect the bearing journals after running a lightweight vs. a standard weight? After a season of running each? Did you document these changes and differences?

"I owned one" vs "I've done in depth, real world research" are two different things.

 

Nope. (but I have torn down a motor that has had a UDP and lightflwheel but didn't mic the bearings to check for additional wear)But then again, has Dave? Has Dofu? Has ANYONE giving their opinion the matter have?? Have YOU?

For singling me out for my "experience" and not everyone else's FTL

 

General rule: Not worth it for daily driving. They are noisy as fck, and make your car sound like it's broken lol

 

I have friends with shops all over, and I try to stop by whenever I can. Although I do not have first hand experience, they've all had plenty of cars in the shop because of the lightweight crank pulleys. Never have I seen anything with damage because of a lightweight flywheel.

Go learn to build a motor. You might spend an entire day learning to properly install the harmonic balancer because it's one of the most important parts on the motor. Learning to properly set the timing only took a few hours at most. If the part wasn't so important, do you think we would have spent so much time on it? You don't have to believe me when I say that the pulley with the little rubber trim is what helps balance the crankshaft, and the flywheel doesn't matter here.

But don't knock my knowledge just because you learned what you know about cars by reading magazines articles because the answer to this whole thing is very simple, and has been stated in this thread plenty of times. But for some reason, you still don't get it.

And beyond the balance of the crank, there are other reasons why people don't like messing with the pulleys... pulleys play with ratios and since there are multiple pulleys, it involves a wider degree of uncertainty in the net outcome of the pulley system as a whole. You need to take into consideration the alternator charge, thrown weight, power steering pull, etc... It's ok, I don't expect you to be able to begin to understand all of this yet...