C3 vs C6: Technical improvement list?

[69427]

I think we all can agree that a C6 (and specifically the ZR1/Z06 versions) are superior to a stock C3 on the track. But you rarely see a list of what is actually better. Obviously the laws of physics apply here. So, specifically, what has been improved? The usual discussed items are:
Horsepower, which is easy to remediate in the older cars.
Tire size, which can be accomodated with common flares and wheel updates.
Suspension geometry, which the C3 is famous for its flaws.

But what about:
Weight?
Weight bias (F/R or corner weights): Is the C6 better in this regard?
Center of gravity height: Any reliable info comparing these two cars?
Aerodynamics: Does the "smooth" C6 underbody contribute measurably to its cornering ability compared to the ugly underside of a C3 (or is this just a mpg improvement)?
Wheelbase: Shouldn't a C3 have a slight advantage during transient cornering due to its shorter WB, or does a C3 suffer from too much overhang weight (and increased moment of inertia)? That C6 rear transaxle sure seems like it would tend to bump up the MoI number, though.
Brakes: Those huge C6 brakes look sweet, but given equal tires/equal vehicle weight, are they significantly (or even moderately) better than the C3 brakes?
ABS: I've never driven an ABS equipped vehicle on a track. I'm pretty good at threshold braking (thanks to multiple Skip Barber schools) and rarely lock up the tires, so I'm curious if ABS is involved all that often on dry tracks?
Other significant differences?

I'm just trying to understand the actual technical differences between these models. During track days it's just nice to have an understanding about what C3 issues can be improved, and what are inherent disadvantages of our antiques.

 

[BBShark]

Your right, physically the two are (or could be made) physically equal. The biggest difference I see is torsional rigidity. I've seen numbers on modern Corvettes of <25,000 Nm/degree. That is supercar territory. I'm guessing a C3 is about 1/10th of that.

 

[clutchdust]

The list might as well be summed up by saying "everything". Except for the feel you get behind that long hood, there just isn't anything the c3 does as well as a c6, not even in the same league.
But if you want to significantly improve the c3, you have to start with the frame. The c3 frame is about as stiff as dried spaghetti noodles. It is the basis on which everything else depends. You want to talk about cornering and polar moment of inertia? Anything you do is pissing away money with a spongy frame. I've been saying for years that our frames are a suspension member (which they are) and that's a terrible way to make a car handle.
As for braking, c3 brakes are pretty dang good, even by today's standards, but you just can't compete with ABS. You may be able to threshold brake, but you're simply making sure you apply the maximum amount of force for the strongest caliper. The other three calipers could have greater clamping potential but you're just trying not to lock up that one (whichever it is) caliper. The ABS cycles all four calipers at their greatest clamping ability.

 

[69427]

The list might as well be summed up by saying "everything". Except for the feel you get behind that long hood, there just isn't anything the c3 does as well as a c6, not even in the same league.
But if you want to significantly improve the c3, you have to start with the frame. The c3 frame is about as stiff as dried spaghetti noodles. It is the basis on which everything else depends. You want to talk about cornering and polar moment of inertia? Anything you do is pissing away money with a spongy frame. I've been saying for years that our frames are a suspension member (which they are) and that's a terrible way to make a car handle. I agree that the stock frame is not as stiff as we'd like. I've made mods to mine to stiffen it a bit, but the basic layout (and the small trans tunnel) doesn't lend itself to adding a backbone structure to stiffen it further. While the C3 frame will never be as stiff as the C6, I don't believe that singular issue is sufficient reason to throw in the towel and just leave the car in the crappy condition it was when it left St. Louis.As for braking, c3 brakes are pretty dang good, even by today's standards, but you just can't compete with ABS. You may be able to threshold brake, but you're simply making sure you apply the maximum amount of force for the strongest caliper. The other three calipers could have greater clamping potential but you're just trying not to lock up that one (whichever it is) caliper. The ABS cycles all four calipers at their greatest clamping ability.

I'm aware of how ABS works. My question earlier was how often does it actually come into play out on a dry road course.

 

[Corvettes White]

I have a C3 and a C5, which is the same basic architecture as the C6.

The C3’s are very well balanced front to rear about 50 – 50. I think the C5 and C6’s are about the same. However, I have to think that the polar moment of inertia is higher on a C6 making it less responsive to turns. The counter is that it would be more stable in a straight line.

The suspension, I do not recall how many links it has but a C6 has more that a C3. Better control?

The magneto radiological (sp?) shocks did not even begin to exist in the late 50’s early 60’s when the chassis was designed.

Which has a higher center of mass? Good question. Keep in mind that the frame on the newer car is aluminum, moving the CG up.

Sprung to unstrung weight ratio? I think that goes to the C6.

Chassis stiffness, any way you measure it, torsion, frequency, beam, as said above; the C6.

Adjustability? You can set the steering and shifter on a C3 both at two different ratios (Manual steering and 4 speed only)

Seats? The C5’s suck.

Aero, Drive a C3 and it literally starts to fly Hands down the new car, I think it has something like half the drag.

I think that you can only take a C3 so far. In the end you well have one great car, but some of the basic underlying frame construction issues are going to always be there.

George

 

[clutchdust]

I agree that the stock frame is not as stiff as we'd like. I've made mods to mine to stiffen it a bit, but the basic layout (and the small trans tunnel) doesn't lend itself to adding a backbone structure to stiffen it further. While the C3 frame will never be as stiff as the C6, I don't believe that singular issue is sufficient reason to throw in the towel and just leave the car in the crappy condition it was when it left St. Louis.

It will never, ever be on a similar level without a full roll cage to stiffen it up. Just way better design in the c6. I agree, that there's no reason to leave it in the same condition it left the factory. I like the backbone idea and have been working on such a solution myself. But I will never road course my car again. It's just not worth it.

I'm aware of how ABS works. My question earlier was how often does it actually come into play out on a dry road course.

Well, if you're doing it correctly, just about every time.