Why GM should NOT build a DOHC V8

[dwightlooi]

so do the hybrid with the v8 then......

Well, I think they were trying to get better economy numbers than the typical V6 while offering V8 power. A V8, pushrod or otherwise, has lower economy numbers than the 3.6 V6. Perhaps, there is also the idea that 350+hp is "enough" since they obviously aren't going for maximum performance here.

Personally, though, I am not big on the two-mode hybrid system. The thing about hybrid drive trains is that you rapidly reach a point of diminishing returns in terms of cost benefit ratios. The value proposition of hybrids are dubious to begin with since it takes an average driver 8~13 years just to break even on the price premium of a hybrid drive train.

Instead, I believe that a good strategy would be to adopt a hybridization for handling and performance enhancement. The system will be more than a mild hybrid but doesn't go as far as to carry a heavy battery and enough electric propulsion power to move the car on electric power alone. Instead, the system will focus on using the electric propulsion system to improve handling. I'll do this with a differential motor -- two 20hp motors coupled to the rear differential. Each capable of helping accelerate or brake each rear wheel separately. An electric active differential if you will. A 2kWH battery would be enough to operate such a device. This way, both the tree huggers and enthusiasts and embrace the car.

Edited February 19, 2010 by dwightlooi

[FAPTurbo]

so do the hybrid with the v8 then......

They did that with their SUV hybrids, and people still ridicule them for it.

[smk4565]

Problem with the XTS being a showcase of hybrid technology, is this car already did that back in 2007, and no one cares or buys it.

Big time luxury cars need V8s driving the rear wheels. Look at how Lincoln dealers are upset that they struggle since Ford has the same car, or how Acura sales have been dropping. Cadillac needs a DOHC V8, Chevrolet may not, but having it can only help them.

[Drew Dowdell]

Problem with the XTS being a showcase of hybrid technology, is this car already did that back in 2007, and no one cares or buys it.

Big time luxury cars need V8s driving the rear wheels. Look at how Lincoln dealers are upset that they struggle since Ford has the same car, or how Acura sales have been dropping. Cadillac needs a DOHC V8, Chevrolet may not, but having it can only help them.

Next Generation hybrid technology. Acura's sales have been dropping because 1. They've all be beaten with an ugly stick 2. They killed their best selling model - Integra

[dwightlooi]

Problem with the XTS being a showcase of hybrid technology, is this car already did that back in 2007, and no one cares or buys it.

Big time luxury cars need V8s driving the rear wheels. Look at how Lincoln dealers are upset that they struggle since Ford has the same car, or how Acura sales have been dropping. Cadillac needs a DOHC V8, Chevrolet may not, but having it can only help them.

Cadillac needs a V8 in the 400~450hp class. The engine should be as small, as light and as economical on fuel as possible. It should also have state of the art features like direct injection, variable timing and cylinder deactivation.

The question is, why shouldn't it be a big displacement Pushrod V8 with these features instead of a (relatively) smaller displacement DOHC V8? Why shouldn't it be the smaller, lighter engine that gets more miles per gallon, which also happens to fall inline with a uniquely American tradition?

[balthazar]

And the XTS as presented is much more than merely a hybrid powertrain in an old vehicle.

[smk4565]

Cadillac needs a V8 in the 400~450hp class. The engine should be as small, as light and as economical on fuel as possible. It should also have state of the art features like direct injection, variable timing and cylinder deactivation.

The question is, why shouldn't it be a big displacement Pushrod V8 with these features instead of a (relatively) smaller displacement DOHC V8? Why shouldn't it be the smaller, lighter engine that gets more miles per gallon, which also happens to fall inline with a uniquely American tradition?

Why doesn't the LS3 have direct injection, VVT, cylinder deactivation now? If it were so easy to add it, and so beneficial, it seems that they would have done it already. A big displacement pushrod won't match the Germans in refinement. Cadillac is already at a disadvantage in perception, they have to go above and beyond with the product.

[Drew Dowdell]

Why doesn't the LS3 have direct injection, VVT, cylinder deactivation now? If it were so easy to add it, and so beneficial, it seems that they would have done it already. A big displacement pushrod won't match the Germans in refinement. Cadillac is already at a disadvantage in perception, they have to go above and beyond with the product.

You haven't been paying attention. The big displacement pushrod LS3 already matches the Germans in refinement. GM is able to beat the Germans right now without DI, VVT and AFM. Adding those in the future will only add to the performance ability of the engine (though I think we're close to hitting a maximum marketable power level very soon)

[dwightlooi]

Why doesn't the LS3 have direct injection, VVT, cylinder deactivation now? If it were so easy to add it, and so beneficial, it seems that they would have done it already. A big displacement pushrod won't match the Germans in refinement. Cadillac is already at a disadvantage in perception, they have to go above and beyond with the product.

Two things...

(1) As long as you don't try to make an engine rev past what the valve spring tension and valvetrain mass combo is suited to handle, there is essentially no refinement difference attributable a pushrod or DOHC valve train. Ultimately, the DOHC powerplant may redline higher, but they should be similarly refined at their respective redlines.

(2) Actually they have incorporated VVT and Cylinder Deactivation on the 6.2 small block. That engine is called the L99. It is tuned to produce a broader torque curve and slightly better fuel economy at the expense of peak power. The L99 makes 400hp and 410 lbft of torque; 26 hp and 14 lb-ft less than the LS3. However, its torque peak arrives 500rpm earlier and it gets 1 mpg better fel economy. This is the standard engine in the Automatic Transmission equipped Camaro SS.

As far as direct inject is concerned, it has been successfully tested on a modified L92 6.2 liter small block in 2007. Compression was increased from 10.5:1 to 11.5:1 in the test engine. Power increased from 403hp to over 450hp. The engine was put through its paces in an Escalade and proved to be fully functional and mature. Direct Injection is now slated to be introduced with the Gen V small block slated to appear this year or in 2011. A racing version of the new DI small block displacing 5.5 liters will campaign in GT2 class racing this year in the C6-R Corvette.

The Gen V small block will feature a new block design with the camshaft raised to a significantly higher position in the valley of the engine. This shortens, lightens and stiffens the pushrods, as well as improving the valve angle by changing the angle of the rods in relation to the heads. In a separate discussion elsewhere, I predicted an output of 432hp for this 5.5 liter engine. In time, I guess we'll see how accurate I was in that prediction.

[Nick]

Why doesn't the LS3 have direct injection, VVT, cylinder deactivation now? If it were so easy to add it, and so beneficial, it seems that they would have done it already. A big displacement pushrod won't match the Germans in refinement. Cadillac is already at a disadvantage in perception, they have to go above and beyond with the product.

It wasn't originally engineered with those features so they wouldn't implement them without doing a completely new LSx series I would imagine. It doesn't need it. If it did have those features it would be undeniably more powerful and more efficient than it currently is. Considering the current specs of the engine and how its performance is arguably superior to most of its competition, adding those features would widen the gap by an even larger margin.

Just because it is more complex does not mean it is better. You are right about perception, and unfortunately, ignorance is bliss among consumers. Throwing more technology at something, and over-engineering is a tactic the Germans are famous for. If only they spent more time perfecting a technology before moving onto something else. That is their downfall. They are horribly unreliable (especially the V8s in regards to BMWs which I have experienced plenty first hand). The upkeep and maintenance costs associated with those German V8s (or anything German for that matter) can be astronomical, and with the addition of new technology, costs are going nowhere but up. Also, your "refined" argument is quite vague. I've driven LS2 equipped vehicles against my M62B44tu, as well as a buddy's S62, and I found the LS2 to be very smooth with a significantly more linear, consistent power delivery.

If it was possible on an OBD2 car like mine, without question I would've swapped out for an LS when the vanos killed my engine a couple years ago.

But consider this, isn't it interesting that dohc engines require all this technology thrown at them to remain somewhat competitive with a "simple" engine such as the LS series?

Edited February 20, 2010 by Nick

[Drew Dowdell]

But consider this, isn't it interesting that dohc engines require all this technology thrown at them to remain somewhat competitive with a "simple" engine such as the LS series?

This.

[regfootball]

Two things...

(1) As long as you don't try to make an engine rev past what the valve spring tension and valvetrain mass combo is suited to handle, there is essentially no refinement difference attributable a pushrod or DOHC valve train. Ultimately, the DOHC powerplant may redline higher, but they should be similarly refined at their respective redlines.

(2) Actually they have incorporated VVT and Cylinder Deactivation on the 6.2 small block. That engine is called the L99. It is tuned to produce a broader torque curve and slightly better fuel economy at the expense of peak power. The L99 makes 400hp and 410 lbft of torque; 26 hp and 14 lb-ft less than the LS3. However, its torque peak arrives 500rpm earlier and it gets 1 mpg better fel economy. This is the standard engine in the Automatic Transmission equipped Camaro SS.

As far as direct inject is concerned, it has been successfully tested on a modified L92 6.2 liter small block in 2007. Compression was increased from 10.5:1 to 11.5:1 in the test engine. Power increased from 403hp to over 450hp. The engine was put through its paces in an Escalade and proved to be fully functional and mature. Direct Injection is now slated to be introduced with the Gen V small block slated to appear this year or in 2011. A racing version of the new DI small block displacing 5.5 liters will campaign in GT2 class racing this year in the C6-R Corvette.

The Gen V small block will feature a new block design with the camshaft raised to a significantly higher position in the valley of the engine. This shortens, lightens and stiffens the pushrods, as well as improving the valve angle by changing the angle of the rods in relation to the heads. In a separate discussion elsewhere, I predicted an output of 432hp for this 5.5 liter engine. In time, I guess we'll see how accurate I was in that prediction.

i am betting that the simple raising of the camshaft will help the valvetrain become more responsive overall and should help contribute to making more progress on refinement.

your talk is somewhat suggestive to me at least that GM should have made more continuous investment in their v6's similar to what you prophecy with the v8. GM didn't even bother with alum blocks for their mass v6's.

Edited February 21, 2010 by regfootball

[dwightlooi]

i am betting that the simple raising of the camshaft will help the valvetrain become more responsive overall and should help contribute to making more progress on refinement.

your talk is somewhat suggestive to me at least that GM should have made more continuous investment in their v6's similar to what you prophecy with the v8. GM didn't even bother with alum blocks for their mass v6's.

Well, two things work against the business case for "advanced" Pushrod V6es...

1. The investment in DOHC V6es have already been made (not just in R&D, but also in production and logistics). Abandoning the architecture and starting over will be very expensive in terms of startup costs.
   
2. Unlike V8s which serve the top tier luxury and performance segments, specific output matters significantly more with mainstream sixes in the 3.0~3.6 liter class. The reason being that many countries still tax cars based on displacement. Even if your 4.0 liter V6 is smaller, lighter, more powerful and more fuel efficient than a competing 3.2 liter product, many countries will still tax it more (sometimes significantly more). While high end luxury and performance buyers are quite tolerant of a few grand in extra taxes, mainstream buyers are not.
   

Instead of Pushrod V6es, I'll rather see GM invest in completely redoing for a ground up family of Direct Injection Ecotec Fours. There are two things which I believe will put GM on top of the 4-cylinder game and these need a complete revamp of the 4-cylinder architecture.

1. Implement a new 4-pot architecture which shares the bore size, piston, connecting rods, lifters, cam followers, valves, guides and springs with the 3.0 and 3.6 liter V6es. This means 89.0 x 80.3 mm and 94 x 85.6 mm for the 2.0 liter and 2.4 liter fours respectively. The slight oversquare design improves engine refinement and raises specific output by reducing piston speeds and increasing valve area to displacement ratios. More importantly, it lowers production costs and make it easier to share future technologies between the V6 and I4 families.
   
2. Implement HCCI and a beltless accessory drive. HCCI gives a significant improvement in fuel economy and offers GM the claim to being "first" on what I believe is the next significant trend in the evolution of the internal combustion engine. I wouldn't even try to make HCCI operate over a wide range of conditions -- it only has to operate at 55~75 mph at 33% throttle or less. This will be adequate to earn a fantastic EPA highway economy rating, and that is sufficient (for now). The second thing will be to get rid of the accessory belt -- this is the last huddle towards the "No scheduled maintenance for 300,000 miles" engine. The waterpump can be driven by the cam chain, the alternator can be an integrated flywheel generator/motor, power steering can be (and is already) electric and the A/C Compressor can be electric. The flywheel generator/motor also makes it easy to make automatic traffic light engine shutoff a standard feature earning a couple of EPA City economy points.
   

With no improvement over their V6 siblings, the new Gen III Ecotecs should make:-

• Ecotec 2.0 (Gen III) -- 180 bhp @ 7000 rpm, 149 lb-ft @ 5200 rpm, 7200 rpm Redline, 87 Oct
  
• Ecotec 2.4 (Gen III) -- 202 bhp @ 6400 rpm, 182 lb-ft @ 4000 rpm, 6500 rpm Redline, 87 Oct
  
• Ecotec 2.0T (Gen III) -- 300 bhp @ 6000 rpm, 270 lb-ft @ 2800~5800 rpm, 6500 rpm Redline, 91 Oct
  

[Drew Dowdell]

Dwightlooi,

Two questions:

1. Can HCCI be made to be operable at lower speeds then 55mph? I think if they could get it to run at 45mph they'd get a knock it out of the park hit. IMHO, running in super efficient HCCI mode at 45 mph would produce far more worthwhile results than getting it to work at 70.

2. What would you suggest for the Ecotec with displacements lower than 2.0? Cruze is getting a 1.4t, but there are also 1.0, 1.6, and 1.8 variants out there. These are far more important for the Euro and Asian markets for certain, but they are a big piece of the puzzle.

[dado]

Will this GEN V engine be new engine with new block?? If they will change position of cam in block they would need new block i assume. Will this engine be also smaller in size and not just displacement?

I think i've read some year ago that there could be two version; one with cam in block and one with cams in head. I know that it is possible but what are the chances GM would make such block.

[Z-06]

Implement HCCI and a beltless accessory drive. HCCI gives a significant improvement in fuel economy and offers GM the claim to being "first" on what I believe is the next significant trend in the evolution of the internal combustion engine. I wouldn't even try to make HCCI operate over a wide range of conditions -- it only has to operate at 55~75 mph at 33% throttle or less. This will be adequate to earn a fantastic EPA highway economy rating, and that is sufficient (for now). The second thing will be to get rid of the accessory belt -- this is the last huddle towards the "No scheduled maintenance for 300,000 miles" engine. The waterpump can be driven by the cam chain, the alternator can be an integrated flywheel generator/motor, power steering can be (and is already) electric and the A/C Compressor can be electric. The flywheel generator/motor also makes it easy to make automatic traffic light engine shutoff a standard feature earning a couple of EPA City economy points.

Unarguably the most important point going forward with Internal Combustion engines.

[dwightlooi]

Dwightlooi,

Two questions:

1. Can HCCI be made to be operable at lower speeds then 55mph? I think if they could get it to run at 45mph they'd get a knock it out of the park hit. IMHO, running in super efficient HCCI mode at 45 mph would produce far more worthwhile results than getting it to work at 70.

2. What would you suggest for the Ecotec with displacements lower than 2.0? Cruze is getting a 1.4t, but there are also 1.0, 1.6, and 1.8 variants out there. These are far more important for the Euro and Asian markets for certain, but they are a big piece of the puzzle.

(1) HCCI will be limited to relatively narrow set of operating conditions. Right now, the 2.2 HCCI experimental engine can do it at idle through 60mph at part throttle. The engine employs a cam switching system (ala VTEC), Dual variable cam phasing, Direct Injection and a centrally located injector. It gets a 15% better fuel economy improvement over a spark ignition 2.2 liter, at a lower cost and weight penalty compared to a hybrid.

Personally, I don't think HCCI functionality at idle is important, neither is HCCI functionality at low speed acceleration situations. The reason being the best fuel economy at idle can achieved relatively easily by shutting off the engine. With a simple flywheel integrated generator/motor (say a modest 5hp unit) that is exactly what we can do. When you are putting around in city traffic from 0~35mph you'll often use more throttle than would be feasible for HCCI anyway, so even if it can work at those speeds it most frequently won't. Therefore, I suggested that HCCI be focused on highway cruising efficiency and an engine shutoff feature be used to improve city numbers.

(2) I was suggesting commonality between the V6 and the I4 families. This cannot be implemented on the really small 4-potters. The Family Zero is OK for now anyway. Add Direct Injection and an Aluminum Block and you have your next generation.

Will this GEN V engine be new engine with new block?? If they will change position of cam in block they would need new block i assume. Will this engine be also smaller in size and not just displacement?

I think i've read some year ago that there could be two version; one with cam in block and one with cams in head. I know that it is possible but what are the chances GM would make such block.

Yes, it'll definitely be a new block.

[Drew Dowdell]

(1) HCCI will be limited to relatively narrow set of operating conditions. Right now, the 2.2 HCCI experimental engine can do it at idle through 60mph at part throttle. The engine employs a cam switching system (ala VTEC), Dual variable cam phasing, Direct Injection and a centrally located injector. It gets a 15% better fuel economy improvement over a spark ignition 2.2 liter, at a lower cost and weight penalty compared to a hybrid.

Personally, I don't think HCCI functionality at idle is important, neither is HCCI functionality at low speed acceleration situations. The reason being the best fuel economy at idle can achieved relatively easily by shutting off the engine. With a simple flywheel integrated generator/motor (say a modest 5hp unit) that is exactly what we can do. When you are putting around in city traffic from 0~35mph you'll often use more throttle than would be feasible for HCCI anyway, so even if it can work at those speeds it most frequently won't. Therefore, I suggested that HCCI be focused on highway cruising efficiency and an engine shutoff feature be used to improve city numbers.

(2) I was suggesting commonality between the V6 and the I4 families. This cannot be implemented on the really small 4-potters. The Family Zero is OK for now anyway. Add Direct Injection and an Aluminum Block and you have your next generation.

1) Thanks. Do you think something like Honda's IMA would help keep the engine in HCCI mode longer by allowing less gas throttle and more electric throttle? That would really help with city numbers as well. If you're already going to be doing a flywheel starter/assist anyway, make it beefy enough to shoulder more of the acceleration burden but not so much so that you're getting into full hybrid status with all the battery weight that implies.

2) thanks for clarifying.

[dwightlooi]

1) Thanks. Do you think something like Honda's IMA would help keep the engine in HCCI mode longer by allowing less gas throttle and more electric throttle? That would really help with city numbers as well. If you're already going to be doing a flywheel starter/assist anyway, make it beefy enough to shoulder more of the acceleration burden but not so much so that you're getting into full hybrid status with all the battery weight that implies.

2) thanks for clarifying.

(1) Not really, HCCI is probably bracketed by engine speed, load and the cam lobe profile. A cam lobe profile which creates the right conditions for HCCI operation at a certain engine speed and load conditions would probably limit the engine to a certain rpm band centered around that condition. Basically, what you want is a particular combination of fuel-air ratio and effective compression so as to achieve engine "knock" at or very near top dead center. The combination of fuel-air ratio, pressure and temperature causes spontaneous ignition, but only if the charge stays at or beyond that threshold for a sufficient period of time. If the engine rpm is too fast, the piston may outrun the knock event and get past TDC before it happens; once temperature and pressure starts to fall, spontaneous ignition may never get to happen. If the engine rpm is too low, the knock event may happen way before TDC and you get highly unhealthy and noisy detonation.

(2) The problem with Hybrids is that the cost-benefit ratio simply does not make economic sense. If you go beyond 3~5hp, or if you want to use the integrated generator/motor for actual engine assist, you end up needing a high voltage, high capacity battery which is bulky, heavy and expensive. The power control module then also needs to be the size of a suitcase and the motor tends to get heavy and expensive. The idea is to avoid all that and make the mildest hybrid possible, but make it STANDARD.

Let's put things into perspective:-

• Toyota Prius -- 80 hp Parallel Motor -- 201.6 volts, NiMH battery (~100 lbs w/o encasement)
  
• Honda Civic Hybrid -- 20hp IMA -- 158 volt, NiMH, 68 lbs battery (68 lbs w/o encasement)
  
• Proposed System -- ~5hp Flywheel Generator/Motor -- 36.3v, LiFePO4 battery (~25 lbs w/o encasement)*
  

* 25 lbs is no more than the weight of the larger size Lead-Acid batteries.

The target system weight would be 60 lbs or roughly 1/3 that of the current Civic Hybrid's system weight. The system will provide engine stop at idle and attempts to recharge with regenerative charging during braking as much as possible. It will provide sufficient power for an ensemble of all electric HVAC, cooling fan and steering assist. It will not attempt to provide acceleration assist because the gains against the back drop of a 180~200hp engine is minimal, thus it is better to shoot for reduced battery size and an extended battery life.

Edited February 22, 2010 by dwightlooi

[Drew Dowdell]

I see what you did there with the 36 volt. Isn't that the proposed "next" standard for vehicle electrical systems?

What is the specs of the BAS system from the Malibu, for comparison?

[dwightlooi]

I see what you did there with the 36 volt. Isn't that the proposed "next" standard for vehicle electrical systems?

What is the specs of the BAS system from the Malibu, for comparison?

BAS is also 36v and about 5hp. But, the BAS -- by definition -- is attached to the accessory pulley with a fat belt. BAS is also NiMH based. NiMH has a 1.2v nominal cell voltage. 30 cells (or a multiple of 30 cells) make up a 36v pack.

I was proposing getting rid of the accessory belt altogether, using a flywheel that doubles as the generator motor and all electric accessories. For the battery, I am suggest Lithium-Iron-Phosphate* for its superior charge-discharge cycle advantageous. LiFePO4 is also 3.3 volts nominal, requiring only 11 cells to be 36.3v, simplify battery complexity and costs.

* Lithium-Ion batteries actually come in many flavors. Lithium Cobalt Oxide being the most common and most developed. Iron Phosphate has a energy density (~0.50kW.H/kg) in the mid-range of the seven or eight Lithium Ion battery chemistries -- about 54% that of the cutting edge Li-Ion (0.92kWH/kg) batteries. However, it's charge-discharge cycle endurance is about twice as good as the average Li-Ion battery and it is still heck of a lot better than Lead Acid (~0.04kWH/kg).

Edited February 22, 2010 by dwightlooi

[Drew Dowdell]

I follow, I was just hoping you'd provide details for comparison purposes... and of course you did. Thanks.

[regfootball]

Well, two things work against the business case for "advanced" Pushrod V6es...

1. The investment in DOHC V6es have already been made (not just in R&D, but also in production and logistics). Abandoning the architecture and starting over will be very expensive in terms of startup costs.
   
2. Unlike V8s which serve the top tier luxury and performance segments, specific output matters significantly more with mainstream sixes in the 3.0~3.6 liter class. The reason being that many countries still tax cars based on displacement. Even if your 4.0 liter V6 is smaller, lighter, more powerful and more fuel efficient than a competing 3.2 liter product, many countries will still tax it more (sometimes significantly more). While high end luxury and performance buyers are quite tolerant of a few grand in extra taxes, mainstream buyers are not.
   

Instead of Pushrod V6es, I'll rather see GM invest in completely redoing for a ground up family of Direct Injection Ecotec Fours. There are two things which I believe will put GM on top of the 4-cylinder game and these need a complete revamp of the 4-cylinder architecture.

1. Implement a new 4-pot architecture which shares the bore size, piston, connecting rods, lifters, cam followers, valves, guides and springs with the 3.0 and 3.6 liter V6es. This means 89.0 x 80.3 mm and 94 x 85.6 mm for the 2.0 liter and 2.4 liter fours respectively. The slight oversquare design improves engine refinement and raises specific output by reducing piston speeds and increasing valve area to displacement ratios. More importantly, it lowers production costs and make it easier to share future technologies between the V6 and I4 families.
   
2. Implement HCCI and a beltless accessory drive. HCCI gives a significant improvement in fuel economy and offers GM the claim to being "first" on what I believe is the next significant trend in the evolution of the internal combustion engine. I wouldn't even try to make HCCI operate over a wide range of conditions -- it only has to operate at 55~75 mph at 33% throttle or less. This will be adequate to earn a fantastic EPA highway economy rating, and that is sufficient (for now). The second thing will be to get rid of the accessory belt -- this is the last huddle towards the "No scheduled maintenance for 300,000 miles" engine. The waterpump can be driven by the cam chain, the alternator can be an integrated flywheel generator/motor, power steering can be (and is already) electric and the A/C Compressor can be electric. The flywheel generator/motor also makes it easy to make automatic traffic light engine shutoff a standard feature earning a couple of EPA City economy points.
   

With no improvement over their V6 siblings, the new Gen III Ecotecs should make:-

• Ecotec 2.0 (Gen III) -- 180 bhp @ 7000 rpm, 149 lb-ft @ 5200 rpm, 7200 rpm Redline, 87 Oct
  
• Ecotec 2.4 (Gen III) -- 202 bhp @ 6400 rpm, 182 lb-ft @ 4000 rpm, 6500 rpm Redline, 87 Oct
  
• Ecotec 2.0T (Gen III) -- 300 bhp @ 6000 rpm, 270 lb-ft @ 2800~5800 rpm, 6500 rpm Redline, 91 Oct
  

i agree with pretty much all of that.

design the 4's and 6's to be modular. the new hyundai motor is 200hp w/ 2.4l so this should be very doable for GM. In a typical (for non GM products at least) roughly 3200-3300 pound midsize sedan with a 6 speed or CVT we could see some really nice mpg numbers. and then make sure the turbo is there for those that want it.

this type of ongoing development would pretty much kill even the one percent chance diesel had of making waves in GM cars here on this side of the pond.

I would like to see the cruze motors get that ecotec 2.0 or at least a midlvel (160-180hp) and top level (200+ hp) options with a four.

Edited February 22, 2010 by regfootball

[dado]

I know i've read somewhere about dohc SBC. I hope GM will also make some effort in looks department. This was also nice looking engine from GM (lt-5)

[dwightlooi]

i agree with pretty much all of that.

design the 4's and 6's to be modular. the new hyundai motor is 200hp w/ 2.4l so this should be very doable for GM. In a typical (for non GM products at least) roughly 3200-3300 pound midsize sedan with a 6 speed or CVT we could see some really nice mpg numbers. and then make sure the turbo is there for those that want it.

this type of ongoing development would pretty much kill even the one percent chance diesel had of making waves in GM cars here on this side of the pond.

I would like to see the cruze motors get that ecotec 2.0 or at least a midlvel (160-180hp) and top level (200+ hp) options with a four.

180hp from a 2.0 is nice enough... especially when it is done on 87 Octane. Besides, making 180hp in a 4-pot 2.0L does not involve a lot of extreme stuff. Just copy the combustion chamber, valve sizing and intake ports of the LF1 3.0 V6 (270hp) and you should be right there with 90hp/liter. If anything a four will get slightly better numbers since it does not have to make compromises to fit the intake runners in the narrow V of a 60 deg V6. Also, exhaust tuning is easier on an I4 with all the exhaust ports lined up on one side, vs in a V6 where it is split on two sides and usually with a lousy 3-into-1 collector casting. Historically, given the same technological content and features I4s have always beaten V6es on specific output by a little bit.

[dwightlooi]

I know i've read somewhere about dohc SBC. I hope GM will also make some effort in looks department.

Yes, there were concepts of an over-under Dual In-Block Cam arrangement. The idea is to separate intake and exhaust valve control into two discrete camshafts. This involves a mess of pushrods and rockers at two different angles, but it permits dual independent VVT.

Personally, I am not impressed with the idea. It'll be much simpler and neater to simply use co-axial camshafts to achieve Dual VVT. Actually, this has already been implemented in the 2008+ Dodge Viper.

[dado]

I can see GM implementing this type of VVT in their future LS series (if future small block will be called LS series at all because all i've read is that for now is being called Gen V).

[dwightlooi]

I can see GM implementing this type of VVT in their future LS series (if future small block will be called LS series at all because all i've read is that for now is being called Gen V).

Collectively, the contemporary Small Blocks are called the "Gen IV" Small Block V8s. The LS series RPO is part of the Gen IV Small Block family, but the Gen IV includes more than the LS engines. They include:-

LS-series (cars): LS1, LS2, LS3, LS4, LS6, LS7, LS9, LSA, etc.

L + "Not S" + Number series (branded Vortec; for trucks): L96, LY6, LZ1, L20, LC9, LH9, LMF, LMG, L94, L9H, etc.

A few stragglers without "LS" RPO, but used in cars: L76, L99

Point of Note: All the RPOs in Red has VVT. As you can see, ALL of the truck engines -- the Vortecs -- have VVT. However, only one car engine (the L99) used in the Camaro SS has VVT.

If you ask me, that's WAY TOO MANY V8s (and we haven't counted the Northstars yet), I'll like to see the variants cut down to one architecture, two displacements and maybe four variants in all.

Perhaps these (all sharing the 103.25mm bore, but with either 82 or 92 mm strokes):-

• 5.5 (420~432 hp, power optimized; DI/VVT/AFM) for performance cars
  
• 5.5 (550~580 hp, Supercharged; DI/VVT) for really fast cars
  
• 5.5 (375~385hp, torque optimized; DI/VVT/AFM) for big trucks
  
• 6.2 (425~435hp, torque optimized; DI/VVT/AFM for bigger trucks
  

[regfootball]

reading on GMI that the northstar is toast in the STS to me makes me wonder if Caddy's lone V8 in the future won't be a small block now.

[dwightlooi]

reading on GMI that the northstar is toast in the STS to me makes me wonder if Caddy's lone V8 in the future won't be a small block now.

The Northstar is not a Small Block to begin with. In general, the term "Small Block" applies to GM Pushrod V8 engines with an 111.76 bore center spacing. The Northstar is 102mm. Despite the ~10mm narrower spacing, the Northstar is a longer, wider, taller engine which weighs more than the Small Blocks due to it's DOHC design. It also has worse reliability record, especially with head bolts that pull off causing the gaskets to fail. IMHO, I don't think the Northstar will be missed.

[Robert Hall]

The Northstar is not a Small Block to begin with. In general, the term "Small Block" applies to GM Pushrod V8 engines with an 111.76 bore center spacing. The Northstar is 102mm. Despite the ~10mm narrower spacing, the Northstar is a longer, wider, taller engine which weighs more than the Small Blocks due to it's DOHC design. It also has worse reliability record, especially with head bolts that pull off causing the gaskets to fail. IMHO, I don't think the Northstar will be missed.

I think by 'small block' the Reg was referring to the pushrod V8s in the Escalade and CTS-v.

[regfootball]

I think by 'small block' the Reg was referring to the pushrod V8s in the Escalade and CTS-v.

right. what has been called small block for quite awhile..the GM pushrod v8.

[balthazar]

>>"The Northstar is not a Small Block to begin with. In general, the term "Small Block" applies to GM Pushrod V8 engines with an 111.76 bore center spacing. "<<

Correction :: the term "small block" is a relative term to differentiate between 2 V-8s of markedly different external dimensions in the same marque. It has nothing "in general" to do with an internal dimension. Chevy, Buick, Olds, Ford, Merc, Plymouth, Dodge all had small blocks.... because they also had big blocks at the same time.

For the catalyst for the term, note than 'SBC' was not applied to the Chevy V-8 when it debuted for '55; it wasn't until the big block 348 showed up in '58 that the term was ever used.

However, in recent times, the term has become synonymous with the GM corporate V-8 that has decended / replaced the traditional SBC.

BTW, the BBC V-8 went out of production last year, IIRC, so by rights, the term 'SB' should fade out of use over time.

[dwightlooi]

>>"The Northstar is not a Small Block to begin with. In general, the term "Small Block" applies to GM Pushrod V8 engines with an 111.76 bore center spacing. "<<

Correction :: the term "small block" is a relative term to differentiate between 2 V-8s of markedly different external dimensions in the same marque. It has nothing "in general" to do with an internal dimension. Chevy, Buick, Olds, Ford, Merc, Plymouth, Dodge all had small blocks.... because they also had big blocks at the same time.

For the catalyst for the term, note than 'SBC' was not applied to the Chevy V-8 when it debuted for '55; it wasn't until the big block 348 showed up in '58 that the term was ever used.

However, in recent times, the term has become synonymous with the GM corporate V-8 that has decended / replaced the traditional SBC.

BTW, the BBC V-8 went out of production last year, IIRC, so by rights, the term 'SB' should fade out of use over time.

Thanks for the clarification. I use the term loosely because it has become synonymous in popular usage to refer to the 111.76 bore center GM pushrods of yore and contemporary times. But, yes, you are right.

[balthazar]

MAYBE if the 'SB' term DID pass out of usage, I could get past the association with Chevrolet & my unacceptance of said termed motor in a Cadillac. Still working to get past the 'Corporate engine' announcement.

[CanadianBacon94]

could it be possible to make an engine block that can utilize both DOHC and CIB?

i do like CIB better mainly because it sounds stonger, pushrods sound powerful, while Cammers sound weezy until you get to AMG's or flat plane ferraris

Edited February 26, 2010 by CanadianBacon94

[Drew Dowdell]

It's been done. The GM 3.4 DOHC twincam comes to mind. The issues that engine is known for have more to do with packaging than the fact that it was based on a CIB engine.

[dwightlooi]

It's been done. The GM 3.4 DOHC twincam comes to mind. The issues that engine is known for have more to do with packaging than the fact that it was based on a CIB engine.

You can, but it usually does not amount to an optimized design. In particular, the cam drive section will be kinda messy. You'll probably end up with having to use an intermediate sprocket in the SBC's location. You then have try to enclose the rest of the chain drive to the heads or resort to belts. Given that the most complex and costly parts an engine design effort is in the heads and combustion control systems, the very act of reusing the block casting may not be worthwhile from a savings standpoint.

[ShadowDog]

You can, but it usually does not amount to an optimized design. In particular, the cam drive section will be kinda messy. You'll probably end up with having to use an intermediate sprocket in the SBC's location. You then have try to enclose the rest of the chain drive to the heads or resort to belts. Given that the most complex and costly parts an engine design effort is in the heads and combustion control systems, the very act of reusing the block casting may not be worthwhile from a savings standpoint.

Even with the cast-sharing between the pushrod and OHC block, did not the LQ1 still end up one of the most expensive engine designs for its time? I would think if the same idea could be used, it would have to be based on development of a new block designed to share the different valvetrains, and not from a design originally for one or the other. This, because the LQ1 ended up a bunch of fussy fixes to accommodate the change from pushrod to DOHC with oil sealer plugs and funky hoses for coolant channeling, etc. Being belt driven wasn't such a bad thing, at least helping to reduce noise levels; however I imagine it was more of a necessity than an exact thought.

I forget whether the fact that the 60 degree engine allowed for a tighter package to enable the cam alterations?

Edited February 27, 2010 by ShadowDog

[regfootball]

let an OHC engine be an OHC engine. Let a pushrod engine be a pushrod.

[dado]

I have read somewhere that ultra V8 engine (which was cancelled) was finished before GM pull the plug on it. Now that engine was supposed to have Direct injection, VVT , Dohc heads, 4 valves per cylinder etc.

But GM didn't want to spend money for investing in engine plant necessary equipment etc. (or something like that).

Dwightlooi will probably now more about this.

I was thinking..if GM doesn't want to spend money needed to build that engine but they already developed it etc. maybe they could outsource some company to build that engine for them if there is need for let say cadillac with DOHC v8 (maybe cosworth, illmor, mclaren etc)

[balthazar]

ShadowDog ~ >>"Even with the cast-sharing between the pushrod and OHC block, did not the LQ1 still end up one of the most expensive engine designs for its time? I would think if the same idea could be used, it would have to be based on development of a new block designed to share the different valvetrains, and not from a design originally for one or the other. This, because the LQ1 ended up a bunch of fussy fixes to accommodate the change from pushrod to DOHC with oil sealer plugs and funky hoses for coolant channeling, etc. Being belt driven wasn't such a bad thing, at least helping to reduce noise levels; however I imagine it was more of a necessity than an exact thought."<<

Would like to delve into this much further.

Designed from scratch, a dual-capcity OHC / IBC engine should not be prohibitively expensive (some more CAD time, of course). But the space taken up by the cam in a IBC set-up is doing a lot of nothing in a OHC set-up.

Since perception has such a heavy thumb on this 'To Overhead, or Not To Overhead' discussion, a dual-capacity block would -decently utilized across a number of lines, seem on the surface to have the greatest chance of pleasing 'both sides' and costing the least. A chain-drive 'tensioner/sprocket' for the OHC set-up, and some chain covers are nickel/dime stuff compared to 2 different blocks. Then, with varied displacements AND both 'pushrod' and OHC heads, you have the greatest degree of differentiation across all the divisions using it.

Someone post some exploded views of a IBC V-8 and a OHC V-8 and let's get started designing this...

[dwightlooi]

I have read somewhere that ultra V8 engine (which was cancelled) was finished before GM pull the plug on it. Now that engine was supposed to have Direct injection, VVT , Dohc heads, 4 valves per cylinder etc.

But GM didn't want to spend money for investing in engine plant necessary equipment etc. (or something like that).

Dwightlooi will probably now more about this.

I was thinking..if GM doesn't want to spend money needed to build that engine but they already developed it etc. maybe they could outsource some company to build that engine for them if there is need for let say cadillac with DOHC v8 (maybe cosworth, illmor, mclaren etc)

I don't know if it is finished. But, even if it is, there is a huge chasm of investment difference between building an engine and vesting it for mass production. Creating a one off prototype or even a race engine is one thing. Getting it through qualification and investing in the tooling for mass production is another.

Personally, I won't try to build a DOHC V8. Instead, I think GM will be best served with DOHC I4s, DOHC V6es and Pushrod V8s -- all fortified with VVT and DI. I4s for displacement sensitive markets and simple single-turbo solutions. DOHC V6es for mainstream luxury. Pushrod V8s for maximum power density applications -- sport luxury and other performance cars. DOHC V8s are a waste of resources because it offers neither better performance, nor better economy, nor differentiation from the competition.

[dado]

Here is something from Mercedes.

New DOHC 5.5 l v8 engine with Twin turbo

I think that Gen V with DI, VVT , and supercharger (or maybe GM will start using turbochargers on their V8) could easily surpasse that number. This is around 100 hp/l. LS9 develops that much and i think GEN V could go even further (with flat torque curve ).

So the top engine in Mercedes will soon be 5.5 l TT v8. And top engine in GM will also very soon be 5.5 l v8 (supercharged or turbocharged), if there isn't anything biger planned.

Can wait to see real spec. when top engine from GM come out.

[Drew Dowdell]

You know what would be a really funny picture.... the GM 5.5 sitting next to a MB 5.5....... just so we could see the size difference.I bet SMK would lawl all over it.

[smk4565]

The 5.5 liter AMG engine makes 660 lb=ft of torque, that is substantially better than the CTS-V's 6.2 liter engine can put out. As far as packaging size, the Merc engine is going to fit under the hood of the E-class, so I don't see how the future GM 5.5 liter pushrod taking up less space matters. And remember this isn't even Mercedes top end engine, they still have the BiTurbo V12.

[Robert Hall]

The 5.5 liter AMG engine makes 660 lb=ft of torque, that is substantially better than the CTS-V's 6.2 liter engine can put out. As far as packaging size, the Merc engine is going to fit under the hood of the E-class, so I don't see how the future GM 5.5 liter pushrod taking up less space matters. And remember this isn't even Mercedes top end engine, they still have the BiTurbo V12.

I assume the 5.5 will be in the C-class AMG as well (the current one has the 6.2 V8). Engine packaging is really only an issue with a FWD transverse setup where there are space constraints....if RWD compacts like the BMW 3-series and Merc C-class can fit a DOHC V8, then the space argument is moot..

What's funny is the truck fans always make an argument against OHC V8s, but Ford has built a lot of them for over a decade now...

Edited March 5, 2010 by Cubical-aka-Moltar

[Drew Dowdell]

I assume the 5.5 will be in the C-class AMG as well (the current one has the 6.2 V8). Engine packaging is really only an issue with a FWD transverse setup where there are space constraints....if RWD compacts like the BMW 3-series and Merc C-class can fit a DOHC V8, then the space argument is moot..

What's funny is the truck fans always make an argument against OHC V8s, but Ford has built a lot of them for over a decade now...

Anywhere you can put a DOHC V8 you can put a Pushrod V8 anywhere from 1 - 2 liter's greater displacement.

Ford's OHC <not DOHC, decent size difference there> has been the laggard of the bunch for years.

[Robert Hall]

Anywhere you can put a DOHC V8 you can put a Pushrod V8 anywhere from 1 - 2 liter's greater displacement.

Don't necessarily need more cubic inches. Cubic inches aren't the only way to make more power and/or torque.

Ford's OHC <not DOHC, decent size difference there> has been the laggard of the bunch for years.

They are still the top selling trucks, so obviously they aren't that much of a laggard.

Edited March 5, 2010 by Cubical-aka-Moltar

[Drew Dowdell]

So are the GM trucks if you scrape the badges off. Ford has gotten to claim "Best Selling Truck" for as long as it has only because GM spreads it's full size trucks over two name plates. I'm sure there are some years in the past 30 where the Chevy+GMC outsold the F-150.