Published, but true?

[LongTimer]

Corvette Magazine is an all gloss rag that has great pics and some nice articles. I have subscribed since their inaugural issue about 1.5 years back. Here's what was in the latest issue:

Warren, Mi -- As the C6 Corvette's January '04 debut gets closer, it's becoming harder and harder for GM to sit on the car's details. Most recently escaping are word of still another exterior redesign (erasing the validity of the last flurry of artists' rendering a year ago); fixed high-discharge headlights; 400-odd base horsepower from an LS6-based engine named LS2; and a reduction in weight of about 300 pounds, give or take a full tank of gas. The latter results from a new lightweight, variable thickness hydroformed alluminum frame and the extensive adoption of low-mass materials and assembly methods throughout the car. In addition to the frame, the C6's glass, wiring, suspension and interior ar also considerably lightened.

Good news even if they are only half right about the weight.

 

[LMN8R]

An aluminum frame would be a huge step in the right direction. If this is the case, then Corvette will raise the bar once again on performance, and we'll soon have to deal with faster Vipers and 911's.

That is a good thing, because everything will be getting faster...

 

[ROCKETBLOCK]

Good info!!! Interesting.

 

[Hib Halverson]

Corvette Magazine, clearly, is the best of the Corvette print media right now...far, far ahead of the two Primedia rags, Vette and Corvette Fever, and (at least for now) a cut above the new (and as yet untested) Corvette Enthusiast.

I think "Corvette" has the C6 "story" fairly accurate.

Some of the "chatter" I hear from my intel sources is that the spy shots (mainly Jim Dunn's stuff) which have made the rounds in print lately may not be truly representative of the C6 exterior and may even be "red herrings". Other sources say what's in the spy shots is the camoflagued version of what we'll see at the GM display in Cobo Hall in Detroit next Jan.

I've been saying for nearly two years that the C6 base engine will be a six-liter at about 400hp. Looks like things are headed that way. As far as the base engine (RPO LS2) being an LS6-based unit, I'm not so sure it's as much LS6-based as it is a derivation of the overall Gen 3, aluminum-block design (LS1, LS6, LM4) with enough improvements and changes that it is called "Gen 4".

No doubt whatever changes are in store for the engine in the 06 car, the lion's share of them will go towards doing a motor which has 400hp in a six-liter package which offers the base C6 owner the increased performance a platform changeover should bring along with the refinement and fuel economy C5 owners have enjoyed. Word is that variable valve timing has been nixed because it makes the car's exhaust note unattractive. For an engine to gain 500cc and 50hp while meeting more stringent exhaust emissions standards and have fuel efficiency the equal of the C5, it going to need further improvement in combustion dynamics and engine controls along with, perhaps, the addition of GM's "Displacement on Demand" feature which arrives on truck V8s next year. Scuttlebutt is that GM will reveal the Gen IV story to media in about 45-60 days, so I'd expect to see lots of official information on the LS2 in late fall or during the winter.

As for "Corvette's" claim that there's been "still another exterior redesign", I think the magazine is all wet, there. At this point (or even six months ago for that matter), it's way, way too late in the program for a change in the exterior design of the car other than very minor details. I suspect the major design features of the C6 have been set for some time. In fact, even the much rumored redesign that was supposedly ordered by Bob Lutz right after he came onboard at GM probably never happened, or at least not nearly to the extent that many of my media friends have characterized.

High-intensity discharge, fixed mount headlights are a virtual certainty. Not soon enough as far as I'm concerned, too. C5 headlights have sucked since 97.

As for the aluminum, hydroformed frame...that got out when reports surfaced of a GM supplier ordering tooling to manufacture hydroformed aluminum. My fearless forcast is the base C6 will not have that. I think its frame will be based on the existing C5 frame which is steel. The performance version of the C6, which many think will continue the Z06 RPO, will be the car that has the mass-saving alum. frame.

What else will be see? No doubt loading of the car with more gadgets, especially, telemetric stuff. Oh Lord...just what we all need.

While I don't think there's going to be any huge changes in the car's structure or suspension...at least not the huge change C5 was from C4... I believe Corvette Magazine has it right when it mentions more extensive use of mass reducing materials and manufacturing techniques. In fact, it may turn-out that the magazine understated that a bit. Confronted with carrying-over the car's basic architecture, one way to gain performance is to lighten things up. Face it: as long as corporate GM mandates the Corvette will not cost its owner the Guzzler tax, the "low-hanging fruit" (ie: a huge but inefficient engine--a la Dodge Viper) is gone as far as making the car accelerate quickly. Further downsizing of electronics and more multiplexing will shed some more of that weight. Taking weight out is as good as adding torque output so GM is spending its money wisely when it does that.

I can hardly wait for the C6. It's gonna be awesome.

 

[CFour]

Every Production car must be road tested in the real world. It must have all its production pieces attached in order for it to be properly tested/evaluated. The cars seen in the Dunn photos are real C6s with paste on fake rear ends etc. It is way to late in the pre production process for them just to have drive train mules testing.
This is not to say that some of the exterior pieces may change slightly to production. The engine will in fact be a 6.0L pushing 410HP. The frame will be as the Cadillac is and not alloy the first 2 years. Expect the same basic electronics as the Cadillac only a little less trickery. The body is very pretty, the interior is nicer then C5 but still only just fair for a 60K car in my opnion.

 

[LongTimer]

As for the aluminum, hydroformed frame...The performance version of the C6, which many think will continue the Z06 RPO, will be the car that has the mass-saving alum. frame.

Thanks for your views Hib, and yours too Ross. Both are very logical given the information stream we have seen ... with the exception of the Al HF frame for the C6 Z06. Engineers have repeatedly told me that the replacement of the steel HF frame with Al is NOT a simple substitution, but rather would require a complete redesign of the structure due to the VERY significant difference in tortional rigidity factors of Al and the current steel. Meaning - a whole new chassis is required for the AL HF Frame.

Unless the GM plan is to produce a car with a completely different structure along side the "standard", non-Al car, it seems more likely, to me, that when the Al HF Frame arrives, it will be standard in everything produced at BG.

That said, how likely is it that the XLR & Vette will undergo complete structural changes and keep their same skins? So, I think we're talking C7 for the Al frame. KEY QUESTION: Does this mean a short life for the C6- despite what we've been told?

 

[Hib Halverson]

Engineers have repeatedly told me that the replacement of the steel HF frame with Al is NOT a simple substitution, but rather would require a complete redesign of the structure due to the VERY significant difference in tortional rigidity factors of Al and the current steel. Meaning - a whole new chassis is required for the AL HF Frame.

I totally agree that aluminum's strength to mass ratio is not as good as steel's. I also agree that a simple substituion of materials would be inadequate. Clearly, some additional changes would be required to get the same numbers in torsion and bending you'd see with a steel frame from an aluminum frame.

That said, I have other intel which says that the manufacturing process at BG is being readied for a "Z06 frame". The implication of that is that the Z06 frame is specific to the car and that, in-turn, implies that the frame might be made of aluminum.

My guess is that whatever other changes are required, besides material, will be acomplished such that two frames can be built on the same line.

My fearless forecast is the 06 Z06's back bone structure is aluminum and the 05 coupe and convertible use steel. I guess we'll find out in about two years.

I don't think the alum. frame will wait until "C7". If that was the case, there wouldn't have been reports in the materials and manufacturing process press a while back about a GM suppier being given orders for aluminum frame parts. Also, I don't think the 05-car's life-span will be much different that is the 97's.

 

[LongTimer]

I totally agree that aluminum's strength to mass ratio is not as good as steel's. I also agree that a simple substituion of materials would be inadequate. Clearly, some additional changes would be required to get the same numbers in torsion and bending you'd see with a steel frame from an aluminum frame.

That said, I have other intel which says that the manufacturing process at BG is being readied for a "Z06 frame". The implication of that is that the Z06 frame is specific to the car and that, in-turn, implies that the frame might be made of aluminum.

My guess is that whatever other changes are required, besides material, will be acomplished such that two frames can be built on the same line.

My fearless forecast is the 06 Z06's back bone structure is aluminum and the 05 coupe and convertible use steel. I guess we'll find out in about two years.

I don't think the alum. frame will wait until "C7". If that was the case, there wouldn't have been reports in the materials and manufacturing process press a while back about a GM suppier being given orders for aluminum frame parts. Also, I don't think the 05-car's life-span will be much different that is the 97's. [/B]

WOW! Great info. Thanks again for contributing.

 

[Senna1994]

Hib it is always such a great pleasure to read your posts as well as your articles. It shows the depth of knowledge you have as well as your ability to give us some insight into the future without jeopardizing your sources. In addition, you remain faithful to the Corvette and the future models we will see.

 

[hippy]

"I totally agree that aluminum's strength to mass ratio is not as good as steel's. I also agree that a simple substituion of materials would be inadequate. Clearly, some additional changes would be required to get the same numbers in torsion and bending you'd see with a steel frame from an aluminum frame."

I, and many materials strength books, completely disagree with this statement. You would be right to say that for equal volumes of steel and aluminum, steel is "stronger", but not by mass. Aluminum alloys tend to be notably "stronger" than most steel alloys by weight (and assuming that both materials are subject the earth's gravitational field, mass as well). Of course "stronger" doesn't mean much. Do you mean it has a higher Young's modulus? Or that the Al frame has a higher yield strength? It's also hard to say much about the final product, the alloy chosen and method by which it is produced will have a dramatic effect on strength and stiffness as well as fatigue life, susceptibility to various forms of corrosion etc. One interesting bit of info about Al, it has no endurance limit, i.e. each time it experiences a stress cycle it will lose strength. It never reaches a limit, thus given enough cycles it will break under it's own weight.

 

[Hib Halverson]

You would be right to say that for equal volumes of steel and aluminum, steel is "stronger", but not by mass.

You are correct. I used incorrect terms.

The point I was trying to make is that if you made an aluminum C5 frame, with all dimensions the same and only the material differeing, the aluminum frame would not be as stiff in bending and torsion.