dwightlooi

Actually this is kind of a disappointment. Cadillac deserves much more than 11.4% given how dramatically they have improved and revamped their products and how comprehensive their lineup is.

Honestly, I think GM can and should consider buying a good tuner shop and delegating the ZL1s, ZR1s and the Z06s to it. Buy Lingenfelter or some good tuner, and make it the performance arm of GM making specialty cars -- very much like the Shelby brand is to Ford. Anything you don't plan on selling more than 3000 a year goes to the specialty tuner unit. The Caddy V-cars is debatable... it can go either way.

Nothing wrong with cushy isolated luxury. There are buyers of that as much, if not more so than, buyers of taunt sport luxury sedans. Just look at Lexus. GM already has Cadillac for the sporty side of the luxury market. Let Buick serve those who doesn't want to feel anything, hear anything or go around a corner in a powerslide.

One thing GM can consider is a 2.0L 60 deg V6 with reverse flow heads and a sequential twin-turbo setup. Reverse flow is key to getting all the exhaust together for sequential bi-turbo design. Use the smallest turbo you can get like the Honeywell-Garrett GT1544 to get you to 17.6 psi @ 1000 rpm. Such a turbo runs out of breathe at about 3200 rpm at those boost levels and boost rate and will normally be unusable. But with a wastegate dumping exhaust into second very big turbo like the GTX2867 which spools well near 3000 rpm, direct injection and 10.3:1 compression you can get a super plateau torque curve with about 270 lb-ft @ 1000~7000 rpm with 360 hp @ 7000 rpm. Such an engine won't be cheap. Being a V6 and with all the turbo accessories and air-to-water aftercooling it won't be all that compact or light. It may not even be very fuel efficient. But it'll be an extremely refined powerplant with six cylinder power pulses and better specific output than the CLA45 AMG without any of the vices of a high boost, big turbo setup. Perfect for refined luxury in markets where there's a displacement tax to skirt.

LOL, it's a typo courtesy of auto-correction. Magnetorological is to correct word. This type of shocks have uses an oil which has ferrous particles in it. When current is applied to create a magnetic field through the fluid the viscousity changes creating greater or lesser resistance to the fluid passing through the offices in the shock piston. This in turns allow electronic and continuous adjustment of the firmness of the shock absorber. Active roll control uses G-meters and wheel deflection sensors to differentiate between bumps on the road and lean whilst a car corners. The outside shocks are firmed up momentarily for the cornering effort reducing body roll without relying on overly stiff anti-roll bars for that purpose. This permits the suspension to be more independent (by nature anti-roll bars reduces independence), and allows the car to have a high degree of cornering flatness without the vices of jitteriness, bump steer or wooden roller coaster ride associated with suspension tunings based on overly thick anti-roll bars, high damping forces and stiff springs.

Going to carbon bodywork IS a big deal and going to dual clutch box IS a big deal.

Right, and that's pushing it!

For a Caddy maybe, but 120K for a Chevy is already pushing it. It'll be like a $200,000 Toyota Supra or Honda NSX. A Chevy -- or Toyota or Honda for that matter -- will never have the prestige of a Ferrari or Lamborghini. The idea isn't to put the Corvette on same price class as these very expensive exotics and make more money per car. The idea is to put it in the same performance class while elevating the image of Chevrolets in general -- both as a manufacturer with supercar creeds and also as the "thinking man's" choice. But, since we are in the cheesy mode, here's how the Stealthray emblem may look like...

BTW, we know that the basic LT1 architecture will make that kind of power... Lingenfelter's performance package makes 720 hp @ 6500 rpm/ 655 lb-ft @ 3800. It runs 7 psi on the stock 11.5:1 compression. But it also has seriously port heads and revised cams. The kind of hand porting used by tuners is impractical for GM to mass produce and high lift/overlap cams may have rougher idles. Dropping the compression by a point and using 3.5 psi more boost helps with using factory manufacturable heads and less aggressive cams. High RPM suffers so max. power drops in both magnitude and rpm. But, higher boosts results in higher maximum torque. 700/700 isn't bad. And, while something like this will require and not simp;y recommend 91 octane fuel, that is unlikely to be a concern for buyers of this type of car.

While the Stingray is a world beating every man's $50K sports car, the Stealthray replaces the ZR1 as the Chevrolet's no-excuse Supercar. The Stealthray sets it sights at beating the Ferrari 458 Italia in every measure of performance -- acceleration, braking and road holding -- while retailing at half the price. It does so quite simply by being a 2.4% lighter car with 24.6% more power, 76.9% more torque, one more gear and bigger tire contact patches. The Stealthray name stems from the full carbon fiber body shell. The Stealthray differs from the standard Corvette in the following aspects:- Full carbon fiber bodywork and floorboards over lightened closed roof aluminum frame 3,200 lbs vehicle weight (100 lbs less than Stingray) despite increased mass from supercharged engine Supercharged 6.2 liter engine (LT9) with titanium rods, intake valves and pushrods 700 bhp @ 6000 rpm, 700 lb-ft @ 3800 rpm @ 10.5 psi boost & 10.5:1 compression 8-speed Dual Clutch gearbox with active differential as sole transmission choice Titanium Exhaust System 8-piston brake rotors with Carbon-Ceramic discs Meteorological shocks with active roll control Forged Magnesium Alloy Wheels 295/35 R20 (Front), 335/30 R20 (Rear), Michelin Pilot Supersport ZP Tires MRSP $119,500 For the everyman stretching his budget, there is always the Z07 starting at $79,995 with a 625 hp / 625 lb-ft version of the supercharged engine (LT5) and making do without the carbon fiber body shell or the carbon brakes. Or, if he desires 4-door practicality, the Cadillac CTS-V with the same engine, 500 lbs more weight but similar pricing.

I have always held the believe that Buick should be the "Comfort Luxury" brand of GM. Leave the "Sport Luxury" stuff to Caddy which is doing a great job in that direction. Instead of trying to make kamikaze turbo AWD Buicks, make one with a $3000 "luxury" package that has double glazed acoustic glass all around, additional acoustic baffles around the engine, active noise cancellation, electrochromic dimming glass, 99.9 UVA/UVB blocking glass, active radar ground sensor ahead of the front wheels which detects upcoming bumps and automatically softens magnetorologic shocks momentarily, etc. The UV block greenhouse will be a big seller in China where they already sell a lot of Buicks. Chinese ladies carry umbrellas and wear long sleeves on sunny days to avoid a tan. 90% of the cosmetics are about skin whitening. If they can spend $700 a jar on La Prairie skin caviar for milky pale skin, trust me, if you can advertise -- "Drive Buick, stay vampire pale" you'll sell lots of cars.

What about a Nissan GT-R? To put things into perspective... the GT-R is a $90K car. The Corvette starts at $51K. Big difference in price there -- almost double. The GT-R isn't a faster car because of the engine, it is a faster car because of it's AWD system with three active differentials. The VR38DETT engine itself weighs 276kg making 485~545hp (depending on the year) for 1.75~1.97 bhp/kg. Compared to the LT1 Pushrod V8's 460 bhp @ 211 kg for 2.18 bhp/kg it has inferior power to weight ratio. If you count the intercoolers and pipings it is also bulkier under the hood. Fuel economy isn't that great either at 16/23 mpg compared to the Corvette Stingray's EPA 17/29 mpg rating. Now, let's say the Corvette gets the LF3 TTV6 making about 420 bhp. The LF3 is not the VR38DETT and it'll never be. It'll be a little slower and a little more expensive for GM to build than the V8 car. With 17/25 mpg on the CTS Vsport expect about 18/27 mpg on the lighter and more aerodynamic Vette -- which isn't exactly better than the V8. Other than trading the V8 soundtrack for the whistle of two turbines what exactly does it offer?

I hope is not simply a 2 door version of the ATS Sedan. Coupes need to be distinct... I like the CTS Coupe even if it was polarizing to some.

GM should do a 2.0T AWD version of the Sonic hatckback boosted to about 300 bhp / 280 lb-ft. They can call it the "Supersonic"

I don't disagree with most of your points. I'll comment on these though: 1) Somehow I doubt they would make a "secretary" Corvette. You don't seem to be that convinced either. 2) Most Mustang fans will point to the old SVO as justification for an I4T today. 3) The 5 Series has offered a 4-cylinder for years. Just not here. :-P But like you and Dwight both said, there's pretty much no justification for the LF3 in the 'Vette. Performance, economy, and cost point to the LT1. Now, a smaller-displacement LT1 (LT3?), maybe....... A smaller displacement small block was evaluated during the corvette C7's development. It was rejected for three reasons... It made less power and less torque It was actually slightly heavier because the cylinder walls were thicker while the external dimensions are about the same It had worse fuel economy -- because lower torque output limited 4-cylinder AFM operation to a narrower rpm and load range Smaller displacement 5th GENeration Small Block engines do exist. It mannifests itself as the 5.3 Ecotec3 V8 with 355 hp on a 87 octane diet. What's next (for sure) for Corvette is a Supercharged version of the LT1. This engine is already done and being certified. Expect at least 600 hp / 600 lb-ft from this engine perhaps as much as 650 / 625. These estimates are based on the 7% output advantage from DI and the apparent air-to-water intercooler size of from the engine photos. There is every reason to believe that this will be the Z07 and CTS-V engine.

Looks very 1990s...

The Corvette is the wrong platform for Rallying... not enough ground clearance, not enough suspension travel from the leaf springs and RWD. You want something with more ground clearance and AWD. A stripped Sonic or ATS perhaps with AWD. You also need it to be no more than 1599cc or 1999cc turbocharged mainly because of WRC and Super 2000 class rules.

Looks quite conventional apart from the vertical orientation of the turbocharger. Conventional as in air-to-air intercooler, conventional (separate) exhaust manifold and single turbo. Will probably be OK engines, but don't look for maximum torque peaking at 1,200 rpm.

Well, what if you simply like the sound of a 5 cylinder Audi engine or a short stroke 4 cylinder with a 12,000 rpm redline? Sure, there's that sort of subjectivity, but it isn't based on technical merit. Besides, how many people are there who simply like the sound a TTV6 in a vette who is also able and willing to pay more for less performance?

Well, the Gas Gallon Equivalent is only used as a standard of measurement when filling up the tank. 1 Gas Gallon Equivalent (GCE) does not have the same energy density as a gallon of Gasoline and it doesn't take you as far in terms of driving range. At 3,600 psi CNG has an energy density of 9 MJ / L. That is to say that 1 liter (0.26 gal) in volume of CNG at 3,600 psi has 9 mega Joules of energy. Gasoline on the other hand has an energy density of 33~34 MJ / L depending on the ethanol and additives in the blend. That's still about 1/4 of the energy for any given volume of fuel carried. So if the internal volume of the tank is exactly the same, CNG takes you 1/4 with engine efficiency being equal.

All the individual preferences aside... offering the LF3 on the Corvette creates a dilemma. Basically, you have a less powerful engine that costs GM more to build. How do you price it? If you price it less than the V8, it doesn't really make economic sense since you are creating a product that costs more but sells for less. If you price it more than the V8, why would anyone pay more than the V8 car to buy the TTV6 when it makes less power, doesn't weigh any less and doesn't really have better fuel economy?

Well, that's factually just not true... In fact, at every point on the torque curve, the LT1 V8 makes more torque. The 3.6TT (LF3) makes 430 lb-ft @ 3,500 rpm with about 90% of that (387 lb-ft) available by 2,500 rpm. At 1,500 rpm it makes 335 lb-ft. The 6.2 (LT1) makes 465 lb-ft @ 4,600 rpm with about 88% of that (409 lb-ft available by 2,500 rpm. At 1,500 rpm it makes 350 lb-ft. You may want to trace the torque curves below and see for yourself. (source: GM Powertrain: http://www.gmpowertrain.com/VehicleEngines/PowertrainProducts.aspx) Beyond the torque curve, one has to also understand that any turbocharged engine has some degree of lag. In otherwords, even if the torque curve says that it makes 387 lb-ft @ 2,500 rpm, when you floor the gas pedal at 2,500 rpm it actually takes some time before the torque actually rises to 387 lb-ft. That's because it takes the idling turbo some time to spool up to speed, then it takes some additional time to pressurize the intake pipe, intercooler and plenum to maximum boost. This can be about two seconds in really laggy engines, down to about half a second in reaaly responsive ones. But it is always there. Many people don't know this, but naturally aspirated engines also have induction lag. With the throttle partially closed, everything ahead of the throttle is at roughly atmospheric pressure, but everything downstream of that throttle is in partial vaccuum caused by the engine sucking against an intake obstruction (the throttle plate). When you open the throttle, it takes a small amount of time for the intake plenum and tracks to normalize to atmospheric pressure. This is why engines like the M3's 4.0 V8 use individual butterflies very close to the intake ports. Because doing so minimize the volume in vaccuum and the time to normalize the pressure volume. This makes the engine more responsive that normal. The big difference here, and the reason turbocharged engines always have more lag, is that turbocharged engines have to wait for the turbo to spin up. This delay is not present in NA engines. Also, turbo engines have to go from vaccuum to twice to three times atmospheric pressure. NA engines only need to go to atmospheric pressure. This is frequently compounded by the fact that the volume to be pressurized is almost always larger on turbocharged powerplants because of the additional ductwork needed to go to and from the Intercooler, and the intercooler itself. We commonly refer to this additional burden of lag "turbo lag".

Honestly, rumors are just that, rumors... I wouldn't put too much faith in rumors. But, just on the technicalities. I doubt they will use the Alfa engine -- it's OLD! If it's the GM HF block the logical thing will be a reduction in bore, not a shortening of the stroke. Reducing the bore has two disirable effects. Firstly, it strengthens the cylinder walls allowing it to better withstand increased working pressures. Secondly, it makes the engine more resistant to detonation because it shortens the distance from the spark plug to the furthest corner of the combustion chamber. Reducing the stroke does not do any of the above. The only thing it does is reduce the piston speed which permits a higher redline. With turbocharged engines it's easier to crank up the boost to get more power than it is to have a turbo system able to keep up with the airflow at very high rpms (say 7000~8000 rpm) while also being responsive at low rpms off idle.

It is not a matter of purism or tradition. It really comes down to the fact that the TT V6 has no weight, size or performance advantage, while being less cost effective and exhibits some degree of turbo lag. Fuel economy is about the same. One can also make the argument that had the CTS VSport been given a LT1 pushrod V8, it'll be faster, similarly balanced, less complex under the hood, similarly fuel efficient and could be made for $2000~3000 less. In terms of desirability, there will be those who prefer a large displacement eight and those who like a turbo boosted six. The difference though is that with the TTV6 Cadillac will be fighting over the same turbo loving crowd with BMW and Mercedes. With the exit of the Germans from the big V8 arena Caddy could have gotten a monopoly on those customers. Powerful RWD cars are in large part traction limited -- especially in 0-60 times for which 2/3rds of the time is spent in 1st gear. In this regard, a heavier car has a mitigating factor. Weight puts additional pressure on the rear wheels which increase traction. A half a second advantage is actually huge. As you get to the low 4 or high 3 sec range, it takes a phenomenal amount of power to lower the times by 1/2 a sec. So when you have the same power to weight ratio, a heavier car tends to be slightly faster just because it tends to have better traction all else being constant.

Counter Points: Five Reasos You shouldn't switch to CNG (1) CNG is much less dense than Gasoline. At atmospheric pressure a given volume of natural gas has 1/1000th the density of gasoline. Even at 3,000 psi (204x the pressure of the air we breathe, CNG has about 1/5th (22%) the volumetric energy density of gasoline. What it means is that for a given size of tank, a CNG car will go 1/5th the distance between refuelings. Or, if it is to go the same distance it has to have 5 times the fuel tank volume. (2) CNG is compressed to a high pressure. This means that tanks have to be cylindrical or spherical to effectively contain that pressure. Spheres and cylinders are much less space efficient than the kind of irregular shaped gasoline tanks cars use to tuck the fuel under the rear seats above and around the drive shaft and suspension bits. (3) CNG is not as available as gasoline or even diesel at today's gas stations. If you drive CNG, you have to plan your refueling stops around stations that sell CNG. If you drive gasoline you just drive and pull over at any gas station when the empty light goes on. (4) Converting existing engines to CNG has no performance or efficiency benefits. In fact, both are a little worse. CNG is best run with increased compression ratios, but most converted CNG engines simply replaces gasoline fuel systems and metering with a CNG compatible alternative without changing the engine internals. If you drive CNG, it is best to get a factory CNG vehicle with an engine designed from the ground up to use CNG. These unfortunately are few and far in between, limiting your choices. (5) Today, US Natural Gas usage in vehicles is about 33 billion cu-ft compared to the total 23,400 billion cu-ft. That is 0.14% of the total usage; quite insignificant in the overall scheme of things. The USA uses a lot of NG and for good reasons we have a lot of it. Can we use more and be less reliant of imported oil? Sure. But is NG in vehicular use the best avenue to increase that usage? In residential and industrial heating, as well as power generation, the storage density issues (CNG's Achilles heels) are largely irrelevant since the fuel is pipe delivered in very mildly pressurized form. Most US powerplants are not NG fired. Many homes use electric stoves and heaters. A drive to convert these to NG has a much larger effect on NG usage than trying to use them in vehicles without all the compromises.