dwightlooi

I am a big believer in the "fewer models is better" philosophy. You want to have as few models and as few brands as possible that will still cover the market segments you are going after. Fewer models save on engineering, logistics and advertising. If it was me, I would have killed off the entire Chevrolet Truck and SUV operation. Basically, I would have made GMC the GM Truck brand. All GM trucks and SUVs will be GMCs, Chevy will make cars and crossovers exclusively. GMC will make Vans, SUVs and Trucks exclusively. Buick makes comfort biased Luxury, Caddy makes performance biases luxury. That's a simple lineup with minimum overlaps. In otherwords... If you want a Suburban? Well buy a Tahoe or Yukon. Want a Silverado? Well get a GMC Sierra. Want a Traverse, pint them to an Acadia. Equinox? Sell them the Terrain. Chevy doesn't make trucks and SUVs. GMC does. Period. If killing the Traverse will save enough money in form of development, supply chain and marketing costs to make the Acadia is a tiny bit better it would have been worth it. Let's put it this way... developing one model instead of two and having to promote one instead of two is probably worth $500~1000 per vehicle. That can mean throwing in a GPS Nav system and putting in better fabrics.

the collector is aluminum instead of cast iron? O2 sensor is in exhaust, and closer to heads, decreasing warmup time: lowering emissions? The collector is part of the cylinder heads and is made of Aluminum like the rest of the head. Proximity to the cylinder heads' water jackets ensures that they never get hot enough to be problematic. Advantages are:- Eliminates the exhaust manifold -- saving weight, space and cost Makes it easier to turbocharge -- there is only one outlet Makes it possible to locate the Catalytic Converter closer to the exhaust valves -- faster light-off, lower emissions This also happens to be the shortest 3-to-1 header -- great for high RPM expiration

LFX 3.6 DI-VVT V6 (Note: Integrated Exhaust Collector and single exhaust port per bank) LF1 3.0 DI-VVT V6 (Note: Integrated Exhaust Collector and single exhaust port per bank) LY7 VVT V6 (Note: Separate Exhaust Ports; three exhaust outlets per bank)

Hopefully

Let's put it this way... the Escalade buyer isn't interested in efficiently hauling 7 bodies in comfort. He is interested in a big brash vehicle with lots of bling and as far removed from a Prius as possible to say that he is "bad ass". Making the vehicle more fuel efficient, or more space efficient, or more practical, does not appeal to him. If anything the Escalade is drawing the Hummer crowd. This may not be a growth segment for Caddy, but it is a good revenue source that is significant and should be exploited. Building big trucks and SUVs was NOT a bad idea and is still not a bad idea. What was a bad idea was building ONLY big SUVs, while neglecting sedans, compacts, crossovers and everything else. In this regard, the new SRX and the CTS Wagon represents prudent diversification. Turning the Escalade into something its customers don't want is simply bad business.

Depends on the size... the TE is not that small. The TE is also pretty porky for its size at 4225 lbs. If the idea is to make a luxurious version of the Chevy Equinox, the Delta II is ~400 lbs lighter.

That is exactly what I want and Buick needs: a Commodore with a Buick package, inside and out. Now, that's backwards... Caddy should be getting a big RWD. Buick should have gotten the XTS.

Let's put it this way... the current "LF1" 3.0 and the "LFX" 3.6 are both 2nd generation GM DI V6es. You can think of the "new" 3.6 as a version of the current 3.0. The original 3.6 DI V6 "LLT" is an older design which is more a DI rendition of the "LY7" 3.6 HF V6. The LF1 and LFX shares details like the integrated exhaust collector (the heads both have only one exhaust outlet per bank). Both are around 90hp/liter. There is a bi-turbo 3.0 on the way... the RPO is LF3.

Nah... Escalades do not have to have great fuel economy or smaller size. For that Caddy already has the Theta based SRX. Escalades should remain a big SUV with a BIG engine, there is still a demand for that kind of thing.

Well, most VVT gears of today have variance of around 60 deg. Going beyond that is not difficult, it is just pointless. VVT is used to achieve the following under the appropriate conditions:- Shifting the torque peak to a higher or lower rpm (flattening the curve) -- accomplished by advancing and retarding both cams in unison Creating an Exhaust Gas Recirculation (EGR) effect -- accomplished by retarding exhaust cam while advancing intake cam Reducing effective displacement and compression -- accomplished by retarding the intake cam into the compression stroke All of the above are limited by the lift and duration of the actual cam lobe grinds. For instance, to get enough intake duration to effect an Atkinson Cycle operation (keeping the intake valves open for first 20~40% of the compression stroke) the required duration is too long for maximizing power output. In another scenario, where you want very light valve lift and overlap for high specific output, the low rpm drivability may be beyond the ability of VVT to tame regardless of how you change the overlap or timing -- there is just too much duration and too much lift. It is for these reasons that Honda prefers switching between two sets of cam lobes with different lift and duration ground into them. It is also for this reason that BMW and Nissan opted to have an intermediate rocker system to allow the amount of effective valve lift to be adjusted. The Honda system cannot provide lift levels in between the two steps, hence it cannot avoid the "sudden" getting on cam effect VTEC engines exhibit when the system switches cams. The BMW/Nissan systems cannot change duration, hence they are not as effective at turning in 120~125bhp/liter solutions that will still drive fine from idle on up. There are system concepts which allow lift and duration to be varied, but these generally require that lift and duration be increased or decreased in unison, and the valvetrain mass of these designs are quite high limiting maximum rpm. Electromagnetically actuated valves will provide complete freedom to have any lift, duration, timing, overlap and ramp profile at any time or even different ones for different cylinders (shutting down some cylinders completely for instance). Engines have infinitely variable effective compression and displacement. They will also be able to have meet emission requirements or fuel requirements for different markets simply with a software flash. The problem is that Electromagnetic valve actuation is not proven to be reliable and requires heavy and bulky hardware that sucks down electric current like its free. This may mean that the energy costs for operating it may be higher than the energy savings garnered from having the best possible cam grind and timing in ALL situations, ALL the time.

Compared to the 3.0 LF1, the LFX offers:- Equal Specific Output (90.6 bhp/liter vs 90.1 bhp/liter) Superior Specific Torque (78 lb-ft/liter vs 74.4 lb-ft/liter) Lower Peak Torque RPM (4800 vs 5700 rpm) Higher Maximum Permissible Engine Speed (7200rpm vs 7000rpm)* No additional demands on Fuel Grade (87 Octane) * Manual Cars only; 6L50 and 6T70 transmissions mandates a 7000 rpm maximum shift speed.

Would you need valve springs? Why not a pair of electromagnets to control movement each way? I understand that size may be large, but that's how all new technologies start. No you wouldn't need springs at all. But, electromagnets that can move the valves fast enough dictate coke can sized solenoid actuators fed with very high voltages and current. It takes something about ~20 times the mass and much larger than springs to provide the same motivating force as the springs. To work these you also need to supply lots of volts and lots of amps, which meas a larger generator, bulky power control circuitry and big fat wires.

For release: April 13, 2011, 9 a.m. EDT 2012 Chevrolet Camaro Engine: More Power, Efficiency New 3.6L V-6 LFX produces 323 horsepower and 30 mpg on the highway DETROIT – A new, more powerful and more efficient version of the 3.6L direct-injected V-6 will be standard in the 2012 Chevrolet Camaro. It delivers an SAE-certified 323 horsepower (241 kW) at 6,800 rpm – 11 horsepower (8 kW) more than 2011 models. It is also 20.5 pounds (9.3 kg) lighter than the current engine, which enhances efficiency and driving dynamics. The changes to the 3.6L V-6 – known by its new “LFX” engine code – represent greater refinements to an already well-balanced package, including the use of new, lighter-weight components and enhancements designed to improve performance, efficiency and durability. And while more powerful than the current 3.6L, the 2012 Camaro 2LS model will deliver an estimated 30 mpg on the highway with the LFX engine. “This is a great engine architecture and our engineers have never stopped working to make it even better,” said Ameer Haider, assistant chief engineer for V-6 engines. “The enhancements for 2012 will deliver reduced engine weight and lower emissions – along with the greater power that Camaro drivers will certainly appreciate.” The 3.6L is a 60-degree design, with the cylinder block and cylinder heads cast in aluminum for low weight. A forged steel crankshaft provides optimal strength in the bottom end, while the cylinder heads include four valves per cylinder, with a dual overhead camshaft design incorporating infinitely variable cam phasing. Compared to the 3.6L V-6 in 2011 models, the new LFX engine features: • New cylinder head design with integrated exhaust manifold • Improved intake port design and larger intake valves within the cylinder heads • Longer-duration intake camshafts • Composite intake manifold • New fuel pump and isolated fuel rail • New, optimized-flow fuel injectors • Structural front cover and cylinder block enhancements • Stronger and lighter-weight connecting rods • Camshaft cap and throttle body design enhancements The LFX engine is significantly lighter than the current 3.6L V-6. The integrated cylinder head/exhaust manifold design saves approximately 13 pounds (6 kg) per engine over the cylinder heads and manifolds of the current engine, while the new composite intake manifold saves approximately 5.5 pounds (2.5 kg) over the current aluminum intake. Additionally, a lighter-weight structural front cover and lighter-weight, high-strength connecting rods bring the total weight savings to 20.5 pounds (9.3 kg), which helps the vehicle’s fuel efficiency and enhances its feeling of driving balance. “It isn’t often we get the opportunity to take more than 20 pounds off an engine. We met some aggressive targets while retaining great strength and reliability,” said Haider. “The engine is as durable as ever but now with improved performance and efficiency.” Additionally, the optimized-flow fuel injectors and integrated exhaust manifolds/cylinder heads promote lower emissions. And along with its weight savings, the composite intake manifold has a smaller radiated surface area to help it maintain noise and vibration characteristics comparable to the previous aluminum manifold. Greater airflow brings more power – and efficiency The new cylinder heads also bring a revised intake port design that enhances airflow to the combustion chambers. Larger-diameter intake valves (38.3 mm vs. 36.96 mm) are used in the heads and work in conjunction with new, longer-duration intake camshafts to provide the engine’s boost in horsepower. The valves let air in and exhaust escape from the combustion chambers. The duration of the camshaft determines how long the valves are open. By using larger valves and holding them open longer, more of the air is pulled into the combustion chamber, for a more powerful combustion. Often, the tradeoff for greater power is greater fuel consumption, but the LFX engineers adapted new fuel injectors that are optimized for the engine’s performance parameters. The result is more power without sacrificing fuel economy. The more-efficient combustion also means reduced emissions. Of course, the LFX engine retains direct fuel injection. It optimizes fuel delivery to the combustion chamber by introducing fuel closer to the combustion chamber. The result is better efficiency in the combustion process leading to increased fuel efficiency at part and full throttle. The LFX uses a new fuel pump for the direct injection system, along with a new, isolated fuel rail. The new fuel pump is quieter, while the isolated fuel rail further reduces fuel system noise. Greater refinement and durability Additional changes incorporated in the LFX deliver greater refinement, quietness and durability, starting with revisions to the front cover. It was redesigned with additional support ribs on the backside and an additional fastener to reduce noise and vibration. The cylinder block is modified slightly to accommodate the front cover’s additional fastener. Inside the engine, the powdered metal connecting rods use a higher ratio of copper, which makes them stronger and enables further mass savings. Also, the camshafts feature new saddle-type caps for improved durability. Finally, the throttle body is updated with a new, digital throttle position feature that eliminates a previous mechanical contact for more trouble-free operation. About Chevrolet Founded in Detroit in 1911, Chevrolet celebrates its centennial as a global automotive brand with annual sales of about 4.25 million vehicles in more than 140 countries. Chevrolet provides consumers with fuel-efficient, safe and reliable vehicles that deliver high quality, expressive design, spirited performance and value. The Chevrolet portfolio includes iconic performance cars such as Corvette and Camaro; dependable, long-lasting pickups and SUVs such as Silverado and Suburban; and award-winning passenger cars and crossovers such as Spark, Cruze, Malibu, Equinox and Traverse. Chevrolet also offers “gas-friendly to gas-free” solutions including Cruze Eco and Volt. Cruze Eco offers 42 mpg highway while Volt offers 35 miles of electric, gasoline-free driving and an additional 344 miles of extended range. Most new Chevrolet models offer OnStar safety, security and convenience technologies including OnStar Hands-Free Calling, Automatic Crash Response and Stolen Vehicle Slowdown. More information regarding Chevrolet models can be found at www.chevrolet.com # # # SPECIFICATIONS LFX 3.6L V-6 DI VVT Type: 3.6L V-6 Displacement (cu in / cc): 217 / 3564 Bore & stroke (in / mm): 3.70 x 3.37 / 94 x 85.6 Block material: Cast aluminum w/ cast-in-place iron bore liners Cylinder head material: aluminum Valvetrain: DOHC, four valves per cylinder, continuously variable valve timing Ignition system: Electronic individual coil-on-plug; individual cylinder knock control and extended-life platinum-tipped spark plugs Fuel delivery: Direct fuel injection Compression ratio: 11.5:1 Horsepower (hp / kW @ rpm): 323 / 241 @ 6800 (SAE certified) Torque (lb-ft / Nm @ rpm): 278 / 377@ 4800 (SAE certified) Recommended fuel: Regular unleaded; 87 Octane Maximum engine speed (rpm): 7200 Emissions controls: Evaporative emissions system, catalytic converter, equal-length exhaust, dual close coupled and dual under floor catalytic converters, positive crankcase ventilation, intake and exhaust cam phasers, electronic throttle control

I don't know about "cheaper". There is no reason to believe that the 3.0 DI Bi-turbo will be cheaper than the 2.8 port injected engine with a single turbo. The problem is that the 2.8 is a surgy powerplant that is problematic in service. Cheaper or not, the 2.8 has to go. The 3.0 is probably going to be between 300 and 360 hp. To maximize its potential, it'll need a new automatic transmission with a greater torque rating than the 6T75 (300 lb-ft). Without it, the 3.0TT will be pretty close to the new LFX 3.6 in output (318~323 hp / 275~278 lb-ft). Yes, it'll have a flatter torque curve and maybe 20~25 lb-ft more twist, but that's a slim difference to try to sell the extra cost, weight and maintenance worries of a pair of turbos and a myriad of IC plumbing on.

I don't have access... but that is probably a good thing!

The problem isn't control. The problem is force. A typical valve spring puts out between 120~300 lbs of force. A solenoid with that kind of power is big and power hungry. This causes three problems... (1) It takes up more room that camlobes and valvesprings (2) It needs a lot more electrical power to operate and is available from a typical alternator or 12V battery. (3) It gets pretty hot and needs to be cooled. And, in the end what do you get? Infinitely variable valve timing and lift? We can already do that via mechanical means. Better efficiency? Perhaps, but it is really a race between reduced frictional losses and increased electric generation losses.

No way! You'll need 16 solenoids, each being the size of a can of soda. That's assuming that you are using one solenoid to operate 2-valves and not counting the electric generation and storage system needed to power them! It'll be bigger and heavier. This is why even Formula One uses mechanically opened valves and electro-pneumatically assisted closure. The valves are opened with a regular cam lobe, but closed with a combination of a valve spring and pneumatics; the latter being electronically controlled so closing force can be varied according to rpm. The solenoids do not actually open or close valves directly, all they do is meter out a "booster" force in form of air pressure to help close the valves at high RPMs.

The Honda SOHC engines do not have continuously variable VVT. They have fixed phasing, but the ability to switch between two sets of cam lobes (some have the ability to switch between three sets). Since it is a completely different grind, this lobe can be of a completely different timing, lift and duration. In the latest J-series (V6) and the R-series (I4) There is a set of cams optimized for modestly high output -- which at 77~81hp/liter really is NOT that aggressive by Honda's or most standards. The other is essentially an Atkinson Cycle cam used for cruising and low load conditions. The Atkinson cam closes the intake valves VERY late -- well into the compression stroke -- kicking part of the ingested air back out the intake ports. This reduces effective displacement and creates an effectively asymmetrical compression vs power stroke ratio. Both contributes significantly towards fuel economy. An SOHC design will indeed have a degree of torque linearity and high end torque fall off between DOHC designs and Pushrod designs, but closer to DOHC than Pushrod. However, it also has higher internal friction at a level closer to DOHC than Pushrod. The beauty of the Pushrod engine is that you only have one cam instead of four (or two in case of SOHC). The less cams, the less bearings and the less valves, equals lower parasitic friction from the valvetrain. While the engine does not breathe as well and this hurts output at higher RPMs, this is essentially irrelevant for fuel economy. At cruising speeds and at light throttle, no matter how well the engine can technically breathe, it will be choked by the throttle butterfly to flow only as much air as is needed to produce the amount of power required to sustain cruising speeds. Actually, if this does not happen what you have on your hands will be a case of "unintended acceleration"!

Personally, I don't believe that Buick should be 2nd Tier Luxury whereas Caddy is 1st Tier. There isn't enough room between a top of the line Chevy and an entry Caddy to accomodate or warrant some intermediate brand. Instead, Caddy should be the Performance Luxury brand focusing on taut, RWD vehicles targeting BMW buyers. Buick should be the Comfort Luxury brand catering to the Lexus buyers. Making the XTS the "new" Lucrene is not whipping the whole lineup. It's still one car, just done as a Buick instead of a Caddy.

They don't and they shouldn't. The problem is being more expensive or just as expensive is not necessarily a good thing either. For example, cars like the ATS-V, C63 and M3 appeals most to the 30-something young professional. You want to price it so it is painful, but affordable to a guy in his 30s who really wants one. The M3 sold very well to such individuals when it was a $40K car. It does less well as a $60K car. $45K is really the sweet spot. You don't need to have a stripper at $45K, you don't need an el cheapo interior at $45K. You don't need to skimp on the brakes or shocks at $45K. You probably have to forgo an active differential, active steering and/or uber exotic materials like titanium rods in the engine. But you don't need any of that to be a excellent handling car with a nice interior.

Mercedes M113 4.3, 5.0, 5.5 liter V8s. SOHC, 3-valve per cylinder, twin spark. Smooth but not particularly high specific output. The advantage of SOHC, includes narrower and lighter heads (not as small and as light as pushrod motors' but smaller and lighter than DOHC designs), plus lower frictional losses by having half as many camshafts and their bearings (again, not as low as pushrod designs but better than DOHC designs). It is for these reasons that Honda 3.0, 3.2, 3.5 and 3.7 V6es in the Accord, TL and RL are SOHC designs. SOHC designs do not necessarily have to forgo independent VVT. In fact, so can a Pushrod V8. They can use a Concentric Cam setup (ala Dodge Viper's pushrod 8.4 V10) to achieve that.

Well, yes and no. A properly engineered and put together Pushrod Engine is not noiser or less refined than a DOHC engine because of the valve train per say. A 5 liter DOHC and a 5 liter pushrod engine with the same bank angle and block stiffness has similar vibration characteristics. The problem is that a pushrod engine has lower specific output because of more restrictive airflow in its 2-valve heads, hence a pushrod engine tends to have higher displacement than a DOHC engine with the same horsepower. Bigger displacement means that the pistons are larger, or the stroke is longer, or both. It is the higher reciprocating mass and piston speeds that result in higher vibration levels. This is especially apparent at higher rpms because vibration is a function of kinetic energy and therefore a function of the square of piston speed. Apart from that, poor workmanship or engineering can also led to valve float and rocker clatter. These tend to be worse in sloppy push rod engines than in sloppy DOHC engines because the valve train mass is higher. But, these shouldn't exist in either if the engine is well designed and in good functioning order. Put simply, a 6.2 liter pushrod is no less refined than a 6.2 liter DOHC, all else being equal. However, it is probably less refined than a 4.8 liter DOHC mill. The same argument can be used against a 6.2 liter design (M-B AMG M156 engine) when comparing it to a 4.4 liter BMW N63 design for instance -- both of which are DOHC. The migration from pushrods to DOHC powerplants are mainly driven by inline-4s and V6es going DOHC and companies garnering expertise in their design and manufacture.

Way to miss my point. The GT-R isn't faster because of any mechanical superiority, but rather the extensive computer programming that allows it to (seemingly) break the rules of physics. For the ATS-V to gain any credibility among the M3/C63/RS4 crowd, it has to be a driver's car in all aspects. Not a car that's programmed to allow any Joe Blow off the street to be able to snap off respectable 'Ring times (should they ever travel to Germany in the first place...). Actually, I have no beef about the ATS-V getting Magnetoriological shocks or an active differential. But, they need to keep an eye on the costs. The ATS-V should be about $45~50K, given the $60K price point of the CTS-V. This also puts at a the same price point as the E46 M3, one which the $60K E90 M3 or C63 priced themselves out of.

Well, there are a few problems with your reasoning. First of all, the 2.0T is actually lighter and more powerful than the old 3.1 V6. There is no advantage to be had from pushrod packaging except in Vee type arrangements. Secondly, for 220~275hp class engines destined for powering mainstream family sedans, a smaller displacement engine has the added advantage of getting under a lower displacement tax bracket in some markets (albeit not the USA). Strictly from a refinement standpoint though, a pushrod V6 is probably better than a DOHC Turbo-I4 and a 4.8 V8 can be better than a 3.6 V6 -- more cylinders, closer firing impulses, you get the picture. However, when you are talking about cars like the ATS-V, C63 or M3, the customer profile does not really make trying to save a few bucks on taxes a top priority. People who buy C63s or M3s are NOT frugality minded individuals, if they are they would have bought a 320 or C180. As far as the Northstar is concerned, it was not a bad engine for its time. But it wasn't necessarily better than the pushrod engines of its time. The 1992 5.7 liter LT1 making (300 hp / 340 lb-ft) was more than competitive with the 275hp Northstar. Fuel Economy with the Pushrod 5.7 is actually better than the Northstar, with the Camaro Z28 hitting 17/24 EPA rated MPG despite being mated to a 4-speed automatic. The Deville was 15/24 mpg with the Northstar, again with a 4A and despite the arguably more efficient FWD transaxle. And, if you have driven a F-body Camaro or C4 Vette, you'll probably note that these were NOT rough, unrefined engines. The problem was that the LT1 was heavy from its cast Iron Block whereas the Northstar was an all Aluminum Engine. This however was a materials choice and cost decision, with no relationship whatsoever to the valvetrain configuration. A Pushrod V8 could have been Aluminum and in fact beginning with the LS1 (circa 1997) it took on an aluminum block and heads. With the LS1, the 5.7 liter Pushrod V8's output climbed to 350hp / 365 lb-ft, completely eclipsing the Northstar.

I am sure a twin turbo V6 can be made powerful enough too. And, yes, handling, braking and steering are very important as well. But that is not the point. The point is this... If a Pushrod V8 is smaller, lighter, cheaper, more powerful and just as economical on fuel, why do you want a twin turbo V6? Speaking of which, have you ever considered the fact that "If" the GT-R has a Pushrod V8, it might be a faster car than it currently is? Think about it... that 520hp/440 lb-ft VR38DETT is heavy -- 276 kg to be exact. A similarly powerful (505hp/470 lb-ft), naturally aspirated LS7 engine is a scant 206 kg. That's 154 pounds of mass removed from the nose of the car. Not to mention the elimination of all the plumbing for the intercoolers and turbos.