dwightlooi

The article has some inconsistencies. (1) There is no way Holden Commodores will be both Epsilon (FWD) and Zeta II (RWD). It is just not practical. They'll either stick to one, or they make one a Commodore and the other an entirely different model with a different styling and a different name. (2) There is no mention of the Small Block V8 going into the "ultra Lux" Caddy based on the Sixteen concept being DOHC. Honestly, an LS9 or its Gen V equivalent of a supercharged SB V8 is more than good enough with over 630 hp and surprisingly civilized character. The biggest problem will be the transmission. Currently, GM's stoutest 6-speed auto transmission (6L90) is rated for 550 lb-ft of torque and a 6200 rpm max shift speed, ultra lux buyers are not going to want to row a stick. They may have to develop a new transmission, or if the usage is limited to this one model, go outside and buy one -- possibly the 5-speed ZF auto used in the S65 AMG.

It'll be interesting, but that wasn't my point. What I was trying to illustrate was that with the same engine, same turbo and same intercooler, you have a broader torque plateau at lower boost levels. As you increase the boost (and hence torque) you narrow that plateau. If you take boost up to the limits, there is no longer a plateau.

The LNF 2.0T engine is a good case study... Here we have the same engine, same turbo, same transverse layout. The only difference is the maximum boost we allow the turbo to reach. On the manual Cobalt, we let it rise to 18.5 psi before arresting it. In the automatic HHR it was only allowed to get to about 14.5 psi. On the former we get a 3250 rpm torque plateau starting at 2000 rpm, on the latter the torque peaks at 1650 rpm but holds its lower value to 5500 rpm. There is only a 10 hp difference between the two engines but there is also a more significant 38 lb-ft gap. At the higher end of things, the extra boost didn't help very much as the turbo was running off the efficient part of its compressor map anyway. Hence, only a 10 hp difference is realized despite the ~4 psi of extra boost. At some point you are making for heat than you are compressing air molecues. If we take things further, such as with the GM Performance Parts upgrade kit which further ratchet up the boost with larger injectors and a new ECU program, power gets to 290 hp @ 5200 rpm, torque climbs to 315 lb-ft @ 4800 rpm. Here, boost climbs to 24~25 psi (under normal sea level conditions) and there is practically no plateau to speak of. http://www.gmpartshouse.com/products/19212670-lnf-turbo-upgrade-kit.html

Right, and how does that point to Turbos or DOHC V8 power plants of smaller displacement at high revolutions? I'll say that you go for the more powerful, lighter and more fuel efficient option. And, that is an advanced Pushrod V8. If it is also lower cost, that is a good thing; that gets you more budget to spend on the rest of the car. It is not better because it has more displacement and appeals to people who look for big cubic inches. It is better because the combination of less valves and less cams equal less mechanical drag which provides for better fuel economy at low loads. It is better because the absence of broad and heavy DOHC heads reduces the engine's size and weight. It is better because its reduced complexity makes the engine less costly to produce. It is better because its performance matches that of turbo sixes and DOHC V8s of greater cost, complexity, weight, bulk and fuel consumption. Actually, it is better for the same very reasons it was created over half a century ago after advent of SOHC and DOHC engines.

Yes, you can do that on a low boost application. 350 hp 365lb-ft from 3.5 liters is calls for about 10~12psi on 9.5~10.5:1 compression. When you start looking at higher specific outputs, boost goes up and the plateau gets narrower. 1700~5500 is about 3800 rpm. I believe that even a 4000 rpm spread is possible. Try drawing a big arch between the start and end of the plateau. That is what the turbo will deliver if you basically let the boost go unchecked and assuming you have fuel with infinite octane. In reality you can't do that of course, but that what the airflow limits of the turbo will provide. The curve becomes a plateau because the waste gate opens, arresting boost rise and manages the boost pressure to keep the torque production at the prescribed level. When you go from 350hp to say 460 hp, you need the turbo to spin to high speeds and deliver more boost before arresting boost rise with the wastegate. In essence you are chopping off the top of the arch at a higher point. At 460 hp your plateau is going to be about 2500~3000 rpm wide.

Actually, the GT-R engine doesn't peak that low. Turbo charged engines typically have a very sharp torque rise followed by a plateau and a sharp fall off. Modern turbos can maintain the plateau for about 3000 rpm at moderate boost levels. At lower boost levels this widens, possibly as much as 4000 rpm worth. At high boosts it is narrower, maybe 2500 to even 2000 rpm. Let's say you are running about 14~15psi. You can set an engine up for a 2000~5000 plateau or 3000~6000 plateau, but you can't do both. To do the former you use smaller turbos, for the latter you use bigger ones. Bigger ones can support higher flow rates but do not spool as quickly and needs more exhaust energy to drive. In the GTR I think they chose the latter. They could also use more boost, less compression and pull everything in to a lower rpm range but they didn't. The GT-R engine is a little soft down low, but doesn't run out of breath all the way to 7000 rpm. I think they want it that way.

Let's consider two engines:- Hypothetical 3.6 liter Bi-Turbo DOHC-32v V6* Power: 470 hp @ 6400 rpm Torque: 420 lb-ft @ 3200 rpm Redline: 7000 rpm Engine Weight: 262 kg Recommended Fuel: 91 Octane Est. Fuel Economy: 18/25 (3700 lbs vehicle) Cost Premium: $5000 Hypothetical Gen V 6.2 liter NA Pushrod-16v V8** Power: 470 hp @ 6200 rpm Torque: 438 lb-ft @ 4200 rpm Redline: 6500 rpm Engine Weight: 183 kg Recommended Fuel: 91 Octane Est. Fuel Economy: 17/26 (3700 lbs vehicle) Cost Premium: $0 * Hypothetical 3.6 Bi-Turbo V6 based on the Nissan GT-R's VR38DETT engine. Same specific power output, same specific torque output, same power peak, same torque peak and same weight-to-displacement ratio. MPG figures assumption are +2 MPG (city) / +4 MPG (hwy) over Nissan GT-R (16/21 MPG) for reduced vehicular weight and elimination of AWD. ** Hypothetical 6.2 Gen V V8 based on LS3 engine with 1 point higher compression, direct injection, VVT and cylinder deactivation. 7% increase in power, 3% increase in torque and +1 MPG (city) / +1 MPG (hwy) improvement over the automatic Camaro SS for reduced weight and increased engine efficiency. Why will you pick the Turbo V6?

Just the facts... The Northstar V8 has a bore spacing 102mm. It has 93mm pistons and 84mm strokes for a displacement of 4565cc. It uses VVT and makes 320hp @ 6400 rpm (70.0 hp/l) with 315 lb-ft, redlining at 6750 rpm. The Northstar weighs 195kg. For comparison, an LS3 V8 has a bore spacing of 111.76mm. It has 103.25mm pistons and 92mm strokes for a displacement of 6162cc. It makes 436hp @ 5900 rpm (70.8 hp/l) with 424lb-ft, redlining at 6600 rpm. The LS3 weighs 183 kg.

Racing series in most cases are limited by class rules stipulating displacements. Race cars are hence forced to make power within the allowance of those rules. Road cars derived from companies involved in these types of racing activities are hence biased towards small displacements and high revolutions, or small displacements and significant boost pressures. Hence, many super cars are so biased as well given their progenitors' experiences. The fact is that today, when you compare the best pushrod powerplants and DOHC powerplants from the leading mass produced vehicles, pushrod engines offer more power, lighter weights, smaller sizes and equal or better fuel economy, at a lower cost and possibly with better reliability. A good example is the BMW S65 V8 in the M3. It displaces 4.0 liters and weighs 202 kg. The S65 spins to 8300 rpms, produces 414hp and 295 lb-ft. In the 3700 lbs M3 it gets 14/20 (city/hwy) mpg. You'll be hard pressed to find a DOHC V8 of a finer pedigree. Don't like BMW? Look at the Lexus IS-F's 5.0 liter 2UR-GSE V8 then. 416 hp, 371 lb-ft, 222kg. The 2UR-GSE spins to a modest 6800 rpm. It gets 16/23 mpg with the help of an 8-speed automatic transmission. Chronologically, their contemporary will be the LS3 V8. It displaces 6.2 liters and weighs 183 kg. It makes 426hp and 420 lb-ft installed in the Camaro. The LS3 spins to 6600 rpm and in the 3900 lbs Camaro gets 16/24 (city/hwy) mpg. Less weight, smaller size, better fuel economy, a little more power, a lot more torque and a lot less money. What's not to like? Refinement? It's not bad. Not any worse than M113 5.5L V8 in the C55 AMG. Not surprising really given that -- despite the M113's lower displacement -- both engines have identical stroke lengths 92 mm, and stroke length more than anything else causes vibration harshness* The LS3 is actually less "raw" than the M156 in the C63 AMG at higher rpms, while not as "soft" on power or response below 4000 rpm. * Vibration forces due to imbalances are in general a function mass x the square of piston speed, which in turn is a function of stroke x rpm.

Let's wait for the EPA numbers... In theory, reducing displacement without reducing the number of cylinders and valves, while adding forced induction does not necessarily translate into better fuel economy. Examples:- Cruze's 1.4T -- it is no more efficient than the Civic or Corolla's 140hp 1.8 liter fours VW/Audi 3.0T (supercharged) -- 18/27 mpg is good, but no better than a 3.6 or 3.8 NA V6. Let's consider what happens when you go from 5.5 to 4.7 liters in a DOHC-32v setup. Your valve train drag remains about the same. Your piston to wall drag is insignificantly lower. Your intake pumping loses at cruise and light loads is the same (choked by the throttle body). Your exhaust pumping losses improves slightly. Your power and torque numbers drop more than the exhaust pumping losses reductions. Net result, small gain in efficiency with slightly larger loss in output. Now, to recover the lost power and gain some, you add forced induction. The following then happens:- The turbos introduce exhaust back pressure reducing cruise economy. The turbos and intercoolers add bulk and weight. You drop compression by about 1 point to accommodate the boost pressure lowering cruise economy. The turbo intake manifold usually doesn't have resonance tuned runners dropping cruise efficiency. Power increased more than the loss in efficiency, offsetting the losses from the reduction in displacement. At power parity, fuel economy is similar, but engine is more expensive, more complex, bulkier and heavier. However, the torque band is broader which may improve the driving experience. If you strive to actually gain power, you end up dropping compression further and fuel economy goes down, although you gain more power than you lose in economy.

I fully expect GM to do a 3.0 or 3.6 Bi-Turbo. I am leaning towards the 3.0 because of wall thickness issues on the 3.6 block. This will replace the 2.8T in the Opel lineup and will provide a high torque power plant to vehicles currently underpowered by a 3.6 NA or is currently using the 5.3 LS4. In the case of the 5.3 replacements, the 3.0BT will create more distinction between a Turbo V6 in the low tier models and a V8 in the upper tier models. I expect a 300~360 hp engine with relatively low boost, very responsive (small) turbos and 87 octane compatibility. For the ATS-V, I expect GM to go for performance and dynamics, and that calls for a NA Pushrod. A high strung, 480hp class 3.0 or 3.6 TT (133~160hp/liter) simply doesn't offer any weight, packaging or fuel economy advantage, while being significantly costlier and possibly a tad laggy due to to boost levels used (about 8.8:1 compression and 20~25 psi of boost is needed). Besides, the Gen V pushrod engine is confirmed for the Vette and building it just for the Vette will be uneconomical. But you are right, it wouldn't be an LS. The LS ends with the LS9 and LSA; a new block means it'll be an L-something else. It also makes sense that the same engine in NA form powers the ATS-V whereas a supercharged version powers the CTS-V.

It is easy to criticize stereotyping, but more often than not stereotypes developed for very valid reasons. Much through the 80s and 90s, American "performance" cars are heavy, not that fast, not that great handling and pretty low rent on the inside. They also used Pushrod motors. These things then become inter-associated. None of those things are particularly true anymore with regards to cars like the CTS (although it is still 300 lbs too heavy). Over time, if Cadillac can deliver the quality, handling and performance customers expect, perception will change. Driving volumes to 3-series levels will take 2, maybe 3 generations.

I think the point is that comparing the price of crate engines are not necessary a good way to decipher the actual cost of the engines. When installed in a car, what really matters is whether the product -- a well handing, 470hp, $45,000 car finished to a standard (presumably) similar to that of the current CTS -- is sellable in the market. Some individuals here contend that it won't be as sellable as a $65,000 product packed with more content or simply more margin, because of the desirability of exotic content or simply price driven exclusivity, or both. I disagree.

The LS3 is around ~$6100 (retail). But these are not a good measures of actual costs to Ford and GM. The profit margins may be different.

The idea that you should make a car more expensive simply to get respect is ridiculous. Based on that logic, you'll sell more iPhones if you simply make them $500 more expensive because the high price makes them more "desirable". Well, it doesn't work because demand for pretty phones and cars are pretty darn elastic. If the price tag is such that it'll force a low rent interior or compromise performance it would have been one thing. But $45,000 won't. The ATS-V at $45K is about $10K more than a fully optioned out 3.6 ATS. The beautiful thing is that the Gen V pushrod V8 is probably no more expensive than the 3.6 DOHC V6. So that leaves $10,000 to play with for brakes, tires, limited slip differentials, magnetologic shocks and whatever else. The interior is not going to be any different from the standard ATS-V save for a few emblems and trim pieces.

Let me put it this way... an ATS-V at $45K is the right price point, whereas an M3 at $60K is the wrong price point. Why? Because cars like the M3 price themselves out of the meat of the market for this class of vehicles. Case and point... The E36 M3 used to go for about $40K. Back then, about 20% of 3-series sold was an M3. Today, the the E90s the M3 is $60K and about 4% of 3-series sold is an M3. I think the reason is very simple. The 22 to 35 year old college grads and working professionals can usually afford a $35K new car. They can also -- with some pain -- afford the $45K car they have always wanted. $60K puts it out of reach. And when it is out of reach, it really doesn't matter if its a $60K M3 or a $250K Ferrari. The other problem here is the CTS-V. If you move the ATS-V to $60~65K, you'll need to move the CTS-V to 75~80K. Then none of the Vs will sell enough to cover their own development costs. If Caddy wants a "halo car" like the LFA or the Viper or the GT-R, then they should go build a supercar for that purpose. Resurrect the XLR or call it something else. Intentionally, making the top model of your bread and butter models too expensive to sell is a horrible way of doing it.

Which is why the ATS-V shouldn't, and probably wouldn't, be $65,000. That pays for a CTS-V. The two wouldn't be the same price, just like the M3 and the M5 aren't the same price. The ATS-V will probably start at $45,000. While the "regular" ATS starts at around $30,000 (around $5000 less than the entry price for the CTS). For $10,000 more than a Camaro, you get a Caddy will four doors, a posh interior, more amenities and a completely different style. That it shares the same basic engine as the Camaro and the Vette isn't an impediment to desirability. For 3/4 the price of an M3 you have a faster, better handling car with a similar level of utility and polish. That it doesn't have to rev to 8300 rpm is actually a positive thing.

Side Note: In FWD/Transverse-AWD applications, the DOHC V6 TT will probably be detuned to:- 335 hp @ 6000 rpm 300 lb-ft @ 1400~5800 rpm Redline: 6000 rpm This is for compatibility with the 6T75 6-speed automatic transmission's 300 lb-ft max input torque rating. The 6T75 is the stoutest transverse auto in GM's parts bin.

Prediction for 3.0 DOHC V6 - Twin Turbo Super Linear Torque Delivery -- 332 lb-ft from 1600 rpm to 5600 rpm Super fast response -- air-water aftercooler = minimum pressurized volume Regular 87 Octane compatibility 6L50 transmission compatibility -- 332lb-ft = 6L50 torque limit Engine Code: LFx Configuration: 60-deg V6 Construction: Aluminum Block and Heads Valvetrain: Chain Driven DOHC 24-valve, Dual VVT Aspiration: Twin Turbocharged, 11.8 psi (max. boost), air-to-water aftercooler Bore x Stroke: 89 x 80.3 mm Displacement: 2997 cc Compression Ratio: 10.2:1 Recommended Fuel: 87 Octane Unleaded Gasoline / E85 Ethanol (at reduced power) Power: 360 bhp @ 5800 rpm Torque: 332 lb-ft @ 1600~5600 rpm Redline: 6000 rpm Applications:- Buick Lacrosse GS Buick Enclave GS Cadillac SRX 3.0T (replacing 2.8T) Cadillac XTS 3.0T Cadillac CTS 3.0T (replacing 3.6 NA V6; 3.6 NA v6 replaces 3.0 V6 as base engine) Chevy Tahoe (replacing 5.3 V8) Chevy Suburban (replacing 5.3 V8) GMC Acadia Denali GMC Yukon/Yukon XL (replacing 5.3 V8; Yukon Denali gets Gen V Small Block) Holden Commodore Series II (replacing 3.6 NA V6; 3.6 NA v6 replaces 3.0 V6 as base engine) Opel Insignia OPC (replacing 2.8T V6)

(1) I won't be surprised if the did a TT DOHC V6. My suspicions is that it'll be a low boost (~0.8 bar; 11.8 psi) ~350hp 3.0 liter rendition. The TT V6 will most likely be in the vicinity of 350 lb-ft with a very low peak of 1600~1800 rpm. This puts it in the same power class as the BMW N55 and the Ford Ecoboost 3.5. It'll be useful in applications where the 3.6 is under torqued. The SRX and perhaps the entry Suburbans and others can use such an engine. The reason I favor the 3.0 over the 3.6 is that it has 14mm cylinder walls whereas the 3.6 has somewhat marginal 9 mm cylinder walls. The 3.0 also has an integrated exhaust collector in the heads (it has one exhaust port per bank) meaning the manifold feeding the turbo can be very simple and efficient. The reason I doubt it'll be a used in the ATS-V is that it'll have to be a high boost engine using the 3.6 block. To match a Small block, it'll be something along the lines of the Nissan GT-R's 480hp VQ38DETT -- neither cheap nor particularly efficient given its low compession, plus those 9mm cylinder walls on the 3.6 and ~17.4 psi of boost is on the edge at best. (2) The ATS and CTS are separated by vehicle size. They are also substantially different in powertrain. The CTS starts with a six andd ends with a Supercharged V8. The ATS starts with a turbo four and ends with a normally aspirated V8. The separation of the ATS-V and the CTS-V will be that the CTS has a superrcharged version of the engine. In many ways it'll be like the previous generation AMG cars. The C55 had a NA 5.5 V8. The E55 had the Supercharged version. In all likelihood, you'll see a 450~470hp engine in the ATS-V and a 550~625 hp engine in the CTS-V -- quite substantially different. (4) Aluminum is not new. Aluminum and its various alloys have been an industrial mainstay for a century. Aluminum is every where from sidings to cases to blinds to shower doors. Any process economies have probably been tapped. If Aluminum usage in cars increase, prices may actually increase due to increased demand and a relatively mature and inelastic supply. Aluminum promises an ~33% weight savings on the chassis, high strength steel about 15%. A typical car has a chassis weight of about 500~750 lbs (227~340 kg) That is about 1/6th the vehicle's curb weight. The rest is the driver train, the interior, the doors, the suspensions, the wheels, etc. So the use of aluminum space frames really amounts to about 150~225 lbs of savings. High strength steel gets you 70~100 lbs off. At some point you start wondering if the 80~125 lbs its worth the cost of aluminum which is almost twice that of steel in a per unit strength basis.

I'll try to make a comprehensive response to the multiple posts above. (1) MPG numbers on the 2.0T are derived from that of the Solstice GXP -- 22/31 MPG. The engine here will have a higher static compression and lower boost (est. 10.2:1 vs 9.2:1; 13.2psi vs 18 psi). This should result in Brake Specific Fuel Consumption (BSFC) numbers lower than the LNF in the Solstice GXP. I expect the EPA City numbers to be unchanged despite a 400 lbs weight growth mainly due to the wider ratio spread of the 6L45 vs the 5L40 in the GXP and improved off-boost/low-load BSFC. EPA Highway numbers are basically a function of the top gear ratio and aerodynamics; weights does not matter very much because it is practically a constant speed test cycle. For the Highway cycle I expect a 1 MPG improvement simply because of the 6.05 ratio spread of the 6L45 vs the 4.56 ratio spread of the 5L40 in the Solstive GXP. (2) I don't believe that they'll go for a 3.0TT or 3.6TT simply because there will be no weight, packaging or performance advantage. Plus it'll be an additional development whereas a DI Small Block V8 is already available from the Vette. The same thing goes for a DOHC V8, that is a new, separate development whereas the SB V8 is already a given. It too offers no weight, packaging or performance advantages. A 6.2 Pushrod V8 will fit in roughly the same space as the 3.6 DOHC V6, a TT 3.6 is actually harder to fit because of the space required for the turbos, intercooler plumbing and intercooler itself. (3) If they do commit to a second V8 line that is DOHC, I strongly believe that it'll be a 60 deg engine based off of the 3.0 and 3.6 V6es. 90 deg engine will have to be all new. A 72 deg based off the 4.5 Duramax DOHC Diesel is unlikely -- that is a relatively heavy iron block. (4) I'll like to see the ATS 2.0 weigh in at 3300 lbs and the ATS-V tipping the scales at 3500 lbs. But I don't think it's going to happen. GM is not going to splurge on aluminum space frames and the like.

I am assuming that they'll keep it as a 6.2. The 5.5 is a racing engine limited by class rules to 5.5 liters, I don't think it'll have any bearings on the production engine's displacement(s). Chances are they'll have a few displacements like they do today. Realistically, though the engine outputs will vary quite a bit depending on displacement and configuration:- Gen V Pushrod Small Block 7.0 Supercharged -- N/A (Cylinder Walls Too Thin) 7.0 NA -- 525hp / 500 lb-ft 6.2 Supercharged -- ~620hp / 620 lb-ft 6.2 NA -- ~470hp / 440 lb-ft 5.5 Supercharged -- ~550hp / 550 lb-ft 5.5 NA -- ~420hp / 390 lb-ft 4.8 Supercharged -- 480hp / 480 lb-ft 4.8 NA -- 370 hp / 340 lb-ft These estimates assume the incorporation of Direct Injection along with a 1 point increase in compression ratio.

What do you think we'll get? In any case, the power trains I forecasted are based on the following deductions:- 2.0T -- Basically a LNF engine tuned for 87 octane; boost goes down, hp decreases by 10, torque by 38, torque plateau extended. 2.0TD -- OPC Twin Sequential Turbo 4-pot Diesel engine burrowed from Opel 3.6 -- Same engine as the Camaro; 87 octane 6.2 -- Gen V Small Block V8; ATS-V gets naturally aspirated version, Supercharged version reserved for CTS-V and Vette The basic Turbo-4 + V6 strategy is similar to VW-Audi's. For the specialty ATS-V, a small block provides class beating performance and unique Cadillac character.

2012 Cadillac ATS Initial Lineup Forecast

Over the past decade and a half, the small block gained an aluminum block, variable valve timing and cylinder deactivation. It now puts out a very respectable 70hp/liter and it beats competing DOHC power plants on fuel economy, engine weight and engine size. Today's small block makes more power and more torque, while weighing less, taking up less underhood volume and having better fuel economy than a superlative DOHC V8 like the 414hp BMW S65 4.0 liter V8 in the M3. I won't characterize this evolutionary record as one of "minor" updates. It is slated to get direct injection next year and perhaps even dual independent VVT. The relocation of the in block cam to a higher location will reduce the valve train mass. Assuming that the Gen V engine gains a modest 6~7% in hp and 1 mpg it is to remain a perfectly competitive. Perhaps you have a different take on this?