DETLTU

I will be attending the congress on the 11-13th and will go to the Corvette presentations all day on Monday. If anyone from the forum is going let me know and we could meet up for lunch or something.

Runge_Kutta

Well, since the SAE papers aren't published, maybe when
you get back, you can give us a preview. The questions that
most interset me, off the top of my head, are those related
to the frame.

1) What are the exact weights of the C5, C6-steel, and C6-aluminum
frames?

2) What are their bending and torsional stiffnesses (all three)?

3) What are the first mode frequencies for each frame in
bending and torsion?

4) Are their estimated costs for the steel versus aluminum
frames for some fixed production run?

5) What happened to Alan Hayman's 3V heads??

6) When does direct injection gasoline arrive and will C6 ever
see it in a 2V or 3V configuration?

7) What about ceramic rotors, a polycarbonate hatch, a rear
magnesium crossmember, or titanium exhaust for C6?

Any thoughts would help!!

DETLTU

I'll try to get as many answers as possible. I was definately thinking about the titanium exhaust and was planning on asking why that was dropped from the Z06 package. I'll ask the rest. Also there is a book coming out soon according to the SAE website:
"Covering over fifty years and six generations of the engineering, styling, and research and development of America's favorite sports car - The Chevrolet Corvette: New Vehicle Engineering and Technical History chronicles the development by the designers and engineers who made it happen!"

Heard anything about it?

korvetkeith

I'm with Runge-Kutta, I think these are the main areas that we could still see lots of improvement. I'd like to see the specific output seriously increased with direct injection, and twin cam in block with variable valve timing and possibly 3v per cylinder. I think 600hp or roughly 85hp/liter would be achievable with these technologies. Further weight reduction would be sweet too, more titanium exhaust, carbon brakes, and an FRC body.

Runge_Kutta

DETLTU,

Here's a list of papers that you might want to pick up while you're there.

2005-01-0340 : Development of the 2006 Corvette Z06 Structural Cast Magnesium Crossmember
2005-01-0337 : Magnesium Engine Cradle - The USCAR Structural Cast Magnesium Development Project
2005-01-0467 : Design Enhancement of the Rear Composite Structures for the 2005 - 6th
Generation - Corvette
2005-01-0465 : 2006 Corvette Z06 Aluminum Frame
2005-01-0468 : 2006 Corvette Z06 Carbon Fiber Fender Engineering, Design and Material
Selection Considerations
2005-01-0469 : 2006 Corvette Z06 Carbon Fiber Structural Composite Panels Design, Manufacturing
and Material Development Considerations
2005-01-0470 : 2006 Corvette Z06 Aluminum Frame Manufacturing Technologies
2005-01-0466 : 2006 Corvette Z06 Aluminum Frame Engineering and Design Technologies
2005-01-0731 : Self-Pierce Riveting of Magnesium to Aluminum Alloys
2005-01-0734 : Wrought Magnesium Alloys and Manufacturing Processes for Automotive Applications
2005-01-1388 : The Warm Formability of Commercial Aluminum Sheet Alloys
2005-01-1392 : Aluminum Tube Hydroforming: Formability and Mechanical Properties
2005-01-1854 : The Supercharged Northstar DOHC 4.4L V8 Engine for Cadillac
2005-01-1937 : Combustion Characteristics of a Spray-Guided Direct-Injection
Stratified-Charge Engine with a High-Squish Piston

http://www.sae.org

2005-01-0093 : Plane Strain Simulation for Corner Fill of Hydroforming Tubes in Oversized Die
2005-01-0095 : Crashworthiness of High and Low Pressure Hydroformed Straight Section Aluminum Tubes
2005-01-0357 : Integrating Metal Forming with Other Performance Analyses Using a Mapping Strategy
2005-01-0385 : Design of the Milford Road Course
2005-01-0416 : Development of a Torque Vectoring Rear Differential Demonstration Vehicle
2005-01-0763 : The Effect of Exhaust Variable Cam Phaser Transients on Equivalence Ratio Control in an SI 4 Stroke Engine

Retired GM Engr

Three suggestions:
1. I assume you get an SAE member discount on papers. You'll need it. Badly.
2. Get a GM credit card. 5% of the paper costs will knock down the price of your C6 Z06 a LOT.
3. Best of all, convince your boss they are VITAL to your job performance and tax-deductible.

Just kidding. Actually, I admire R-K for the patience to look through the catalog. A LOT of good stuff is in there. Just don't do more than two beers at lunch, or it's a LONG afternoon. I miss those lunches.

leaftye

Runge Kutta, I plan on buying a few, if not all, of those pubs. Are you getting them too? That book sounds interesting too.

Runge_Kutta

None are available as of today. I will go to a big state university and
download them for 13 cents/page at the library.

DETLTU

I don't know if I'll go after all of those R-K but I will definately pick up a few and yes I do get a discount. I may try to find them at a university as well. The book sounds really cool it's significant papers throughout the history of the Corvette linky:http://www.sae.org/servlets/productD...PROD_CD=PT-118

"The Chevrolet Corvette: New Vehicle Engineering and Technical History

AUTHOR(S):
Daniel J. Holt More publications by this Author


The Chevrolet Corvette: New Vehicle Engineering and Technical History chronicles the development of America's favorite sports car by the designers and engineers who made it happen.

This technical collection contains thirty papers covering over fifty years and six generations of the engineering, styling, and research and development of America's favorite sports car. Twenty-two papers focus on the first five generations, with the last eight papers detailing the new six-generation Corvette.

Two specific papers stand out for their unprecedented historical value. Paper number 540257 by Maurice Olley was presented to the SAE Michigan section in 1954 and is a technical description of the first production Corvette. The second, Sports Car Development, section three of the preface was written by Zora Arkus-Duntov in 1953 and gives some insight into the reasons behind the development of the Corvette. The preface contains seven sections including comments from Corvette's Chief Engineer, David C. Hill; a press release created by General Motors on its fiftieth anniversary; and a timeline with photos documenting the evolution of the Corvette. "

leaftye

Damn, I guess I need to get down to SDSU then!

leaftye

Runge_Kutta, any tips on where to look at the library? I'm at SDSU, and can only find the older paper journals, and not the electronic. Thanks!

Eugene

Runge_Kutta

Eugene,

Go to the public terminals. Then go to

http://infodome.sdsu.edu/research/da...ineering.shtml

I don't think they have an SAE subscription but ask the librarians.

http://infodome.sdsu.edu/about/departments.shtml

========================================

OK, maybe UCSD has it. Call the Engineering library [858-534-3258]

http://scilib.ucsd.edu/

I think they have access to this website:

http://scilib.ucsd.edu/news/new.html
http://www.elecpubs.sae.org/

I assume that if you access the database from a UCSD
computer, the database will recognize the IP address and
let you in.

Hope that helped!!

leaftye

Thanks for the help. I couldn't find much more while I was at SDSU, but I was in a rush. I'll give them a call and see if they have that subscription, but their library computers didn't have access to that last link, so I'm not expecting much. If UCSD doesn't have access, I'm surprised your school does....seeing as how the UCSD library group is among the biggest in the world and all. The SAE has a lot more than I really thought about, and perusing thru the bound journals helped bring forth a lot of other interesting subjects, like xenon lighting (1998 article) and sliding brake rotors. There's a lot of good information there that just doesn't make it to the mainstream mags. Thanks again!

Eugene

Runge_Kutta

OK, it's April 11th!! What happened??

The papers are not listed as being available here:

http://www.elecpubs.sae.org/

but are here:

http://www.sae.org/servlets/techSess...ESSION_DETAILS

It's also the day that we learn about the ordering details of the 2006
Coupe and Convertible.

DETLTU

well I'm reporting in for lunch and am about to go back for some more presentations so far I've heard from Dave Hill, Tadge Jeuchter, and Dave Asero(sp the head of GM small block design). I didn't get all of my questions in but I did get some good info.

As to why no Carbon Fiber hood:
The hood for the Z06 is a carryover piece from the C6 to reduce cost. The fenders had to be redesigned anyway to accomodate the larger wheels.

as to the possibility of Ceramic rotors:
the main issue was cost plain and simple.

Z06 pricing!!!
He wouldn't say specifically but on one chart of Cost versus power to weight ratio he had the Z06 between 65 and 70K.

The drilled rotors may or may not make it to production.
It will probably not make the 200mph mark.
it is officially 505hp and is the first engine ever certified under SAE J 1349 Revised. All GM engines (and probably other manufacturers) will be certified by this procedure.

More to come.

Runge_Kutta

DETLTU,

Thank you! I appreciate your effort here. Can you find any
hardcopy versions of the technical papers? Don't buy them.
Just quickly peruse them for the essential numbers. And then,
of course, immediately report back to us!!

leaftye

And if you want to scan the papers in and email it to a few of us to find the numbers for you, I'd be happy to help you out!

ivan111

Thanks for the info

Ask Dave if the Pistons are Cast or Forged?

That has been an endless debate.....

DETLTU

Alright guys here is the bulk of my notes, I have some pics and some video if anyone will help me host them (pics I can host but if I could host them all on one spot that would be great. I have some of the technical papers and i bought the new book but can't do that stuff right now because I'm at the internet connection here( hotel doesn't have internet connection more on that later). I will not be corresponding now for a few days because of the hotel but I'll get back with the rest at the end of the week or this weekend. I typed this last night and it's rather long but here goes:

SAE World Congress Update: You can probably find some of this info on the web:
First of all some of the exhibits:
GM:
Cadillac STS SAE 100 Technology Integration Vehicle
Supercharged LS2 producing 505hp @ 5600 rpm, 520 ft-lbs @ 3600 rpm
6 speed automatic w/ driver shift control
Dymag 2-piece Carbon Fiber rims with magnesium spokes and fastened titanium bolts 19” front 20” rears
Pirelli P Zero Rosso Asimmetrico tires
255/40 ZR19 front and 275/40ZR20 rears
Brembo Composite Ceramic Discs (15” front 14”) w/6pison calipers front and 4 piston calipers rear
Next gen Onstar
Valeo blind spot detection system
Mobileye lane departure system
Lots more

H2H
Hydrogen powered H2
180 hp
60 mile range

C6 convertible [yellow one at GM and red one at an SAE booth (Corvette won best engineered vehicle for 2005)]

LS7 cutaway
Z06 cutaway
Z06

Dodge:
Viper SRT-10 coupe
Charger SRT-8

Ford:
Mustang GT convertible
Shelby GR-1
Heard from Huai Thai-Tang today and he quoted 480hp for the GT500 I think that was already known but 450 was being said for a while.


Now my notes from the corvette technical sessions:
The LS7 produces 505hp @ 6300 rpm
and 470 lb-ft @ 4800 rpm
400 lb-ft is available from 2000 rpm
This is the first engine tested under SAE standard J 1349 revised
All GM engines will be tested under this standard from now on. This standard basically requires a third party certified SAE representative to certify the horsepower. All other manufacturers will probably use this standard soon as well.

The C6 was the first 400hp car that did not require the gas guzzler tax and they are hoping the C6 Z06 will be the first 500 hp car w/o the ggt. This is not in the bag but preliminary results look promising.

On one presentation by Tadge Jeuchter (assistant vehicle chief engineer) he listed price versus power to weight. The price was between 65 and 70K. The power to weight ratio was better than the Ford GT and the Ferrari 360.

The aluminum frame saved 136 lbs
Mg roof panel saved 6.6 lbs
CF floors and wheel housings saved 7.5 lbs
Mg suspension cradle saved 12 lbs
CF fenders saved 11.7 lbs

The frame was engineered to match steel frame physical and functional interfaces.
First time a frame engineered in steel has been reengineered for aluminum. Their basic goal was to make the production process at Bowling Green no different than with the steel frame.

The reason for CF fenders in stead of hood is mainly the fenders had to be changed anyway to accommodate the wider tires and the hood is a carryover part from the C6. More on that later.

The shared panels between the C6 and Z06:
Hood, Roof Skin, Doors, Hatch, Rear Facia

Unique parts:
Front Fascia, Fenders

The 2005 clutch was designed for the Z06 output so the clutch is the same used on the base C6

The LS7 is actually 11 mm narrower than the LS2.

The intake on the LS7 is 25% less restrictive than the LS2
Same restriction as LS6 but with 23% higher airflow at peak horsepower

Cylinder Heads flow 40 % more than the LS6 on intake 25% more on exhaust

Valve angle went from 15-12 degrees due to racing experience
Rocker ratio went from 1.6 to 1.8
Lift on Cam is 15mm or 591

The titanium valves and con rods are coated for thermal protection
Titanium intake valve (56mm) is 26% lighter than LS2
Sodium filled exhaust valves(41mm) are 18% lighter than LS2

LS7 has 37% lower back pressure than LS2

Crankshaft is 4140 steel w/ undercut and rolled filets
Piston: floating pin with polymer coated skirts
Rods are tapered on piton pin end to reduce mass
Engines are balanced, hot tested, and shipped to Bowling Green

Z06 gear ratios: 2.66, 1.78, 1.3, 1, 0.74, 0.5
C6 Z51 ratios: 2.97, 2.07, 1.43, 1, 0.84, 0.57
Does not reduce Z06 top speed but the Z06 will probably not reach 200 mph. It will top out above 190 though.

Tires were developed by Goodyear and feature Goodyear patented technology developed on the C5-R called DTS.
DTS= dynamically tuned solution
It basically features an asymmetrical trade pattern so tires “lean” into turns

Tires C5 Z06 C6 Z06
Front 265/40ZR17 275/35ZR18
Rear 295/35ZR18 325/30ZR19

Wheels
Front 17x9.5 18x9.5
rear 18x10.5 19x12

Brakes
C5 Z06 2 piston front
1 piston rear
2 pads per caliper

C6 Z06 6 pistons front
4 pistons rear
1 pad per piston (all same part number)

Rotors C5 Z06 C6 Z06
Size weight(lbs) size weight
Front 325x32 8.2 355x32 11.5
Rear 305x26 6.3 340x26 8.9

Exhaust went from 2.5” nominal diameter to 3”

Aerodynamics
Drag coefficient 0.34

Added mass saved
Brakes 27.5 lbs Aluminum Frame 136 lbs
Dry sump oil 17.6 lbs Interior and acoustics 33 lbs
Exhaust 11.7 lbs Mg front cradle 11.9 lbs
Rear battery 8.8lbs CF fenders 11.7 lbs
High capacity Axle 8.8 lbs CF floors and wheel housing 7.5 lbs
EOC and diff cooler 7.7 lbs Fixed roof 6.6 lbs
Wheels and tires 6.2 lbs

88.3 lbs added 206.7 lbs removed


Some power to weight ratios
Enzo 4.53
Saleen S7 5
Carrera GT 5.03
Z06 6.26
Ford GT 6.31

Weight distributions Front Rear
C6 Z06 50.6 49.4
C6 coupe 52.3 47.7
C5 Z06 53.6 46.4

Z06 is capable of 205 in 5th gear although it won’t hit 200 mph due to aerodynamics
60 mph in 1st gear


Power and efficiency
Same chart as in back of the book C6 and in the April issue of Automotive Engineering International so I won’t post everything
Power Fuel Economy Index
Z06 505 hp 20.7 mpg (conservative) 10,500
C6 400 22.6 9040
911 GT2 477 18.2 8681
Viper SRT-10 500 15.5 7750

Reason Ceramics were not used for Rotors –affordability (duh)

Aerodynamics
Nf / N @ 300 kph 0.48 Normal Force Distribution
Ram FEAF 48.9 Cooling flow
Powered FEAF 63 powered cooling flow

300 lb reduction in lift at 186 mph
Side mirrors actually produce downforce

Part reduction in drag
Splitter 202 lbs
Wheel opening leading edge extension 22 lbs
CHMSL 80 lbs
Total 304 lbs

Brake flow @ 80 kph
C5 Z06 C6 Z06
Front 2 cmm 10 cmm
Rear 1 cmm 2 cmm

Dual durometer front air dam is common to XLR, C6, and Z06
Consists of stiff upper section to keep its shape at speed and softer lower section to reduce scraping on curbs.

Still being worked on is a brake duct incorporated into front splitter

They actually brought in a 360 modena to test it’s aerodynamics because Ferrari claims it actually produces downforce. The Corvette guys were not able to duplicate that in the lab but said it is possible that it may produce a little downforce.

AL space frame:
Total weight of frame 285 lbs
Steel frame is 421 lbs


Their goal in developing the AL frame was seamless integration into the assembly process

The aluminum frame increase in effective gage by 1.9 mm
Steel frame gage is 2mm
AL frame gage is 4mm

AL Steel
Bending Stiffness 22.9 Hz 21.5
Torsional Stiffness 28.3 Hz 26.9


As to why they didn’t use magnesium for the rear cradle:
The main goal for the C6 Z06 was weight reduction in the front
Engineering restrictions would have been basically the same as the front

Carbon Fiber

2004 hood was first class A surface CF panel

They plan on building 7000 Z06 a year

Main priority for weight reduction was front parts and high parts to improve weight distribution and center of gravity

Candidates for CF body panels
Hood, Fenders, roof, rear quarters

Structural candidates
Interior and outer wheel house, Tub reinforcement, floor panels, Upper and lower plenum


Rear quarter panels were not chosen even though they had to redesign them anyway because of low priority for weight reduction in the rear. Same for Tub reinforcement.
Hood was a carryover part so cost would have been even more to develop new part out of CF. More later


Wheel house outers accounted for 22 lbs of weight savings with no increased tooling costs.

The floor panels are Balsa wood sandwiched inside CF (Carbon molding compound to be exact). The continuous random glass strand mat on the C6 is 1.25mm thick top and bottom versus 0.9 mm of CF.

Specific gravity is 1.5 vs 1.9 for glass
1.41 kg saved per panel

Carbon Fiber wheel housing
2mm thick versus 2.5 mm for normal part
1.1 specific gravity versus 1.4
0.73 kg saved per part

The Z06 will be the highest production volume of Carbon Fiber parts @ 7000 cars per year
2004 Z06 Carbon Fiber hood was largest previously at 2000 parts in a year

Choice of Fenders over hood:
Tooling costs
Validation complexity because of opening and closing of hood and other reasons
More Quality improvement for the fenders than the hood
No bonding or bond readout problems with fenders because of no need for bonding

Risks with fender
Complex shape
Die locks

RRIM CF
Specific gravity 1.33 gm/cm 1.58
Thickness 3.5 mm 1.2 mm
Natural Frequency 1st mode 32.4 Hz 70.8

$500 k in tooling costs saved in development of Fenders

They are looking at other technologies than glass for rear hatch

Ti exhaust was scrapped pretty much purely for cost reasons but the priority of weight reduction in the front also played a small part.

leaftye

Wow, really good info! Thanks!