No torsional spec for rigidity found on the 2013 srT Viper

[vancouver-gts]

We all read about 50% stiffer chassis but no mention of actual specification for the 2013 Viper anywhere on the web.

here's some older specs on all cars, Veyron being stiffest of all

numbers claimed by the companies



Alfa 159 - 31.400Nm/degree
Aston Martin DB9 Coupe 27,000 Nm/deg
Aston Martin DB9 Convertible 15,500 Nm/deg
Aston Martin Vanquish 28,500 Nm/deg
Audi TT Coupe 19,000 Nm/deg
Bugatti EB110 - 19,000 Nm/degree
BMW E36 Touring 10,900 Nm/deg
BMW E36 Z3 5,600 Nm/deg
BMW E46 Sedan (w/o folding seats) 18,000 Nm/deg
BMW E46 Sedan (w/folding seats) 13,000 Nm/deg
BMW E46 Wagon (w/folding seats) 14,000 Nm/deg
BMW E46 Coupe (w/folding seats) 12,500 Nm/deg
BMW E46 Convertible 10,500 Nm/deg
BMW X5 (2004) - 23,100 Nm/degree
BMW E90: 22,500 Nm/deg
BMW Z4 Coupe, 32,000Nm/degree
BMW Z4 Roadster: 14,500 Nm/deg
Bugatti Veyron - 60,000 Nm/degree
Chrysler Crossfire 20,140 Nm/deg
Chrysler Durango 6,800 Nm/deg
Chevrolet Corvette C5 9,100 Nm/deg
Dodge Viper Coupe 7,600 Nm/deg
Ferrari 360 Spider 8,500 Nm/deg
Ford GT: 27,100 Nm/deg
Ford GT40 MkI 17,000 Nm/deg
Ford Mustang 2003 16,000 Nm/deg
Ford Mustang 2005 21,000 Nm/deg
Ford Mustang Convertible (2003) 4,800 Nm/deg
Ford Mustang Convertible (2005) 9,500 Nm/deg
Jaguar X-Type Sedan 22,000 Nm/deg
Jaguar X-Type Estate 16,319 Nm/deg
Koenigsegg - 28.100 Nm/degree
Lambo Murcielago 20,000 Nm/deg
Lotus Elan 7,900 Nm/deg
Lotus Elan GRP body 8,900 Nm/deg
Lotus Elise 10,000 Nm/deg
Lotus Elise 111s 11,000 Nm/deg
Lotus Esprit SE Turbo 5,850 Nm/deg
Maserati QP - 18.000 nm/degree
McLaren F1 13,500 Nm/deg
Mercedes SL - With top down 17,000 Nm/deg, with top up 21,000 Nm/deg
Mini (2003) 24,500 Nm/deg
Pagani Zonda C12 S 26,300 Nm/deg
Pagani Zonda F - 27,000 Nm/degree
Porsche 911 Turbo (2000) 13,500 Nm/deg
Porsche 959 12,900 Nm/deg
Porsche Carrera GT - 26,000Nm/degree
Rolls-Royce Phantom - 40,500 Nm/degree
Volvo S60 20,000 Nm/deg
Audi A2: 11,900 Nm/deg
Audi A8: 25,000 Nm/deg
Audi TT: 10,000 Nm/deg (22Hz)
Golf V GTI: 25,000 Nm/deg
Chevrolet Cobalt: 28 Hz
Ferrari 360: 1,474 kgm/degree (bending: 1,032 kg/mm)
Ferrari 355: 1,024 kgm/degree (bending: 727 kg/mm)
Ferrari 430: supposedly 20% higher than 360
Renault Sport Spider: 10,000 Nm/degree
Volvo S80: 18,600 Nm/deg
Koenigsegg CC-8: 28,100 Nm/deg
Porsche 911 Turbo 996: 27,000 Nm/deg
Porsche 911 Turbo 996 Convertible: 11,600 Nm/deg
Porsche 911 Carrera Type 997: 33,000 Nm/deg
Lotus Elise S2 Exige (2004): 10,500 Nm/deg
Volkswagen Fox: 17,941 Nm/deg
VW Phaeton - 37,000 Nm/degree
VW Passat (2006) - 32,400 Nm/degree
Ferrari F50: 34,600 Nm/deg
Lambo Gallardo: 23000 Nm/deg
Mazda Rx-8: 30,000 Nm/deg
Mazda Rx-7: ~15,000 Nm/deg
Mazda RX8 - 30,000 Nm/degree
Saab 9-3 Sportcombi - 21,000 Nm/degree
Opel Astra - 12,000 Nm/degree
Land rover Freelander 2 - 28,000 Nm/degree
Lamborghini Countach 2,600 Nm/deg
Ford Focus 3d 19.600 Nm/deg
Ford Focus 5d 17.900 Nm/deg

 

[Viper808]

viper looks like a wet noodle by comparison

 

[DMan]

Ok so according to that chart, if they increased rigidity by 50%, then the gen5 now has rigidity about equal to a 2005 mustang convertible!?! ***

 

[BlackSnake99]

At least the Viper was stiffer than the Durango.

 

[I Bin Therbefor]

We all read about 50% stiffer chassis but no mention of actual specification for the 2013 Viper anywhere on the web.

here's some older specs on all cars, Veyron being stiffest of all

numbers claimed by the companies

You don't happen to have this list sorted by stiffness rather than model name do you?

In addition, I need to do some serious research on this topic as GM made some heavy claims for the C5 Corvette stiffness when it was announced. However, I don't remember the metric that was used. I've got an SAE paper somewhere around the house on that.

 

[mnc2886]

Out of curiosity, has anyone ever accused the Viper of not being stiff enough?

I'm going to go out on a limb and say no, but let's see the responses.

 

[vancouver-gts]

For comparison to street cars, an F1 race car has 90.000 Nm/deg. My buddy won't be happy with his Lambo Countach's stat of 2.600 Nm/deg haha. I did see some stress cracks towards the roof next to the right air intake where my bald friend is looking, hmmmm?

You must be registered for see images

 

[TrackAire]

Something is not right with that list.

I own both a Viper coupe and a Mustang of the 2003 model year they've listed (coupe also). Before frame and chassis stiffeners, you couldn't open the door if you jacked up the Mustang from the front or rear jacking points. The Viper coupe you can lift the whole car from one spot. Notice no aftermarket frame stiffeners for the Viper...wonder why??

Also, the Rolls Royce on the list is a big heavy and long car....no way it is as stiff as listed.

Problem with torsional specs is this, I do not think there is any guidelines that the manufacturers have to follow. Does the SAE have a way to measure torsional rigidity that all manufacturers follow so we can compare apples to apples?

Most of the specs you see are for marketing purposes IMO.

Cheers,
George

 

[WDW MKR]

2003 Mustang coupe carries more than double the stiffness of a Viper? That discounts the entire list for me. I spent several years building my 03 Cobra and would bet my life savings against that. There's a reason that full-length subframe connectors are the first mod for those cars.

 

[WDW MKR]

Beat me to it!

 

[Makara]

It doesn't mention which model. Don't forget, three generations, now four with the 2013 model have had coupes. The Gen Is were rather flimsy. I wonder what it's torsional rigidity is. My GTS seemed considerably more rigid than my Gen I. Jacking up both cars, it was easy to see the difference. My Gen IV seems more rigid than my GTS was, once again, jacking up the car seems to show a lot. It is totally possible that the figure in this list is accurate, and I am guessing was from a GTS given that no other information was given.

 

[vancouver-gts]

I My GTS seemed considerably more rigid than my Gen I. Jacking up both cars, it was easy to see the difference.

There is still no global kind off ISO/DIN norm for car torsional-rigidity testing but I'm sure the engineers at Chrysler have the spec for torsional rigidity of our beloved Vipers tucked away somewhere. Here's an interesting link to read about structural tests of cars or vehicles. Page 11 take you to chassis testing giving an idea. Adding cross brace in the engine compartment can increase stiffness well over 1000Nm /deg alone. No wonder the 2013 srT Viper has it now! I wish it would be easy to add to my 99 without too much fabrication involved.

http://www.ika.rwth-aachen.de/ueber_uns/ausstattung-filme/pruefstandskatalog-fka-ika-e.pdf.pdf

 

[madninjaskillz]

Interesting list. I am wondering if there is a standard of measure. What kind of calibration tools are used etc? Also, list the model year of cars tested.

 

[Makara]

There is still no global kind off ISO/DIN norm for car torsional-rigidity testing but I'm sure the engineers at Chrysler have the spec for torsional rigidity of our beloved Vipers tucked away somewhere. Here's an interesting link to read about structural tests of cars or vehicles. Page 11 take you to chassis testing giving an idea. Adding cross brace in the engine compartment can increase stiffness well over 1000Nm /deg alone. No wonder the 2013 srT Viper has it now! I wish it would be easy to add to my 99 without too much fabrication involved.

http://www.ika.rwth-aachen.de/ueber_uns/ausstattung-filme/pruefstandskatalog-fka-ika-e.pdf.pdf

Your link looks interesting, I'll be sure to go through it later. Since I haven't read the whole thing yet, I may be repeating, but there are a few ways to measure torsional rigidity. What was in the list in this thread was predominately Nm/deg though I did see a few measurements from the Ferraris that had kg/mm. Clearly, wheelbase length throws a whole wrench into comparing the two measurements. Throw in what I am more accustomed to hearing, resonance in Hz of the frame, and there are three very different ways to assess torsional rigidity and bring in slightly different factors. What I do know is that the fastest production car around the nurburgring could quite possibly be a wet noodle, so go figure...

 

[WDW MKR]

It doesn't mention which model. Don't forget, three generations, now four with the 2013 model have had coupes. The Gen Is were rather flimsy. I wonder what it's torsional rigidity is. My GTS seemed considerably more rigid than my Gen I. Jacking up both cars, it was easy to see the difference. My Gen IV seems more rigid than my GTS was, once again, jacking up the car seems to show a lot. It is totally possible that the figure in this list is accurate, and I am guessing was from a GTS given that no other information was given.

If compared using the same methods, there is no way in hell a 2003 Mustang is more rigid than a GTS... It being listed as double laughable. The aforementioned points related to different measurement methods are likely one reason.

 

[DMan]

I know in one of the vids on the gen5, like Andretti or someone referred to the older gens as wet noodles, and I was like what?!?, but maybe this is what they were referring to. I've raced mustangs since the 80's, have had 8 of them. They are far more stable and handle way better than the urban legend of them snapping in two, but to think they come close let alone surpass the viper ... I don't get that at all. I have GT500 sitting right next to my gen4, both have been on-track, the GT500 is quite able-bodied, the viper is friggin shifter kart feel. And like posted above try jacking up a wheel on the gen4, the whole one side is in the air, lol, more rigid than an 18 yr old in a ***** house on 5 ******'s.

 

[vancouver-gts]

When we lift our Vipers we do it at the frame closer to mid section of the car, hence the whole car lifts on its side! Torsional rigidity is measured at suspension anchor points front to back. Would like to see a Chrysler engineer put his input here with Nm stats given on the new car. The low number for the older Vipers doesn't mean its worse than the Mini,a that has much higher number. The Mini being a short and boxy car like a brick! Looking at both C5 and Viper stats ,they are better comparos apple to apple.

 

[ViperSmith]

Looking at the numbers for other cars, was it a gen I or gen II? Seems like that is about par for the course for vehicles of that time period.

 

[VENOM V]

Although I agree torsional rigidity is important, it's only one element of a system that needs to work well together. I personally am not that concerned about what the number is, for the reason others have mentioned- that car companies may not measure it with the same method, so we may be talking apples to oranges. It feels like comparing HP to weight ratios, where some use tricks like using dry weight when we all know that wet weight is what matters.

The stat that I care about is the lap time, and that's the bottom line. Clearly, the Gen V, as a system, has been executed exceptionally well, as it was able to take the Laguna Seca production car record on R-compound rain tires (Corsas) Vs. others on R-compound dry tires (MPSC).

 

[vancouver-gts]

Looking at the numbers for other cars, was it a gen I or gen II?

The answer is Coupe!

 

[ViperSmith]

The answer is Coupe!

doh!

i'm on vacation, cut me some slack

 

[MoparMap]

I'm guessing a fair portion of those numbers may have come from computer analysis as well. I don't think many supercar producers that make less than a few hundred to a few thousand cars a year are going to buld a frame and throw it in a test jig just for a marketing number. I've been doing the same thing with the trucks I design. Been going through lots of analysis runs with different configurations and have some torsional rigidity info, but what it actually is in real life is a whole different quesiton. How you constrain models and apply loads has a lot to do with the results you get back. For isntance, we get different torsional numbers based on which end of the frame you fix (fix the front suspension and twist the rear or fix the rear and twist the front). I've always said you can make analysis tell you whatever you want, it's backing it up with real world testing to validate your answers that really matters.

 

[vancouver-gts]

I've always said you can make analysis tell you whatever you want, it's backing it up with real world testing to validate your answers that really matters.

Did you read through the link I've posted? It shows more than just computer analysis testing! In the days of ISO certification one would think there's a benchmark testing for cars in general. Especially for high end sport cars with more than average HP ratings. I'm just curious what our cars stand against others in the same class.

 

[MoparMap]

Wow, I didn't look through the whole thing till now. That's some pretty impressive test setups they've got.

I'm not saying that companies don't perform actual physical testing, I just suspect that not all the numbers on that list are from actual physical tests. Back in the day I believe it was Porshe who wouldn't import one of their really high end cars to the states because they refused to crash one for highway safety testing. I have a feeling some of these super exotics (something like a Veyron or Zhonda that they make less than a few hundred a year) would be of the same mindset that they aren't going to build a car just to ruin it through testing. I'd think a smaller exotic company would have a hard time footing the bill to build a several hundred thousand dollar car just to twist the crap out of it for a marketing number.

 

[vancouver-gts]

. Back in the day I believe it was Porshe who wouldn't import one of their really high end cars to the states because they refused to crash one for highway safety testing.

Yes it was the Porsche 959. Reason I brought the question up was that I've read about the Ultima GTR. The Chassis were uprated to fix torsional rigidity that had some issues on earlier models. Friend had an earlier model GTR with 383 stroker that felt a bit like a wet noodle high speed cornering. Also, I've read the Australia is getting strict on imports. Another friend has a 2007 Noble M400 that feels solid like a brick on twisty roads.

Link to the Ultima GTR http://www.ultimasports.co.uk/Content.aspx?f=gtrintro

 

[Mister Viper]

First off -

Let me compliment you, Vancouver GTS, on your meticulous research. Impressive effort! Like you, some of us are avowed fans of an "appropriate level of" structural stiffness, for very important engineering reasons. The trick is figuring out the best stiffness vs. (inevitable) mass-add trade-off in a sports car.

Now for the bad news, don't believe everything auto companies tell you, nor all the 'data' journalists publish. As an example, some of our journalist friends do not understand even the difference between 'curb weight' and 'dry weight'!.... (all fluids are included in curb, in case any of you were wondering..., and SRT will ONLY talk about curb weight - dry weight is irrelevant). So consider the weights reported by some Italian and English supercar builders with appropriate suspicion.

Back to structrual stiffness, according to the "data" you show above, the new Viper must have gained well over 100% stiffness increase! Dang, we should have claimed that!! (kidding). Actually, our lab test data showed that the old car was better than your list indicates, and that we have further improved the all-new Gen 5 space frame by (well) over 50%. And, we also lightened the space frame significantly too! But, because we realized that this data was becoming an issue of competitive intelligence, we at SRT decided early on that we would not publish this information for the all new Gen 5 Viper spaceframe; rather we would just share directional indications. You can understand why.

We believed that a significant increase in structural stiffness, as well as a dramatic decrease in curb weight, would yield an amazing 'light on it's feet" performance for the new Gen 5 Viper. And, having just spent more time driving this car ******* the track this week, I think we succeeded; the Gen 5 Viper is amazing on a track, and runs hard all day long - this car is an amazing and proven (time and again) track warrior.

But, please go drive the Gen 5 Viper for yourself, and tell us if you believe we have achieved the right balance between stiffness, and lightweight. In contrast, the Audi R8 is even stiffer than a new Viper. But the Audi is also hundreds of pounds heavier (despite a much smaller motor). And slower. Not knocking VW's decisions, just sharing some data. You decide for yourself what you enjoy more! (and please let us know).

(and, as always, thanks for listening)

 

[vancouver-gts]

Mister Viper, thank you very much for your response! Information is never accurate from dealers be a car, boat or any vehicle albeit one would expect correct info from the actual manufacturer. It sounds like the Viper has gained tremendous improvement over the gen 1 and II as chassis design. I understand the decision made, quote; "we at SRT decided early on that we would not publish this information for the all new Gen 5 Viper spaceframe; rather we would just share directional indications. You can understand why". I'm looking forward to test drive the Gen V at my local srT dealer. Driven the AudiR8 and it's a great car with manual transmisson but the overall design doesn't blow me away like the GTS did! Again ,thanks for the quick response!

 

[Stuntman]

Digging up an old thread.

After a quick search, i found a few quotes and extrapolated the relative stiffnesses to try to figure out the torsional stiffness of the Gen 2:


1992 RT-10:
"The Viper has a high driveline tunnel, which also houses structural members that help account for its outstanding 5000 lb-ft-per-degree torsional stiffness."

http://www.roadandtrack.com/new-cars/first-drives/reviews/a6319/flashback-1992-dodge-viper/


1996 Second Gen (GTS):
"The second-generation Viper included engine modifications to add power, while reducing weight by 50 pounds. The Viper chassis was reengineered to eliminate 60 pounds in comparison to its predecessor, yet provide a 25 percent increase in torsional rigidity."

http://www.drivesrt.com/news/2014/01/viper-heritage-the-first-decade.html


1996 RT-10 (Same chassis as 1996 Gen-2 GTS, but with 400hp Gen-1 engine)
"The changes, however, go deeper than cosmetics. With the goals of shaving excess weight and improving high-speed control, the Viper team was able to trim about 200 pounds from the car while improving the frame's torsional rigidity by about 25 percent."

http://www.motortrend.com/roadtests/exotic/112_9509_1996_dodge_viper/


2003 SRT-10:
"This drivetrain rests in an updated chassis that offers a 31-percent increase in torsional rigidity (Dodge claims it's stiffer than the outgoing 2002 GTS Coupe)."

http://www.edmunds.com/dodge/viper/2003/road-test.html


2003 Comp Coupe:
"The Comp Coupe team started with the 03 Viper frame, but “chopped some parts off and added a cage,” says Petersen. It has a safety cage of 1.75-inch-diameter 4130 steel tubing with a 0.095-inch wall thickness. The cage protects the driver and ties into rear suspension attachment points. It also works with special X-, V- and diagonal bracing underhood and an aluminum rear bumper to double the car’s torsional stiffness. The effort reportedly improves the carÂ’s resistance to beam flex by 60 percent."

http://www.edmunds.com/dodge/viper/2003/road-test.html


2006 SRT-10 Coupe:
"Torsional rigidity is expected to improve by about 30 percent, which is likely to pay off with crisper handling."

http://www.motortrend.com/roadtests/coupes/112_0502_2006_dodge_charger_viper/exterior_engine.html

"Unlike most other coupe/convertible vehicles, this generation of the Viper was developed as a convertible first; therefore, the already impressive torsional rigidity of the convertible has been improved by about 30 percent with the addition of the solid roof."

http://www.car.com/content/shared/a...order_int/2/article_id_int/435/make_vch/Dodge

"Of course the Viper Coupe's real performance payoff over the roadster is its stiffer overall structure. Rather than the convention of building a convertible model from a hardtop, Dodge began with the already reinforced roadster and constructed the coupe to extremely high torsional rigidity tolerances. It features a backbone tubular space frame with separate cowl structure, plus SMC and RIM body panels, aluminum sills, RIM front and rear fascias with composite impact beams. In English, the 2003 roadster was 31 percent stiffer than the old roadster, and even more rigid than the old GTS coupe. The new coupe should be rock solid.

https://www.auto123.com/en/news/2006-dodge-viper-srt10-coupe-preview/42887/?page=5


2013 Gen V:
"Rumors that Chrysler would switch to the Alfa Romeo 8C’s platform turned out to be untrue, and the car rides on the same steel structure as did the last generation. Its wheelbase is unchanged and the aluminum front suspension is only slightly tweaked, but the front track gets wider and the rear suspension geometry is new. (The rear suspenders are also aluminum.) More important, an underhood X-brace headlines a 50-percent increase in torsional stiffness."

http://www.caranddriver.com/news/2013-srt-viper-photos-and-info-news

"The carbon fibre X-brace under the hood improves torsional rigidity by 50 per cent" -Seems like the X-brace is the main difference to the SRT-10 chassis and primary reason it has a stiffer chassis.

http://driving.ca/dodge/viper/auto-news/news/srt-unveils-2014-viper-time-attack

"Without increasing cost, enhancing the torsional rigidity and lowering the curb weight contradict to each other. Initially, the engineering team planned to increase the torsional rigidity 100% more than the previous generations. But due to a tight development time frame (2 years) and limited budget, the team can only achieve a 50% rigidity enhancement in the end. You can check out our extensive data list here, the current Viper’s torsional rigidity is only 11,400 nm/deg, not very good for sports cars in this price range.

Another effort the engineering team made to lighten the weight is the V10 engine. IT is now 100 lbs lighter than the one found in previous generations.

During the design phase, at one time the engineering team even considered using aluminum to build the car chassis. But the drawback to that would lead to a $20,000 increase of the final MSRP, so the idea was abandoned. There is other reason that the aluminum chassis design is not accepted, due to the fact that when the Viper was under development, the C7 Corvette Stingray was not in the market at that time, so the benchmark is set to the C6 Corvette, and the frame of the C6 (except the Z06 and ZR1) is not made of aluminum. For your reference, the SRT Viper’s chassis is using the same OEM supplier that makes the space frame of the Chevy Corvette.

Furthermore, if Chrysler had decided to use aluminum, it is not that simple to use the same chassis design while using steel rather than aluminum. This is due to different physical characters of the aluminum, and you cannot use the same design to achieve similar strength and rigidity requirements. Therefore it needs a completely new design and new production equipment. Obviously for such a short development period and low project budget, this is impossible."

http://blogs.youwheel.com/2014/05/07/the-design-of-srt-viper-some-insider-information/

Actually, our lab test data showed that the old car was better than your list indicates, and that we have further improved the all-new Gen 5 space frame by (well) over 50%. And, we also lightened the space frame significantly too! But, because we realized that this data was becoming an issue of competitive intelligence, we at SRT decided early on that we would not publish this information for the all new Gen 5 Viper spaceframe; rather we would just share directional indications. You can understand why.

The Audi R8 is even stiffer than a new Viper. But the Audi is also hundreds of pounds heavier (despite a much smaller motor). And slower. Not knocking VW's decisions, just sharing some data.

Audi R8 (2014 – ) 40,000
Dodge Viper Coupe (2008 – 2010) 7,600
Dodge SRT Viper (2013 – ) 11,400 - that's a 66.7% increase, which can be called '(well) over 50%' increase in torsional rigidity. If true, it's still very low and half of a 458 spider.
Ferrari 458 33,120
Ferrari 458 Spider 23,184 (70% of the Coupe)

http://blogs.youwheel.com/2014/04/25/car-body-torsional-rigidity-a-comprehensive-list/ -A more comprehensive list of various cars' torsional rigidity.


If the above is true, then so should the following (depending on how you interpret the quotes regarding the SRT-10 Coupe to determine the Gen 2's stiffness):

RT-10 (1992-1996): 5,000* - 3,569 (Calculated from above relative stiffness, this is incorrect, so the 'relative' stiffnesses are wrong)
RT-10 (1997-2002: 6,250 (25% more than Gen 1) *It's probably less since I would bet MotorTrend took the 1996 GTS' press kit and mistakenly used it for the 1996 RT-10. The GTS would have to be stiffer and IS said to be 25% stiffer than the Gen 1, so I would imagine the RT-10 is still at or slightly more than 5,000lb-ft-degree.
GTS (1996-2002): 6,250 (25% more than Gen 1)
SRT-10 Convertible: 6,550 (31% stiffer than RT-10, and stiffer than GTS *Sounds about right) 5,845 (30% softer than SRT-10 Coupe *Think its wrong)
SRT-10 Coupe (2008 – 2010): 7,600*
Comp Coupe: 11,690 (double the SRT-10)
SRT Viper (2013 – ): 11,400*


Here's a list (in order) of notable sub 10K nm/deg cars:

Lamborghini Countach 2,600
Lotus 33 3,253
Chrysler Sebring (convertible) - 4400
Ford Mustang Convertible (2003) 4,800
BMW E36 Z3 5,600
Lotus Esprit SE Turbo 5,850
Mazda MX-5 (NA 1st-gen, NB 2nd-gen) 6000
Chrysler Durango (not the latest generation) 6,800
MG MGF 7,100
Honda S2000 7,100 (rumored)
Lotus Elan 7,900
MG MGTF 8,500
Mazda MX-5 (NC 3rd-gen) 8800
Lotus Elan GRP body 8,900
Mini Cooper Convertible (1st gen) 9,000
Chevrolet Corvette C5 9,100
Mazda RX-7 (FB) 9150
Ford Mustang Convertible (2005) 9,500

http://www.s2ki.com/s2000/topic/722146-nc-miata-vs-s2000-cr/page__st__50


Other random, unverified tid bits of info:

Z06 bending frequency = 24hz
Z06 weight distribution = 51 front / 49 rear
Viper SRT10 bending frequency= 27hz
Viper SRT10 weight distribution = 48 front / 52 rear

and just for a laugh so you get an idea of how strong these cars are.....
(these might not be right)
'02 Camaro Z28 bending frequency = 14hz
'02 Camaro Z28 weight distribution = 56 front / 44 rear
'03 Mustang Cobra bending frequency = 16hz
'03 Musting Cobra weight distribution = 57 front / 43 rear

http://www.z06vette.com/forums/f5/stiffer-frame-gen-ii-viper-srt-10-viper-z06-58502/



...There's a reason why the majority of cars are unibody. Much stiffer than the frames used on the Viper. Then again, NASCAR still uses frames...

 

[ViperJeff]

damn..... you spent some time on this

 

[MoparMap]

That's another interesting question. Are stiffness values measured as a fully assembled car or just a frame? As mentioned in a few posts, a unibody style car or one with bonded panels on a frame will likely have increased stiffness over just a bare frame like the Viper uses. While the Viper panels aren't necessarily intended as structural members, I would still attest that they offer some increased rigidity to the structure.