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2005 Cadillac CTS-V
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Discussion Starter #1
How did it change the drivability? Any chatter from the drop in weight? How much lighter is this aluminum flywheel compared to the factory dual mass? Thank you for any info. :)
 
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here is the write-up straight from UUC. i will post the actual weight difference tomorrow morning when im back at work. call me or email me if you are interested.

How does a lightweight flywheel work? Amongst the majority, there are two schools of thought concerning light flywheels. The first is that they do not contribute to power output. The second is that they do. Which thought is correct? In fact both, in a way, are correct.

If we measured the power output of an engine first with light flywheel and then again with the standard part on an engine dyno, no change in power will be seen to occur. At first it appears that the light flywheel has done nothing and was a total waste of cash. This is not the case. A dyno that shows max power at constant revs does not demonstrate what happens to an engine's power output in real life situations - like acceleration. If an engine is accelerated on a dyno (we are talking about a rate of around 2000rpm a second ) it would show a power output of around 20%-25% less than at the constant rev state.

The reason for this is that when accelerating a vehicle the engine not only has to push the total mass of the car but the internal components of the engine need to be accelerated also. This tends to absorb more power as the extra power is used accelerating the internal mass of the engine components and is why a motor accelerating on a dyno will produce less power than at constant revs. Also it must be remembered that the rate of acceleration on the engine internals is much greater that the rest of the car. This would then suggest that by lightening the flywheel, less power would be required to accelerate it and therefore more power would be available to push the car along.

Now, it may seen unbelievable that by removing a few pounds from the flywheel a noticeable difference to a 3000lb+ car’s acceleration will be made. In fact the difference is quite noticeable and the secret behind this is hidden within the gearbox. Everyone knows that cars accelerate at a greater rate in low gears, this is because a car’s gear box basically a mechanical lever and just like when using a leaver to lift a heavy object, the gearbox reduces the mass of the car that the engine sees. For example, in first gear an engine will see the car's mass as only around say 250lbs but the engine internal mass would still remain around 45lbs.

As for the "virtual" weight loss of a typical lightweight flywheel in the 3-series or M3, we've prepared the full mathematical analysis:

Calculations for UUC flywheels showing exact "virtual" weight loss in each gear - click here to download Acrobat .pdf file

It is now easier to see were the extra performance comes from when you lighten a flywheel. You effectively "lighten" a car by more than 10% in first gear just by removing mass from the flywheel. As the gear used increases this "lightening" effect is reduced. This is why car’s acceleration improvement reduces in higher gears, to very effect in top gear. Great for drags and tight race tracks but will not increase a car's top speed.

You will see the calculations include the diameter of the flywheel, weight lost (same overall rotating mass difference in UUC Stage1 or Stage2 due to pressure plate weight differences), gear ratios including 6-speed application, and typical diff ratio.

The effective "virtual" weight losses are:

GEAR "virtual"
weight lost:
1st gear 394.4 lbs.
2nd gear 151.7 lbs.
3rd gear 75.4 lbs.
4th gear 48.5 lbs.
5th gear 37.6 lbs.
6th gear 31.0 lbs.


A general rule of thumb for weight loss equivalence to "gained" power is approximately 10lbs/hp. That is for every 10lbs lost, the car gains the effective performance increase of 1hp.

With that in mind, the effective performance increase expressed in gained power can be expected to be the same as the "virtual" weight lost due to the flywheel in each gear divided by 10:

GEAR "virtual"
performance gain:
1st gear 39.4 hp
2nd gear 15.2 hp
3rd gear 7.5 hp
4th gear 4.9 hp
5th gear 3.8 hp
6th gear 3.1 hp



This gear-dependent gain is also another reason why a typical 4th-gear dyno pull may not show a significant difference - the calculations show that little more than 4hp would be detected, yet a 4th-gear dyno run shows nothing of real-world acceleration through the gears. Improvements in rev-matching and upgraded clutch clamping power remain regardless of gear.

Due to the nature of the "virtual" weight loss, typical 4th-gear dyno runs may show miniscule differences. Real-world acceleration runs will show improvement equivalent to the "virtual" weight loss.
 

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Hi, I had a uuc put on when the car had 2000 miles on it. I used the stock pressure plate and clutch disk. I think the drivability of the car is much better, I would rate it up there with the uuc shifter. Not only is the engine more responsive but in some ways it makes the car feel lighter. On up shifts you don't have to wait (for what seems like for ever) for the revs to match when you let out the clutch. On down shifts a small blip is all that is required to match revs. Now there are, in my opinion at least one reason why Cadillac whent with the fly wheel they did. There is, for lack of better term, a gear noise that you easily hear under some very limited situations. The noise is mostly in 3rd & 4th gears between 1200-1800 rpms. Also if you are the type who likes to slip their cluch a lot when starting to move there is an almost inperceptiable shudder (I'm talking goin to 2000 rpms and slowly let out the clutch). In my opinion I think the uuc is a must have but I can see why Caddy did not put it in from the factory.
 

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Discussion Starter #5
Thank you for the Feedback! I notice that my LS6 revs up a little slower than most LSx motors, and it also revs down slower.

Patientally waiting for the weight comparison. Thank you Luke!
 
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per my GM parts catalog stock is 51 lbs. UUC is aprox 18lbs
they list for $425.00 if theres a renewed interest in them i can do better on the price ($395.00 ish) plus shipping. email or call at the info below.
 

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I've had the UUC flywheel in my V for about 30,000 miles... I have not had a single issue with driveability since it was installed. I would agree 100% with everything Ak Jim said; the RPM's increase and decrease quicker making it much easier to rev match while shifting. There is a little transmission noise at very low RPM's with the transmission in higher gears (what I would call lugging).
 

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P.S. I purchased my UUC flywheel, shifter, 4 tps, and spare tire stuff from Lindsay, what a class operation! Thanks. It is nice to have someone on the other end of the phone who knows what they are talking about.
 

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Lightened flywheels are a great source of "free" power in that not only is "power" (defined broadly") increased, but also economy is increased.
Still, some drivers insist and perhaps correctly that a heavy flywheel is good for drag racing in that its mass decreases bogging at the start line.

As for "chatter", gears do not chatter when engaged. The "chatter" referenced is usually seen when the gearbox is in neutral and motor impulses not dampened by the flywheel cause the loose gears to vibrate=chatter.

The concept of "mass" is not well understood. Mass = the weight of the object X the square of the speed. A flywheel spinning at redline has a huge amount of mass, whereas contrasted a wheel weighing roughly the same has much less mass because through gearing its rotational speed is much less.

UUC's comments are well written. Below is another source. Graham Bell is a Brit who has been writing rather well about motors for many years.

Graham Bell in his book Four Stroke Performance Tuning writes:

“Over the years there ahas been a fair amount of controversy with regard to flywheel lightening. Some claimed that a lightweight flywheel improved acceleration due to reduced inertia, others stated that the only benefit was better crankshaft life because the twisting load on the end of the crank was reduced, and there was less risk of flywheel explosion due to inertia load on the centre of the flywheel being lessened. At this time we can state and prove that any reductions in an engine’s reciprocating mass or rotating mass will improve acceleration. Thus lightweight pistons, rods, cranks, clutches and flywheels all benefit performance.
The problem was that we had no reliable means of measuring the performance advantages of light components. However, the situation changed when relatively inexpensive computerised engine dynos like the Superflow SF-800 became available. These dynos can accelerate an engine at a fixed rate and accurately print out the horsepower on a tape. This means that we can programme the dyno to accelerate the engine at, say, 2000 rpm per second, and record the power levels every 250-rpm. When such a test was carried out on a 388 cu. in. Chev speedway engine, it recorded almost 25 hp more when titanium rods and a light flywheel were fitted. The driver claimed that the car was quicker by about a half-length out of turns, which backed up what the dyno had showed. Tested with a static load as we had to with the older dynos, the engine showed no difference in hp when the lightweight parts were fitted.”
 

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04 CTS-V, 05 STS, 07 SRX- All sold :(
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Lightened flywheels are a great source of "free" power in that not only is "power" (defined broadly") increased, but also economy is increased.
Still, some drivers insist and perhaps correctly that a heavy flywheel is good for drag racing in that its mass decreases bogging at the start line.

As for "chatter", gears do not chatter when engaged. The "chatter" referenced is usually seen when the gearbox is in neutral and motor impulses not dampened by the flywheel cause the loose gears to vibrate=chatter.

The concept of "mass" is not well understood. Mass = the weight of the object X the square of the speed. A flywheel spinning at redline has a huge amount of mass, whereas contrasted a wheel weighing roughly the same has much less mass because through gearing its rotational speed is much less.

UUC's comments are well written. Below is another source. Graham Bell is a Brit who has been writing rather well about motors for many years.

Graham Bell in his book Four Stroke Performance Tuning writes:

“Over the years there ahas been a fair amount of controversy with regard to flywheel lightening. Some claimed that a lightweight flywheel improved acceleration due to reduced inertia, others stated that the only benefit was better crankshaft life because the twisting load on the end of the crank was reduced, and there was less risk of flywheel explosion due to inertia load on the centre of the flywheel being lessened. At this time we can state and prove that any reductions in an engine’s reciprocating mass or rotating mass will improve acceleration. Thus lightweight pistons, rods, cranks, clutches and flywheels all benefit performance.
The problem was that we had no reliable means of measuring the performance advantages of light components. However, the situation changed when relatively inexpensive computerised engine dynos like the Superflow SF-800 became available. These dynos can accelerate an engine at a fixed rate and accurately print out the horsepower on a tape. This means that we can programme the dyno to accelerate the engine at, say, 2000 rpm per second, and record the power levels every 250-rpm. When such a test was carried out on a 388 cu. in. Chev speedway engine, it recorded almost 25 hp more when titanium rods and a light flywheel were fitted. The driver claimed that the car was quicker by about a half-length out of turns, which backed up what the dyno had showed. Tested with a static load as we had to with the older dynos, the engine showed no difference in hp when the lightweight parts were fitted.”
Could you be more specific, please? :D Nice post.

I don't have a UUC, but the stock flywheel/PP/clutch out of the '05 Z06 gave my car a nice little kick in the pants. Revs much faster, and the car seems to "jump" a lot harder on the 1-2 shift. Great mod for the money, IMO. Had I known about the UUC having the ability to keep the stock disc and PP, I might have gone with that instead (1/2 the price of my setup).
 

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I went with the stock Z06 clutch and flywheel which reduced rotating mass by about 30 lb or so. It requires a spacer, which TPIS and Katech sell.
I liked the idea of the Z06 clutch/flywheel because I can still lighten it further through something like a Fidanza aluminum flywheel.
But my sense is that the UUC combination is just as good as the Z06 in all respects.

Another little though - mass is concentrated at the rim of a flywheel simply because the rim is moving much faster than the center. Therefore, placement of weight reduction is extremely important.
 
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