dwightlooi

The Cadillac ELR is a beautiful car. It almost begs for a performance focused version -- something with Performance as first priority and Fuel Economy as a secondary but amicable goal. The idea here is not produce produce a Prius beater, rather it is to produce a car capable of reaching 60 mph in under 6 seconds yet able to deliver fuel economy that is superior to a Cruze Eco and approaching that of mid-size Hybrids. Cadillac VLR MSRP: $42,000 Type: 2-door, 4-passenger, FWD coupe Platform: Delta II w/ Aluminum hood, fenders and trunk lid. Curb Weight: 3195 lbs Transmission: GM Electramatic 6E70 6-speed automatic w/ lock-up converter Generator-Motor: 6E70 built-in 20kWe (27 bhp) DC Permanent Magnet Flywheel Integrated Motor-generator-starter (FIM) Battery: 0.8 kWh Lithium-Iron-Phosphate (40 lbs) Electric Output: 27 bhp @ 3000 rpm, 95 lb-ft @ 0 rpm Internal Combustion Engine (ICE): 2.0L DOHC-16v Inline-4 (LTH) Features: Direct Injection, Dual-VVT, Cylinder Deactivation (0 or 4 cylinders), turbocharged and intercooled Displacement: 1998 cc ICE Output: 275 bhp @ 5500 rpm, 260 lb-ft @ 2000~5500 rpm Maximum ICE speed: 6000 rpm* Max Combined Output: 283 bhp @ 5500 rpm, 323 lb-ft @ 2000 rpm 0-60 mph: 5.6 sec 60-0 Braking: 113 ft EPA Fuel Economy: 35 (city) / 42 (Hwy) MPG -- 22 / 32 MPG in Fault Mode (ICE only) Range: 378 miles (11.2 Gallon fuel tank w/ 10.8 Gallon useful fuel capacity) * LTG engine is basically the LTH engine with Cylinder Deactivation added to enable all valves to be shut off. This is necessary for the FIM to perform regenerative braking to maximum effect and to allow the electric only propulsion without having to fight the engine's aspirational resistance. Maximum Engine Speed is lowered to 6000 rpm because of the limitations of the collapsible lifters, and because the FIM should not be spun faster than it's no-load velocity of 6000 rpm -- @ 6000 rpm the DC motor produces 0 lb-ft of net torque. ---------------------- Operating Modes The VLR has four distinct operating modes ECO Mode (Driver Selectable) ICE limited to 228 hp @ 6000 rpm, 200 lb-ft @ 1600~6000 rpm Shift Logic biases towards smooth transitions and keeping ICE rpms low when possible Idle Stop engages at zero vehicular speed Propulsion is fully electric at 0~5 mph; Engine starts at 5 mph (~1200 rpm) 1st 20% of Accelerator Pedal travel invokes only electric power with ICE cylinders deactivated 1st 20% of Brake Pedal engages only FIM regenerative braking with ICE cylinders deactivated (no engine braking) Launch Control is not available SPORT Mode (Driver selectable) ICE is allowed to operate at full boost with 272 hp @ 5500 rpm, 260 lb-ft @ 2000~5500 rpm Shift logic biases towards aggressive shifts and keeping ICE in the optimal powerband Idle Stop never engage; ICE is kept running at all times Propulsion is ICE + Electric from 0 rpm 1st 20% of Accelerator Pedal travel invokes only ICE + Electric assist power 1st 20% of Brake Pedal engages only FIM regenerative braking with ICE cylinders active (with engine braking) Launch Contro is available* * Vehicle must be stationary, with transmission in "D", Brake Pedal must be depressed. Depressing the Accelerator without releasing the brakes will activate launch control. ECU automatically maintains 2000 rpm by partially closing the throttle. The ICE pre-loaded using the FIM to provide 63 ft-lbs of reverse load while the torque converter absorbs the rest. This allows the Turbocharger boost to pre-build to about 10~12 psi. Once the Brake Pedal is released, the FIM reverses to providing full assist and the throttle is opened fully. If the driver does not launch the car within 5 seconds, Launch Control is cancelled automatically to avoid overheating the transmission fluid. Emergency Mode (Automatically engaged if VLR completely runs out of fuel, or if the ICE has overheated or otherwise rendered inoperable) ICE cylinders are deactivated Propulsion is fully electric Battery is allowed to run down to 0% Fault Mode (Automatically engaged if the battery, FIM or charge controller has overheated or has otherwise failed) FIM is set on neutral mode Propulsion entirely via the ICE Battery is disconnected

Again, you refuse to compare apples to apples. The whole purpose of this thread was the comparison of Pushrod vs DOHC, yet you bring a Bi-turbo, Dual VVT, direct injected, 7-speed Dual Clutch equipped, M157 into comparison with a port injected, Supercharged (which costs additional consumption to drive), LSA engine with a 6-speed torque converter automatic. How is that supposed to "show" that DOHC is more efficient? It doesn't. The fact is that, in every instance where two engines of comparable power output and features (VVT, Cylinder Deactivation, Direct Injection, materials, etc) are compared. The Pushrod configuration turns out to the the more efficient design -- in terms of fuel economy, weight, size or cost. What will be a valid comparison will the between the Direct Injected 5.5L M152 engine in the SLK55 AMG and the upcoming Gen V pushrod V8 in the C7 Corvette. That however will have to wait till 2013. The fundamentals do not change though and the advantages of the Pushrod design in terms of size, weight, frictional efficiency and cost shall always remain when compared to DOHC designs.

The 7.0 (LS7) fit in exactly the same space as the 6.2 (LS3) or the 5.3 (LS4) if you disregard external factors like the placement of the alternator and AC compressor. The blocks' exterior dimensions are the same. The smaller displacement engines simply have more metal in the cylinder walls. The 7.0 is really not bad from a fuel economy stand point. At 505 hp / 470 lb-ft, the LS7 powered Corvette Z06 nonetheless turns in 15 (city) / 24 (hwy) mpg. That's 1~2 points down from the 6.2 powered run-of-the-mill Corvette, but not bad at all in the company of 500+ hp supercars. The 7.0 is also the highest reving production smallblock with a 7000 rpm rev limit and a 6300 rpm power peak. And, that's without variable timing, cylinder deactivation or direct injection -- features we can confirm will be in the Gen V V8s. The Mercedes M156 DOHC 6.2 V8 in the E63 made 518 hp / 465 lb-ft and turned in 13 (city) / 20 (hwy) EPA MPG. Although the MPG comparison is hardly fair given that the E63 is a 1000 lbs heavier.

I want to see criteria which smk4565 use to determine which engine is better? Fuel consumption doesn't depend only on engine but also on car, transmission etc. Specific fuel consumption is one of the criteria which is in relation to engine only. Just like Weight of the engine/ Hp of the engine. Or physical size of the engine. All this (and much more) can be used as criteria (by individual) to determine why is one engine better than the other. I don't have that much (and more) information to determine which engine is "better". i don't considere type of valvetrain to be criteria..but i know some people who does. What I try to do when making fuel economy comparisons in this regard is to compare two cars of similar horsepower, weight and transmission type. Afterall, we are comparing the merits of engine layouts here not chassis, aerodynamics and/or transmission technology. I cited the BMW M3, Camaro SS and the C63 AMG, not because I like these cars or because they sell into the same market segment (they don't) but because they are relatively close in weight and engine output. Both the M3 and the SS can also be had with 6-spd Manual Transmissions which helps with comparing apples to apples. That all three engines lack diret injection or VVL also helps equalize the technological field. The C63 actually has the advantage of a 7-speed auto (but it loses the mpg game anyway). In anycase, the Pushrod LS3 is the clear Fuel Economy winner here and is midpack on power while being the lightest and most compact engine amongst the trio. BMW M3 -- 4.0 DOHC V8 (445lbs) engine -- 3705 lbs veh wt -- 414 hp / 295 lb-ft -- 14 (city) / 20 (hwy) EPA MPG Chevy Camaro SS -- 6.2 Pushrod V8 (403 lbs) engine -- 3859 lbs veh wt -- 426 hp / 420 lb-ft -- 16 (city) / 24 (hwy) EPA MPG C63 AMG -- 6.2 DOHC V8 (438 lbs) engine -- 451 hp / 443 lb-ft -- 12 (city) / 19 (hwy) EPA MPG You cannot make a case for DOHC being more efficient or providing better performance amongst these three cars.

It is perfectly alright for you to have that opinion. However, to sway anyone you'll need to explain how it is better. And, you'll need to articulate it better than "everyone is using it, therefore it must better" or simply declare that it is so -- that won't do anything but make your case sound kinda silly. You'll notice that I do not simply say that Pushrod engines are more fuel efficient. I explain why are. I don't simply say that they are lighter and smaller, I show you the weights and the photos. I don't simply make a declaration, I support my positions with facts. You are free to challenge my reasonings or facts. Let's start with one advantage of the DOHC setup -- any one -- and why you feel that it is important. Do that and I am sure everyone can have a meaningful discussion.

Without going into the details of 30~40 V8 engines, I can make the following general statements with confidence:- At the same displacement, a Pushrod Design is almost always more Fuel Efficient than a DOHC design, although it will make less power At the same power output, a Pushrod Design needs 15~20% greater displacement and delivers comparable fuel economy At the same displacement or the same output, a Pushrod Design is almost always smaller, lighter and cheaper than a DOHC engine Without cluttering this post with over a 100 V6 and V8 data points, I can also make the following statements with confidence:- A Pushrod V8 design can deliver higher output at a lower weight, size and cost than a DOHC V6 Bi-turbo design At a comparable output, a Pushrod V8 design can also deliver Fuel Economy comparable to a DOHC V6 Bi-turbo design if it has similar technological content (eg. DI, VVT, etc) A DOHC V8 does not enjoy the same advantageous because of its increased frictional losses, weight, size and costs. Finally, I will like to say that the common objections to American Pushrod engines in terms of refinement, performance and/or fuel economy is generally true in the 80s and 90s. However, these have nothing to do with the valvetrain configuration but rather the reluctance of American automakers to incorporate the technological content into their Pushrod designs. This is no longer true, but perceptions linger.

Riiiight... How about all the Crown Vic taxis, etc w/ hundreds of thousands of miles or the Merc Taxis in Europe w/ hundreds of thousands of miles? Or Ford F-series trucks from the last 15 years? Those are all OHC engines... Mercedes Cabs (when not diesel), Crown Vics and F-150s are SOHC not DOHC. So? Still OHC. SOHC or DOHC are equivalent for this discussion which is OHC vs pushrod. And Merc diesels are OHC, aren't they? Bottom line, 99% of the worlds' automakers long ago moved on from pushrod to OHC engines...GM has for everything except V8s. What's holding them back? inertia? stubbornness? myopia? Can't use the truck excuse as Ford has built a hell of a lot of OHC trucks over the last 15 years. It's interesting how people keep defending an obsolete approach when the world clearly has moved on. It's all a moot point, though, because the future is clearly 1.4L 4 cyls... How about clarity on the technical merits of Pushrods vs OHC designs. The argument that you should do what everyone else does without any factual or technical justification is no better than to say that if everyone believes that the sun orbits the earth you should jump on that bandwagon. As far as Ford OHC V8s vs GM Pushrod V8s, the GM engines had always beaten and continues to beat Ford's SOHC and DOHC designs in output, fuel economy and weight -- and always in at least two of the three categories simultaneously. This is true both in pickup trucks and in muscle coupes. Ford F150 4x4 w/ 5.0 DOHC V8 -- 14 (city) / 19 Hwy MPG Ford F150 4x4 w/ 6.2 SOHC V8 -- 12 (city) / 16 Hwy MPG Chevy Silverado 4x4 w/ 5.3 Pushrod V8 -- 15 (city) / 21 (Hwy) MPG Chevy Silverado 4x4 w/ 6.2 Pushrod V8 -- 403 hp / 417 lb-ft -- 12 (city) / 18 (Hwy) MPG Ford Mustang BOSS w/ 5.0 Hi-Po DOHC V8 -- 444 hp / 380 lb-ft Chevy Corvette Z06 w/ 7.0 Pushrod V8 -- 505 hp / 470 lb-ft Where's the OHC advantage?

The one thing that most people do not realize is that having more cams and more valves actually hurt fuel economy at cruise. The reason is simple. Having more cams and more valves incur more frictional losses -- wasted power from each drop of fuel burned. Their advantage having mulitple valves and a direct acting DOHC head is that it permits higher engine rpm limits and higher airflow potential which translates to higher specific output. However, none of that has ANY value at cruise or when accelerating moderately around the city. The reason being that any airflow advantage is negated by the fact that the throttle is not fully open. In otherwords, the valvetrain and the airflow capacity of the head is not choking the engine -- the throttle plate is. If it isn't you'll have unintended acceleration! So at cruise and with moderate acceleration, all the multi-cam and valves do is increase friction with no benefit whatsoever. Having said that, I don't see the Pushrod arrangement as being particularly beneficial in an Inline-4. The packaging benefits apply primarily to Vee-type engines, especially wide 90-deg V arrangements where the heads add significantly to engine width and bulk. The frictional benefits of having one camshaft and a minimum number of valves can be had in an Inline-4 by simply using an SOHC head and 2-valves per cylinder -- this is in fact arrangement currently being used in Honda's Insight Hybrid for its fuel economy over DOHC 4-valve setups.

All of this is true.. But buyers of luxurie cars (and luxurie performance cars) don't really care about price of the engine, weight of the engine, complexity of the engine. Do you think owner of Ferrari , Aston Martin go and change oil or tune their car by themselves?? No..they can pay others people to do that. Yes small block are lighter but by how much?? Also engine (small block) is lighter but cars with that engine(camaro, CTS-V) doesn't seems to be much lighter or much more nimble then their competition. If GM can't use lightness of small block what is the point.. Like i sad before if GM are serious about Cadillac they should offer special engine especially for future flagship. LSA engine is an excellent engine..but it can be found in Camaro which cost about 50 000$. Imagine 120 000$ Cadillac with same engine. Yes you know, and i know, and some car enthusiasts knows it is an excellent engine. But large number of people will see expensive car(cadillac rwd flagship) with engine from cheaper and less exclusive brand (Chevrolet) And reading different forums, car magazines i'm not sure people would not realize -it is not the same engine from truck -it is not the same engine as it was before 60 years -because it has big displacement it doesn't have to weight 1 tone etc. Outside USA small block are not favorite luxurie cars engine and it is not first thing people will think when they think about luxurie. And it seems there are very large number of people inside USA that thinks the same way. IF GM is serious about Cadillac as luxurie car maker,and offer small block in real luxurie flagship (i'm not talking about CTS-V here or some SUV) GM should prove to buyers of Mercedes S , BMW 7. Jaguar XJ etc that small block are excellent engine for luxurie cars, that it is not same engine as the one in 50 000 $ car. You think they can do it? I'm not sure GM is determine to do so. Through the last few decades GM builded nortshtar V8, presented concept of XV12 engine (DOHC design and it could easily be an ohv engine and i bet ohv v12 would be lighter and smaller than DOHC V12), started building ultra v8, builded northstar supercharger just for Cadillac STS-V and XLR-V, than when bankrupcy came along they've cancelled all of it. There was talk about buying v8 from other engine manufacturer... and now there are rumors that they are thinking again about it if they go with real Cadillac flagship. IF it so easy to dismiss need for DOHC v8 GM wouldn't think much about it ..or would they? What is good for Cahevrolet doen't alway have to be good for Cadillac? Maybe in luxurie class being good enough isn't enough That a unique engine or a dedicated variant of an engine for Cadillac will help with exclusivity and perception is definitely valid. However, that such a move will also incur $1~2K in additional costs per caddy from a small volume engine line is also a reality. The question then is how much that perception benefit weighs against the price tag hit. This however has nothing to do with Pushrod vs DOHC; a Toyota Tundra and a Lexus LS460 both us a Toyota UR-series DOHC V8 that is no more or less a problem than using an LS3 in a Camaro and an LSA in a CTS-V. One thing that I have always been critical of GM on is the way they dress up their engines. I mean GM's current dress covers are better off left on the factory floor. I say that for two reasons. Firstly they look no better than Rubbermaid Trash Bin covers and really have no aesthetic value. In fact, if you remove the LFX dress cover the fancy resonance intake manifold makes the engine look better. Secondly, they can call it an acoustic cover or whatever they want. Fact is, I have deliberately test driven a LaCrosse and a CTS (previous gen) with and without the cover on an it makes absolutely no difference in the noise signature inside the vehicle. I am actually a fan of engine dress covers when they are well done and I seriously hope that GM will emulate the efforts of turn of the Millenium Volkswagen efforts in this regard. The previous gen passat's underhood dressings are exemplary and a Caddy or a Buick deserves at least as much. This will cost not more than $100 or 200 per vehicle and it possibly will have a bigger perception impact that giving the engine a caddy specific tune, displacement or compression.

While I bemoan the depature of the posh Golfs, Jettas and Passats of 2000-ish VW-AG. The move to position the brand at a lower price point to compete more directly with the domestics and Toyota is the right thing to do. Leave the posh compacts and the luxury cars to Audi. The Phaeton cannot succeed as a $80K Volkswagen. It can however replace the CC as a big VW one step above the Passat in the $35~40K price point. Above that, leave it to Audi. Afterall, isn't that why you have the two brands in th US? Overlap didn't make sense for GM and it won't make sense for VW.

As I have discussed exhaustively in the past, the point is that reducing displacement is not an effective means of reducing fuel consumption. So, regardless of CAFE or the lack thereof, the point is that going from 6.2 liters to, lets say 5.0 liters -- a good 20% reduction -- may yield no fuel economy gains or not enough to make a 1 mpg difference. If the point is to reduce fuel consumption, simply closing the intake valves on a 6.2 liter engine 20% past BDC will product greater fuel savings that reducing the displacement by 20%.

I do not expect 3 or 4 valve setups for two reasons:- It runs counter to and dilutes the key Pushrod V8 advantage -- valvetrain simplicity and minimum valvetrain frictional drag At up to the mid-6000 rpm range, 2-valve heads can follow enough as much air as the engine can ingest. Therefore, additional flow capacity has very little if any power or economy benefits. This is evident from the fact that an engine like the LS6 has a power peak at 6300 rpm, if the layout is incapable of sufficient volumetric efficiency at 6300 rpm the power peak would have been lower. You really only need 4-valves when you are aiming for power peaks above the mid-6000s.

I have always liked the CTS coupe. And the overall look of the Hennessy car is not rodiculously over the top which helps preserve the car's clean looks. Personally, I'll skip the hood louvers because I don't like the clutter from the slats. If I have to do a hood vent I'll prefer a cleaner implement like that on the C6-R race cars or the Shelby Series-1. One thing I'll really like to see on mechanically supercharged engines is a hydraulic supercharger coupling. Basically, it is a fluidic drive as opposed to a belt-n-pulley. The fluidic drive allows a variable bleed valve which can reduce the supercharger drive ratio in response to rpm, throttle position and/or altitude. This is actually a very neat arrangement as it is actually more compact than the fat belt drive. This is actually a 75 year old concept. As far back as 1941, the Messerschimitt BF109's Daimler-Benz DB601 (later DB605) inverted V12 SOHC-48v engine has a fluidic supercharger drive for automatic alttitude compensation by continuously varying the super charger ratio. That engine, believe it or not, also has a Bosch Direct Petrol Injection system instead of carburettion typically on allied engines like the Merlin. Unfortunately, due to the low quality of German Gasoline in WWII they had to resort to larger displacements, lower compression and lower boost to generate the same amount of power.

First of all you may want to revise the title to "Gen V Folder". Fodder is means either livestock feed fillers or "Cannon Fodder"! Anyway, I largely agree with the article's assessments. Aluminum Blocks are 100% confirmed (even for truck engines) Direct Injection are 100% confirmed Cylinder Deactivation are 100% confirmed (at least on some Gen V engines) Variable Valve Timing are 100% confirmed (at least the synchronous variety) Pushrods are 100% confirmed (GM's next Gen V8 will not be an SOHC or DOHC design) What I'll like to see are:- Independent Exhaust / Intake VVT via concentric cams (>50% chance) Variable Valve Lift via variable fulcrum rockers or switching lifters (~25% chance) Mixed Otto / Atkinson mode operation (<25% chance) HCCI (<10% chance) It is important to note however that none of the "like to haves" have much of a direct impact on performance potential. Indepedent VVT makes emissions cleaner and the torque curve more linear, but generally speaking will not raise maximum output. Variable Lifters or Lift ratios are the same way -- allows more aggressive lobes without compromising idle and low rpm drivability. The limits imposed by relatively low rpm ceiling 6000~7000 rpm of mass produced pushrod engines mean that cams more aggressive than you currently see on the Gen IV LS6 are unusable anyway regardless of the mitigating effects of VVL and/or dual VVT because they would make peak power above the rpm limit of the engine. Mixed Cycle and HCCI actually compromise power for efficiency. Given the "known" attributes of the Gen V engine it is safe to project a ~10% increase in output compared to Gen IV simply from the increase in compression and fueling precision of DI alone. That brings us to 468~480 hp if the displacement stays at 6.2 liters -- which is more than enough to be competitive with any other V6 Bi-Turbo or V8 DOHC designs. Fuel Economy can be expected to be at least 1 mpg better than with the Gen IV engine, or minimum of about 18/27 mpg on a 3000 lbs car (Corvette C7), 17/25 mpg in a 3900 lbs car (Camaro) and somewhere in between for a 3600 lbs ATS-V if it uses the V8. This again, is as good as or better than the numbers turned in by 450~500 hp class turbocharged V6 engines on the market. I do believe that displacement will stay around 6.2 liters because there is no significant improvement in fuel economy from displacement downsizing while keeping an otherwise identical layout. There is no truth whatsoever to a rumored 5.5 liters displacement, the racing engine beinf 5.5 is solely the result of class rules -- otherwise they would be running 7.0 liters -- and is no indication of production displacement(s).

I usually use a simple "rule of thumb" formula for determining if a car has too much power -- at least for 0-60, 0-100 and 1/4 mile runs. This formula is:- 0.7 x Tire Width (mm) x Number of Driven Front Wheels x Vehicle Weight (lbs) / 3500 + Tire Width (mm) x Number of Driven Rear Wheels x Vehicle Weight (lbs) / 3500* Eg. A Corvette would benefit from extra HP up to about 0 + 275 x 2 x 3200 / 3500 = 503 hp Eg. A FWD Cobalt would benefit fro up to about 0.7 x 235 x 2 x 2900 / 3500 + 0 = 273 hp Eg. A Nissan GT-R would benefit from up to about 0.7 x 255 x 2 x 3830 / 3500 + 285 x 2 x 3830 / 3500 = 390 + 627 = 1017 hp Based on this rule of thumb, the Hennesy CTS-V Coupe mounting 345/30 R20 rear tires has a power handling limit of 0 + 345 * 2 * 4200 / 3500 = 0 + 828 = 828 hp. Anything more really just produces additional wheel spin, and really does not have a tangible yield in acceleration times and can in fact make the car harder to launch and control. Also, you'll noitce that FWD cars have about 30% less power handling than RWD due to weight transfer away from the front wheels during acceleration and AWD cars have essentially unlimited traction for "sane", mass produced, engines. Also, heavier cars actually handle more power simply because they have more mass pressing down on the same tires. * The formula is really an over simplification as it is really torque to the wheels not power at the crank, contact patch, coefficient of friction and weight applied rather than just the width of the tire. But using a 3500 lbs correction constant, assuming the typical grip of summer compound tires and correcting for FWD lift, this rule of thumb is within +- ~10% of actual values and is easier to apply.

Again, this was never about getting more power, more torque and/or more performance. This was about delivering the a similar level of power as the 1.4T, 1.8 and 2.0 engines used by cars in this segment with the greatest level of fuel efficiency. And, why the answer may be completely the opposite of the move to reduce engine displacement and add forced induction. If the idea is to produce the same level of power as a 1.6T with 200 hp, again a 2.5L engine with a Miller Cycle Camshaft and a turbocharger may be a more economical solution. Bigger displacement, not smaller. Lower specific output, not higher. You take a low boost, high compression 2.5T that normally makes 250~270hp drop a miller cycle camshaft on it. You end up with a more efficient 200hp engine than a 1.6T.

To be fair, the 1.4T does not need to have its guts revved out all the time. It makes 148 lb-ft just below 2000 rpm. It simply isn't as efficient as similarly powerful 1.8~2.0 liter engines from the competition. The idea here is not to make the Cruze higher performance. The idea here is that a 2.5 liter Atkinson cycle engine may be a more economical powerplant that a turbocharged 1.4L or a 1.8 liter Naturally Aspirated Otto cycle engine.

Should GM reverse course on displacement reduction and put a 2.5L engine on the 2014 Cruze Eco? Is the Cruze 1.4T an improvement over past GM efforts and is it a decent engine for a well executed small car? Absolutely. This, however, doesn't change the facts that downsizing displacement and adding a turbocharger does not result in better fuel economy numbers than doing the opposite. The Cruze 1.4T is basically bottom of the pack in fuel economy and horsepower:- 2012 Cruze Eco -- 1.4L Turbo (6-spd automatic) -- 26 / 39 MPG (EPA); 138 hp / 148 lb-ft 2012 Civic HF -- 1.8L NA (5-spd automatic) -- 29 / 41 MPG (EPA); 140 hp / 128 lb-ft 2012 Focus SFE -- 2.0L NA (6-spd automatic) -- 28 / 40 MPG (EPA); 160 hp / 146 lb-ft 2012 Hyundai Elantra Blue -- 1.8L NA (6-spd automatic) -- 30 / 40 MPG (EPA); 145 / 130 lb-ft [Worst] [Best] I am not making this up. Feel free to look up the numbers @ fueleconomy.gov which has all the official EPA numbers. Contrary to popular beliefs -- downsizing displacement is an ineffective means of improving fuel economy. A more effective path lies in increasing displacement, adopting Atkinson Cycle and going to as few cylinders, as few camshafts and as few valves as you can get away with while meeting your performance and refinement objectives. The money GM spent on the turbocharger and intercooler for the 1.4T is better spent on adding direct injection, a 2.5 liter aluminum block and an Atkinson Cycle camshaft. The Malibu's 2.5L with an Atkinson Cam if you will, which actually cost less than the 1.4T. Output will be around 140 hp / 134 lb-ft. But fuel economy will be better than the Honda, Ford and Hyundai 1.8~2.0 liter engines -- all of which beat the 1.4T. GM can do even better if they go to 3-cylinders and/or a SOHC head, but I am keeping it simple and drawing from the existing parts bin. The new engine will look like this:- Ecotec 2.5 FXE Configuration: Inline-4 Operating Cycle: Atkinson-Miller Cycle Aspiration: Naturally Aspirated Fuel Injection: Direct Gasoline Injection Valvetrain: DOHC-16v w/ intake & exhaust VVT Displacement: 2457 cc (Static); 1843 cc (Effective) Bore x Stroke: 88 x 101 mm Compression: 15.0:1 (Static); 11.3:1 (Effective) Power Output: 152 bhp @ 6000 rpm Torque Output: 144 lb-ft @ 4500 rpm Redline: 6300 rpm Fuel Requirement: 87 Octane Unleaded Gasoline Estimated Fuel Economy: 30 (City) / 43 (Hwy) mpg (Cruze Eco chassis w/ 6-spd Automatic)

The fundamental reason we don't have electric cars is because gasoline and diesel offer superior convenience, range and performance at a lower price. Despite the rise of oil prices in the past decade, oil is still the most economical, most portable and convenient form of energy available -- by a wide margin. I have no doubt that ultimately human civilization will transition to Nuclear Generation, Grid Distribution, Battery Storage and Electric Propulsion. But that day is not today and not anytime soon. Gasoline will have to be $100 a gallon, it is not and it won't be for a long time.

Unknown is better than damaged. In a way, the lack of presence over the last two decades is a good thing.

I'll be like the current L99 V8 running on 4-cylinders in AFM mode just less powerful in that mode because of the Atkinson cycle operation.

No, no. It's just one camshaft. 4-cylinders get the Otto intake lobes, 4 cylinders get Atkinson intake lobes. The Otto cylinders get disabled when AFM kicks in, meaning that in its fuel saving mode the 6.8 V8 is running on four Atkinson cylinders and operate with an effective displacement of 2.38 liters -- because half the cylinders get all their valves shut off and the remaining is regurgitating 30% of the intake charge. In full song, the engine is still running 4 cylinders in Atkinson mode and four in Otto mode. The Atkinon cylinders contribute about 181 hp, while the Otto Cylinders pitch in with 258 hp for a total of 439 hp. Essentially the same as the LS3. A potential "performance first" version of the engine for the Z06 can then run with all eight with Otto lobes making 516 hp out of 6.8 liters. It'll still benefit from Cylinder deactivation, but the savings won't be as pronounced because the remaining cylinders are not operating in the efficient Atkinson cycle. Unlike the LS7 it won't rev to 7000 rpm and it won't use Titanium valves and other exotic materials (the AFM lifters can't go that high anyway). But it still makes 11 more horsepower from 0.2 liters less displacement from the increased compression and direct injection. Again, I try to err on the conservative side with estimates.

The big difference is that Mercedes do not have different brands for different segments and neither does BMW for that matter. VW-Audi does and so does GM. So it is not un-natural that there are M-B garbage trucks and trailers. However, if GM has Cadillac branded garbage trucks that kind of defeats the purpose of having the separate Chevy, GMC, Buick and Cadillac brands.

This is tricky for two reasons. Two cams (presumably one on top of the other) means pushrods at two distinct angles which complicates the rocker and channel placements. It also means additional friction for the additional cam and sprocket. More importantly, it is completely unnecessary. Having two cams only has one tangible advantage -- being able to alter intake and exhaust timing independently. There is no other benefit for all the added hassles and packaging difficulties. If that is the goal, a cam-in-cam design (ala the Viper's 8.4 V10) meets that objective without incuring the penalties. The Viper engine is rated at 640 hp / 600 lb-ft from 8.4 liters. At the same specific output, a 6.2 liter Small block will deliver 472 hp / 443 lb-ft. And, that is without Direct Injection which is 100% confirmed on the Gen V Small block so it has the potential to do better.

How about "Shared Unified Cam" -- SUCK? LOL Really, I don;t the the moniker matters. At the end of the day, if the Horspower, Torque and MPG numbers are superior that is good enough for gear heads. For non-gear heads probably just the MPG numbers and the test drive experience.