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Old 07-28-2013, 06:05 PM   #1
bob53
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Default How is GM going to reduce the curb weight of the future Hi-Po C7?

Hoping to spur some insightful discussion re: how the general is going to reduce the curb weight of the next Z car? I am not looking for a C6 vs C7 debate...

Now that the cat is out of the bag, it is clear the base C7 puts up some impressive numbers. The only disappointment for me is the weight gain. That was not a step in the right direction. A fully loaded C7 Z51 is now north of 3400 lbs.

While it is clear that some of the weight gain was important for improved tract performance (E-diff, suspension, driveshafts), it still seems like they could have saved a bit more by making the car a bit smaller (that ship has sailed obviously). What concerns me most is that the same strategy used to reduce the mass of the C6Z cars is already in place with the base C7. The frame is already aluminum and there is already quite a bit of CF body panels. Just looking at the weight manifest, perhaps they could loose 50-75 lbs with more CF body panels, less sound insulation, use of Ti for the exhaust, and perhaps dumping the AFM and swapping the steel torque tube for Al or CF. However, they are likely to gain 150+ lbs with either a larger displacement motor or one with a supercharger, brakes, and larger rims/tires. Are we going to see a 3500 lb Z car? For people who track their cars, that's going to be disappointing even if it does post some crazy numbers.

Just curious if you see GM being able to drop more weight from the car than this?
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Old 07-28-2013, 06:16 PM   #2
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You touched on some of my thoughts already.

They will ditch AFM and lose maybe 10-15 lbs.
Aluminum Tq tube will help a lot (was it 38 lbs?)
Hopefully they go back to Ti exhaust...but the performance to cost factor just may not be worth it since the base systems already flow so well and Ti cost so much.

But yes they are gaining weight with a blower, bigger (at least wider) wheels and tires and bigger brakes. If they are smart they may be able to but a great braking system on without a huge weight penalty.

I expect more lightweight materials here and there...more CF bod panels, maybe some other materials they have here and there etc....If it's not any lighter, and has a blower....I wonder if they will call it a Z06. Name plate is to popular to abandon at this point.
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Old 07-28-2013, 06:49 PM   #3
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A larger bore/stroke LT1 won't make a weight difference.
I am hopeful for no AFM, more cubes, ~400-427, more compression, higher flow heads with valvetrain(and rotating assembly) suitable for 7000+ rpm... Widebody fenders for sticky 285/345, aluminum torque tube, ti catbacks, more swaybar, splitter, side skirts, etc.

Who knows, maybe the high perf. Model will introduce a DCT, not that i care for one.
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Old 07-28-2013, 07:27 PM   #4
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If it's FI, then yes, we'll see a 3500 lb hi-po variant.

I do hope they ditch the AFM, cast exhaust manifolds, steel torque tube etc and recover that weight. But as you point out, they'll give it back in supercharger, intercooler, heavier axles, heavier diff etc. components.

I just think folks are going to have to come to grips with the fact that given the improvement in interior and sound insulation the 7 is simply going to be a bit heavier than the 6. Those refinements add weight. Given the focus to push the 7 toward a younger and possibly more import oriented customer, I don't see them making a "stipper" Z variant.

It's simply going to be heavier than in the past.
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Old 07-28-2013, 08:26 PM   #5
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Excellent posts by all you guys. Let me say this, if SRT can cut weight I'd like to think GM can.
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Old 07-28-2013, 08:35 PM   #6
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I agree with posts 1, 2, and 4

A) the 2015 C7Z's performance will be outstanding

B) It will be heavier than the base C7, for reasons mentioned in 1, 2, and 4.

The days of Dave Hill and his lightweight Z06s have passed.


.

Last edited by ZL-1; 07-28-2013 at 08:37 PM.
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Old 07-28-2013, 08:40 PM   #7
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I specifically recall Team Corvette saying 'each gram of weight had to earn it's way onto the C7 Stingray'. One might reasonably conclude from that statement that the C7 is as light in weight as TC could make it. Hi Pro variants are likely to add weight from the high pro 'sources' whatever they may be. Are there still sufficient weight offsets that can be made with reasonable cost consequences? I don't know?
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Old 07-28-2013, 08:54 PM   #8
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Ive thought about this a lot.

At first i was angry when i found out the c7 base car was heavier than previous cars, and had already used an aluminum frame and carbon body parts because I saw little hope for the z06 or zr1 to lose further weight.

But after further thought, i saw the glass half full instead of half empty.

If one comes to the reality that 55g gets all of these amazing things stock (aluminum frame, carbon body)... then another 55g will ultimately result in the ability to afford the following...

1. Carbon ceramic brakes. (while they may not be lighter by the time you upgrade their size, you can still break even or maybe shave a couple pounds. Usually its the caliper that weighs the most however, not the rotor, so odds of losing weight are slim, instead of just breaking even)

2. Magnesium spoke/carbon drum wheels (callaway has used them on their cars in the past)

3. Carbon race seats (still a lot of weight in the stock seats)

4. Carbon fiber dash board and interior (im not talking the facia that snaps in... I'm talking the firewall... the glove box... everything... the door handles, the inner door panels... the center console arm rest lid... everything still has an opportunity to lose weight)

5. Magnesium and carbon in the frame. (the c6z06 had a magnesium front cross bar as the frame. Magnesium is very rigid, and very light. There is no reason magnesium couldn't be substituted in the frame to bring it more rigidity, and also lighter weight. Carbon can obviously also be used.

6. Technically, if you bore out the engine to a bigger displacement, you are removing material (correct me if im wrong) So you drop a couple pounds there, but then you put a blower on top and gain even more back.

7. There are a number of other parts you can make out of aluminum, titanium, magnesium, and carbon. For instance... if you wanted to spend the money on the steering rack, im sure one of those materials could be used to make it lighter. If you wanted to reduce the weight of the sway bars, one of those materials can make them lighter. Same goes for the shocks, springs, etc.

8. I believe we are going to get a lightweight double clutch trans like porsches PDK. I dont see how corvette is going to let all other race teams go to PDK stock and still be stuck forcing their drivers to spend time shifting gears.

9. Titanium exhaust, and without all the complicated valves etc. A z06, or a zr1, will probably just come loud... standard single option. When one looks at the corsa extreme's and how they reduced their size, there is no reason a z06 exhaust shouldnt do the same thing. GM dropped the ball making the c6 z06 exhaust lighter like they did on the c5z06. I have a feeling they wont overlook this again. If they wanted to get really radical, they could have the exhaust exit out the sides of the car just behind the front wheels. Do i think this will happen? No. Do i think its a last option way they could save weight and also turn a few heads. Yes.

10. Fuel tanks out of carbon fiber perhaps? Don't know if this is possible or what one would have to coat them with on the inside so they wouldn't deteriorate.

11. Torque tube. I think if they messed with it, they will go to carbon fiber. They didn't go to steel for no reason... the tubes twist and fail on high hp c5 and c6... so they were obviously spooked about this on the c7. aluminum is too soft. Personally, I think they will just leave it steel, but I hope im wrong and it comes standard in carbon fiber.

12. Carbon Drive shaft. Hell, if you rubber mounted the ends, you could also do a magnesium drive shaft. I think Chevy is in love with carbon implementation on this car however. Frankly, magnesium is probably more expensive. (i will go ahead and ask the question then, on an apples to apples part, like a beam or a circular tube, which is more expensive, carbon or magnesium?)

In summary, While i was originally worried about shaving weight on the upgraded models, it finally dawned on me, that for another 55g... and dont forget we are talking a "mass produced 55g" ... there is a lot to be had.

I am glad chevy did the most they could do with the 55g for the base car, instead of ask "well then how will we make it better for the upgraded versions?!"

In the end, that is proper engineering and that is proper advancement, to not hold back on the base car, do your all, and then when the piggy bank allows, go back and do even better once you've had time to let the dust settle.

This car will become faster, more rigid, and possibly, even lighter.

And if it doesn't become lighter, I still believe it will gain very little weight, and I feel there is enough performance upgrade possibility to TREMENDOUSLY increase actual performance numbers and track times on the z06 and zr1 models.

Last edited by irun4cops; 07-28-2013 at 09:56 PM.
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Old 07-28-2013, 08:59 PM   #9
george vee
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Gm may do what they did with the 2014 Z28 Camaro. No radio,no trunk lining ETC.
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Old 07-28-2013, 09:23 PM   #10
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The performance C7 will shed sufficient weight. You can count on this.
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Old 07-28-2013, 09:32 PM   #11
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Quote:
Originally Posted by b4i4getit View Post
The performance C7 will shed sufficient weight. You can count on this.
i guess thats the end of the discussion guys, everyone go home now
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Old 07-28-2013, 10:35 PM   #12
MikeG37
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A carbon fiber tub center section. Similar to MclarenClick the image to open in full size.
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Old 07-28-2013, 10:37 PM   #13
Michael A
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Quote:
Originally Posted by george vee View Post
Gm may do what they did with the 2014 Z28 Camaro. No radio,no trunk lining ETC.
Let's hope not. That's a pure track car.

Michael
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Old 07-28-2013, 10:45 PM   #14
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The Stingray fairy came to me in a Fosters-induced dream on my pool floatie today and told me the following:

The Hi-Po Z-version will solve the "weight issue" three ways; 1) Blower on the LT1 to become at LT4 with 700 HP, 2) wider rubber under new front fenders and new rear quarter panels, and 3) 200 lb.s of weight savings by using ALL carbon-fiber body panels (the moldline has to change anyway), acrylic rear windows in place of glass, and a bolted-in roof panel to allow some weight reduction in the aluminum chassis without losing stiffness.

It will be an awesome track machine with few compromises for the street - think Z06 on steroids.
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Old 07-28-2013, 10:47 PM   #15
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a blower and wider tires add weight...

and last time i checked, the body panels were already carbon fiber.

I believe the part about the beer fairy tho.
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Old 07-28-2013, 10:51 PM   #16
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I hope (but not holding my breath) the 7 hi-po model has a bolted in roof. Not just for the weight savings but for the rigidity benefits. My ZR is over 3 years old and doesn't squeak, groan or rattle. She's tight; benefit of the bolted roof IMO. With the 7's better frame it'd be even better with a bolted in roof. I understand there are a lot of targa fans, even for the hi-po variants, and b/c of that, I won't be shocked if with the better frame it's a targa. Just hoping it's not.
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Old 07-28-2013, 10:51 PM   #17
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I would imagine even more carbon fiber throughout the car as well as lightweight wheels, carbon brakes, etc. I also wonder if they're going to go the Z/28 route and really put the car on a diet?
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Old 07-28-2013, 10:56 PM   #18
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Quote:
Originally Posted by irun4cops View Post
a blower and wider tires add weight...

and last time i checked, the body panels were already carbon fiber.

I believe the part about the beer fairy tho.
You should have seen her - just like the green Absinthe fairy in Moulin Rouge, but larger parts in a tiny G-string !!

I was thinking ALL the body panels - front fenders, rear quarter panels, aft deck, etc. In the base C7 these are heavier Sheet Molding Compound, (SMC). They probably could save a lot of weight by getting rid of the sound insulation, (astroturf in the wheelwells, etc), and other NVH measures, and using the radio active audio cancellation more aggressively.
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Old 07-28-2013, 11:26 PM   #19
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Quote:
Originally Posted by MikeG37 View Post
A carbon fiber tub center section. Similar to MclarenClick the image to open in full size.
Yup, this would work too, but I don't think GM wants to sell a car for $ 250K.

IMHO, the McLaren F1 and MP4-12C are the two best engineered sports cars the world has ever seen. Ferrari, Lamborghini and Porsche try hard but don't really come close to Ron Dennis's designs. I dream about driving a MP4-12C someday, but I dream about various movie starlets too. At my age, it probably ain't gonna happen. BTW, Jay Leno has the same opinion, and owns one of each !!

The similarity between the McLaren and C7 chassis arrangements is striking....I wonder if Juenter benchmarked the 12C chassis ??
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Old 07-28-2013, 11:28 PM   #20
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Here is the manifest:

http://forums.corvetteforum.com/c7-g...ght-gains.html

I'll take a stab at what I think they might do to loose weight while keeping the cost low using similar molds or technology in hand. These are nothing more than my guesses:

1. Torque tube (back to AL or CF) = -15 lbs or more
2. Remove AFM -(5 for valves + ~10 in the engine) = -15 lbs
3. Lightweight seats = -25 lbs
4. Ti Exhaust without valves = -20 lbs
5. Low mass rims = -15 lbs total
6. Smaller battery = -10 lbs
7. Additional CF body panels = -10 lbs
8. Lower weight or Lexan rear window = -20 lbs
9. Additional Magnesium in the Frame or Suspension = -30 lbs
10. Reduced sound absorbing material = -15 lbs
11. Increased use of Alacantra in the interior = -5 lbs
12. Deletion of the hardware for a targa top = -10 lbs

Total Savings for minimal additional cost = -190 lbs = 3250 curb weight

Additional weight saving could be had by more extensive use of CF, Magnesium, and Ti. I think these things would add a lot to the MSRP but would certainly be great ways to drop the weight...
1. CF tub = -30 lbs?
2. Ti Exhaust Manifolds -30 lbs?
3. CF interior = -50 lbs?

Weight adding or weight neutral items:
1. Carbon ceramic brakes - They'll probably draw from the same parts bin as before on the ZR1 and Z06 Carbon = hopefully weight neutral.
2. Larger displacement motor = + 10 lbs vs FI = +80 lbs
3. Wider tires = +20 lbs

That would suggest a NA Z car could come in around ~ 3300 and a FI Z car would be ~ 3350 (hopefully) using relatively inexpensive weight saving mods. 3200 lbs would be possible on the C7 platform but the cost probably starts to rise dramatically.

I'm skeptical about them going all out with a CF interior and tub and other more extreme measures because the sales volume of the C6 Z06 and ZR1 was not that strong. Hard to know how much of the economic downturn of the country impacted these numbers, but as the Z06 rapidly increased in price, the production numbers sharply fell. By the end, a well-optioned Z06 carbon cost nearly 6 figures! I think the general needs to figure out how to give us more performance for less additional $$$.

I worry the same dismal sales production volumes are going to plague any sports car that is priced above 6 figures. The market for a car like that is not going to grow.
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