dwightlooi

Of course, light weight alloys and chassis refinement matters a lot. But, how does going for a heavier, more expensive and less powerful engine help?

Yes, I realized that and went on to change the JPEG, but the edit option timed out... Anyway... one thing of note here is that by adopting the 60 deg bank angle, the engine will not only benefit from the convenience of sharing the production line and components with the high volume V6, it also makes the engine considerably narrower such that there is no longer a width disadvantage compared to a pushrod 90 deg V8

Essentially, what we have here is two engines which achieves exactly the same power output. One does it with 4.8 liters and 99 hp/liter, the other does so with 6.2 liters and 76 hp/liter. Both are realistic possibilities. The Pushrod engine has better torque across the rev range and lighter engine mass. The DOHC engine has better specific output and lower displacement.

This should have been the 2010 Impala...

Well, length of the wheelbase doesn't have to be the differentiating factor. Areas which an "XTS" like Park Avenue could be different from the LaCrosse is as follows:- Different Powertrain -- Exclusive 360hp LF3 Biturbo V6 with AWD (eAssist optional) Additional Technology -- Magnetic Ride Control, Electrochromic windows/moonroof, 4-zone climate control, Active Parking Assist, Infrared Backup Camera, active cruise control, blind spot cameras (triggers with turn signal), aluminum hood, and fenders, automatically leveling/steering HID headlights, powered trunk lid operation, etc. Superior Luxury -- "Handmade in USA" interior (w/emblem), Napa Leather upholstery, heated and cooled seats with memory foam cushions, lumbar and thigh support adjustable rear seats, real leather wrapped dash and instrument pod, heated steering wheel, real burled walnut trim, Tri-coat paint, 1/2" thick premium carpeting, premium stereo system, headphone jacks for front & rear passengers, solid state refrigerated storage bin, etc. Enhanced Quiet Tuning -- Additional sound deadening, Acoustic Sandwich Glass all round (vs just front windows), Active Noise Cancellation, Helmholtz resonators in intake & exhaust, viscoelastic sandwich "Quiet Steel" in door and floorpan in addition to firewall, triple layer headliner, etc. These stuff would have raised the price of the LaCrosse to $50K. Instead of not offering them or spreading the LaCrosse price spectrum over $27~50K, you put it in a different car with a different styling and make it your flagship.

Well... I think that Cadillac stole Buick's flagship. The XTS should have been a Buick, it could have been the new Park Avenue, replacing the Lucerne. Big, comfy, state of the art Bi-turbo V6, FWD/AWD and an optional Hybrid drivetrain if you want one. The overall formula fits in more with today's Buicks and today's Caddies.

The ability to say that you outperform the competition is a very powerful marketing tool and one that is pretty easy to wield. Sure as hell easier to wield than having to recite the number of valves, turbos or intecooler systems while justifying why you make less power than M3 or C63. Let's put it this way... for the technically inclined audience, the merits of your engine does not need any convincing once you post your power, torque, fuel consumption, weight and/or acceleration times. For the technically challenged, it won't matter if you cite acronyms like DOHC, DI, VVT or IBC. They don't know what these mean nor do they care. To these types of crowd, you simply tailor the add to convey the message that it's a pretty car and it is very fast.

Yeah but the V8 gave the car some actual character. well, until the tranny blew up. we have a GXP G8 on our lot right now....took it for a spin recently.....that 4 speed holds it back. the GXP is nice to drive (nothing special) but the Impala SS v8 did not have a driving experience to go with the engine. The Impala SS was just a motor to an otherwise boring and sedate car. Uh... the GXP G8 only comes with a 6-speed Manual, the GT G8 comes with a 6-spd automatic. They never made a V8 G8 with a 4-speed.

Noise, Vibration, Harshness will be no worse than an DOHC powerplant of equivalent displacement. It is only worse because pushrod engines tend to have larger displacement and higher reciprocating mass. But is really not bad at all. If you believe it's bad you probably haven't driven a Vette or CTS-V. Actually, the 3.6 DI V6 sounds harsher and is noisier than a pushrod 3.5 V6 -- really. Fuel economy can actually be equivalent or better. CO2 and displacement taxes do not apply to the USA, and generally does not sway buyers of this category of cars. BTW, a Pushrod V8 is not what I have, but it is what I'll prefer in an ATS-V over a DOHC V8 or a bi-turbo V6. My current cars are a M-B C55 AMG with an SOHC 5.5liter V8, before that it was a Bi-turbo Audi S4. GM thought the Pushrod was cheap in the 90s. They never strove to make their pushrods state of the art. This has nothing to do with the configuration, it has everything to do with the bean counting mentality. If they put a Pushrod V8 in the ATS-V it will have a more unique powerplant and better performance than a twin turbo V6. Everybody has a twinturbo, DOHC DI V6. No other luxury compact has a Pushrod V8.

The SRX is still porky but at least it is now getting the engine it should have from day 1 -- the 3.6 -- instead of the seriously under torqued 3.0 and the disastrously surgy 2.8T, neither of which beats the 3.6 in fuel economy.

doesn't that 3-1 collector also make turbocharging the thing quite a bit easier? Yes, a litte, but the primary motivation is to make the exhaust manifold much simpler (One pipe instead of three) and much more compact. In fact, the close coupled cat converter can be bolted directly to the engine, with the exhaust pipe then bolted to it... For turbocharging to be really convenient and efficient, it would have been better if the engine is a reverse flow design -- the intake is on the flanks with the exhaust inside the Vee. This will allow you to use one larger turbo instead of two smaller ones. The intercooler plumbing becomes half as complicated and a larger turbo is usually more efficient than two small ones.

Superior power packaging efficiency!! Certainly a numbers guy like smk HAS to acknowledge the more advanced engineering here! This is NO DIFFERENT than proclaiming 'larger insides with smaller outside' superior! WIN!! Actually, let me back this up with emprical statistics on output vs engine mass (power density):- Ford Ecoboost 3.5 DOHC-V6 (SHO) = 365 hp / 350 lb-ft @ 204 kg = 1.79 hp / 1.72 lb-ft [per kg] Ford Ecoboost 3.5 DOHC-V6 (F-150) = 365 hp / 420 lb-ft @ 204 kg = 1.79 hp / 2.06 lb-ft [per kg] Ford Coyote 5.0 DOHC-V8 (Mustang GT) = 412 hp / 390 lb-ft @ 195 kg = 2.11 hp / 2.00 lb-ft [per kg] BMW S65 4.0 DOHC-V8 (M3) = 414hp / 295 lb-ft @ 202 kg = 2.05 hp / 1.46 lb-ft [per kg] BMW S85 5.0 DOHC-V10 (M5) = 507 hp / 384 @ 240 kg = 2.11 hp / 1.6 lb-ft [per kg] Nissan VR38DETT 3.8 DOHC-V6 (Nissan GT-R) = 520 hp / 451 lb-ft @ 276 kg = 1.88 hp / 1.63 lb-ft [per kg] GM LS3 Pushrod-V8 (Corvette) = 436 hp / 428 lb-ft @ 183 kg = 2.38 hp / 2.34 lb-ft [per kg] GM LS7 Pushrod-V8 (Corvette Z06) = 505 hp / 470 lb-ft @ 206 kg = 2.45 hp / 2.28 lb-ft [per kg] GM LSA Pushrod-V8 (CTS-V) = 556 hp / 551 lb-ft @ 212 kg = 2.62 hp / 2.60 lb-ft [per kg] GM LS9 Pushrod-V8 (Corvette ZR-1) = 638 hp / 604 lb-ft @ 241 kg = 2.65 hp / 2.51 lb-ft [per kg] Pushrods are clearly superior...

There were a couple of 8-speeds under development before the whole bankruptcy debacle. Above is the actual trademark registered by GM in anticipation of their launch. As far as I know all work ceased in the months leading up to insolvency. Whether they have resumed and how far along they are is anybody's guess. However, there is no reason to believe that an 8-speed transverse tranny will be significantly stronger than the current 6T75 (300 ft-lbs). A prudent guess would be that if they make something stronger it'll be in the 350~360 lb-ft range (very much like the Ford 6F55 used in the Ecoboost SHO) If anything, priority would be given to developing a 170~240 ft-lb 8-speed to replace the 6T40 (177 ft-lbs) and 6T45 (232 ft-lbs). Engines these "milder" trannies are mated to modest engines which will benefit more from the additional gears than a twin-turbo powerhouse V6. In anycase, stronger is not better. The best -- or at least most efficient -- transmission is the weakest you can find which meets or slightly exceeds the engine's torque output. All else being equal, strength means broader gears, fatter bearings, a larger converter and higher frictional losses. If you use a 6T70 (280 lb-ft) on a Cruze instead of a 6T40 (177 lb-ft) fuel economy suffers and acceleration times suffer, all owing to higher drivetrain losses. This is why they build various different variants of the 6T and not ONE 300 lb-ft version and use it on everything.

The problem is that it is not. At least it is not as economical as it could have been if GM went with a bigger engine with higher compression and taller gearing. Conventional wisdom has it that smaller displacement engines are easier on gas. This has lead to some governments passing displacement taxes to encourage the sale and adoption of cars with small engines. It has also lead to the new government owned Chevrolet introducing the Cruze with a decidedly tiny 1.4 liter – 1364cc to be exact – turbocharged four with the aspiration to claim the fuel economy crown of the compact segment. But conventional wisdom is wrong. As it turns out, the 1.4 liter turbocharged four was not only more expensive to build and made less power compared to its competitors – 138 hp versus 160 hp in the Ford and 148 hp in the Hyundai respectively – it was using burning more gasoline. When equipped with a 6-speed automatic transmission, the 1.4 liter Cruze Eco's 26 / 37 mpg was easily beaten by the 2.0 liter Ford Focus's 28/38 mpg and the 1.8 liter Hyundai Elantra's 29 / 40 mpg. How did that happen? To start with, the Cruze's power plant was geared in such a manner that it spins at a relatively brisk 3000 rpm at 75 mph. This is considerably higher than the competition. And it has to be gear in this manner because highway cruising is typically done at very low engine loads and with the turbocharger making very little boost. The tiny displacement means that the engine has to be geared in a manner that will allow the engine to easily maintain highway cruising speeds off-boost. In addition, the combination of turbo-charging and the lack of direct injection meant that the engine operates with a relatively low compression ratio of 9.2:1 – a far cry from the Focus's 12:1. Combined, these more than negated marginal savings in pumping and frictional losses gained through displacement reduction. That is apparently only true for the automatic. The manual ECO is doing very well with MPG, I'm regularly seeing reports of over 42mpg. Well, we have to compare apples to apples right? It won't be fair or meaningful to compare a manual Cruze to an Automatic Focus or Elantra. GM actually went out of the way to lower the gearing of the 6T40 transmission as applied to the Cruze. In prior applications, such as the Regal or Malibu, the 6T40 had a 2.89:1 axle ratio (vs 3.83:1) which would have placed its cruising RPMs within 50 rpms of the manual ECO's. But the engine was so weak off boost that the car probably wouldn't be able to maintain 65 mph without hunting between 5th and 6th gear on the freeway. Remember, a 1.4T is very much like a 1.4 NA with low compression and lousy intake runner design, until you give it enough throttle (and time) to compound enough exhaust energy and spin up meaningful boost. This is a big problem when the engine is lugging around at under 2000 rpms and 10~20% throttle.

cheaper to build. This sums up Cadillac, not "standard of the world" Well... more expensive and inferior does not make you standard of the world either. GM has lots of failings, Cadillacs have lots of failings, but the Pushrod Smallblock isn't one of them. Forget about a 380hp or 400hp turbo V6, even the 500hp turbo H6 in the 911 Turbo or the 480hp mill in the GT-R does not match a 6.2 liter small block in power density. The Pushrod simply makes more power per pound of engine weight or per cubic-ft of engine space. And, it does so with an equivalent or better fuel consumption. That it is also cheaper to build should not be seen as a demerit. The Pushrod V8 should not be seen as a disadvantage, it should be seen as a unique advantage. The Gen V Pushrod V8 will is expected to make 450~470hp. It can also be expected to have 8~10% better fuel economy numbers than today's LS3. This translates to about 7.6 lb/hp and 17~18/27~28 mpg on a 3600~3800 lbs car we expect the ATS-V to be. This is better than the RS4, C63 or the M3. There is simply no smaller, lighter and more fuel miserly way of making 450+ hp. But all of that aside, the key factor is that the Pushrod V8 will exist with or without the ATS-V because it is already being built for the Corvette among others. A 400hp class turbo V6 does not currently exist and it will not exist unless GM goes out of the way to build one for the ATS-V because it is fundamentally incompatible with the drivelines of the transverse FWD or AWD applications GM may want a turbo V6 for (which are limited to the 300 lb-ft rating of the 6T transmission).

It's speculation at best, and I think they are wrong. My guess is that the ATS-V will get a Normally Aspirated Pushrod V8. This alone puts differentiates it from the bigger and more expensive CTS-V. The Gen V Direction Injected Pushrods will make about 450~470hp out of 6.2 liters. This is less than the 556 from the LSA, but it'll be adequate to trump the M3 and the C63. The Pushrod V8 will have the additional advantages of being lighter, smaller and cheaper to build. Fuel Economy probably won't be that different and may actually be better since you are not dragging along 32 valves, four camshafts and all their drive parts.

The problem is that it is not. At least it is not as economical as it could have been if GM went with a bigger engine with higher compression and taller gearing. Conventional wisdom has it that smaller displacement engines are easier on gas. This has lead to some governments passing displacement taxes to encourage the sale and adoption of cars with small engines. It has also lead to the new government owned Chevrolet introducing the Cruze with a decidedly tiny 1.4 liter – 1364cc to be exact – turbocharged four with the aspiration to claim the fuel economy crown of the compact segment. But conventional wisdom is wrong. As it turns out, the 1.4 liter turbocharged four was not only more expensive to build and made less power compared to its competitors – 138 hp versus 160 hp in the Ford and 148 hp in the Hyundai respectively – it was using burning more gasoline. When equipped with a 6-speed automatic transmission, the 1.4 liter Cruze Eco’s 26 / 37 mpg was easily beaten by the 2.0 liter Ford Focus’s 28/38 mpg and the 1.8 liter Hyundai Elantra’s 29 / 40 mpg. How did that happen? To start with, the Cruze’s power plant was geared in such a manner that it spins at a relatively brisk 3000 rpm at 75 mph. This is considerably higher than the competition. And it has to be gear in this manner because highway cruising is typically done at very low engine loads and with the turbocharger making very little boost. The tiny displacement means that the engine has to be geared in a manner that will allow the engine to easily maintain highway cruising speeds off-boost. In addition, the combination of turbo-charging and the lack of direct injection meant that the engine operates with a relatively low compression ratio of 9.2:1 – a far cry from the Focus’s 12:1. Combined, these more than negated marginal savings in pumping and frictional losses gained through displacement reduction.

A way to do it will be to build a 60 deg V8 of 4.8 liters using the HF V6 architecture. You can build it on the same lines, they'll used the same pistons, rods, valvetrain parts, etc. A balance shaft can be used to smooth out the 60 deg configuration (ala Volvo's Yyamaha built 4.4 V8). It'll be a DOHC 32v engine making about 420~430 hp. But, again, such a V8 will be a heck of a lot more work and money than a variant of the LFX V6 with different pistons and a cam grinds.

The current bore is 94mm, the bore centers are 103mm. That's 9mm between in the walls between the cylinders. You can probably shave it to 8mm or even 7mm. The HF V6 also has a rather short deck so you can't really stroke it much without the rods getting overly short and side loads getting rather high -- which is bad for durability and bad for fuel economy. I mean, yes, you CAN change the bore centers and redefine the crank to deck height, but that'll basically be a clean sheet engine. Let's shave it to the limit and go with a 96mm bore. That's say 96mm x 85.6mm which gets you to 3717 cc. But it'll require major changes to the engine's block and liners. Maybe going to an sleeveless aluminum block which then requires a silicon impregnated alloy block or a Teflon-Ferrous plasma coating because aluminum-on-aluminum has very high friction coefficients. It's definitely more than higher compression pistons and a revised cam grind. And, at the end of the day, you have to ask if 3717 cc is really worth it.

(1) LFX is the official designation; or at least it is the RPO code GM certified the motor output under when it did so with the SAE. If you want to see the report you can get it here... http://standards.sae.org/cpgm1_12cadcts (2) No, a bump to 280 lb-ft won't feel that much different when the car is driven moderately. However, the fact that torque doesn't falter and stays at or above 270 lb-ft all the way to 7000 rpm means that the engine feels more alive and more willing at 5500~7000 rpm. Make no mistake about it though. 280 lb-ft is not wimpy for a 3.6 liter engine. It is actually very good at 77.8 lb-ft/liter, it'll be slightly less than a full on race engine but not by much. (3) If you want more torque you'll need more displacement, forced induction or run on something other than gasoline + air. These come with a bunch of their own baggage. The 3.6 is about as big as the current 103mm bore center HF V6 block will go. Turbos and Intercoolers are expensive, bulky, heavy and put out too much torque for the 6T75 or 6L50 transmissions. The only current GM alternative is the 6L80 which introduces two problems -- the 6L80 must shift at 6500 instead of 7000 rpm, this means a lower redline and no front drive applications. As far as Methanol-Water or Nitrous-Oxide injection... I don't even want to go there.

Getting another 40 hp or even 80 hp NA is easy compared to getting another 25 lb-ft. 300 lb-ft out of 3.6 liters is about 83 lb-ft per liter. At 12:1 you are probably not going to get much above about 78 lb-ft per liter. 78 lb-ft/l is about what you get at 100% volumetric efficiency with no parasitic losses. For comparison the BMW M3 is at about 74 lb-ft per liter, the new Focus 2.0 DI is a 72.5, the Ferrari 430 is at 79. Most of these engines are operating at over 100% volumetric efficiency at their torque peaks and losing some torque to frictional losses.

To keep the long story short, the GM has a new 3.6 liter V6. It's called the LFX. It'll be used in the Camaro, the CTS and everything else that currently use the 3.6 DI V6. It makes 318~323 hp / 275~278 lb-ft. As is desirable for a across the board engine, it runs on 87 Octane with 11.3:1 compression. The question is whether Cadillac should get a "Premium" version of this powerplant. Premium as in "Premium" performance as well as "Premium" fuel. Going to 91 Octane will enable the compression ratio to go up about a point to about 12.3:1 with higher compression pistons, this alone should bump output by about 7~8% which will take you to about 340hp horses. With some minor changes to the cam profile and VVT programming one can move the torque curve slightly to the left for a total of about 12%. That makes a 100hp/liter, 360 hp engine with about 280 lb-ft of twist. Not shabby by any standard and the premium fuel recommendation is not particularly out of place on a luxury marque like Cadillac. The cost equations wouldn't change significantly since the engine is still 95% the same as its more mundane siblings and the parts that are different aren't actually more expensive. LFX -- 91 Octane ~ 360 bhp @ 7000 rpm ~ 280 lb-ft @ 5500 rpm

Strictly from a component standpoint, we are talking about a more complex intake cam assembly -- concentric shaft and an additional cam phaser -- and a set of cylinder pressure sensors. Probably less than a turbocharger, intercooler and their plumbing. Most of this is going to be R&D and proofing costs.

I think 30-45-75 is not a bad bad strategy for a luxury marque. That is... Assuming that you have three models... a compact, a midsize and a flagship they peg their average price at $30K, $45K and $75K. $15K separates the entry level model from the mid-tier model. $30K separates that from the flagship. For Cadillac, that means:- ATS -- $30K CTS -- $45K XTS -- $45K STS --- $75K Now, remember that this is the average price. You can spend $28K or $35K on an ATS. But a typical example sells for around $30K. By this pricing scheme, the CTS (which currently starts at $35,165 and sells for about $40K reasonably equipped) will have to move $5K upmarket. This brings it inline with BMW 5-series pricing. The XTS will basically be the same price, but biased towards ES350 type buyers who want roominess, refinement and luxury but not necessary driving dynamics and performance (This car really should be a Buick, but... oh well.) The ATS on the other hand will move downmarket by a good $5K so its there with the TSXes and IS250s of the world. Makes sense if it is to have a 4-pot turbo as its mainstream powerplant. This leaves the room open for a $75K full size which doesn't have to make compromises to stay cheap.

I'll like to see the new seats... this, I believe they can fix without expensive changes to the car. The current Corvette seats are worst in class. Not only in their lack of support and generally poor ergonomics, but also in their flimsiness and el-cheapo appearance. I mean, I'll rather than the cloth seats in a base Honda Accord than a Corvette -- that's how bad.