dwightlooi

You may only choose one... so choose wisely.

I believe in neither Global Warming nor the importance of reducing carbon emissions. But, I can see a place for entry luxury vehicles with a refined, fuel efficient and sprightly power train. Such a vehicle will have significant appeal regardless of the potential buyer's propensity to drink Climate Change Coolaid. In this regard, the Volt is lacking in terms of cost effectiveness and performance -- it is a nice Halo car, but it won't be a volume seller. Paying $15,000 extra to save even 70% on the average $1000~1200 annual gas tab doesn't make sense because you won't break even for 17~22 years, and the public is already beginning to awaken to the fraud that is global warming. However, paying $7500 extra for the silence of electric propulsion and V6 class performance with ~50 mpg (combined) thrown in as a bonus may make a lot of sense. I think GM will be well served by making a low cost derivative of the Volt drive train. Here's how I'll do it. Models: Buick Electra / Cadillac ETS Platform: Modified Epsilon II (SWB) Price: $35,000~40,000 Engine: 138hp 1.4 liter Turbocharged Inline-4 --(from Chevy Cruze) Motor-Generator: 138hp (uprated) Electric-Motor: 149hp (Unchanged) Battery: 3.2 kWh Lithium Ion battery pack (down from 16kWh) Electric only range: 8 miles Fuel Type: 87 Octane Plug-in charging: Not supported Operating Modes:- Below 70 mph with light-moderate throttle; 30~100% battery charge: Vehicle is fully electric Engine and Generator Motor are not connected to planetary gearset Engine is stopped; Generator Motor is not turning Below 70 mph, light-moderate throttle, 0~30% battery charge: Vehicle is operating in series hybrid mode Engine and Generator Motor are not connected to planetary gear set Engine runs to provide electricity to recharge battery, only electric motor drives the wheels Above 70 mph or heavy throttle; 0~100% battery charge: Vehicle is operating in parallel hybrid mode Engine and Generator Motor are connected to planetary gear set Engine is supplies up to 138hp to assist 149hp electric motor Vehicle is out of gas; 0~100% battery charge: Vehicle is fully electric Engine and Generator Motor are not connected to planetary gear set Maximum Vehicle speed limited to 70 mph Basically, it's the Volts Drivetrain with the capacity of the $10000 battery reduced by 80%, while the 1.4 liter is uprated from 84hp to 138hp.

Deep discharge cycle endurance is not a forte of Lithium Ion cells. This is not a matter of GM's research or the lack thereof. It is a matter of the chemistry of choice. In general Lithium Ion cells are good for power density, but not particularly good in cycle endurance. NiMH is actually better in this respect (by about 20%). People like to think of the Lithium Ion battery as one type of battery. It is actually an extensive variety of very different battery chemistries that happen to share the use of Lithium compounds in its electrolytes and cathodes. Cathodes can be Lithium Nickel Oxide, Lithium Cobalt Oxide, Lithium Manganese Oxide, Lithium Iron Phosphate or some other (more complex) Lithium compound. The electrolyte is a matching lithium salt solution. In general, there is an inverse relationship between cycle endurance and energy density. Lithium Iron Phosphate for instance is great in endurance, but is near the bottom in energy density. In a car where the battery is already the biggest single real estate and weight adder, it is a balancing act between getting the power pack small and light enough yet having high storage capacity and having a high endurance pack that lasts longer but holds less. Right now the math works out that using the high density chemistries, but using only a portion of the charge capacity is smaller and lighter than using a high endurance chemistry and using a fuller range.

OK, this is a bit confusing so let me clarify it a bit... When battery is above 30% charge (4.8~16 kWh): Gasoline Engine (84hp) --> NOT CONNECTED TO ANYTHING (NOT RUNNING) Generator-Motor (84hp) --> NOT CONNECTED IF BELOW 70 mph; CONNECTED TO ADD POWER IF ABOVE 70mph Main Electric Motor (149hp) --> CONNECTED TO DRIVE WHEELS When battery is below 30% charge (below 4.8kWh)*: Gasoline Engine (84hp) --> CONNECTED TO GENERATOR-MOTOR (RUNNING) Generator-Motor (84hp) --> GENERATES ELECTRICITY EXCLUSIVELY IF BELOW 70 mph; CONNECTED TO ADD POWER ABOVE 70mph** Main Electric Motor (149hp) --> CONNECTED TO DRIVE WHEELS * Note: It is important to note that even at 30% charge when the engine kicks in to sustain and replenish the battery, the Volt still has 4.8kWh of battery power remaining. This is MASSIVE. For comparison, the 2010 Prius has a 1.3kWh battery. 4.8kWh is practically the same capacity as the Prius "Plug-in" Hybrid's battery (5.2kWh). Based on materials published to date, the engine will not strive to bring the battery back to 100% charge. Instead, it'll just keep the charge level at or slightly above 30%. This is more than enough to provide bursts of acceleration without the driver feeling the difference. It also keeps car more efficient on gasoline use by not using gasoline to recharge the battery fully, but differing that until the car can be plugged in to the power grid. ** Note: Because the generator motor is connected to add power above 70mph, and the engine is always connected to the generator motor when the battery is low, there exists a situation where both are connected to drive the wheels. This ONLY happens when the battery is low and the car is being driven at over 70mph.

I was thinking more along the lines of 10.2:1~10.7:1 compression and 11.8~13.2 psi. This increases the off-boost static compression by about 1 full point. Plus, regardless of how responsive the LNF already is, that any turbocharger will reach 13 psi sooner than it reaches 17 psi is refutable. The effects are also compounded by the fact that with a lower boost level, the intercooler becomes smaller. A smaller intercooler in turn reduces the amount of pressurized volume and further reduce the lag time it takes to bring the plumbing and IC volumes up to boost. As far as better fuel economy with retuned LNFs it may not be from the increased maximum torque. The reason I say this is that you typically do not accelerate at WOT all the time in daily driving. What may also be at play is the revised fuel map. When you go from premium recommended to premium required, you have more leeway to play it less safe. In general many stock maps dump fuel for safety and run richer than they have to. This actually produces a little less power than a leaner mixture, but it also runs a cooler. If they lean up the map a bit, especially the part throttle mappings that'll probably affect MPG numbers more than maximum boost which is not always reached when you "ease" the car away from a stoplight or onto the freeway. In the C55, I have the map retuned with a leaner mixture and a few degrees of advance in the base timing. Only 7~8hp was gained (at the wheels), but mileage at 65 mph steady went from 24.0 to 25.2. No boost was involved and with measurements starting at 65mph on cruise control, any increase in torque is not at play here.

Torque steer occurs for two of reasons on FWD cars. These include:- Unequal inertial between the left and right driven wheels (unequal length half-shafts) The steering axis is usually not on the centerline of the wheel, but slightly offset inboard and at some caster. Both car be tackled somewhat. Eg. most high torque FWD cars which do not have horrible torque steer uses equal length, mass compensated half-shafts. Also certain suspension geometries like the Hiper Strut in the Buicks or the multilink fronts in Audis try to push the steering axis closer to the centerline of the contact patch. For the most parts, dry pavement torque steer can be quite well controlled up to 250~300 lb-ft. However, that is not to say that torque steer is no longer a problem. The ugly head rears itself when one wheel momentarily loses traction. This can happen in a cornering situation, in the wet or simply when wheel spin occurs during hard acceleration. Because it is practically impossible to guarantee that both wheels will lose traction at the same time under all conditions, it is practically impossible to prevent one wheel from applying accelerative force while the other doesn't or doesn't apply the same amount. When that happens, the steering tugs. The only way to completely eliminate the problem is for the drive wheels and the steering wheels to be separate. Having said that, the reason you drop torque is not solely to cope with torque steer. It is also to gain fuel economy and produce an engine with a more linear power delivery. By dropping maximum torque, you are also dropping maximum boost. This in turn allow you to use a higher static compression which benefits fuel economy. In addition, because it takes the turbo less time to take the pressurized volume to a lower peak pressure, response is improved and turbolag is reduced.

This is why the torque is reduced to 228 lb-ft from 260 lb-ft we see in the Cobalt SS. The reduced boost level and increased static compression also increases fuel economy at cruise when the engine is operating in vacuum.

Personally, I don't think much of CVTs. This is one of those things which sounds good on the surface, but whose economy gains did not ever pan out. The typical CVT is basically two clamping pulleys sandwiching a metallic belt or chain. The problem is that it takes a relatively strong external force application on the pulley halves to prevent the chain/belt from slipping. In most instances, the parasitic losses from the powerful hydraulic pump needed to work those pulleys is equal to or more than the efficiency gains from having infinite ratios. Plus, the ratio spread of a typical CVT is less than that of a conventional automatic or dual-clutch transmission. Case and point: Check out the Fuel Economy numbers of the CVT and conventional automatic versions of the the Ford 500 and/or Audi A4. The CVT version is did not have better mileage numbers.

Because a three cylinder engine has 25% fewer valves and cylinders. At the same displacement, frictional losses is about 10~15% lower. This equates to better fuel economy. In addition, because a 3-cylinder does not have two pistons at the top and bottom of their travel at the same instance, there is no need for a segregated exhaust and twin-scroll turbine when you turbocharge it. In general, if you are after fuel economy, a 3 is better than a 4 of the same capacity.

Cruze LT / LTZ 2.0 Liter Inline-4* DOHC-16v (Intake & Exhaust VVT) Direct Gasoline Injection 170 hp @ 6300 rpm 152 lb @ 4300 rpm 23 MPG (City) / 35 MPG (Hwy) w/6T40 6-speed automatic Regular Unleaded (87 Octane) Cruze ECO 1.5 Liter Turbocharged Inline-3** DOHC-12v (Intake & Exhaust VVT, Idle Stop Control) Direct Gasoline Injection 170 hp @ 6200 rpm 150 lb @ 1600~5600 rpm 28 MPG (City) / 40 MPG (Hwy) w/6T40 6-speed automatic Regular Unleaded (87 Octane) Cruze SS 2.0 Liter Turbocharged Inline-4*** DOHC-16v (Intake & Exhaust VVT) Direct Gasoline Injection 270 hp @ 6300 rpm 228 lb @ 2200~6200 rpm 22 MPG (City) / 32 MPG (Hwy) w/6T70 6-speed automatic Premium Unleaded (91 Octane) * Naturally aspirated version of the DI 2.0T engine (LNF) ** Turbocharged 3-cylinder based on halving the DI 3.0 HF V6 (LF1) *** DI 2.0T engine (LNF) retuned with lower boost & higher compression ratio (~10.2:1)

Well, the idea is that there would be a new gasoline V6 displacing 3.0 liters that replaces the 3.0 and 3.6 HF V6. The corner stone of that engine is that instead of a traditional DOHC layout, it'll have an concentric cam layout. The concentric can looks like an SOHC head except that it actually has one camshaft inside another. It combines the lower friction and compactness advantage of SOHC with independent intake/exhaust adjustability of DOHC. The hypothetical Diesel V6 is then based on the gasoline V6, replacing the lower block half with a cast iron structure for additional strength and reversing the flow direction on the heads such that the exhaust exists in the Vee. This allows it to use one larger turbo instead of two smaller ones. In general, larger turbines and compressors are more efficient, plus they are also lower cost than two separate units. From a technical standpoint, it is better because:- The aluminum upper block + iron lower block construction is lighter than an iron block engine. The SOHC heads are lower friction and more fuel efficient than DOHC heads The SOHC heads are slimmer than DOHC heads The commonality with the Gasoline engine makes installations and adaptations simpler. An in-house engine is potentially lower cost than an outsourced engine and brings expertise in house for the future.

Side note: The 4.5 is Duramax DOHC 72 deg V8. The 6.6 is the Duramax Pushrod 90 deg V8. Both already exist. The 3.0 is a new diesel version of the 3.0 OHCC gasoline engine. Here it is simplified to an SOHC layout and probably has a cast iron lower block for the extra strength to handle compression ignition. The 1.5 is half a 3.0. The 2.25 is half the 4.5. Both of these share the piston, rods, valves, cam layout, etc with their bigger brothers.

GM Diesel Engine Lineup - Circa 2013

A better question is why not just use the 600hp Supercharged V8 for the Z06? After all, this is a positive displacement air pump we are talking about; no turbo lag to worry about. Besides, I am not sure which is more expensive -- the titanium innards on a LS7 like high revving engine r a plain vanilla 2.1L Eaton supercharger. If you want to do a "special" limited production engine, do that for the next ZR1. You can probably push 800 hp from the 6.2 with a pair of turbos. It'll very quickly get to the point where the transmission and managing traction becomes a dorminating factor.

Personally, I don't think the ZR-1 will stick around as a standard member of the Vette lineup. Instead, I see the Z06 moving from the current LS7 engine to an engine between the LSA and the LS9 in performance. This will probably be shared with the next CTS-V as well. It will be very much like the LS2 being practically as good as the LS6, and the LS6 disappearing. It'll be difficult to push an NA 2v engine to 530 hp. And I don't see them going to the expense of adding a compressor and specifying 26hp less than the LSA. As far as slotting in an engine between 360 and 470hp, I thought about a higher boost 3.0 V6 or a "87 Octane" torque tuned 6.2 V8. But, I decided against it for the sake of keeping a 1+1 variant geometry for each engine.

The whole exercise is to see if we can reduce the entire GM gasoline lineup to eight engines that cover the entire application spectrum. If you look at the vertical axis, the idea is to cover the entire power spectrum evenly with as few engines as possible. The corner stone here is that we are using the same Cam-in-cam concentric camshaft layout across the board. In the overhead cam engines it enables a more efficient SOHC like layout (lower frictional losses due to less parts and less space usage due to having only one apparent camshaft) without sacrificing the ability to advance and retard intake and exhaust events independently. In pushrod applications, the heads are already very compact, but the cam-in-cam arrangement allows one to implement independent intake and exhaust VVT without having over-under or side by side twin cams. The 1.5 liter covers the mini cars like the Aveo and the Smart. The NA version for typical versions, the 1.5 turbo for the SS. The 1.5 is also basically half a 3.0 using the same rods, pistons, valves, followers, springs, etc. A 1.5 liter three is more efficient than a 1.5 liter four. The 2.1 covers all the duties currently handled by the 1.8, 2.0, 2.2 and 2.4 engines. I simply picked a middle displacement. An NA version goes into the base Chevys. A Turbo goes into SSes and base Caddies. The NA 3.0 replaces 3.0 and the 3.6. The turbo V6 also replaces the 4.8 and 5.3 V8s. The 6.2 Pushrod replaces the 5.3, 6.0, 6.2 and 7.0 V8s in performance RWD applications. Here we go for the biggest displacement small block that supports NA and force fed configs in an effort to obtain the highest power-to-weight and size ratio. Up level trucks, the Vette and even the ATS-V can use the same NA 470hp engine. The Z06, CTS-V, STS-V and Escalade-V can use the supercharged 600hp unit. (Torque is limited to 438 & 550 lb-ft for 6L80 & 6L90 tranmission compatibility respectively)

Eight Engines -- starting with 3-cylinders and ending with Pushrod V8s.

A turbocharged engine's main source of fuel economy penalty comes from the reduction in compression ratio. If the compression ratio is no lower than the NA engine or is insignificantly lower the fuel economy impact is minimal. Whatever disadvantage remains comes from having a relatively restrictive exhaust and short, fat, intake runners without resonance tuning. If you really want to build the most fuel efficient turbocharged engine, you stick to a compression of about 10.2~10.7:1 and run rather mild boost levels of 10.3~13.2 psi. You'll make a decent 100~110 lb-ft/liter. The power output will depend largely on how you skew the torque plateau. If you want something that comes on strong at 1600~1800 rpm, it'll probably be about 100~105hp/liter. If you push the plateau to the right by about 1000 rpm (using a bigger turbo with the same low boost levels) you can hit about 120~130 hp/liter. Such an engine will reach maximum torque at about 2600~2800 rpm and hold it to about 6600 rpm. It won't be a Lancer Evo ad it might be a little soft off the line, but it'll be perfectly competitive with a 3 liter class V6. Having said that, I'll wait for official EPA numbers before passing judgment on the Sonata's turbo four. As the Cruze's EPA numbers show, the manufacturer's estimates can sometimes be a little "optimistic".

The new corporate standard issue steering wheel is a great improvement over the overtly crude one in the current Malibu. The dash and the rest of the interior isn't as clean as I like them to be -- too many unnecessary lines, too many curves that don't flow together. The biggest flaw of the Malibu however is the lack of headroom. If the new car gains an inch of cabin height, or life they drop the seat cushions lower by an inch it'll help sway a lot of buyers. Power train wise, the 182hp 2.4 liter DI 4-potter is OK. Not best in class, but for the kind of buyers it is targeting it is good enough. Only two types of people buy the 4-pot cars -- people who don't really care about the engine and people who care more about fuel economy than performance. I am split on whether the up level cars should be a V6 or a Turbo-4. A 312hp DI VVT V6 is actually class leading and it will appeal to both the performance crowd and the smooth motor crowd. With the turbo four, you get better economy numbers. But if it is the 220hp/258lb-ft version, that is sort of a step backwards compared to today's 252hp six. If its the 255hp/295lb-ft version, on the same perch as the Regal GS. Plus, the turbo fours drink Premium. Personally, I'll go with a I4 + V6 lineup. If not anything because that is different from Buick's options.

From GM's Specifications, on GM's website. Allison 1000 Specifications on archives.media.gm.com The 4300 rpm figure is just an estimate.

You can live with the weight if you have to. After all, his will probably be a large car that may be in excess of 5,000 lbs. A shift speed of 3300 rpm however makes it unusable.

Allison 1000 6-speed (MW7) has a stout 660 lb-ft torque rating. But it is unsuitable for gasoline engines in car applications because the maximum shift speed is too low at 3300 rpm. I am sure they can raise the shift speed somewhat given that the GVW will not be anywhere near the 23,500 lbs it is rated for. But even if its 4300 rpm, that's still way too low. Unless you plan power the Ultra Luxury Caddy with a Duramax Turbo Diesel.

Yes, you are right. I thought the M-B 722.6 5-speed Auto is a ZF sourced part. It is NOT. It was developed in house. If you want to go above the power and torque levels of the CTS-V, this is the only game in town. It all comes down to torque ratings:- M-B 722.6 5-speed auto --> 796 lb-ft GM 6L90 6-speed auto --> 550 lb-ft M-B 722.9 7-speed auto --> 542 lb-ft GM 6L80 6-speed auto --> 439 lb-ft

The Daewoo stuff isn't bad. The Cruze is a Daewoo stuff.

Holden already has a FWD mid-size. It's called the Epica.