Bye-bye Small Block, hello Microblock!

[dwightlooi]

-- FICTION --

The Microblock V8

The 2011 Microblock V8 engine is designed to succeed both the Small Block and Northstar families as GM’s sole V8 for the second decade of the millennium. The design objective is to create a highly compact engine equaling the LS-family’s performance, while being more compact, more economical and weighing no more than the 3.6 liter DOHC V6. The engine is a pushrod OHV design incorporating the latest technologies including direct gasoline injection and variable cam phasing. Variable rocket ratio was considered but relegated to a future upgrade due to the additional costs and complexities it will incur.

The Microblock engine is based neither on the LS family nor the Northstar family. Its 103mm bore spacing matches that of the high feature 3.6 liter V6 rather than either of the V8s.

The extensively webbed block is a lost foam aluminum casting and terminates at the crank line rather than being deep skirted. A die cast lower block with five cast in place bearings complete the bottom end and holds a forged steel cross plane crank. The connecting rods themselves are forged steel with fractured rod ends. Nestled within the valley of the block is a chain driven camshaft actuating hydraulic roller lifters with provisions for active fuel management on four of the eight lifters. On the topside, roller tipped rocker arms actuate two valves per cylinders. A vane type camphaser is incorporated into the sprocket assembly with the ability to advance and retard the camshaft by 15 degrees. Like the LS family, the intake plenum and runners are composite

With both the bore and stroke being 94mm, this is a perfect square motor displacing 5,219cc (318ci). The 9mm spacing between the cylinder walls is rather conservative and lends itself well to forced induction or future displacement increases. The wedge shaped combustion chamber is very similar in geometry to that used in the LS3 small block engine with the exception of the addition of a direct injector and a little parabolic ramp on the piston face for directing the fuel jet. Compression ratio is a lofty 12.3:1 even though premium gasoline is recommended but not required. The engine utilizes a capacitive discharge ignition system which also doubles as the knock sensing unit by measuring the ionization levels between the spark gaps. AC Delco Iridium plugs are specified. Lubrication is provided by a baffled wet sump filled with low viscosity 0W-20 Mobil 1 Synthetic oil and is scheduled for 10,000 mile service intervals or as indicated by the oil life monitoring system. The oil filter is attached topside for easy servicing.

On the electrical front, the Microblock does away with the starter motor, alternator and the belt driven accessories. In their place is a 5hp flywheel integrated generator-starter (FIGS) and an all electric accessory system. With the exception of the water and oil pumps which are gear driven off the camshaft, every thing else on a Microblock equipped vehicle – power steering, A/C compressor, radiator fans and the air injection pump – are electrically driven. When the transmission is placed in Economy “E” mode, FIGS also shuts down the engine at stop lights and restarts it automatically as the driver lifts off the brakes. Even though the FIGS system is capable of a small amount of regenerative braking and motor assist, this is not utilized in the interest of battery life on the 24V electrical system.

While the Microblock lays no claim to being the highest specific output V8 on the market, it boasts of being smaller and lighter than the 414hp BMW 4.0 liter V8 used in the M3. At 168 kg, it is the lightest 400hp normally aspirated mass production engine period and weighs approximately the same as the direct injected DOHC 3.6 liter V6 although it is a tad longer and a little lower in height. With a quarter as many camshafts and half-as many valves as DOHC 4-valve V8 designs, the engine also tenders up superior brake specific fuel consumption numbers at low loads.

Introduced on the 2011 Corvette, the compact and featherweight Microblock plays a large role in enabling the smaller and lighter 7th generation Corvette to meet its 2,900 lbs target weight. The combination of a 2,900 lbs curb weight, active fuel management and homogeneous direct injection also allows the C7 Corvette to boast best in class fuel economy figures of 17 mpg in the city and 28 mpg on the freeway whilst equipped with a Hydramatic 6-speed automatic transmission.

As the Northstar and Smallblocks of various capacities are phased out, the Microblock will serve as the sole V8 engine on GM vehicles. A 600hp supercharged and aftercooled variant (LZA) will follow in the second production year and will be the standard powerplant on the Z06 and Cadillac V-series vehicles. Meanwhile, a cam-in-cam dual independent variable valve timing system and a two-step variable rocker ratio setup is being considered for a 2015 update.

-- FICTION --

[gm4life]

Interesting for cars I would be in favor of such as for trucks OHV V8's aren't such a bad thing.

[balthazar]

Just an FYI- Since HP is a mathmatical calculation derived from TRQ, the 2 curves always intersect at 5252 RPM.

As soon as I read OHV, what flashed thru my mind was the inevitable reaction by far too many: EPIC FAIL.

BTW- you should start calling this what it is relative to OHC- it may fool some of the bench racers for a good while : IBC - In Block Cam. It'll sound like something new- plenty of people are easily swayed by just that.

Interesting proposal overall from a business standpoint, but you have to consider the media's reaction when all GM V-8s are 'the same engine' - further upping the clamor that a 'Cadillac is a rebadged Chevy'.

[loki]

Just an FYI- Since HP is a mathmatical calculation derived from TRQ, the 2 curves always intersect at 5252 RPM.

yes, but you noticed the separate linear scales for torque and hp, right?

very nice idea overall... but the premium fuel required doesn't fit.

[balthazar]

>>"yes, but you noticed the separate linear scales for torque and hp, right? "<<

Obviously.... no.

[dwightlooi]

yes, but you noticed the separate linear scales for torque and hp, right?

very nice idea overall... but the premium fuel required doesn't fit.

Not really... not if it is recommended but not required. The engine won't ping on 87 octane, it will however retard the spark timing a little and lose about two dozen horsepower and foot pounds. Still perfectly adequate I'll say, and for people who are cheap enough to want to save 20 cents on a gallon of juice a most reasonable trade off.

These DI engines are very knock resistant -- primarily because there is no fuel in the cylinder during the intake stroke and through much of the compression stroke. Air alone is not capable of detonating.

[Robert Hall]

A compact, light V8 would be an interesting idea to explore.

[dwightlooi]

A compact, light V8 would be an interesting idea to explore.

Well.... let's remember why the push rod OHV engine was originally invented. It wasn't that SOHC or DOHC designs didn't exist -- most WWII V12 fighter engines were SOHC 4-valve per cylinder powerplants, the German ones largely featured direct gasoline injection too! It was the desire to produce a smaller and lighter Vee-configuration engine that let to the incarnation of the OHV push rod V6 and V8 engines.

Daimler Benz DB605 -- 35 liters, 48-valve, inverted V12, with Bosch Mechanical Direct Gasoline Injection

[NOS2006]

Need turbocharged version.

[Sixty8panther]

Most on here know I'd be ALL for this idea.

As far as most of what Balthazar said I agree

but have this to say to the objection of Chevy

motors being used in a Cadillac... I'd say

make this MINI-V8 even smaller, say about

the size (displacement wise) of the BMW 3.0

from the 1990s, then, give Cadillac V12 & V16

variants exclusivelly.

On a side note, I NEED to own an airworthy Bf109/Me109 before I die.

[NOS2006]

3 liters is way too small for 8 cylinders IMHO.

[Sixty8panther]

WHY?

Mazda had a 1.8 liter V6, by that logic a

2.4 liter V8 is production worthy.

Ferraris of the 1940-60s had V-12 with

displacement lower in CuIn/Liters than

a modern Honda Civic's 4-cylinder!

The first few Ferrari V-12 was a 1.5 liter

IIRC.

Also:

What would you rather own... a 3.0 liter

V8 or a 3.6 liter V6?

Displacement will go down more & more

in comming years IMHO, but there's no

reason why we have to be all stuck

driving four cylinders.

The only 4-banger I'll ever aspire to own

will be a Brass Era Cadillac.

[NOS2006]

There's no replacement for displacement. 3.6 > 3.0

I bet that 3.6 V6 would be more torquey and powerful using the same technology, too.

[G. David Felt]

Why does engines always have to go up on Horsepower but be weak in Torque? I do love the idea of a microblock V8, but come on, if you are going to do 400HP at least get 400 LBs of Torque or more. I just have not been impressed with these high reving HP engines with little itty bitty Torque numbers. Reminds me of the Small Man Syndrome,

Small man with little itty bitty Wee Wee drives big ass truck to make him feel important.

[Sixty8panther]

I disagree. And as far as "no replacement for

displacement", (I agree) why did you buy a

3800 powered Camaro?

You need to drop a Caddy 8.2 liter 500 in that

Cobalt!

AGAIN:

in a world where the government would have

us all drive Civic EX sedans, I'd rather have

a baby-V8 thab none at all!

And by your logic (V6 vs. V8), I guess GM

needs to make a 700 cubic inch ONE cylinder

Corvette ZR1!

The annalogy was to illustrate that a 3.0

liter V8 is STILL a V8, but a V6, no matter

how BIG is still NOT a V8 and therefore

lacking in the image & smoothness dept.

[NOS2006]

I disagree. And as far as "no replacement for displacement", (I agree) why did you buy a 3800 powered Camaro?

I didn't, my parents did. And I was 16. Giving me a 315+ HP V8 would've been stupid.

You need to drop a Caddy 8.2 liter 500 in that Cobalt!

Doesn't fit without major modifications.

in a world where the government would have us all drive Civic EX sedans, I'd rather have a baby-V8 thab none at all!

I understand that, but if I'm gonna have a V8, I hope to God it's not gonna be under five liters.

And by your logic (V6 vs. V8), I guess GM needs to make a 700 cubic inch ONE cylinder Corvette ZR1!

No, that's not my logic. And we don't need 700 cubic inches when we can get 650 HP out of 6.3 liters. That's plenty.

[CaddyXLR-V]

Personally, I'd rather have the smaller V8 instead of a bigger V6, especially if the V8 has a higher redline.

[NOS2006]

All things equal, I'd take a smaller V8 over a larger V6, but if all the technology is the same, I think the V6 would be more powerful thus I would want it more.

[dwightlooi]

I think there are a few misconceptions here...

(1) Smaller displacement -- in and of itself -- does not equal better economy. Smaller displacements = smaller pumping losses. However, a larger number cylinders = a larger number of cylinder wall area, valves, etc. -- all of which increase mechanical friction and reduce economy.

(2) In general the maximum specific power output and fuel economy is achieved by using the fewest cylinders for a given displacement that you can stay under the knock threshold. A 1-cylinder 2 liter engine -- if you can stand the vibrations and prevent it from knocking -- will be more powerful and more economical on fuel compared to a 4-cylinder 2 liter engine. The Mazda 1.8 liter K-series V6 is neither powerful (130hp) nor economical (29mpg on the freeway) compared to other 1.8 liter engines of the period such as the Honda B18C.

(3) 5.2 liters was suggested because it was a convenient displacement with a 94x94mm (bore x stroke) engine. This allows the engine to share the 3.6 V6's bore spacing and bore diameters which makes it easier to build both engines on the same line even if they have different V angles. It is also a displacement which allows the engine to get close to LS3 power levels without radical cams or forced induction.

(4) As far as torque is concerned, more is not always better. 375hp is plenty fof a 2,900 lbs car. Any more will simply equal more wheel spin in 1st and second,.

[Sixty8panther]

No, that's not my logic. And we don't need 700 cubic inches when we can get 650 HP out of 6.3 liters. That's plenty.

Well said... you just proved MY point.

6.3 liters = 650 horse

So why is a HALF scale SCB displacing 3.15 liters

for the sake of argument, and putting out 300+

horsepower such a horrible idea?

Everyone wins. Packaging, MPG, weight....

Cost would be about the same.

Edited February 26, 2009 by Sixty8panther

[Hopeful for GM's Future]

While the Microblock lays no claim to being the highest specific output V8 on the market, it boasts of being smaller and lighter than the 414hp BMW 4.0 liter V8 used in the M3. At 168 kg, it is the lightest 400hp normally aspirated mass production engine period and weighs approximately the same as the direct injected DOHC 3.6 liter V6 although it is a tad longer and a little lower in height. With a quarter as many camshafts and half-as many valves as DOHC 4-valve V8 designs, the engine also tenders up superior brake specific fuel consumption numbers at low loads.

This is why I still think OHV has a lot of life left in it. The power to weight ratio can be good even if power displacement is not.

Dwight, just wondering do you think there is potential for HCCI with something like this? Or does HCCI have more potential with something like a series Hybrid (Chevrolet Volt) where the ICE is not directly connected to the wheels via gears and differenetial?

[dwightlooi]

This is why I still think OHV has a lot of life left in it. The power to weight ratio can be good even if power displacement is not.

Dwight, just wondering do you think there is potential for HCCI with something like this? Or does HCCI have more potential with something like a series Hybrid (Chevrolet Volt) where the ICE is not directly connected to the wheels via gears and differenetial?

I am sure HCCI is possible, but it may not be practical on an OHV engine. HCCI is tough enough to achieve with carefully designed, highly symmetrical combustion chambers of a 4-valve cylinder head. And, even so it only works in a narrow rev and load range (up to about half loads at up to 55mph in top gear), and requires a cam lobe switching variable valve lift system to be incorporated (a GM first) in the 2.2 liter demonstrator engines. Try to do it on an OHV V8 and you'll need to fit VTEC style dual lobes, dual lifters and dual push rods per valve. You'll also probably end up with an even narrower HCCI operating envelope. At some point the added complexity, costs and compromises in operable envelope makes it impractical.

Yes, HCCI works best at a constant load and engine speed. I guess there is enough developmental risks on the Volt and enough efficiency margins over conventional hybrids that GM does not want to debut HCCI on it (yet). And, that makes sense.

If you are looking for a "breakthrough" powertrain for efficiency, there are other things as well. Try a recuperated gas turbine for instance. 30~40% thermal efficiency (comparable to contemporary spark ignition engines) but the entire 100 hp engine is probably small enough to be integrated as part of the MUFFLER! Weight is the biggest robber of fuel economy. making the engine basically disappear saves a lot of weight. It also saves a lot of space which in turn saves even more chassis weight. All the disadvantages of a turbine -- horrendous response time, poor economy at part loads, inability to idle slow, unable to start quickl -- are pretty much retired by decoupling the engine directly from driving the wheels through a series hybrid arrangement. Want even more efficiency? Rout the heat from the exhaust to a heat exchanger and use it to boil water for a secondary closed loop steam turbine. Do that and you can try to break the 60% efficiency barrier. That's how the natural gas power stations and high efficiency cruise ships do their generation.General Electric -- with COGES arrangements like the General Electric MS7001H or LM2500+STM)

[Hopeful for GM's Future]

If you are looking for a "breakthrough" powertrain for efficiency, there are other things as well. Try a recuperated gas turbine for instance. 30~40% thermal efficiency (comparable to contemporary spark ignition engines) but the entire 100 hp engine is probably small enough to be integrated as part of the MUFFLER! Weight is the biggest robber of fuel economy. making the engine basically disappear saves a lot of weight. It also saves a lot of space which in turn saves even more chassis weight. All the disadvantages of a turbine -- horrendous response time, poor economy at part loads, inability to idle slow, unable to start quickl -- are pretty much retired by decoupling the engine directly from driving the wheels through a series hybrid arrangement. Want even more efficiency? Rout the heat from the exhaust to a heat exchanger and use it to boil water for a secondary closed loop steam turbine. Do that and you can try to break the 60% efficiency barrier. That's how the natural gas power stations and high efficiency cruise ships do their generation.General Electric -- with COGES arrangements like the General Electric MS7001H or LM2500+STM)

Dwight,

Just wondering if "noise issues" with a jet turbine could be settled in some satisfactory way?

I watched some Youtube videos of Jay Leno's Y2K Jet bike and wow that is thing loud! (Apparently that machine uses the same jet turbine that is in a Bell Helicopter and it puts out 320 shaft horsepower but weighs only 138 lbs)

Also with regard to a very small combined cycle turbine do you think there would be an issues with the steam turbine not being used very much? Apparently "Peaker powerplants" use simple turbines rather than combined cycle due to the fact they are not "on" very much during a 24 hour period?

How much weight do you think a very small combined cycle would add compared to an equivalent sized small turbine?

Thanks

Edited March 1, 2009 by Hopeful for GM's Future

[dwightlooi]

Dwight,

Just wondering if "noise issues" with a jet turbine could be settled in some satisfactory way?

I watched some Youtube videos of Jay Leno's Y2K Jet bike and wow that is thing loud! (Apparently that machine uses the same jet turbine that is in a Bell Helicopter and it puts out 320 shaft horsepower but weighs only 138 lbs)

Also with regard to a very small combined cycle turbine do you think there would be an issues with the steam turbine not being used very much? Apparently "Peaker powerplants" use simple turbines rather than combined cycle due to the fact they are not "on" very much during a 24 hour period?

How much weight do you think a very small combined cycle would add compared to an equivalent sized small turbine?

Thanks

(1) Noise from turbine engines, very much like noise from any other exhaust producing motors, depends largely on exhaust velocity. Reducing the former is the job of the muffler. In the case of the turbine engine, this job is actually easier because the exhaust is not pulsatile. Expand the cross section and if necessary dilute it and it'll sound like a turbocharger on boost -- which is quite pleasant by any measure.

(2) It is always a trade off between efficiency, complexity and mass. Simple turbines are about 25~42% efficient depending on how advanced it is (how high a compressor pressure ratio and turbine inlet temperature you can get). For small, single-stage, single shaft, turbines tend to be close to the 25% mark whereas large 60,000hp units on ships are near the 42% mark (eg. GE LM6000, R-R MT30). To go above that you need to recapture the energy in the exhaust heat. The simplest way to do this is with a recuperated turbine. Here, the exhaust is passed through a heat exchanger and is used to heat up the intake air between the compressor output and the combustor. This earns you another 5~10%. A Combined Cycle engine uses the same exhaust heat to boil water and run a steam turbine. Because of the efficient air-water heat exchange interface due to the high thermal conductivity of water, and the high amount of heat which can be captured due to the specific latent heat of vaporization of water, the combined cycle unit is much better at capturing wasted exhaust heat energy than the air-to-air recuperated turbine. It is usually good for 10~20%.

(3) The secondary Rankine cycle turbine is often idle when the primary turbine is operated a partial power. However, in the case of a series hybrid, we can always design the turbine to operate at full power or not at all to achieve maximum efficiency. Unlike a parallel hybrid or direct drive setup, a series hybrid simply uses the turbine to generate electricity. Given the presence of a battery, there is no reason to operate the turbine at 1/4 power or 1/2 power when you can operate it at full power for 1/4 or 1/2 the duration.

[aldw]

(1) Noise from turbine engines, very much like noise from any other exhaust producing motors, depends largely on exhaust velocity. Reducing the former is the job of the muffler. In the case of the turbine engine, this job is actually easier because the exhaust is not pulsatile. Expand the cross section and if necessary dilute it and it'll sound like a turbocharger on boost -- which is quite pleasant by any measure.

(2) It is always a trade off between efficiency, complexity and mass. Simple turbines are about 25~42% efficient depending on how advanced it is (how high a compressor pressure ratio and turbine inlet temperature you can get). For small, single-stage, single shaft, turbines tend to be close to the 25% mark whereas large 60,000hp units on ships are near the 42% mark (eg. GE LM6000, R-R MT30). To go above that you need to recapture the energy in the exhaust heat. The simplest way to do this is with a recuperated turbine. Here, the exhaust is passed through a heat exchanger and is used to heat up the intake air between the compressor output and the combustor. This earns you another 5~10%. A Combined Cycle engine uses the same exhaust heat to boil water and run a steam turbine. Because of the efficient air-water heat exchange interface due to the high thermal conductivity of water, and the high amount of heat which can be captured due to the specific latent heat of vaporization of water, the combined cycle unit is much better at capturing wasted exhaust heat energy than the air-to-air recuperated turbine. It is usually good for 10~20%.

(3) The secondary Rankine cycle turbine is often idle when the primary turbine is operated a partial power. However, in the case of a series hybrid, we can always design the turbine to operate at full power or not at all to achieve maximum efficiency. Unlike a parallel hybrid or direct drive setup, a series hybrid simply uses the turbine to generate electricity. Given the presence of a battery, there is no reason to operate the turbine at 1/4 power or 1/2 power when you can operate it at full power for 1/4 or 1/2 the duration.

If Cadillac ever made a production version of such an engine into a series hybrid luxury vehicle, I can definitely see them come back up to tbe bleeding edge of technology and luxury again.

[ZL-1]

Need turbocharged version.

No, no no... TWIN turbocharged version :AH-HA_wink:

[dwightlooi]

If Cadillac ever made a production version of such an engine into a series hybrid luxury vehicle, I can definitely see them come back up to tbe bleeding edge of technology and luxury again.

Let's sum it up simply...

(1) The gas turbine is attractive for its mechanical simplicity, light weight and small size. A 100 hp unit can be about the size of a 100 pcs stack of CDs.

(2) A gas turbine is only feasible as a daily driver engine if it is used in a series hybrid drivetrain. This is the only way to make irrelevant the 5-10 sec throttle lag and also allow the engine to always operate at its peak efficiency (at ideal speed and load).

(3) The problem with series the turbine-electric series hybrid is not the turbine but the battery. Constant charging and discharging shortens the battery life and batteries are extremely expensive today ($10,000~16,000 for the Volt's 40 mile range pack).

[dwightlooi]

If Cadillac ever made a production version of such an engine into a series hybrid luxury vehicle, I can definitely see them come back up to tbe bleeding edge of technology and luxury again.

Not necessarily...

A larger, single turbo is not less efficient or more laggy than two small ones. The reason twin turbocharged engines are favored traditionally for Vee configuration engines is that it is difficult to route exhaust from one side of the engine to the other, and when you do that you also invariably introduce thermal losses which negatively impact turbo response and performance. Regardless, there are many examples of dual bank engines using a single turbo. The Subaru EJ20 (2.0l) and EJ25 (2.5l) H4s do that, and so does the GM LP9 (2. engine in Saabs.

However, if one reverses the cylinder intake and exhaust ports such that the air enters the engine on the sides and the exhaust exits in the Vee of the powerplant, one can then mount a single turbocharger in the valley of the engine without the exhaust routing woes. Some european diesels already do that. A single Garrett GT 35 medium frame turbo will do just fine for 600 hp.

[aldw]

Let's sum it up simply...

(1) The gas turbine is attractive for its mechanical simplicity, light weight and small size. A 100 hp unit can be about the size of a 100 pcs stack of CDs.

(2) A gas turbine is only feasible as a daily driver engine if it is used in a series hybrid drivetrain. This is the only way to make irrelevant the 5-10 sec throttle lag and also allow the engine to always operate at its peak efficiency (at ideal speed and load).

(3) The problem with series the turbine-electric series hybrid is not the turbine but the battery. Constant charging and discharging shortens the battery life and batteries are extremely expensive today ($10,000~16,000 for the Volt's 40 mile range pack).

The solution regarding the battery problem at present would be to use an ultracapacitor for short-term storage alongside a battery for long-term storage, so that the stress of rapid charge and discharge is on the capacitor instead. This allows for longer battery life.

[dwightlooi]

The solution regarding the battery problem at present would be to use an ultracapacitor for short-term storage alongside a battery for long-term storage, so that the stress of rapid charge and discharge is on the capacitor instead. This allows for longer battery life.

Yes, except that capacitors are big, heavy and have an exponential discharge curves. The last is very problematic because an electric motor cannot be powered by an exponential discharge -- the motor will just blow up and not go anywhere. This means that you need a big, bulky, power conversion circuitry to convert exponentially falling voltages to relatively linear voltages. Power density of Capacitors also fall between 1/100th and 1/1000th that of a battery.