The Last Small Block

[dwightlooi]

FACTS: We know that the C8 Corvette and a number of her contemporaries in GM's 2020 stables will have a Pushrod Small Block Engine. This may very well be the last and the finest small block engine. We do not know much beyond that.

PREDICTION: The following is my prediction on its specifics. You will have to wait half a year to find out if I am right or if I am close...

• RPO:  LT2
• Aspiration:  Naturally Aspirated
• Construction:  Aluminum block and heads
• Cylinder Spacing:  111.76 mm (4.400")
• Bore x Stroke:  103.25 mm x 101.6 mm (4.065" x 4.000")
• Displacement:  6,805 cc (415 cu-in)
• Static Compression:  11.5:1
• Fuel requirement:  Premium Unleaded Gasoline (91 Octane) recommended / not required
• Valve Train:  Push rods with roller lifters, concentric cams-in-block with dual cam phasing, cylinder deactivation via collapsible lifters
• Power Output:  525 bhp @ 6000 rpm
• Torque:  512 lb-ft @ 4200 rpm
• Maximum engine speed:  6,300 rpm

 

[A Horse With No Name]

You may well be right. Still...were I to buy a car of this caliber/type...currently a huge fan of German iron.

Time will tell what they come out with.

[A Horse With No Name]

 

The future here...electric. Ready for the next generation of electric cars.

[G. David Felt]

3 hours ago, A Horse With No Name said:

 

The future here...electric. Ready for the next generation of electric cars.

I watched live that run and it still is awesome even on YouTube. Future is Electric screaming by!

[A Horse With No Name]

Pensy T1 was  a steam engine that never really lived up to its full potential because diesel came on the scene so fast post WWII.  There is a trust trying to re create one...

https://prrt1steamlocomotivetrust.org/

I could see in 40 or 50 years people looking back at this small black the same way...never really lived up t0o its potential because electric came on the scene.

[balthazar]

1 hour ago, A Horse With No Name said:

I could see in 40 or 50 years people looking back at this small black the same way...never really lived up t0o its potential because electric came on the scene.

That... makes no sense. 65 years, millions upon millions built in all sorts of vehicles, a burgeoning aftermarket, the #1 hobbyist choice, reliable, affordable, powerful.... where did it ever fall short of it's 'potential'?

[A Horse With No Name]

43 minutes ago, balthazar said:

That... makes no sense. 65 years, millions upon millions built in all sorts of vehicles, a burgeoning aftermarket, the #1 hobbyist choice, reliable, affordable, powerful.... where did it ever fall short of it's 'potential'?

I am saying there will be additional potential left untapped when ICE is eventually replaced with electric

[oldshurst442]

These are a few OHV pushrod engines Im currently salivating after.

They are not exactly factory OEM engines. Well, one of them is a crate engine based on a production engine and the other is a hopped up, souped up, bored and stroked version of a production engine built by a reputable yet unnammed NASCAR engine builder.

A legit 426 cubic inch "HEMI"  from Mopar.  I could do without the supercharger and have it naturally aspirated but if you twist my arms for half a second, Im sure Ill be convinced to accept this set-up.

 

This next one is a legit 455 cubic inch V8 based on the LT1.  Trans Am depot's SD455 percistant effort on selling us  Trans Ams even though there are no more Trans Ams. But I think they bought the rights to use the name and logos so I think this effort is as legit of an SD455 Trans Am as there ever will be.  Both on the 455 part and on the Trans Am part.  

 

[oldshurst442]

But....

But...

Im also equally giddy about AC induction motors.  

 Tesla's version for me as of now, (other manufacturer's automobile AC induction motors to follow I guess) would be like the equivalent Ram Air IV 400, or Pontiac's-Olds'-Buick's respective 455s. Or Mopar's 440 six pack of the good ole days.   

 

 

[balthazar]

3 hours ago, A Horse With No Name said:

I am saying there will be additional potential left untapped when ICE is eventually replaced with electric

Huh. I don't find myself wondering about things that will happen after I am dead, much. ;)

[A Horse With No Name]

2 hours ago, balthazar said:

Huh. I don't find myself wondering about things that will happen after I am dead, much.

I wonder about crazy things all of the time...probably why you are sane and I am a bit insane...

[balthazar]

You could not believe the insanity coursing thru my veins. I temper it well here.

[A Horse With No Name]

Getting back to the V8 in question...nothing earth shattering but nice performance numbers. Curious to see what GM does with the C8...I really like the C7.

[dwightlooi]

15 hours ago, oldshurst442 said:

Im also equally giddy about AC induction motors.  

 Tesla's version for me as of now, (other manufacturer's automobile AC induction motors to follow I guess) would be like the equivalent Ram Air IV 400, or Pontiac's-Olds'-Buick's respective 455s. Or Mopar's 440 six pack of the good ole days.  

The problem with Electric Propulsion isn't mechanical. It is chemical. Specifically, it relies on an energy storage medium -- batteries -- which has an energy density of ~0.8 MJ/kg vs about 46 MJ/kg for Gasoline, and which cannot be replenished in 5 minutes but in many hours. This is why you will never fly from LA to Beijing on an electric airliner; you may get halfway to San Francisco on electric power if you are lucky. Automotively speaking, it takes a 1,000 lbs 60 kW/h battery to go 200 miles in a compact car, whereas it it takes 8 gallons of gasoline weighing 48.6 lbs to do them same.

As far as induction vs magnet motors, it is also very simple. The Induction motor is CHEAPER but heavier and larger for a given output. It also requires a more expensive controller (variable frequency drive). The Magnet motor is more expensive but smaller and lighter, and can be DC driven. The Induction motor has a torque curve that is shaped like a "rainbow"; the Magnet motor starts at the peak at 0 rpm and falls linearly to 0 at it's maximum speed. From a geo-political stand point, there is the added issue that Induction motors DO NOT use rare earth metals (which the USA and western countries do not have a huge supply of), whereas Magnet motors (by definition) do.

Edited January 2, 2019 by dwightlooi

[G. David Felt]

38 minutes ago, dwightlooi said:

The problem with Electric Propulsion isn't mechanical. It is chemical. Specifically, it relies on an energy storage medium -- batteries -- which has an energy density of ~0.8 MJ/kg vs about 46 MJ/kg for Gasoline, and which cannot be replenished in 5 minutes but in many hours. This is why you will never fly from LA to Beijing on an electric airliner; you may get halfway to San Francisco on electric power if you are lucky. Automotively speaking, it takes a 1,000 lbs 60 kW/h battery to go 200 miles in a compact car, whereas it it takes 8 gallons of gasoline weighing 48.6 lbs to do them same.

As far as induction vs magnet motors, it is also very simple. The Induction motor is CHEAPER but heavier and larger for a given output. It also requires a more expensive controller (variable frequency drive). The Magnet motor is more expensive but smaller and lighter, and can be DC driven. The Induction motor has a torque curve that is shaped like a "rainbow"; the Magnet motor starts at the peak at 0 rpm and falls linearly to 0 at it's maximum speed. From a geo-political stand point, there is the added issue that Induction motors DO NOT use rare earth metals (which the USA and western countries do not have a huge supply of), whereas Magnet motors (by definition) do.

Excellent valid points and finally we are getting out of ICE what was proven and shown 40 years ago. Efficiency for the time being as R&D takes place to get EV's to the same point and even better for society.

Looking at 40 years ago and the smog level of LA which is what Shanghai is like today shows that technology must push forward for the betterment of human health. No reason to not us both technologies where they make excellent sense. EV's in the inner city and suburbs where you have short trips, can easily plug it in at night and have a full tank the next morning and ICE for many other uses that EVs are not ready for.

In regards to the V8, I truly like your design you have suggested above, I just will never be a fan of DOHC engines and the lack of torque they have compared to HP naturally aspirated. I get what can be done here with this motor and the use it would bring.

Happy you are back and stating your ideas and beliefs, Happy New Year Dwight!

[oldshurst442]

Yes.  Not all engineering solutions are viable for all scenarios.  (gasoline vs electric motors in today's junction in time and reality).

Both @dwightlooi and @dfelt brilliantly defined both advantages of ICE vs induction motors vs magnetic motors and their disadvantages. 

Areas where hydro-electricity is being used, there is an added benefit where the production of electricity is even cleaner for the environment. (Yes, no propulsion system is 100% earth friendly and clean. Unless we use horse and buggy. Wooden buggy as trees are a re-usable resource, if we replant that is and wooden boats to travel by water. And no traveling by flying, ever...) (No usage of iron and steel and aluminium as shaping and producing these resources causes...pollution...bronze too, is an iffy material choice as there are 7 billion of us today...if we really want to be 100% clean for the environment that is...)  

Therefore, there will always be some sort of compromise, whether its environmental or efficiency.  

But by picking and choosing what solution best works for our immediate and personal surroundings, then that is all us humans could do.  

Dfelt mentioned  Los Angeles and Shanghai and air pollution.  I remember as a young kid, living in Montreal Quebec...very far away from LA... that even on Montreal news stations, the news got out and told us that Los Angelinos would be advised to stay home certain days because of how bad smog was in the 1970s and early 1980s. Today, I see Shanghai residents wear those medical face masks in pictures when they go outside....  I guess that is why the Chinese government has taken measures to abolish the internal combustion engine in their country. China is also the world's biggest hydro-electric producer.  Makes sense pollution wise for them as well as a monetary one.  Also, China has plenty of the rare earth metals we were talking about...

 

 

 

 

 

Edited January 2, 2019 by oldshurst442

[Drew Dowdell]

On 12/31/2018 at 8:37 PM, dwightlooi said:

FACTS: We know that the C8 Corvette and a number of her contemporaries in GM's 2020 stables will have a Pushrod Small Block Engine. This may very well be the last and the finest small block engine. We do not know much beyond that.

PREDICTION: The following is my prediction on its specifics. You will have to wait half a year to find out if I am right or if I am close...

• RPO:  LT2
• Aspiration:  Naturally Aspirated
• Construction:  Aluminum block and heads
• Cylinder Spacing:  111.76 mm (4.400")
• Bore x Stroke:  103.25 mm x 101.6 mm (4.065" x 4.000")
• Displacement:  6,805 cc (415 cu-in)
• Static Compression:  11.5:1
• Fuel requirement:  Premium Unleaded Gasoline (91 Octane) recommended / not required
• Valve Train:  Push rods with roller lifters, concentric cams-in-block with dual cam phasing, cylinder deactivation via collapsible lifters
• Power Output:  525 bhp @ 6000 rpm
• Torque:  512 lb-ft @ 4200 rpm
• Maximum engine speed:  6,300 rpm

 

Why 6.8 liter specifically? 

You've been talking about concentric cams for years now with the General not going that route.  Why do you think they'll go that way now?

[G. David Felt]

1 hour ago, oldshurst442 said:

Yes.  Not all engineering solutions are viable for all scenarios.  (gasoline vs electric motors in today's junction in time and reality).

Both @dwightlooi and @dfelt brilliantly defined both advantages of ICE vs induction motors vs magnetic motors and their disadvantages. 

Areas where hydro-electricity is being used, there is an added benefit where the production of electricity is even cleaner for the environment. (Yes, no propulsion system is 100% earth friendly and clean. Unless we use horse and buggy. Wooden buggy as trees are a re-usable resource, if we replant that is and wooden boats to travel by water. And no traveling by flying, ever...) (No usage of iron and steel and aluminium as shaping and producing these resources causes...pollution...bronze too, is an iffy material choice as there are 7 billion of us today...if we really want to be 100% clean for the environment that is...)  

Therefore, there will always be some sort of compromise, whether its environmental or efficiency.  

But by picking and choosing what solution best works for our immediate and personal surroundings, then that is all us humans could do.  

Dfelt mentioned  Los Angeles and Shanghai and air pollution.  I remember as a young kid, living in Montreal Quebec...very far away from LA... that even on Montreal news stations, the news got out and told us that Los Angelinos would be advised to stay home certain days because of how bad smog was in the 1970s and early 1980s. Today, I see Shanghai residents wear those medical face masks in pictures when they go outside....  I guess that is why the Chinese government has taken measures to abolish the internal combustion engine in their country. China is also the world's biggest hydro-electric producer.  Makes sense pollution wise for them as well as a monetary one.  Also, China has plenty of the rare earth metals we were talking about...

Totally agree that the powertrain needs to work for what is envio friendly. Washington state is all Hydro, Solar and Wind, so power is cheap and ultra clean, so running EV's make the cities quiet and cleaner.

China only recently joined the worlds biggest hydro production with the completion of some massive dams in the last 20 years, they still also suck down the largest amount of Coal, so rolling Coal Power Production with no exhaust filtering is pretty dirty there.

@dwightlooi Really like your engine thoughts here, so in adding to @Drew Dowdell questions in regards to the 6.8 Liter size.

Why only 11.5:1 compression and not go higher and require the Premium? After all Europe points to the benefits of running the cleaner higher octane with the power/performance benefits from premium.

[dwightlooi]

6 minutes ago, Drew Dowdell said:

Why 6.8 liter specifically? 

You've been talking about concentric cams for years now with the General not going that route.  Why do you think they'll go that way now?

#1 6.8 because it is a simple combination of the current 6.2L's bore with the LS7's 4.0" stroke. This eliminates the need for pressed in cylinder liners and it is stroke length that they know how to accommodate.

#2 Concentric Cams is EASY. It was done on the Viper and it does not add to the actuated mass. GM's Tri-power cam switching  scheme based on finger followers and pivot lash adjusters is incompatible with the cylindrical lifter system in the small block.

[Drew Dowdell]

3 minutes ago, dwightlooi said:

#1 6.8 because it is a simple combination of the current 6.2L's bore with the LS7's 4.0" stroke. This eliminates the need for pressed in cylinder liners and it is stroke length that they know how to accommodate.

#2 Concentric Cams is EASY. It was done on the Viper and it does not add to the actuated mass. GM's Tri-power cam switching  scheme based on finger followers and pivot lash adjusters is incompatible with the cylindrical lifter system in the small block.

It's not a matter of easy or not.  It just doesn't seem to be something GM is interested in. They could have done it years ago if they felt it was needed to get the results they wanted.  I assume this new engine will have their new Dynamic Fuel Management system too. 

But this leads to another question... with that power output, why not just go with the Cadillac Blackwing V8?  It certainly has the pedigree, and it's not like they'll need it for CT6 production much longer. 

[dwightlooi]

49 minutes ago, dfelt said:

Totally agree that the powertrain needs to work for what is envio friendly. Washington state is all Hydro, Solar and Wind, so power is cheap and ultra clean, so running EV's make the cities quiet and cleaner.

China only recently joined the worlds biggest hydro production with the completion of some massive dams in the last 20 years, they still also suck down the largest amount of Coal, so rolling Coal Power Production with no exhaust filtering is pretty dirty there.

@dwightlooi Really like your engine thoughts here, so in adding to @Drew Dowdell questions in regards to the 6.8 Liter size.

Why only 11.5:1 compression and not go higher and require the Premium? After all Europe points to the benefits of running the cleaner higher octane with the power/performance benefits from premium.

Three things...

#1 Solar and Wind are NOT cheaper than fossil fuels. Not at $44 a barrel and not even at $100 a barrel. Parity is somewhere around $130~140 a barrel. Just because something has zero fuel costs doesn't mean it is free.  Eg. Solar costs about $6,000 per kW. It costs about $600 to produce a kW/h from natural gas 24/7 for a whole year. Hence, the cost of the solar panel is equivalent to the fuel cost to generate it's rated power with gas for 10 years. And, solar produces zero at night and a fraction of its rated power during most of the day. So, the cost of the panels is about 30 years of fuel costs to generate the same amount of power. This is not counting batteries which are tremendously expensive and which you will need of you use Wind or Solar as the primary means of power generation and do not want to light a candle at night. That is why they need huge subsidies and mandates or nobody will use them.

#2 There is also the issue of power density. Neither wind not solar has the density to supply today's electric needs without occupying more land than is needed much less tomorrow's needs. Before we get comfortable with an electric future, we MUST get comfortable with a NUCLEAR future.

#3 11.5:1 and Regular 87 Octane gas allows you to put it in TRUCKs and SUVs! The biggest consumer of the LT1 and its 6.2L direct injected pushrod sibblings is NOT the Corvette. It is the Suburban, Silverado, Sierra, Escalade, Yukon, etc -- in form of the L86 which also has 11.5:1 compression, but is tuned for 420 hp and to deliver its 460 lb-ft at a lower 4,100 rpm. Going to 12.2:1 or there abouts gets you at best maybe 10~15 additional hp which is not really worth it. Higher octane fuel does not actually burn any cleaner or dirtier.

Edited January 2, 2019 by dwightlooi

[dwightlooi]

2 hours ago, Drew Dowdell said:

It's not a matter of easy or not.  It just doesn't seem to be something GM is interested in. They could have done it years ago if they felt it was needed to get the results they wanted.  I assume this new engine will have their new Dynamic Fuel Management system too. 

But this leads to another question... with that power output, why not just go with the Cadillac Blackwing V8?  It certainly has the pedigree, and it's not like they'll need it for CT6 production much longer. 

Because, a DOHC V8 is more expensive, bulkier and heavier. Because a DOHC Bi-turbo V8 is doubly so with a pair of turbos and a myraid of air-to-water heat exchangers. Because a DOHC V8 is actually no better in fuel economy. And, because GM had declared that the the more complex and more expensive way to achieve the same result should be reserved for Cadillac exclusively.

BTW, the current Generation V Smallblock V8 already has Dynamic Fuel Management albeit they call it Active Fuel Management. The limitation of the current AFM is that it limits the redline to about 6,200 rpm because of the added mass of the collapsible lifters. Well, since we are reducing the redline due to the lengthening of the stroke and the consequent increase in piston speeds, that fits very well with the lower rev ceiling from the AFM/DFM lifters.

Edited January 2, 2019 by dwightlooi

[Drew Dowdell]

1 hour ago, dwightlooi said:

Three things...

#1 Solar and Wind are NOT cheaper than fossil fuels. Not at $44 a barrel and not even at $100 a barrel. Parity is somewhere around $130~140 a barrel. Just because something has zero fuel costs doesn't mean it is free.  Eg. Solar costs about $6,000 per kW. It costs about $600 to produce a kW/h from natural gas 24/7 for a whole year. Hence, the cost of the solar panel is equivalent to the fuel cost to generate it's rated power with gas for 10 years. And, solar produces zero at night and a fraction of its rated power during most of the day. So, the cost of the panels is about 30 years of fuel costs to generate the same amount of power. This is not counting batteries which are tremendously expensive and which you will need of you use Wind or Solar as the primary means of power generation and do not want to light a candle at night. That is why they need huge subsidies and mandates or nobody will use them.

#2 There is also the issue of power density. Neither wind not solar has the density to supply today's electric needs without occupying more land than is needed much less tomorrow's needs. Before we get comfortable with an electric future, we MUST get comfortable with a NUCLEAR future.

#3 11.5:1 and Regular 87 Octane gas allows you to put it in TRUCKs and SUVs! The biggest consumer of the LT1 and its 6.2L direct injected pushrod sibblings is NOT the Corvette. It is the Suburban, Silverado, Sierra, Escalade, Yukon, etc -- in form of the L86 which also has 11.5:1 compression, but is tuned for 420 hp and to deliver its 460 lb-ft at a lower 4,100 rpm. Going to 12.2:1 or there abouts gets you at best maybe 10~15 additional hp which is not really worth it. Higher octane fuel does not actually burn any cleaner or dirtier.

4

#1 Your costs are out of date. Solar costs about $3,100 per KW (before tax credits) these days and it continues to fall at a rapid pace. I'd also want to see a link to your natural gas assertion... NG is cheap, but not that cheap, and you're not figuring in the cost of the equipment and the maintenance to keep it running.

#2 I'm fine with a nuclear future, however, a wind future is not outside the realm of possibilities. For what we've spent on the Iraq and Afganistan wars, we could have blanketed the mid-west (the Saudi Arabia of wind power) with enough wind turbines to power the entire US with quintuple redundancy.  (Not saying that we would build to 5-times required capacity, just that for that amount of money, we could have).

There is more to the cost of fossil fuels than just the number on the pump.  While autos have become remarkably cleaner, ships, trains, and factories have lagged behind. There are external costs that never get priced into that gallon you pump into your car. 

Dynamic fuel management is just a more advanced Active fuel management that can shut down a greater number of cylinders. 

[dwightlooi]

4 minutes ago, Drew Dowdell said:

#1 Your costs are out of date. Solar costs about $3,100 per KW (before tax credits) these days and it continues to fall at a rapid pace. I'd also want to see a link to your natural gas assertion... NG is cheap, but not that cheap, and you're not figuring in the cost of the equipment and the maintenance to keep it running.

#2 I'm fine with a nuclear future, however, a wind future is not outside the realm of possibilities. For what we've spent on the Iraq and Afganistan wars, we could have blanketed the mid-west (the Saudi Arabia of wind power) with enough wind turbines to power the entire US with quintuple redundancy.  (Not saying that we would build to 5-times required capacity, just that for that amount of money, we could have). 

There is more to the cost of fossil fuels than just the number on the pump.  While autos have become remarkably cleaner, ships, trains, and factories have lagged behind. There are external costs that never get priced into that gallon you pump into your car. 

Dynamic fuel management is just a more advanced Active fuel management that can shut down a greater number of cylinders. 

Actually...

#1 The cost of Solar Panels is about $3,100 per kWh. The cost of Solar Systems is about twice that because photovoltaic that produces between 0V~17V depending on the intensity of the sun is useless to the power grid or to home appliances without proper power conversion. Electricity generated from NG rnages between 7 and 10 kWh in the USA depending largely on geographic distance from the production and storage sources. I was using 8 kWh.

#2 Well, good thing we are getting back from the foreign wars of zero gain in Syria and Iraq! You CANNOT power the country with wind or solar irrespective of expense and land use without BATTERY FARMS.

#3 DFM is AFM with Start/Stop and Tri-Power. The latter being three step valve lift control -- Zero, Low and High Lift (Zero is only available on half the cylinders; those which are capable of being shut off).

[Drew Dowdell]

No, DFM definitely operates on all 16 valves. 

[dwightlooi]

2 minutes ago, Drew Dowdell said:

No, DFM definitely operates on all 16 valves. 

Uh... yes... and your point is?

[Drew Dowdell]

8 minutes ago, dwightlooi said:

#3 DFM is AFM with Start/Stop and Tri-Power. The latter being three step valve lift control -- Zero, Low and High Lift (Zero is only available on half the cylinders; those which are capable of being shut off).

 

My point is that any cylinder can be shut off... not just half the cylinders. 

From GM's press release:

Quote

An electromechanical system deactivates and reactivates all 16 of the engine’s hydraulic valve lifters, controlling valve actuation.

 

[dwightlooi]

2 minutes ago, Drew Dowdell said:

My point is that any cylinder can be shut off... not just half the cylinders. 

From GM's press release:

 

IC... Maybe they do that during start/stop activation to make it easier to crank over the engine. But you will not actually shut off 1 in 4 cylinders or 4 in six. If you did, the engine will no longer be even fire and power delivery will feel like you have a misfiring engine.

[Drew Dowdell]

1 minute ago, dwightlooi said:

IC... Maybe they do that during start/stop activation to make it easier to crank over the engine. But you will not actually shut off 1 in 4 cylinders or 4 in six. If you did, the engine will no longer be even fire and power delivery will feel like you have a misfiring engine.

Supposedly, they figured it out and yes they can indeed do exactly that. 

[dwightlooi]

Just now, Drew Dowdell said:

Supposedly, they figured it out and yes they can indeed do exactly that. 

Not on the L3B (2.7T) or LSY (2.0T)  engines... these are either 4 or 2 when driven. They never run on 1 or 3.

[Drew Dowdell]

1 minute ago, dwightlooi said:

Not on the L3B (2.7T) or LSY (2.0T)  engines... these are either 4 or 2 when driven. They never run on 1 or 3.

I think 2 is the minimum and everything else depends on how you count.  That is, a cycle could fire 3 times, but it might skip 1 or 2 or 3 cylinders before that third cylinder fires.   There was a youtube video that showed it. I'll try and find it.

That said, I've driven the Sierra Denali with it and the system is absolutely seamless. Even less noticeable than the V8/4 of Active Displacement. 

[Cmicasa the Great]

Why are we discussing a 6.8L when the 6.2L can easily be bumped to 500HP with a simple tune? To achieve an additional 25HP and get proper NVH, Fuel economy, and longevity a balanced set up with  a more aggressive cam is probably all that is needed

[dwightlooi]

1 minute ago, Cmicasa the Great said:

Why are we discussing a 6.8L when the 6.2L can easily be bumped to 500HP with a simple tune? To achieve an additional 25HP and get proper NVH, Fuel economy, and longevity a balanced set up with  a more aggressive cam is probably all that is needed

Because we are not talking about tuner cars but cars with a 6 year 70K miles GM powertrain warranty and which does not have a lumpy idle or a cammy powerband? And, also because a 101mm stroke compared to a 92mm stroke costs exactly ZERO more.

[Cmicasa the Great]

3 minutes ago, dwightlooi said:

Because we are not talking about tuner cars but cars with a 6 year 70K miles GM powertrain warranty and which does not have a lumpy idle or a cammy powerband? And, also because a 101mm stroke compared to a 92mm stroke costs exactly ZERO more.

OK.. granted, but to go from 6.2L to 6.8L seems a bit far fetched considering that the jump was made under 6.2L guise from 430-465HP just 5 years ago. A 6.4L at best is what I expect

[Drew Dowdell]

1 minute ago, Cmicasa the Great said:

OK.. granted, but to go from 6.2L to 6.8L seems a bit far fetched considering that the jump was made under 6.2L guise from 430-465HP just 5 years ago. A 6.4L at best is what I expect

There was also the 7.0

[Drew Dowdell]

Starting at 4:30 you can see the differences in power management. 

[dwightlooi]

3 minutes ago, Cmicasa the Great said:

OK.. granted, but to go from 6.2L to 6.8L seems a bit far fetched considering that the jump was made under 6.2L guise from 430-465HP just 5 years ago. A 6.4L at best is what I expect

6.8 is the same bore and block as the 6.2 with no need for cylinder sleeves. The 101mm stroke is exactly the same as was used on the 7.0L LS7.

You got 30 hp with the LT1 largely from Direct Injection and 11.5:1 compression. BTW, the estimated output for the 6.8 assumes ZERO gain in specific torque output, just a slight broadening of the torque curve from dual cam phasing.

[Cmicasa the Great]

1 hour ago, dwightlooi said:

6.8 is the same bore and block as the 6.2 with no need for cylinder sleeves. The 101mm stroke is exactly the same as was used on the 7.0L LS7.

You got 30 hp with the LT1 largely from Direct Injection and 11.5:1 compression. BTW, the estimated output for the 6.8 assumes ZERO gain in specific torque output, just a slight broadening of the torque curve from dual cam phasing.

We are also having to remember that GM is an international cocorp. The original international corporation of the modern age. They have markets where the limited vs regular C6.. C6 Z06 was extremely penalized for having a 7.0L.. why the hell would they up the liters for 60HP just to have a naturally aspirated engine? My bet is that a break thru in HP is announced and they up the ante on a 6.2L or even 6.4

 

 

[dwightlooi]

25 minutes ago, Cmicasa the Great said:

We are also having to remember that GM is an international cocorp. The original international corporation of the modern age. They have markets where the limited vs regular C6.. C6 Z06 was extremely penalized for having a 7.0L.. why the hell would they up the liters for 60HP just to have a naturally aspirated engine? My bet is that a break thru in HP is announced and they up the ante on a 6.2L or even 6.4

 

 

Uh... how was the Z06 penalized for being 7.0L? In the USA, or any country with a sensible policy on fuel economy, engine displacement has no bearing on taxes. The 2008 Z06 7.0L was 15/24MPG -- the 2008 M3 4.0L was 14/20 mpg, the Porsche 911 Turbo 3.6L of the same year was 16/23 MPG and the Audi RS4 4.2L was 14/20 MPG. None of these cars measure up to a Honda Civic; but the 7.0L was actually as good or better on fuel economy than its competitors all of which had less than it's 505hp/470 lb-ft.

In stupid countries with displacement rather gas guzzler taxes, you are completely screwed whether it is 6.2L, 6.4L, 6.8L or 7.0L. For such markets, you'll want some souped up LF4 3.6TT engine to get you 460+ hp or better yet some souped up 4-cylinder running 30 psi of boost on as few liters of displacement as possible.

[dwightlooi]

23 hours ago, Drew Dowdell said:

Starting at 4:30 you can see the differences in power management. 

Great Video!

#1 It illustrates what I was trying to explain -- that Tri-Power can only shut off two cylinders in the 4-cylinder engines. You'll notice that there are 6 solenoid switcher units. All four cylinders have them on the intake valves, but only the middle two cylinders have them on the exhaust valves. There is no way to put the exhaust valves of the outside cylinders in zero-lift mode and disable those cylinders. Tri-Power in the L3B and the LSY either operates on 4 or 2 cylinders; never 3 ,1 or 0.

#2 BTW, the Tri-Power switcher is SCARY. It is scary because it is not a "safe-on-fail"

In engineering, that is an important concept which ensures that should a device fail it will not render an essential function inoperable or cause damage to the machine. Tri-Power is not a safe-on-fail design the way VTEC, VVTL-i or GM's own iVLC systems were. When any of these systems fail either because of hydraulic failure or solenoid failure, they simply will not engage. The spring(s) then keeps them perpetually in the low-lift mode under which the engine is perfectly operable even if it runs out of breath above 5000 rpm and does not produce its rated power.

Tri-Power has (up to) two solenoid units for every cylinder. Each has two cam pins. When the solenoid unit triggers the cam pins, they shift the cam slider left or right on the camshaft. There are up to three positions -- zero, low or high lift profiles. The spiral grove is such that it slides the cam sleeve only when the rollers are riding on the base circle to guarantee that no movement is possible when the valves are being actuated so the rollers won't be forced against the side walls of a higher lift cam lobe and damage the rocker catastrophically. Still, this is SCARY in two ways...

• If the solenoid units fail and the cam pins retract mid cycle and or are unable to extend, you can be stuck on a no-lift cam (in which case the cylinder won't work) or worse you can be stuck on the ledge between two lobes and fail.
• If the solenoid units fail and the cam pins fail to extend, it is possible that a cylinder gets stuck in shut off mode for its intake or exhaust valves. This will cause severe drivability problems all the way down to idle.

[Drew Dowdell]

yeah, we were talking about the V8s though... those can go as low as 2 cylinders.