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Does anyone remember the turbocharged Atlas I6 TrailBlazer SS original concept? I know why the Atlas 6 was replaced but I can not help but think that a base Atlas 4.2 DI 6 cylinder at 320 hp, and a single or twin turbo Atlas DI I6 would have been a unique Ecoboost competitor that would have easily shaded it for power , torque, and NVH.
Basically given the way things have gone and GM's apparent preferences with regard to this and that ....... the I5s with boost...... are imo, the bigger missed opportunity.

And then..... the I4s......

And then with regards to the tooling and such...... the diesel conversions.... yes, I really did say that. :yup:

The big banger six needed to get down to around a 3.5 - 3.8 ( so back to the I5s we go..... ) although sometimes.... one wonders about some other things.

Would be interesting to know where all the engine line tooling ends up.

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So..... 'many things' seem possible..... wouldn't be surprised about 'any' of them - pretty much.

Including on the outside, more than one ...... over a 'relatively' short period of time.

A revised 4.3, a new 4.3...... and then ...... we need to remember this from October 2003....

( A na 3.6 without a stronger AT program just isn't going to work for the trucks or so one might think..... although it might work for some of the Vans....

2004 CTS 3.6L VVT Engine Info.

GM gives birth to a new generation of V-6 powerplants that promise to be world class.

Once the preserve of luxury car powerplants, variable valve timing is now spreading to more mainstream engines. Case in point: the arrival of General Motors’ new ‘high feature’ global V-6 engine family, the first engine from GM to feature VVT on both intake and exhaust camshafts.

The first of this V-6 family, a 3.6L will make its debut in Cadillac’s 2004 CTS, replacing its existing, U.K.-sourced 3.2L V-6. The new 255 hp CTS motor is one of several versions of the modular V-6, which will also come in 2.8L and 3.2L displacements, to be used in major markets worldwide.

Engine size can be expanded to 3.8L, or as large as 4.0L when the cylinder liners are eliminated in favor of bore coatings. -

- here just a bit........ but also to some other threads.....

Versions of the engine will be both naturally aspirated and turbocharged and applications will include front-, rear- and all-wheeldrive, as well as hybrid vehicles.

One key to the new engine family’s success, maintains GM, is that it will be competitive with the best in the V-6 class, such as the Honda/Acura 3.2L and Toyota/Lexus 3.0L units, yet be built at a lower cost. All GM’s V-6s will share the following features: aluminum construction, dual overhead camshafts, fourvalve- per-cylinder valvetrain, roller-finger followers, continuously variable cam phasing, electronic throttle control, forged-steel crankshaft, piston-cooling oil jets, coolant-loss protection software, GM’s oil-life system, 32 bit microprocessor and coil-on-plug ignition.

A valve in the dualstage manifold closes to boost cylinder charging in the low- to midspeed range. It opens at higher speeds to feed all cylinders from a common larger plenum.

GM says the output of the most powerful variant of the new engine family will exceed 370 hp, with torque in excess of 350 lbs.-ft.

Work on the new V-6 family started in 1999, and was completed in record time, says Tim Cyrus global V-6 chief engineer.

“The goals for the engine were industry leading reliability, flexibility, package size, pleasibility, efficiency and value,” Cyrus says. The engine can be easily integrated into most platforms, has industry leading NVH and performance with three discrete combustion systems MPFI, SIDI and turbo.”

Importantly, the V-6 engine architecture was designed to incorporate different options, in order to create a broad range of configurations. As well as normally aspirated/ sequential port fuel injection ‘foundation’ architecture, there are two potential major variants. One is a spark-ignition direct-injection (SIDI) V-6 of either 2.8L or 3.2L displacement.

To account for differing market regulations and conditions, particularly in Europe, the engine design can accommodate both stratified-charge (lean-burn) and stoichiometric- charge SIDI architectures. Also in the pipeline are turbocharged 2.8L or 3.2L variants, with a variety of power and torque outputs depending on specific content.

As well as its adaptability, the key feature of GM’s V-6 family is its use of variable valve timing. Moving to full VVT eliminates the traditional compromise in engine design between power and torque outputs, and also improves fuel economy and lowers emissions. In the case of the 3.6L engine, the improvement in torque output is notable: 90 percent of the 252 lbs-ft. peak torque is available across a broad operating range, from 1,600 to 5,800 rpm.

Compared to an existing GM double overhead cam V-6, the 3.6L develops 20 percent more peak power, a 13 percent increase in peak torque — and a 24 percent increase in torque-integral, or the amount of torque available at most points throughout the rpm range.

“Flexibility was very important,” says Bob Jacques, base engine design system engineer. “We insisted on going after high performance and high refinement at the same time.”

A 32-bit micro-hybrid engine control unit embeds all of the necessary electronic circuitry on a four layer substrate that reduces the size of the unit. The new design can be engine mounted, freeing up valuable engine compartment space.
The four-cam continuously variable cam phasing system is electronically controlled and hydraulically actuated. The phasers allow intake cam adjustment through 50 degrees of crankshaft rotation and 50 degrees for exhaust-cam adjustment.

An added benefit of the VVT system is that it allowed for the elimination of the exhaust gas recirculation system, thus reducing weight and complexity.

The V-6’s intake system includes a dualstage variable manifold. A valve in the manifold changes the plenum volume available for resonance tuning of the inlet flow path. When the valve is shut, the cylinders feed from two separate plenums. In this mode the system boosts cylinder charging in the low- to midspeed range. At higher engine speeds, the valve opens and the cylinders all feed from a common larger plenum.

Another significant technical advance is the V-6’s 32-bit micro-hybrid engine control unit, which GM claims is the most powerful currently used in the industry. The ECU design embeds all of the necessary electronic circuitry on a four-layer ‘sandwich’ substrate that reduces the size of the control unit. More robust and resistant to vibration than previous ECUs, the new design can be engine mounted. This move frees valuable space in the engine bay and eliminates attachment problems at the assembly plant.

The four-cam continuously variable cam phasing system is electronically controlled and hydraulically actuated. The phasers allow intake cam adjustment through 50 degrees of crankshaft rotation and 50 degrees for exhaust-cam adjustment.
One function of the ECU is torque-based engine control strategy. Engine output for the driver’s desired throttle opening is determined by the ECU. The torque-based strategy calculates optimal throttle position, variable intake manifold position, continuously variable cam phasing positions and various other operational inputs and then translates that information into an ideal throttle position. GM says the torque-based engine control strategy is superior to early electronically controlled throttle-based engine-management systems that relied only on the throttle position sensor to govern throttle opening.

In terms of detail refinements, Jacques says the target was to be class leading. “We went after all the benchmarks,” he says. “You name it — if there is a good V-6 out there, we found out how and why it was good.”

Refinement measures include specially isolated cam covers, which incorporate an isolated gasket around the cover perimeter and radial lip seals at the tubes through which each spark plug is inserted. These components decouple the cam cover from vibration created by the combustion process.

The structural aluminum oil pan is attached by a full-circle mounting that enhances bending stiffness. Specially contrived curves on the major panel surfaces and the sidewalls mitigate ‘drumming’ from the oil pan.

The engine front cover has internal damping plates that quell vibrations caused by the engine. The steel plates, made in two different thicknesses ‘tune’ at differing frequency from the aluminum front cover; the frequency separation dampens noise output.

While several rival Japanese V-6 engines use belt cam drives, GM Powertrain chose chain drives for the new engine family. “We went with chains for longer life,” says Jacques. “The Japanese engines have used belts because they are less expensive and quieter, but they are also moving to chains now.” In the case of GM’s new V-6, Jacques says the noise of the camshaft drive chain engaging the sprocket teeth is reduced by use of molded-rubber ‘cushion rings’ on the crankshaft sprocket.

GM plans to assemble its new V-6 engine family for all global applications at plants in St. Catharines, Ontario, Canada and Port Melbourne, Victoria, Australia.

Beyond the Cadillac CTS, initial North American market applications for the 3.6L V- 6 include Cadillac’s forthcoming mid-sized Rendezvous. -
From - with more there - la3/15894-2004-cts-3-6l-vvt-engine.html

Original source and author @ Automotive Industries | May 1, 2003 | McCormick, John | magazine @

eh, a way to it @

15,633 Posts
Im comparing 2011 ram hemi vs my 2011 silverado max FE. I dont believe the 8spd will help FE on highway much unless the tranny has way less parasitic loss then now because the final ratio is the same in the 8-6spd. The thing that will help is the aerodynamics and if you order the 1500 dollar air ride that lowers the truck at cruising speed. Thats just my opinion though
The 8HP is a PT 'engineer's' dream.... in all ways possible.

And yes, it uses less power internally...... although by what amount varies considerably as you cycle each one through a regime. The net is a hugely favorable number.

There is much more to how a an 8HP contributes to a better 'highway' number although there is always the question of what the OEM wants do with it.

That may be true against a l92 with 6l80 but then here comes the genV 6.2 with about 60 ftlbs more compared to the l92 at 2000rpm and a truck that is way lighter at the same time ram comes with the 8spd so that will make the difference in the 2 more gears down low.
The choking time comes..... after the 8HP comes out ..... with an updated Hemi.

- and perhaps........... some other things.

An 8spd is basically just a crutch for no low end tq. Then wait gm throws in an 8spd later alone with alot of low end tq then we have our selves a stump puller :yup:
An 8sp CAT outside an 8HP is either an expensive but useful improvement - but of a lesser sort than an 8HP - or a gimmick with a dose of 'we don't want to buy from ZF thrown in'.

You really should not run them all together like that.

Unlike any other , the 8HP has what it takes to stand up to all other 'rwd' offerings - whether with 6,7, 8, '9' or '10' and regardless of type ie CVT, DCT, CAT, etc etc


One of the ( really ) 'cool' things 'imo' concerning the LT1 announcement is the inclusion of an ( intake air ) active relative humidity sensor - for more reasons than one.

Hope this makes into all the 'trucks'.

Not sure anyone else here likes to shall we say.... 'play with water' including steam injection but on the face of it...... hey, they got a sensor in play now......

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What makes the 8hp so much better then an ordinary 8spd?

In regards to the 'first' A - AW / 'A' ....'TL'xxxxx and Hyundai's whatever they call it + an approximation for the HD A - AW / 'A' 'TR'xxxxx.

Over simplified......... the first two appear to be technically speaking, modified 6sp ATs and the TR still has at least a really big piece of that in it.

ZF on the otherhand, started with a strong Management commitment, a design staff, a highly motivated and 'helpful' ? 'first' customer ( BMW ), a big or big enough budget - and timeframe, some seriously kickass 'design' process software ( at the time ) and ....... a clean sheet.

They do say they evaluated thousands of configurations.........

Hyundai and 'Aisin' / Toyota were motivated to have 8 gears quite arbitrarily - so they could 'attempt' to lord over MB's 7G on gear count marketing wise.Or perhaps better said, that was what happened with Aisin / Toyota, and then in part because of that, Hyundai wanted to at least match Lexus while pulling out in front of MB on gear count.

Which unit btw, they miscalculated in terms of it's ZF inspired improvement program.

The second gen 7G is 'better' to have than either of those two - although down 1 gear for marketing purposes. It may be - key phrase " may be " a different story with regard to the TRxxxxx in it's HD torque range and or in certain kinds of vehicles.


So..... the first 8 speed from A - AW for Toyota / Lexus ie the A -AW or 'A' TL80SN comes as a modified 6 sp - still using a Lepelletier gear train concept ( common on almost all 6 sp CATs ) ie a single basic planetary gear set connected to a now augmented Ravigneaux gear set but with a slight twist. And that is the terrible mistake of using a double planetary gearset in first position. The TR series corrects this error although that does not make it all right - just better than the failed TL series.

Which Ravigneaux assembly is as always, in this 'L' gear train concept - 'R' gear set - composed of two interconnected planetary gear sets via shared planet gears. So, a total of three planetary gear sets ie one double planetary connected to a paired Ravigneaux set.

What they did was to - the other thing was to - within one of the planetary sets in the Ravigneaux 'section' - was to pair up the existing shared planet gears - with an additional 'brother' - not shared.( And then fiddle with the control elements. )

Total gear spread is about 6.709x vs approximately 7.04x for the ZF 8HP.

I cannot remember the details of the second 8 speed under discussion ie from Hyundai although we have had big parts of it posted previously.

Since GM is not potentially buying 'that one', it will suffice to say that although it does vary from the TL80SN and also the details of how it falls short from the 8H P........ it does not matter.

Basically, it ends up the same sort of difference with a little plus and minus variation here and there.

Then we come to # 4 ( 8HP IS #3 ).

Which is the one of most interest in terms of the topic - or so we can hope.

That would be the second A - AW / 'A' unit aka the TR80SD - and formally in words as the " High Torque Capacity Rwd 8 Speed Automatic Transmission ".

As suggested previously, this one is both an improved derivative of - and also separately a higher torque capacity unit derived from the earlier TL80SN ( aka @ Toyota / Lexus as the 'AA80E'. )

Also per previous , it's also appears to be 'better' than the Hyundai unit - in it's original form...... so this is the one to find out about.

It is in essence a redo with a significantly different gear train and function.

VAG..... may have helped....



ZF started with the number of gears as a variable to be solved for.

Could've been, one supposes based on the way they speak about it....... 'somewhere' between '1' - 10 +.

So....... ZF ends up with.........

1. ) A wider gear spread, better apportioned.

2. ) Critically, a better type of gear train composed of one relatively simple Simpson gearset with it's two planetary elements, and then the mind blowing aspect ie two simple planetary gearsets ( thought to be obsolete at this point ) for a total of four planetary sets -

Then mind blower #3 - controlled by only five shift elements of which only two are open in any given gear. The thing of it is...... it is that combination + the specifics within that combination that are so different and so powerful - and so efficient.

In otherwords, the type of gear train, the arrangement of that gear train, and then how you use it - and control it - which is all very much - completely interdependent is different - and better - all around for everything or every consideration.

There is also with the HP8 some super clever eh, benefits from the exact details of the shift element designs........

It is a more balanced box in all ways possible and this plus all the other means it ends up, lighter, cheaper, stronger, more efficient, faster, and more adaptable.

And that is not the whole list.

Torque converter - pump etc ie all of it and again with even an extra dose because of the synergistic effects.

In comparison.......

The twenty / twenty plus year old WA580 / 5G that was at intro the cat's meow - gets 5 ( forward ) gears out out of 3 planetary sets - arranged as a less efficient Simpson plus a simple - which is pretty good except ..... it has 8 control elements of which 3 or 4 are always open - which means among other things more mass / dynamic 'spinning mass' / more fluid volume / pressure requirements / fluid drag ......although second gear may just be 2 - I always screw that one up for some reason.

The A -AW 'A' TL has 3 planetary sets but of of a more expensive yet less efficient/ higher friction type - with a lower gear spread less ideally split that requires 7 shift elements to control and eh, I cannot remember but does run with 3 or 4 open often....... maybe 2 or 5 once or both or something like that.

3. ) A bunch of other from the specifics of the torque converter to the mechtronics to the hydraulic pump etc etc etc. Much of these parts can be duplicated elsewhere to at least some extent - eventually. For example many have already incorporated much of the torque converter improvements although again because of other differences ( gear train / gear splits ) they cannot do that as strongly.

4. And then the other biggy. The integration factor ie all of this decided pretty much simultaneously. So..... a unique amalgamation of many 'common or somewhat common elements - resulting in an extra dollop of synergy.

Think - like - a block of stone representing all possible AT design space.

Then think of Michelangelo's 'David' - that kinda' catches the essence of it.

So if we crudely sum up just the most important main parts of it, it uses less power to run itself, reacts quicker and with a higher quality, has a better geartrain in all ways possible - with a wider and better apportioned set of gear splits, weighs less, and cost's considerably less - and pound for pound can handle more torque while also generating less heat.

One has to wonder.... if GM is still sore about the ZF second gen 6HP / BMW.......dirty play...... which kinda' helped fund the somewhat simultaneous 8HP development program.......

Any idea what the new improved hemi will be and when it arrives
No, not really....... I've my list like everyone else but .....

I expect them for certain to bring 'more active tech' to it than GM is going to for the LT1.

You will notice that GM is kinda' strongly in the mode of doing as little as possible for the conventional stuff ala the last DM update - and the LT1.

Great - even superlative results for sure but ...... there was more to be had if the teams hadn't of been so constrained ( and yes, they should have their own flavor of something special in the pipeline - that flows like sludge on a really cold day - ) Others...... like Chrysler are not going to let that mid game space go by like GM is - to shift resources to the electrification efforts.

I hope it is clear that I am complaining as one who wishes and wants them to do well - and not as a 'nother brand spin doc.

Finally worth remembering, the 8HP program is so good, so strong that ZF is going to drop the world's best rwd 6speed CAT in or around mid 2014........Which, besides being quite quick - and therefore early, is mostly about their 8HP production capacity - and perhaps their customer's timing - it is not about technical merit in any aspect - or cost.

Notice also - although coming much much later than the all other 8sp CATs, the 8HP is fully dominating the volume space - which will increase even more as each day goes by. As far as speed of rollout, it's a bit like a man leading a small donkey all loaded up who had a big head start - vs an F14 for coast to coast travel.

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Well, we can feel better in some aspects and worse in others about this potential GM purchase.

'Toyota Motor Corporation' ie the big enchilada, does in fact net ( much ? ) more than a 50 % ownership interest in the Aisin business unit that makes this box.


Technically speaking, this transmission the TR80SD while still short of the 8HP especially when cost, simplicity, weight etc etc is considered - does come a useable amount closer in terms of certain functional aspects - while trading just a bit in other.

Simply put, A -AW has been feverishly fiddling with this unit in addition to tryin' to catch up @ inception.

Interestingly enough, although employing the same basic gear train / gear train concept or system as the TL, they have widened the gear spread considerably - past in fact, the 8HP. < No, that is wrong - it is a redo with a significantly different geartrain although somewhat similar. >

No, that will not overcome all the other, and no, it will not beat much less fully match, but it will really help make up some of it - especially for highway mpg rating and use. In light of what A - AW says about it along with ZF's info and proven record, if one had to guess - should end up providing somewhere between eh........ 30 - 60 % of the total 8HP FE improvement.

Currently seems to be several splits and spreads available somewhere between about 7.12x , 7.17, 7.20/ 7.20x.

15,633 Posts

I agree, larger displacement and more low end tq will allow for more time in v4 mode. Prolly why
The hybrid has the 6.0l and not the 5.3.

Frontal area is the big reason for lower highway fuel economy in full size trucks.

Couple of years ago I drove our '04 Tahoe with 3.42 gears and '07 20"rims 237 miles from Hendersonville, nc to charleston, sc. I got 21.0 mpg. Never drove faster than 68 mph, never let it kick out of 4th, never used cruise, and lost speed uphill.

Did the same trip a few weeks ago, drove 80, kicked it down, passed on the right, my normal thing.
Sure, but that's not the only way to do it.

Nor must AFM be restricted to just 4/8 operation.

I believe the LT1 and intro conversation has thrown people off a bit.

Simply put, it is for the Corvette..... and for a specific period of time.

In other words, another type of combustion system is coming not all that far out.

For that one.... and perhaps milder LT timeline cousins.... more VVT and or some VVL(D) can / could allow a smaller relative displacement to use AFM more aggressively.

No matter how it all ends up in terms of the details, apparently GM is going take two steps fairly fast and fairly close together with the sb.


If you read between the lines of the LT1 announcement just a little bit..... you can also develop the sense that the LS / gen 3 / gen 4 s needed some other improvements of the indirect sort in order to use AFM more aggressively - just as they are and furthermore...... that's somewhat the ( lesser ) case possibly for the LT1 - which very likely will be addressed - later.

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You keep saying "LT5". The 2014 Corvette engine is the LT1.

Yes indeed.

Thank you for pointing that out - it is corrected now in the one post at least.

For those of us who can't/don't read between the lines, could you be more specific? Thanks!

Dr. Show-Me, we kinda' did all that somewhere previous in one or two of these LT1 threads.

Take a look at the details in all the presser material...... 'think' about NVH and...... some things..... 'related'.

Especially if one is in an AFM mode .... with more load.

Look at how it's more robustly and precisely put together..... and less..... how to say 'asymmetric' in a sense.

Now add up all the little things here and there ..... and yes, there are other purposes being met as well -

If that doesn't work out, then consider...... why exactly has Chrysler to date been able to engage and hold MDS longer and more often. Careful , you kinda' have to sort out why they also would want to as say - more of a necessity rather than a nice to have.

Perhaps later, maybe closer or @ launch, GM will go into more detail about the 'new' AFM capabilities and how they see it will come out more.

Like so much involved with even 'just the LT1, this feature is going to require some different thinking on the part of the community - in a good way I might add.

Specifically as an example, nobody with even a wisp of common sense will be disabling AFM on the street.

That was dumb further back anyway - it's what you do when you really do not have a handle on the better ways to solve things.

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Basically there are some inherent harmonic disturbances, and weaknesses that the previous GEN IV engine had that in many ways limited the AFM activation envelope in the interest of NVH among other things.

Chrysler's MDS system allows more NVH to enter the interior of the vehicle but it's activation envelope is far greater than GM's AFM system at this current time because of improvements made in these areas in many ways.

If you truly look into the relatively thirsty, and dirty combustion chamber design of the HEMI it also shows that it's greater MDS activation envelope has a notable affect on fuel economy. < Hmmmmm yeah 'ok'...... sorta'..... but...... >

I believe that America123 is alluding to the fact that they for all intents and purposes have barely scratched the service of what active fuel management is capable of, and in many ways they simplified it because of inherent GEN IV issues.

. In fact my Escalade does not even have AFM, and they only recently started to offer AFM on the L92 utilized in the Escalade. < Yes indeed, there is also the aspect of what displacements - and installations got AFM.... when >

One would have to really peruse the LT1 data as America 123 and I have to read between the lines, and see exactly what we are referring to.

In many ways the changes that were made had other reasons aside from those relating to power.

This Gen V V8 in it's initial format will offer only a slight increase in < HP with a large torque increase - which also 'needed' some of the seemingly more generic improvements to be workable > power but significant increases in fuel economy in my opinion.

Basically the Gen V V8 had very necessary changes made to it that were needed circa Gen III V8 many of which were not related directly to power, and basically when they say new combustion system we are truly looking at a combustion system that is the only one of it's kind.

In essence they have been robbing Peter to pay Paul, and not only do Peter and Paul need payment but the whole manner in which they are paid needs to be changed.
Yep, pretty much most of it and pretty well said. :yup::yup::yup:

And I know you will understand what I say next and not take it the wrong way.....

Now you very likely have the basis for ..... a fully and truly world class xyz - good enough for Cadillac installation in the best sense of those terms - btw. ;):):D

People are worried about the new 5.3L being 'only' 350hp, but DI is really only supposed to boost power about 1/8th. So 315hp x .125 = 40hp. This puts it right at 355.

America123, I'm guessing the 'stage two' will be sparkless ignition? I would think that would work better with big inch, low rpm engines that aren't running up and down the rev range all the time. That would be something. You'd think it would be perfect for series hybrids where the engine runs at one rpm or a very narrow rpm range.

But in the near term, just a 24mpg, 350hp Silvy seems like a big deal. I think despite all the kvetching we did about Eco-Boast that Silvy will be retaining that 'least expensive to own' laurel with better across the board economy.

I think the trick from the bean counter viewpoint will be that they will be selling less expensive-to-make Silvys that match Ford's DOHC V6 against a DI OHV V6, and an OHV V8 against a turbo DOHC V6.

WRT to the HEMI, I get 20mpg hwy evert time in mine - but with the AFM kicking in and holding for long periods even at 65mph. Chevy 5.3 gets that kind of mileage with the AFM only kicking in downhill. With a more 'aggressive' AFM that can go down to 2 cyls < I think ? you mean lose two and down to six ? >and/or have 'rolling' deactivation that might decrease the vibration factor - and factor in the 500lb weight loss - I think we may be seeing the "V8 power V6 economy" ads. 18mpg city would match the '13 V6 8spd Dodge.
Lot to this post.

Well worth discussion....

I'm short, so just a few things for now - but you are definitely on some of the right tracks available - which under the right circumstances, still does not preclude smaller displacements in certain smaller and lighter applications........ if you will.

Yes, the later type is all about providing - if you allow some latitude in the terms - all about getting to an HCCI....... or........ a related type combustion mode or better said, - getting in and out of something like that - it's the transitions and transients that are the really hard part for all that.

So yes, perhaps more ....... and definitely more and different modes of combustion and therefore - yet again a different combustion system.

'Imo' this LT1 and it's likely brethren address all the inherent deficiencies or limitations in all the previous sbs - that not only are 'desirable' for other reasons both generic and specific - including creation of the LT1 pkg itself but are also required for that second combustion system.

Just look at how they handle the basic wet sump oiling system and related air /oil separation - pcv.

On the one hand, gee, a gen 3 or 4 etc could have really benefited from that in practical real world terms.... - big useful margin for real world ****ty oil and fueling effects as they specifically express in these - and including when all ****ed up by that and then also in AFM mode.

However, is all of that really required for all of the LT1s - or more to the point - for a LT1 truck derivative ?

Maybe.... maybe not...... or maybe........ not so much.

What is absolutely clear - is you do need it for HCCI and related.

And lets be clear you need it to be real strong and real good - so why not run it out there 'early' and make sure of it... besides, it can only also 'be good' for the LT1 etc.

So again, multiple ( possible ) and possibly shifting in sense purposes or reasons for a feature - with regard to past, soon to be present, and ..... future.

The LT1 and it's compatriots are apparently ...or perhaps...... the bridge...... somewhat like aspects of some of the Gen 2s were. That's a very imperfect analogy but has an element that's useful .

Geermezy1 does point out something real relevant - much of this other improvement is 'catch up'. Beyond belief - if you want to get real hard nosed about it.


You can kinda' put it all together from one point of view ie 'catch up' that now has sufficient value - according to 'Mgt'.

You know, some of the same bozos who put it off for a really long time..... to chase the Prius - a task not worth doing.

I wouldn't - but some would and by golly, they most certainly did.

Oh well......

Five to ten years late is still better than -

The important thing is - now it's done.:yup:

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The LT1 will have an AFM system with a wider activation envelope, and will also have significant fuel economy as well as power curve improvement.

It however will still be just scratching the surface of what AFM, and the new combustion system are capable of.

Also keeping in mind that the LT1 is capable of at least 13.0 to 13.5 to 1 SCR which in and of itself would improve BSFC, and torque but GM does not need to utilize all of the capability now especially with a lighter Silverado as well as Corvette.
Germeezy1, I'm not sure where you're getting that from.

The expectation is that AFM will be ' real large ' / ' real effective' on the LT1 and related and it is beyond premature to suggest anything for what comes after...... either way.

It's most likely one of the main - if not the main driver as to why the LT1 shares nothing but a handful of token parts with any of the previous.

I'm wondering if the 'next thing' for AFM is closer to the original Cadillac 8-6-4 - or at least the concept that the typical V8 engine has so much 'excess' displacement that it's not a matter of sometimes shutting down 4cyls but only activating all 8cyls more like 'turbo' style when you put your foot to the wood.

In other words, you'd have a 'high cylinder pressure' 6cyl for like the first half of throttle travel. Just like the current MDS or AFM, lighter weight vehicles would benefit most, but it would be more like you only have the full V8 when you have like the 'carb secondaries' kicking in in the olden days.
:yup::yup: - Exactly.

In addition.....

Honda's made a 6-4-3 work.... and although it's another 50 % er, VW's coming shortly with a 4 -2.

If you can take a compromised to begin with I4..... and run it as a '2' then anything less than 8 - 6 - 4 that does not have a 'big' VVT capability at the very least......... is just excuses..... for a mere pittance of lower initial cost

And then the individual PCV and oiling - as perhaps a 'rolling' AFM would be able to better hold up under the the strains of being a 'high pressure' V4 or V6 *most of the time* rather than the current idea of it being a 4cyl with high pressure only when loafing and a regular low cyl pressure v-8 most of the time because of limits in the current design which count on the engin not being pushed to its limits most of the time.
:yup: - along those lines.

15,633 Posts
Interesting -

By MarketWatch

PARIS--General Motors Co. GM +2.48% is in advanced negotiations to sell its French transmission operation in Strasbourg, the company said Friday, as it works to cut costs in its troubled European operations.

Belgium's Punch Metals International and Germany's ZF Friedrichshafen AG, a major car-transmission company, are involved in advanced talks that could lead to a sale, a GM spokesman said.

As part of the potential deal, Punch would buy the site and would enter a long-term deal with GM and ZF to make 8-speed transmissions, a spokeswoman for the plant added, saying that the sale terms would safeguard the roughly 1,000 jobs at the factory.

15,633 Posts
No, that's not it -

For now until we know better, just figure a much stronger, wider ranging - and better feeling 4 /8 operation - which will really be a large and useful improvement.

And really a decent possibility of 6 -3 for at least one of the V6s (ohv) that have been mentioned.

Then, a possible for 8 -6 -4 ..... more for things outside the Corvette at least to start.


Related..... we need to see if the 5.3 is a 5.3......which seems most likely but then again a 5.5 is not a complete no go....and would possibly - key word 'possibly' be of interest in a different way than a 5.3

2 'out' of a 6 or 8...... assuming of some kind of legitimate interest and basic feasibility - a humongous question in and of itself - would require stuff outside this discussion and anything we have heard.

Let's just arbitrarily call that a "special support / 2 cylinder mode" - which even if it got thru the above, might then get squeezed by a combination of start stop + the same sort of thing for a special support / 3 cylinder .... or 4 cylinder mode.

If you can vary the range of 'efficient' 4 out of 8 cylinder operation by other means - probably get a better result than by tryin' to go to 2.

As a simple example, imagine a 'special' eAssist mode for 4 out of 8 running.

15,633 Posts
We need somebody to clip and post the comparison charts @ the end of the GM pressers the little darlin' can't read.
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