[Z06] SAE papers and other stuff (Very long)
04-27-2005, 10:42 PM
#1
Burning Brakes
Thread Starter
SAE papers and other stuff (Very long)
I thought I'd do several things simultaneously; mention some content of several
of the SAE papers presented at the recent 2005 SAE World Congress related to C6
including some interpretive remarks and mention some things that I'd like to see
one day.
1) Spread the aluminum frame across the entire C6 line. For that matter,
start designing SUVs with hydroformed aluminum frames. Just as most
engine blocks and heads are aluminum these days, we need a shift from
steel to aluminum frames. The aluminum C6 frame was mandated to drop 56kg
from it's steel C5 cousin. They got 62kgs out of it (down to 124.6kg). For some
reason, they INTENTIONALLY chose to not match the frame deflections of the
C6 steel frame but rather trimmed off 10kg instead. As is, deflections of
the aluminum frame without the magnesium roof structure are within 5% of
those for the steel frame. Apparently, the frame enters the Bowling Green
plant at 285 pounds and is 140 pounds lighter than the C6 steel frame.
(some of the numbers here are slightly inconsistent between papers)
[Imagine you have a coupe with the roof out. Measure the distance from
where the roof piece touches the windshield to where it touches the
corresponding back location where the roof piece mounts. I would
guess it's about 24-30 inches. Now put 2 400 pound guys in the car and
repeat that measurement. The frame will have bent (elastically) a slight
amount and the distance will be ever so slightly less. The difference in
the measurements is the deflection. In essence, if the steel frame were
to deflect 1 millimeter, the aluminum frame will deflect 1.05 millimeters.
That's basically what the mean by having matched the steel frame's deflection
to within 5%.]
By the way, the contract to Dana for the first year is 7000 frames. Also,
the side rails are not AA5754 but AA6063-T5 (4 mm). AA6063-T5 has a higher
yield strength but LOWER fatigue strength (at 10^7 cycles). My read on this is
that the vast majority of cycles are well below the fatigue strength of AA6063-T5
and a 5-10% loss in fatigue strength was worth the increased yield strength.
This increased yield strength probably helped the weight loss (AA6xxx alloys
help weight loss more than AA5xxx alloys):
http://msl1.mit.edu/msl/meeting_0419...nstantine.pdf/ (page 12)
http://www.autoaluminum.org/downloads/corpub.pdf (See tables 2 and 6 in Appendix
______A. Fatigue strength correlates with ultimate tensile strength in these alloys)
It looks like the choice of materials also had to do with managing crash energy.
Ultimately, there are thresholds for both deflections and first mode frequencies.
Meeting these values may require putting back 10kg of aluminum alloy mass but I
doubt it. By the way, again, the aluminum frame used a good bit of tooling
that is used for the steel frame. Extrusions (21) were made from AA6063-T5,T6 and
AA6061-T6 (54% by mass) while sheet metal panels/stampings (63) used AA5754-O
(36% by mass) and castings (8) used A356-T6 (10% by mass). My read on this 10kg
issue is that in designing the steel C6 frame, some compromises were made to allow
a more optimal aluminum frame design (optimal designs for each frame material
would result in very different frame details). I think the steel C6 frame
is a bit overdesigned for not just the coupe but the convertible also. Besides,
GM can ill afford to be in the business of boutique aluminum frames. Hib Halverson
and a banned member (WhiteIce, BlackIce, CFour, C4FantaC, etc.) said, a year ago,
that the aluminum frame goes across the C6 line in MY2007. The GM engineer I spoke
with about the frame apologized for having to be so vague about the frame details.
A few other tidbits. The final Z06 frame including the magnesium roof structure
is 97% as stiff (frequencies not force per unit displacement or moment per unit
angular rotation) as the steel C6 frame. It appears that the fixed magnesium roof
structure increased the first mode frequencies by about 4%. As an interesting aside,
if the frame weighs 285 pounds and 54% of the mass is extrusions and most of
the mass in extrusions is included in the two side frame rails, then the two side
rails weigh about 154 pounds. Therefore, each likely weighs about 75 pounds or so.
For a bit of history, Dana was given a contract by GM for work on this aluminum
frame back in October 1999. Concurrently, within GM there were some early
publications and patents heading in this direction.
[September 24, 1996]
http://patft.uspto.gov/netacgi/nph-P...S=PN/5,557,961
and a closely related SAE paper [September 1999]
http://www.sae.org/servlets/productD...D=1999-01-3180
I don't know when ALCOA was brought into the process but it appears to
have done the initial design of the frame. One of the key design goals
of this frame is that the new aluminum frame must be integrated into
the C6 assembly process with minimal disruption, i.e. seemless integration.
All interfaces must match the steel frame.
Another thing to remember here is that the loss in stiffness of the frame when
it is built up into a full C5 or C6 is influenced by the stiffness of the
subsystems for the vehicle (C6 has a stiffer rear composite structure) as well
as the the mass caught up in the front and rear overhangs. C6 loses less stiffness
than C5 upon building the full vehicle. (The frame doesn't really lose stiffness.
The first mode frequencies of the frame are generally much higher than the
full vehicle because of all of the stuff now attached to the frame. It is this
difference to which I refer.)
The frequencies that were mentioned by DETLTU were a bit misleading.
The numbers 22.9Hz (bending) and 28.3Hz (torsion) were the program objectives
but the final numbers were 4% higher. Also, these numbers were not for the
frame alone. The are the frame, the entire roof, the windshield, the entire
rear of the car behind the driver minus the drivetrain, and parts of the front
fenders. That is my best guess from the picture. DETLTU also gave some numbers
for the steel frame but I see no mention of them anywhere.
Compare this with the SUV frame Ford studied in SAE 2003-01-0572
http://www.autofieldguide.com/articles/050303.html (scroll down 90% )
http://www.sae.org/servlets/productD...D=2003-01-0572
They got a 44% weight reduction if they had dimensional freedom but
only 20% if they did not. GM got 140/(285+140)= 32.9% with a 5% increase
in deflections at the roof and an essentially interchangable part. Also,
the "steel" C6 frame, I thought, already had a few aluminum parts, unlike
the C5 frame.
I predict C7 uses largely this same aluminum frame but the side rails will
be enlarged 20% or so in cross-section to take full advantage of the
aluminum. There may be a simple way to get some carbon fiber into this frame.
See:
2005-01-0095 : Crashworthiness of High and Low Pressure Hydroformed Straight Section Aluminum Tubes
2005-01-0465 : 2006 Corvette Z06 Aluminum Frame
2005-01-0466 : 2006 Corvette Z06 Aluminum Frame Engineering and Design Technologies
2005-01-0467 : Design Enhancement of the Rear Composite Structures for the 2005 - 6th
______________Generation - Corvette
2005-01-0470 : 2006 Corvette Z06 Aluminum Frame Manufacturing Technologies
2005-01-1392 : Aluminum Tube Hydroforming: Formability and Mechanical Properties
2005-01-1388 : The Warm Ductility of Commercial Aluminum Sheet Alloys
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2) Since titanium is still rather expensive and the new process technologies
like FFC don't appear to have reduced the prices yet, big pieces seem out
of the question and magnesium usage needs to increase rapidly. Both C6 crossmembers
should be converted to AE44 (a magnesium alloy used in the Z06 front crossmember).
The slight increase in NHV [Noise, Vibration,& Harshness], the one undesirable
result, is quite likely a nonissue with most C6 owners.
http://www.sae.org/automag/material/...-113-4-106.pdf ( Page 4 )
Other places to use it are:
Interior: Instrument Panel, Seat Components, Trim Plate
Body: Inner Door, Door and Roof Frame, Sunroof Panel, Bumper Beam,
___Radiator Support, A and B Pillars, Inner Decklid/Hood, Outer Hood/Fender,
___Outer Door, Dash Panel, Frame Rail.
Chassis: Wheels, Engine Cradle, Subframe, Control Arm.
That rear crossmember is likely to be worth nearly the same mass savings as
the front (5.5 kg = 12.1 lbs). The front crossmember/engine cradle is the
first production part from the USCAR team (fast-tracked).
http://www.uscar.org/Media/releases/castmagnesium.html
It may be too early for them to also have a rear crossmember for any C6
model.
See:
2005-01-0337 : Magnesium Engine Cradle - The USCAR Structural Cast Magnesium Development Project
2005-01-0340 : Development of the 2006 Corvette Z06 Structural Cast Magnesium Crossmember
2005-01-0734 : Wrought Magnesium Alloys and Manufacturing Processes for Automotive Applications
Still, I'd certainly be willing to pay extra for a titanium exhaust or titanium half-shafts.
http://www.webs1.uidaho.edu/imap/Fin...0in%20Auto.pdf
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3) What's the holdup with the polycarbonate rear hatch? The Mercedes C230 Sports
Coupe hatch-back is already using Exatec's polycarbonate technology.
http://www.apreport.com/pub/intervie.../184151-1.html
The current one in the coupe and Z06 weighs 23.08 pounds. There is
11 pounds of high Cg mass to shed.
http://www.google.com/search?num=100...ng+automotive+
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
4) The LS2 needs an analog to the LS7 heads. Keep the titanium valve springs
but use steel valves if they must. Drop the lift from 0.591 a bit and they'll still
easily outflow the current LS2 heads. By the way, an LS2 sure is cheap ($5495):
http://www.sdpc2000.com/catalog/120/...e-Assembly.htm
Now that the 4L65-E is history and the number of 400+hp cars grows, it's time
for more juice out of the LS2. It would help base model owners worry about
a new Carrera S, a 6.L Hemi, or a GT500 a bit less.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
5) Put the Z06 CHMSL on all C6's. It reduced lift of the Z06 by 79 pounds at
186 mph. The Cd for the 2006 Z06 is 0.342, this is identical to the value
for the 2004 Z06. At 186 mph, the 2006 Z06 has 1337 pounds LESS lift than
the 2004 Z06. The lift experienced by the car is very symmetrical relative
to the front and back of the car. Front brake cooling flow on the 2006 Z06 is
400% more than the 2005 model. Rear cooling flow is 200% of the 2004 Z06. The 2006
Z06 is 15mm lower than the 2005 C6 (0.60 inches).
See:
2005-01-1943 : 2006 Chevrolet Corvette C6 ZO6 Aerodynamic Development
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
6) The sulfur is almost out of the gasoline (30ppm by 01Jan06 in all but
several small regions like Montana and Idaho). It's time for LS7-type
heads with high pressure, direct, side injection. Speaking of DI, where
are the 3V heads with Orbital's low pressure, air-assist, central injection??
01Jan06 is 8 months away.
http://www.orbitalcorp.com.au/orbita...dioverview.htm
http://www.orbitalcorp.com.au/orbita...automotive.htm
http://www.delphi.com/pdf/techpapers/2003-01-0062.pdf
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
7) At the risk of dropping the mileage into gas guzzler territory, put
a 6L90-E behind the LS7 as an option. If the engine has DI then there will
be no gas guzzler issue. It'll never happen but it would be a great car
to own.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
8) It looks like the 6L80-E is about 34 pounds heavier than the 4L65-E. I
wonder if GM is going to try to offset this gain by dropping 34 pounds
out of the rear of the car for 2006. The rear hatch is a good place to get a third
of that back. Next, use the Z06 floor panels for another 6.22 pounds. A magnesium
rear crossmember would be worth about 12 lbs more.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
9) If there is going to be some MY2007 or MY2008 C6 that fits the description
given for the Blue Devil then front end weight addition will be a concern. As
I see it, you can turbocharge it, supercharge it, run a 3V design, or add
direct injection. Depending on how lean you want to run your DI will dictate
how much after treatment is needed. Still, I bet a 3V DI engine or even a
2V DI engine can get the 7.0L engine to over 600 hp with minimal weight
increases and still not get hit with the gas guzzler tax.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
10) The Milford Road Course was designed based on an assessment of the more
favorite features of:
Grattan Raceway, Virginia International Raceway, Spring Mountain Motorsports
ranch, Mid-Ohio Sports Car Course Watkins Glen International, Road Atlanta,
Putnam Park Road Course, Mosport International Raceway, Sebring International
Raceway, Gingerman Raceway, Road America, and Nurburgring Nordschleife.
2005-01-0385 : Design of the Milford Road Course
describes this course in detail including the 18 turns and several alternate
courses. While they do not use the phrase "toilet bowl," I assume this
refers to turn 6. This turn resembles the Karussell turn at Nurburgring.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
As best as I can tell from these papers, the carbon fiber fenders saved
3.03kg - 1.20kg = 1.83kg each (this may be a subset of the full fender
as the paper also states that the weight loss is 3kg per fender), the
front wheelhouse outer panels saved 0.73kg each, and the floor panels
saved 4.74kg - 3.33 kg = 1.41kg each. From earlier papers, the 2004
Z06 hood saved 7.9kg (or 56%) over the regular C5 hood. Just like the
aluminum frame articles, the production goal is 7000 cars per year.
The fenders are made by Vermont Composites Inc.
http://www.vtcomposites.com/performance-automotive.htm
The floor panels are made by
http://www.mfgresearch.com/intranet.htm
By the way, one kilogram equals 2.204622 pounds-mass. If the production
capacity is there and the price differential is minimal then the floor
panels could be put in the coupe and convertible to save 2.82kg=6.22 pounds.
It is clear from many different articles that the emphasis was on front end
weight loss. I wouldn't be surprised to see a CF hood on the Z06 soon.
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
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
12) I copied these also but I don't have much to say about them. The DI
paper is about 4V engines.
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
Papers on the Northstar engine (3) are much nicer papers than the rest. The authors
spend much more time on them.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
of the SAE papers presented at the recent 2005 SAE World Congress related to C6
including some interpretive remarks and mention some things that I'd like to see
one day.
1) Spread the aluminum frame across the entire C6 line. For that matter,
start designing SUVs with hydroformed aluminum frames. Just as most
engine blocks and heads are aluminum these days, we need a shift from
steel to aluminum frames. The aluminum C6 frame was mandated to drop 56kg
from it's steel C5 cousin. They got 62kgs out of it (down to 124.6kg). For some
reason, they INTENTIONALLY chose to not match the frame deflections of the
C6 steel frame but rather trimmed off 10kg instead. As is, deflections of
the aluminum frame without the magnesium roof structure are within 5% of
those for the steel frame. Apparently, the frame enters the Bowling Green
plant at 285 pounds and is 140 pounds lighter than the C6 steel frame.
(some of the numbers here are slightly inconsistent between papers)
[Imagine you have a coupe with the roof out. Measure the distance from
where the roof piece touches the windshield to where it touches the
corresponding back location where the roof piece mounts. I would
guess it's about 24-30 inches. Now put 2 400 pound guys in the car and
repeat that measurement. The frame will have bent (elastically) a slight
amount and the distance will be ever so slightly less. The difference in
the measurements is the deflection. In essence, if the steel frame were
to deflect 1 millimeter, the aluminum frame will deflect 1.05 millimeters.
That's basically what the mean by having matched the steel frame's deflection
to within 5%.]
By the way, the contract to Dana for the first year is 7000 frames. Also,
the side rails are not AA5754 but AA6063-T5 (4 mm). AA6063-T5 has a higher
yield strength but LOWER fatigue strength (at 10^7 cycles). My read on this is
that the vast majority of cycles are well below the fatigue strength of AA6063-T5
and a 5-10% loss in fatigue strength was worth the increased yield strength.
This increased yield strength probably helped the weight loss (AA6xxx alloys
help weight loss more than AA5xxx alloys):
http://msl1.mit.edu/msl/meeting_0419...nstantine.pdf/ (page 12)
http://www.autoaluminum.org/downloads/corpub.pdf (See tables 2 and 6 in Appendix
______A. Fatigue strength correlates with ultimate tensile strength in these alloys)
It looks like the choice of materials also had to do with managing crash energy.
Ultimately, there are thresholds for both deflections and first mode frequencies.
Meeting these values may require putting back 10kg of aluminum alloy mass but I
doubt it. By the way, again, the aluminum frame used a good bit of tooling
that is used for the steel frame. Extrusions (21) were made from AA6063-T5,T6 and
AA6061-T6 (54% by mass) while sheet metal panels/stampings (63) used AA5754-O
(36% by mass) and castings (8) used A356-T6 (10% by mass). My read on this 10kg
issue is that in designing the steel C6 frame, some compromises were made to allow
a more optimal aluminum frame design (optimal designs for each frame material
would result in very different frame details). I think the steel C6 frame
is a bit overdesigned for not just the coupe but the convertible also. Besides,
GM can ill afford to be in the business of boutique aluminum frames. Hib Halverson
and a banned member (WhiteIce, BlackIce, CFour, C4FantaC, etc.) said, a year ago,
that the aluminum frame goes across the C6 line in MY2007. The GM engineer I spoke
with about the frame apologized for having to be so vague about the frame details.
A few other tidbits. The final Z06 frame including the magnesium roof structure
is 97% as stiff (frequencies not force per unit displacement or moment per unit
angular rotation) as the steel C6 frame. It appears that the fixed magnesium roof
structure increased the first mode frequencies by about 4%. As an interesting aside,
if the frame weighs 285 pounds and 54% of the mass is extrusions and most of
the mass in extrusions is included in the two side frame rails, then the two side
rails weigh about 154 pounds. Therefore, each likely weighs about 75 pounds or so.
For a bit of history, Dana was given a contract by GM for work on this aluminum
frame back in October 1999. Concurrently, within GM there were some early
publications and patents heading in this direction.
[September 24, 1996]
http://patft.uspto.gov/netacgi/nph-P...S=PN/5,557,961
and a closely related SAE paper [September 1999]
http://www.sae.org/servlets/productD...D=1999-01-3180
I don't know when ALCOA was brought into the process but it appears to
have done the initial design of the frame. One of the key design goals
of this frame is that the new aluminum frame must be integrated into
the C6 assembly process with minimal disruption, i.e. seemless integration.
All interfaces must match the steel frame.
Another thing to remember here is that the loss in stiffness of the frame when
it is built up into a full C5 or C6 is influenced by the stiffness of the
subsystems for the vehicle (C6 has a stiffer rear composite structure) as well
as the the mass caught up in the front and rear overhangs. C6 loses less stiffness
than C5 upon building the full vehicle. (The frame doesn't really lose stiffness.
The first mode frequencies of the frame are generally much higher than the
full vehicle because of all of the stuff now attached to the frame. It is this
difference to which I refer.)
The frequencies that were mentioned by DETLTU were a bit misleading.
The numbers 22.9Hz (bending) and 28.3Hz (torsion) were the program objectives
but the final numbers were 4% higher. Also, these numbers were not for the
frame alone. The are the frame, the entire roof, the windshield, the entire
rear of the car behind the driver minus the drivetrain, and parts of the front
fenders. That is my best guess from the picture. DETLTU also gave some numbers
for the steel frame but I see no mention of them anywhere.
Compare this with the SUV frame Ford studied in SAE 2003-01-0572
http://www.autofieldguide.com/articles/050303.html (scroll down 90% )
http://www.sae.org/servlets/productD...D=2003-01-0572
They got a 44% weight reduction if they had dimensional freedom but
only 20% if they did not. GM got 140/(285+140)= 32.9% with a 5% increase
in deflections at the roof and an essentially interchangable part. Also,
the "steel" C6 frame, I thought, already had a few aluminum parts, unlike
the C5 frame.
I predict C7 uses largely this same aluminum frame but the side rails will
be enlarged 20% or so in cross-section to take full advantage of the
aluminum. There may be a simple way to get some carbon fiber into this frame.
See:
2005-01-0095 : Crashworthiness of High and Low Pressure Hydroformed Straight Section Aluminum Tubes
2005-01-0465 : 2006 Corvette Z06 Aluminum Frame
2005-01-0466 : 2006 Corvette Z06 Aluminum Frame Engineering and Design Technologies
2005-01-0467 : Design Enhancement of the Rear Composite Structures for the 2005 - 6th
______________Generation - Corvette
2005-01-0470 : 2006 Corvette Z06 Aluminum Frame Manufacturing Technologies
2005-01-1392 : Aluminum Tube Hydroforming: Formability and Mechanical Properties
2005-01-1388 : The Warm Ductility of Commercial Aluminum Sheet Alloys
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2) Since titanium is still rather expensive and the new process technologies
like FFC don't appear to have reduced the prices yet, big pieces seem out
of the question and magnesium usage needs to increase rapidly. Both C6 crossmembers
should be converted to AE44 (a magnesium alloy used in the Z06 front crossmember).
The slight increase in NHV [Noise, Vibration,& Harshness], the one undesirable
result, is quite likely a nonissue with most C6 owners.
http://www.sae.org/automag/material/...-113-4-106.pdf ( Page 4 )
Other places to use it are:
Interior: Instrument Panel, Seat Components, Trim Plate
Body: Inner Door, Door and Roof Frame, Sunroof Panel, Bumper Beam,
___Radiator Support, A and B Pillars, Inner Decklid/Hood, Outer Hood/Fender,
___Outer Door, Dash Panel, Frame Rail.
Chassis: Wheels, Engine Cradle, Subframe, Control Arm.
That rear crossmember is likely to be worth nearly the same mass savings as
the front (5.5 kg = 12.1 lbs). The front crossmember/engine cradle is the
first production part from the USCAR team (fast-tracked).
http://www.uscar.org/Media/releases/castmagnesium.html
It may be too early for them to also have a rear crossmember for any C6
model.
See:
2005-01-0337 : Magnesium Engine Cradle - The USCAR Structural Cast Magnesium Development Project
2005-01-0340 : Development of the 2006 Corvette Z06 Structural Cast Magnesium Crossmember
2005-01-0734 : Wrought Magnesium Alloys and Manufacturing Processes for Automotive Applications
Still, I'd certainly be willing to pay extra for a titanium exhaust or titanium half-shafts.
http://www.webs1.uidaho.edu/imap/Fin...0in%20Auto.pdf
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3) What's the holdup with the polycarbonate rear hatch? The Mercedes C230 Sports
Coupe hatch-back is already using Exatec's polycarbonate technology.
http://www.apreport.com/pub/intervie.../184151-1.html
The current one in the coupe and Z06 weighs 23.08 pounds. There is
11 pounds of high Cg mass to shed.
http://www.google.com/search?num=100...ng+automotive+
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
4) The LS2 needs an analog to the LS7 heads. Keep the titanium valve springs
but use steel valves if they must. Drop the lift from 0.591 a bit and they'll still
easily outflow the current LS2 heads. By the way, an LS2 sure is cheap ($5495):
http://www.sdpc2000.com/catalog/120/...e-Assembly.htm
Now that the 4L65-E is history and the number of 400+hp cars grows, it's time
for more juice out of the LS2. It would help base model owners worry about
a new Carrera S, a 6.L Hemi, or a GT500 a bit less.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
5) Put the Z06 CHMSL on all C6's. It reduced lift of the Z06 by 79 pounds at
186 mph. The Cd for the 2006 Z06 is 0.342, this is identical to the value
for the 2004 Z06. At 186 mph, the 2006 Z06 has 1337 pounds LESS lift than
the 2004 Z06. The lift experienced by the car is very symmetrical relative
to the front and back of the car. Front brake cooling flow on the 2006 Z06 is
400% more than the 2005 model. Rear cooling flow is 200% of the 2004 Z06. The 2006
Z06 is 15mm lower than the 2005 C6 (0.60 inches).
See:
2005-01-1943 : 2006 Chevrolet Corvette C6 ZO6 Aerodynamic Development
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
6) The sulfur is almost out of the gasoline (30ppm by 01Jan06 in all but
several small regions like Montana and Idaho). It's time for LS7-type
heads with high pressure, direct, side injection. Speaking of DI, where
are the 3V heads with Orbital's low pressure, air-assist, central injection??
01Jan06 is 8 months away.
http://www.orbitalcorp.com.au/orbita...dioverview.htm
http://www.orbitalcorp.com.au/orbita...automotive.htm
http://www.delphi.com/pdf/techpapers/2003-01-0062.pdf
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
7) At the risk of dropping the mileage into gas guzzler territory, put
a 6L90-E behind the LS7 as an option. If the engine has DI then there will
be no gas guzzler issue. It'll never happen but it would be a great car
to own.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
8) It looks like the 6L80-E is about 34 pounds heavier than the 4L65-E. I
wonder if GM is going to try to offset this gain by dropping 34 pounds
out of the rear of the car for 2006. The rear hatch is a good place to get a third
of that back. Next, use the Z06 floor panels for another 6.22 pounds. A magnesium
rear crossmember would be worth about 12 lbs more.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
9) If there is going to be some MY2007 or MY2008 C6 that fits the description
given for the Blue Devil then front end weight addition will be a concern. As
I see it, you can turbocharge it, supercharge it, run a 3V design, or add
direct injection. Depending on how lean you want to run your DI will dictate
how much after treatment is needed. Still, I bet a 3V DI engine or even a
2V DI engine can get the 7.0L engine to over 600 hp with minimal weight
increases and still not get hit with the gas guzzler tax.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
10) The Milford Road Course was designed based on an assessment of the more
favorite features of:
Grattan Raceway, Virginia International Raceway, Spring Mountain Motorsports
ranch, Mid-Ohio Sports Car Course Watkins Glen International, Road Atlanta,
Putnam Park Road Course, Mosport International Raceway, Sebring International
Raceway, Gingerman Raceway, Road America, and Nurburgring Nordschleife.
2005-01-0385 : Design of the Milford Road Course
describes this course in detail including the 18 turns and several alternate
courses. While they do not use the phrase "toilet bowl," I assume this
refers to turn 6. This turn resembles the Karussell turn at Nurburgring.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
As best as I can tell from these papers, the carbon fiber fenders saved
3.03kg - 1.20kg = 1.83kg each (this may be a subset of the full fender
as the paper also states that the weight loss is 3kg per fender), the
front wheelhouse outer panels saved 0.73kg each, and the floor panels
saved 4.74kg - 3.33 kg = 1.41kg each. From earlier papers, the 2004
Z06 hood saved 7.9kg (or 56%) over the regular C5 hood. Just like the
aluminum frame articles, the production goal is 7000 cars per year.
The fenders are made by Vermont Composites Inc.
http://www.vtcomposites.com/performance-automotive.htm
The floor panels are made by
http://www.mfgresearch.com/intranet.htm
By the way, one kilogram equals 2.204622 pounds-mass. If the production
capacity is there and the price differential is minimal then the floor
panels could be put in the coupe and convertible to save 2.82kg=6.22 pounds.
It is clear from many different articles that the emphasis was on front end
weight loss. I wouldn't be surprised to see a CF hood on the Z06 soon.
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
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
12) I copied these also but I don't have much to say about them. The DI
paper is about 4V engines.
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
Papers on the Northstar engine (3) are much nicer papers than the rest. The authors
spend much more time on them.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
04-28-2005, 12:16 AM
#4
Burning Brakes
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Runge-
In your extremely knowledgeable opinion,
would you feel comfortable unbolting the top of your own, personal 2006 ZO6 in order to retrofit a targa top?
-Do you think the aluminum frame could handle being operated with no top in place and remain structurally sound?
-Do you think there is a way to retrofit the targa from the coupe into the Z?
Do you know how it could be done?
-Would you want an aluminum frame in your personal C6?
If so, do you think it's worth waiting for the MY 2007 to buy a C6 coupe for the aluminum frame?
-Do you have any info that GM will offer the ZO6 with a targa option?
MY 2007? MY 2008?
Thank you for any information you may be able to provide.
You informative posts are most appreciated.
In your extremely knowledgeable opinion,
would you feel comfortable unbolting the top of your own, personal 2006 ZO6 in order to retrofit a targa top?
-Do you think the aluminum frame could handle being operated with no top in place and remain structurally sound?
-Do you think there is a way to retrofit the targa from the coupe into the Z?
Do you know how it could be done?
-Would you want an aluminum frame in your personal C6?
If so, do you think it's worth waiting for the MY 2007 to buy a C6 coupe for the aluminum frame?
-Do you have any info that GM will offer the ZO6 with a targa option?
MY 2007? MY 2008?
Thank you for any information you may be able to provide.
You informative posts are most appreciated.
04-28-2005, 09:35 AM
#5
☠☣☢ Semper Ebrius ☢☣☠
Originally Posted by Runge_Kutta
The Cd for the 2006 Z06 is 0.342, this is identical to the value for the 2004 Z06.
I've always heard 0.31 for the C5 Z06.http://www.sae.org/automag/globalveh.../1-113-1-8.pdf
04-28-2005, 01:46 PM
#6
Melting Slicks
Excellent information...thanks.
04-28-2005, 05:59 PM
#7
Burning Brakes
Member Since: Jun 1999
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Good information. As it stands, I will be making my decision between a Z06 and the Z51 coupe after the prices and specifications are announced for the MY 2007 cars. With the aluminum frame added to the base car, there will be even more difficulty justifying a huge price spread between the base coupe with Z51 and the Z06
04-28-2005, 09:44 PM
#8
Race Director
It would be nice to see some cost comparisons between the steel and aluminum frame. With the goals of seemless introduction into the C6 build line, one would assume your information, or that info from others, on a 2007 MY aluminum frame for all C6's would be right one. I guess a good 'estimate' of the frame could come from the price introduction of the C6 Z06.
Todd
Todd
04-28-2005, 11:04 PM
#9
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
Here are some photos of the Bolted In roof section.
The following shots show the permently bolted on magnesium roof panel
It is held inplace with 10 fasteners. I wonder how long it will be before the aftermarket segment comes up with a removable roof kit??? 
PUT ME ON THE LIST!!!
I too am interested in your opinion as to will the car be adversly effected by removing the roof section.
BC
The following shots show the permently bolted on magnesium roof panel
It is held inplace with 10 fasteners. I wonder how long it will be before the aftermarket segment comes up with a removable roof kit??? PUT ME ON THE LIST!!! I too am interested in your opinion as to will the car be adversly effected by removing the roof section.
BC
04-29-2005, 01:02 AM
#10
Melting Slicks
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Aluminum rocks!
I'd love an aluminum 2006 Pontiac Solstice. That would help it compete more closely with the new Mazda MX-5, but the Solstice already looks better than the new MX-5.
Jaguar's XJ has an aluminum chassis. Aluminum underbody components are fastened together with aerospace-grade epoxy adhesives and some 3,200 self-piercing rivets to create the new XJ's chassis.
"The complete body with paint weighs 650 pounds compared with an estimated 1,058 pounds for the same car in steel, 952 pounds for a Mercedes-Benz S-class, and 955 pounds for a 7-series BMW."
- from The Inside Guide to the all-new aluminum Jaguar XJ by Automobile Magazine
I'd love an aluminum 2006 Pontiac Solstice. That would help it compete more closely with the new Mazda MX-5, but the Solstice already looks better than the new MX-5.
Jaguar's XJ has an aluminum chassis. Aluminum underbody components are fastened together with aerospace-grade epoxy adhesives and some 3,200 self-piercing rivets to create the new XJ's chassis.
"The complete body with paint weighs 650 pounds compared with an estimated 1,058 pounds for the same car in steel, 952 pounds for a Mercedes-Benz S-class, and 955 pounds for a 7-series BMW."
- from The Inside Guide to the all-new aluminum Jaguar XJ by Automobile Magazine
04-29-2005, 10:36 AM
#11
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Good information. Would be nice to get Dave Hill's take on these.
With VVT as part of GM's 3.9L OHV V-6 going into the Pontiac G6 GTP, I wonder if that technology will make it to the LS2/LS7. Might be good for 5+% more HP.
With VVT as part of GM's 3.9L OHV V-6 going into the Pontiac G6 GTP, I wonder if that technology will make it to the LS2/LS7. Might be good for 5+% more HP.
04-30-2005, 05:54 PM
#12
Burning Brakes
Thread Starter
Originally Posted by 427 C5
-Would you feel comfortable unbolting the top of your own,
personal 2006 ZO6 in order to retrofit a targa top?
personal 2006 ZO6 in order to retrofit a targa top?
bends and twists. This causes obvious problems because clearances
change and these may or may not be noticed by the passengers.
The next thing is that if the frame vibrates at 21Hz then this
may feed energy into the vibrational mode of, say, the engine
and motor mounts. The aluminum frame is scarcely different from
the steel frame in either bending or twisting deflections and
also in terms of vibrational frequencies. So, I would say to
you that the issue of what top the vehicle has is 95% of what
matters and not what the frame is made out of. Since the Z06
has, as it's intended application, the most nasty duty then I
might make a Coupe with a removable top but when I'm going to
go thrash the car, I'd bolt the roof in for that period of time.
Remember, you design the frame to the nastiest case: the convertible.
When you then stick the same frame in the coupe, the frame is over
designed. The steel frame was designed to make the convertible "work"
however they chose to define "work." One other thing that I didn't
mention in the post. A polycarbonate hatch will stiffen the structure
a bit (doesn't help the convertible though).
Taking the comment more literally, I'd be reluctant to surgically
alter any expensive car for cosmetic reasons.
Originally Posted by 427 C5
-Do you think the aluminum frame could handle being operated
with no top in place and remain structurally sound?
with no top in place and remain structurally sound?
The aluminum frame and the steel frame are very nearly structurally and
completely dimensionally interchangable. There is a myth that an aluminum
frame MUST be inferior to a steel frame just because the aluminum is
less stiff than steel. People need to dump this bias and look at the
numbers. What ever you'd do with the steel frame should largely work
for the aluminum frame as well. The aluminum frame matched the steel
frames deflections to within 5% at the roofline. That's very similar
performance. It's tough to believe that this 5% will take an acceptable
situation to a completely unacceptable situation. Also, remember that
they knew how to get the aluminum frame to exactly match the steel
frame's deflections by adding 22 pounds (285+22=307) but intentionally
chose not to do it. I ask you, what do you think that they were
thinking?? What did they know that we do not??
Originally Posted by 427 C5
-Do you think there is a way to retrofit the targa from the
coupe into the Z? Do you know how it could be done?
coupe into the Z? Do you know how it could be done?
just add this. I think there is a 90% chance that the aluminum frame
will go in all C6's pretty soon. There are just too many things
that say yes and so few that say no. Aluminum frames are the future.
Anybody who thinks that GM has the money to do boutique frames is
crazy. The decision to use it on all C6's, in my opinion, is
far less a technical one than a cost, production capacity,
and marketing matter. I also got the impression from these articles
that the frame was very much designed with cost minimization in
mind. My best guess is that the cost differential of this frame
relative to the steel frame at similar production rates is less than
$1000.
Originally Posted by 427 C5
-Would you want an aluminum frame in your personal C6?
If so, do you think it's worth waiting for the MY 2007 to
buy a C6 coupe for the aluminum frame?
If so, do you think it's worth waiting for the MY 2007 to
buy a C6 coupe for the aluminum frame?
Some things need to remain exclusive to the Z06 for marketing reasons.
I don't think the frame is one of these. The LS7 and the fixed roof
are "Z06" items.
Originally Posted by 427 C5
-Do you have any info that GM will offer the ZO6 with a targa option?
MY 2007? MY 2008?
MY 2007? MY 2008?
a car. The difference between a coupe with the roof in and the bolted
Z06 frame is extremely small in terms of stiffness. It's about the
attitude of going to the extreme. No, I don't think there will ever
be a targa Z06 but the reasons will not be terribly defensible on
technical merit. Like with the C5 Z06, they may blow some smoke
about unacceptable loses in stiffness. However, the C5 paradigm may
get changed with GM in such deep financial trouble.
04-30-2005, 08:28 PM
#13
Burning Brakes
Thread Starter
Originally Posted by Scissors
Scissors,
The paper whose lead author is KBAeroBiscuit (Tom Frohling)
clearly says 0.342.
I can only offer two comments that have unknown value. First,
the flowfield around the car changes in important ways as the
velocity is changed. At low speed, the flow is laminar
http://www.engineering.uiowa.edu/~cf...mages/lim2.jpg
but at higher speeds and further back on the vehicle, it goes
through a transition region and then becomes turbulent
http://www.engineering.uiowa.edu/~cf...ages/turb4.jpg
Here's a cartoon for a flat plate:
http://www.overclockers.com/articles511/d1.gif
The idea here is that the coefficient of drag is not exactly
constant and depends a bit on essentially where on the car the
transition point is and where does the boundary layer become
turbulent. The point of all of this is that the coefficient of
drag is a weak function of velocity and an even weaker function
of temperature. In more technical terms, it is a weak function of the
Reynolds number of the car. If someone computed the Cd of the Z06
at one speed and someone else did it at another, they might get slightly
different numbers.
Second, with Cd I assume that on goes into a wind tunnel and
measures the drag force on the car. Next one says that the
Force/Area is proportional to the momentum flux of fluid perpendicular
to that area. Convention says that one simply uses the kinetic energy
of the flow (introduces the 1/2). The "constant" of proportionality
is Cd
(Drag Force)/(Frontal Area) = Cd*(density*velocity^2)/2
Now, what area do you use? Do you take the maximum area of the
car at any location. Does your area include the ground clearance
that is not obstructed by the tires? Even if two people measure
the same drags, that doesn't mean they used the same frontal areas.
If two people choose areas that are 5% different then their Cds will
differ by 5% also.
05-01-2005, 08:46 AM
#15
Get Some!
Originally Posted by Runge_Kutta
As I read GM and Dave Hill, the Z06 is a philosophy as much as it is
a car. The difference between a coupe with the roof in and the bolted
Z06 frame is extremely small in terms of stiffness. It's about the
attitude of going to the extreme. No, I don't think there will ever
be a targa Z06 but the reasons will not be terribly defensible on
technical merit. Like with the C5 Z06, they may blow some smoke
about unacceptable loses in stiffness. However, the C5 paradigm may
get changed with GM in such deep financial trouble.
05-01-2005, 11:30 AM
#16
Burning Brakes
Thread Starter
First of all, I am not a structural engineer so you need to take
some of my interpretive comments with a degree of skepticism. As
I read papers on the fatigue strength of the 5xxx and 6xxx series
of aluminum alloys, the discussion is always couched in terms of
10 million (10^7) cycles. AA5474 and AA6063 can take 10^7 cycles
at a stress of about 145MPa and 135MPa, respectively. More stress
and the material fails in fewer cycles. One can only assume that
GM and ALCOA have a design that keeps the cyclic loading below
these numbers for "one" anticipated lifetime. I have a vague recollection
of them designing for the 2-sigma driver; two standard deviations
from the mean. Maybe it was the 95th percentile. Frames can fail
for many reasons. I think GM is very aware about fatigue issues.
Alan Luo has published on this topic
http://www.climaxresearch.com/papers.htm
I have no idea about the details for the crash performance of the
aluminum frame. I was particularly surprised by two things that I
read in all of those papers on the frame. If I had a chance, I'd ask
Dave Hill why the side rails were made of AA6063 and not AA5754.
It now appears to me that the reason was weight and crash performance
but some fatigue life was lost. Normally when one speaks of the
deformation of solids, as opposed to fluids, one speaks of deformation
but not rates of deformation. AA6063 may have more desirable
rate of deformation characteristics for crashes. Ductility and toughness
also matter here.
http://www.dynamore.de/download/eu03...LM_A-II-19.pdf
http://ussautomotive.com/auto/steelv...worthiness.htm
http://www.normas.com/AA/pages/AT-5.html
http://www.autoaluminum.org/crash.htm
http://www.autoaluminum.org/downloads/corpub.pdf
http://www.aluminuminsight.com/publications/aei.pdf (page 5, right column,
second bullet beginning with "Pound ...".
The second question is why did GM not add the extra 10kg=22lbs to
stiffen the frame.
some of my interpretive comments with a degree of skepticism. As
I read papers on the fatigue strength of the 5xxx and 6xxx series
of aluminum alloys, the discussion is always couched in terms of
10 million (10^7) cycles. AA5474 and AA6063 can take 10^7 cycles
at a stress of about 145MPa and 135MPa, respectively. More stress
and the material fails in fewer cycles. One can only assume that
GM and ALCOA have a design that keeps the cyclic loading below
these numbers for "one" anticipated lifetime. I have a vague recollection
of them designing for the 2-sigma driver; two standard deviations
from the mean. Maybe it was the 95th percentile. Frames can fail
for many reasons. I think GM is very aware about fatigue issues.
Alan Luo has published on this topic
http://www.climaxresearch.com/papers.htm
I have no idea about the details for the crash performance of the
aluminum frame. I was particularly surprised by two things that I
read in all of those papers on the frame. If I had a chance, I'd ask
Dave Hill why the side rails were made of AA6063 and not AA5754.
It now appears to me that the reason was weight and crash performance
but some fatigue life was lost. Normally when one speaks of the
deformation of solids, as opposed to fluids, one speaks of deformation
but not rates of deformation. AA6063 may have more desirable
rate of deformation characteristics for crashes. Ductility and toughness
also matter here.
http://www.dynamore.de/download/eu03...LM_A-II-19.pdf
http://ussautomotive.com/auto/steelv...worthiness.htm
http://www.normas.com/AA/pages/AT-5.html
http://www.autoaluminum.org/crash.htm
http://www.autoaluminum.org/downloads/corpub.pdf
http://www.aluminuminsight.com/publications/aei.pdf (page 5, right column,
second bullet beginning with "Pound ...".
The second question is why did GM not add the extra 10kg=22lbs to
stiffen the frame.
05-01-2005, 12:32 PM
#17
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BELIEVE IT OR NOT..... I actually printed , AND read, the whole article! 
Thanks for taking the time to do all that.
One part of your article that really caught my eye was the comment about GM contracting for 7,000 frames. That's pretty good news to someone who's #56 on a waiting list for one of these cars! Perhaps I might be lucky enough to get one!
Thanks for taking the time to do all that. One part of your article that really caught my eye was the comment about GM contracting for 7,000 frames. That's pretty good news to someone who's #56 on a waiting list for one of these cars! Perhaps I might be lucky enough to get one!
05-01-2005, 02:00 PM
#18
Le Mans Master
lots of great information here. 
thanks.
yep .. like me.
thanks.
Originally Posted by CPT Z06
Great info as usual, but you're gonna make a lot people want the vert even more now!
05-08-2005, 02:29 PM
#19
Melting Slicks
Originally Posted by Runge_Kutta
If I had a chance, I'd ask
Dave Hill why the side rails were made of AA6063 and not AA5754.
It now appears to me that the reason was weight and crash performance
but some fatigue life was lost. Normally when one speaks of the
deformation of solids, as opposed to fluids, one speaks of deformation
but not rates of deformation. AA6063 may have more desirable
rate of deformation characteristics for crashes. Ductility and toughness
also matter here.
Dave Hill why the side rails were made of AA6063 and not AA5754.
It now appears to me that the reason was weight and crash performance
but some fatigue life was lost. Normally when one speaks of the
deformation of solids, as opposed to fluids, one speaks of deformation
but not rates of deformation. AA6063 may have more desirable
rate of deformation characteristics for crashes. Ductility and toughness
also matter here.
Unfortunately I'm not as up to date as I would like to be. Also I didn't get to read all the way through each of the papers you linked to (working on it). Last time I read much about it they were discussing the process of hydroforming the side rails from aluminum extrusions, thereby affording control of the thickness of the material at various parts of the rails cross section. Did they do this, or are they just hydroforming from seam welded tube? If they are going with the extruded/hydroformed rails, I think this would explain the choice of 6063 aluminum over 5754. Note that in the tables you pointed out at this site:
http://www.autoaluminum.org/downloads/corpub.pdf
5754 is listed under sheet alloys and 6063 is listed under extrusion alloys. In a quick search on Google I wasn't able to find much about the extrudability properties of 5754, but I did find this mention of 6000 series aluminum alloys as being popular for use in extrusions.
"Aluminium Alloys and Extrusion
All aluminium alloys can be extruded but some are less suitable than others, requiring higher pressures, allowing only low extrusion speeds and/or having less than acceptable surface finish and section complexity. The term ‘extrudability’ is used to embrace all of these issues with pure aluminium at one end of the scale and the strong aluminium/zinc/magnesium/copper alloys at the other end. The biggest share of the extrusion market is taken by the 6000, AlMgSi series. This group of alloys have an attractive combination of properties, relevant to both use and production and they have been subject to a great deal of R & D in many countries. The result is a set of materials ranging in strength from 150 MPa to 350 MPa, all with good toughness and formability. They can be extruded with ease and their overall ‘extrudability’ is good but those containing the lower limits of magnesium and silicon e.g. 6060 and 6063 extrude at very high speeds - up to 100 m/min with good surface finish, anodising capability and maximum complexity of section shape combined with minimum section thickness."
taken from http://www.azom.com/details.asp?Arti...ium_Alloys_and
Also, just found this site http://aluminium.matter.org.uk/aluse...ion_browse.asp
If you check out the extrudability ratings of 5754 vs 6063 you'll find that 5754 is only "good" whereas 6063 is "excellent"
A recap on the reason for using extrusions in the hydroformed rails:
If memory serves, the ability to have varied wall thickness was the only way to get the aluminum rails to match the performance levels of the steel rails inside of the same dimensions, and without losing the weight advantage of aluminum. In other words, since aluminum has a lower strength to volume ratio it requires much more aluminum to match the strength of steel (measured by volume....by weight it's a lot less). Ideally they would be able to re-design the rail entirely to account for this. Since they want to stick with the same external dimensions they are forced to increase wall thickness. But if they simply increased wall thickeness for the entire rail it would add a lot more aluminum than they need, as some parts could stand to be thinner, but would be thickened along with the rest of the rail. The answer is to make an extrusion with walls of varied thickness, and then hydroform it, making the walls thick where you want them thick and thin where you want them thin.
If this is indeed what they did with the Z06 frame rails then it explains the use of 6063 aluminum.
Scott
Last edited by LymanSS; 05-08-2005 at 02:32 PM.
