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Two new powerful V8s on GM's NG C3XX pickups


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Gen V 6.2l DOHC V8 to Power C3XX Fullsize Pickups
Second United Auto Workers Agreement Reveals General Motors' Potential Future Truck Plans
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By: Mike Levine Posted: 10-01-07 12:30 PT | Link to Original Article @ PickupTruck.com


A document found online (using Google) at the Future of the Union website suggests that General Motors is preparing to substantially overhaul the engine lineup used in its next generation full size trucks.

Future of the Union has published an internal memorandum of understanding that contains detailed information about contract negotiations that took place in June 2007 among the United Auto Worker (UAW) union, General Motors (GM), and GM’s largest supplier, Delphi.

The document contains GM’s future product commitments to UAW-represented employees at Delphi, similar to the future product timelines that emerged from the recent strike settlement contract between GM and the UAW.

Most notable are the powertrain components that Delphi is expected to supply for use in the C3XX truck program, starting in 2011. The C3XX platform will replace the current GMT 900 architecture that underpins the Chevrolet Silverado and GMC Sierra full size pickups.

According to the document, C3XX pickups will feature a new 'Gen V' 6.2-liter dual overhead cam (DOHC) V8 engine - a major departure from GM's traditional overhead valve (OHV) pushrod engine design used in its trucks, like the ‘Gen IV’ 403-horsepower / 417 lb-feet L92 6.2-liter V8 under the hood of the GMC Sierra Denali. The only DOHC V8 GM currently offers is Cadillac’s 320-hp / 310 lb-ft 4.6-liter Northstar engine.

The Gen V 6.2 motor will use variable valve timing (VVT) like the Gen IV 6.2, but the use of dual overhead cams holds the promise of four valves per cylinder instead of the current two valves, for better intake and exhaust flow and increased power. This is a similar setup to the 5.7-liter i-Force V8 used in the Toyota Tundra, but the Gen V 6.2 will also offer GM's active fuel management (AFM) system. AFM shuts down half the cylinders during steady state running for improved fuel economy – a feature not currently available for the i-Force. Up until this point, it’s been conventional wisdom that implementing cylinder deactivation on OHC engines is impractical for reasons of cost and complexity.

Pushrod engines won’t be disappearing entirely from GM’s truck line. A new ‘Gen V’ OHV V8 will replace the current 320-hp / 340 lb-feet 5.3-liter V8. Apparently the final displacement hasn’t been determined yet, because it’s referred to as 5X.

The new 5X gasoline engine will feature spark ignition direct injection (SIDI), like a diesel. SIDI places the fuel injector right inside the combustion chamber, so fuel can be directly mixed with air entering the chamber during the intake stroke instead of before it enters the chamber, like in a conventional multi-port fuel injected gas engine. This approach enables a leaner burn of the fuel at higher compression ratios than current gas engines, resulting in greater fuel economy, cleaner emissions, and more power.

Initial production of both engines is slated to start in 2011 with full production in 2012.

Of course, it's possible that because this information is still approximately three years out in time, plans detailed in this document for the full size truck powertrains could still change.

Contacted for comment, a GM spokesperson told PickupTruck.com that GM doesn't make statements about documents like this.

There was no phone number or names listed to contact the Future of the Union website for comment.
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The only DOHC V8 GM currently offers is Cadillac’s 320-hp / 310 lb-ft 4.6-liter Northstar engine.

And the 275hp and 293hp Northstars in the DTS which are substantially different from the 320hp Northstar.

Up until this point, it’s been conventional wisdom that implementing cylinder deactivation on OHC engines is impractical for reasons of cost and complexity.

Except that Honda already does it with some of their OHC engines.

5X gasoline engine will feature spark ignition direct injection (SIDI), like a diesel.

uh, no. SIDI is NOT like a diesel. Diesel is compression ignition... Spark ignition, by definition is not Compression ignition. HCCI is like a diesel, there is no spark plug but it runs on gasoline.... but yes GM is working on that also.

SIDI is already available on the 2008 CTS and some of GM's Ecotechs.

Edited by Oldsmoboi
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Hey Griffon,

What one of Oldsmobois comments do you have trouble with?

A Spark Ignition engine is not like a Diesel, a Diesel doesn't have spark ignition. Is the direct injection aspect common rail? That would be the only similarity I could think of.

Honda has had OHC with cylinder deactivation for four years now on the Pilot, oddysey and now Accord.

Are the DTS northstar engines not overhead cam? Wait... yes they are.

Congrats to GM for obviously working very hard on their near-future engines.

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Will this new 6.2L DOHC 4VPC V8 be like the PREMIUM OHV 6.2L V8 used by CADILLAC/GMC now? That would be my guess that the DENALI GMC's and CADILLAC models will use this engine. Maby GMC should have a entire line of 4VPC DOHC V8's to better split it from OHV CHEVROLET's witch by then may be useing 3VPC OHV TECH! Let CHEVROLET/PONTIAC use OHV V8's and CADILLAC/BUICK/GMC use DOHC ones while CORVETTE becomes its own BRAND useing the BEST HIGH PERFORMANCE versions of BOTH!!

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OHV CHEVROLET's witch by then may be useing 3VPC OHV TECH!

that'd be nice. +1 for more power and lower emission tech.

this is the stuff i wish would have gone M.E. for in college....anyway.

could this 6.2L be loosely based on the ~4.5L diesel coming out for the trucks/H2? (no comments about it not being diesel and a bigger displacement ok)

i bet the 5X will be about a 5.5L making ~400hp and similar mileage to what it has now(givin it's not a hybrid)

well.. it's exciting anyway.

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DOHC is good news, the more DOHC engines the better. 6.2 liters is rather big though, that could use up a lot of gas. It seems like the only way GM knows how to make power is increase engine size, the Corvette was 5.7 liter 4 years ago, then 6.0, now 6.2, 7.0 in the ZO6. At some point they need real technological breakthroughs, hopefully more direct injection and these gas engines that act like diesel are it. I'm curious to see what they do with the Ultra V8.

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DOHC is good news, the more DOHC engines the better. 6.2 liters is rather big though, that could use up a lot of gas. It seems like the only way GM knows how to make power is increase engine size, the Corvette was 5.7 liter 4 years ago, then 6.0, now 6.2, 7.0 in the ZO6. At some point they need real technological breakthroughs, hopefully more direct injection and these gas engines that act like diesel are it. I'm curious to see what they do with the Ultra V8.

Uh... yeah. But it's pretty common knowledge that ANYONE who wants more power increases engine size...

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DOHC is good news, the more DOHC engines the better. 6.2 liters is rather big though, that could use up a lot of gas. It seems like the only way GM knows how to make power is increase engine size, the Corvette was 5.7 liter 4 years ago, then 6.0, now 6.2, 7.0 in the ZO6. At some point they need real technological breakthroughs, hopefully more direct injection and these gas engines that act like diesel are it. I'm curious to see what they do with the Ultra V8.

Not just GM look at the Lexus ES model. It started with a 2.5L V6 in the ES250. Then it got a 3.0L V6 in the ES300 and now it has a 3.5L V6 in the ES350. Nissan used a 3.0L V6 in the Maxima and nothing but a 2.4L I4 in the Altima but now it uses a 3.5L V6 in both of those models. Honda with its accord use to use I4 only power till they offered a V6 of 3.0L's. Now with the new one they use a 3.5L V6 as the opt engine!--It seems like the ASIANS only know how to make power by increasing engine size, to me!! :rolleyes:
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DOHC is good news, the more DOHC engines the better. 6.2 liters is rather big though, that could use up a lot of gas. It seems like the only way GM knows how to make power is increase engine size, the Corvette was 5.7 liter 4 years ago, then 6.0, now 6.2, 7.0 in the ZO6. At some point they need real technological breakthroughs, hopefully more direct injection and these gas engines that act like diesel are it. I'm curious to see what they do with the Ultra V8.

There's no replacement for displacement.

Who'd want to drive an Avalanche with a 2.2 litre turbo?

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quite possibly the only way to go down in displacement and make power is to at 2 more pistons and then decrease the size... but who wants a truck that sounds like and indy car? oh you could go diesel as the other choice... not everyone needs those unless you carry your stuff to work on a goose neck.

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I don't even know what to think. For a long time now, I have been criticizing GM for not having enough DOHC engines but I was focused on their car and small vehicle lines. I have always thought that the LS based pushrods have been great engines and do a great job in the full size trucks. They are simple, powerful, and efficient.

I can't even imagine how they are going to fit a 6.2 DOHC AFM engine in the engine bays of the next gen trucks. The typical argument that comes up when talking about DOHC and OHV is the massive physical size of DOHC engines. The perfect example is the 6.0L LS2 fitting in the CTS engine bay but not the 4.6 Northstar.

I guess I just don't see the need to spend so much time and money developing such a ridiculously complex engine when it's not needed. If it ain't broke, don't fix it. GM has so many great pushrod V8s right now that have tons of potential. They already have two pushrod V8s in that ~400hp territory. Why reinvent it rather than improve it? They already know how to implement AFM for a OHV engine. Would it be that hard to engineer Direct Injection into the OHV engines that it would be better to just design an entirely new DOHC engine? I don't see it.

Edited by bcs296
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Uh... yeah. But it's pretty common knowledge that ANYONE who wants more power increases engine size...

You don't have to, you can keep it the same and make more, or be like BMW and go from a 360 hp 4.8 liter V8 to a 410+ hp 4.4 liter V8 like they are about to do for the 555i. They are going smaller with better fuel economy and adding 50 horsepower. Honda's 3.5 liter V6 used to make 215 hp, they are at 244 hp now.

Going from pushrod to DOHC should allow a huge gain, look at the 3.8 liter in the Lucerne making 197 hp and the smaller 3.6 liter in the CTS making 304. 107 more hp from a smaller engine. Makes sense to do everything DI and DOHC. Never hurts to add a turbo if needed.

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I think a 5.5 liter DOHC with a lot of technology in it would make far more power than a pushrod 6.2 liter. They could reduce to 5.5, which is still big, and have the power they need.

Switching to DOHC is a good idea, because people are going to demand it in trucks, just like they do with cars. The Tundra has a DOHC V8 with 380 hp, everyone else is going to have to do a similar engine. Just like the Camry and Accord's DOHC V6s made all the pushrod American sedans almost no factor, the Tundra is going to promote DOHC in trucks, and the F150 has OHC too, so GM might as well jump on board.

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I think a 5.5 liter DOHC with a lot of technology in it would make far more power than a pushrod 6.2 liter. They could reduce to 5.5, which is still big, and have the power they need.

Switching to DOHC is a good idea, because people are going to demand it in trucks, just like they do with cars. The Tundra has a DOHC V8 with 380 hp, everyone else is going to have to do a similar engine. Just like the Camry and Accord's DOHC V6s made all the pushrod American sedans almost no factor, the Tundra is going to promote DOHC in trucks, and the F150 has OHC too, so GM might as well jump on board.

Why then, do GM trucks consistently outsell the competition?

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if i aint mistaken... didnt nissan beat toyota to the dohc scene with the v8 titan? i really dont think the yota 5.7 is a good role model what with the whole cam self destruct option. even if it wasnt the manufatures fault that calamity still is their responsibility. i havent seen anyone around here towing anything with a camry or an accord but i am not about to put it past some dummy out there. after all i saw a vette towing a pontoon once... oh wait that was a push rod v8 doing that though.

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I think a 5.5 liter DOHC with a lot of technology in it would make far more power than a pushrod 6.2 liter.

Why not have a block with displacements between 5.0 and 6.2, with the extra tech and smaller displacement going into Cadillac cars, and the larger displacement engine going into the premium trucks, for the 'macho-my-engine's-bigger-than-yours' crowd? Edited by ZL-1
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I think a 5.5 liter DOHC with a lot of technology in it would make far more power than a pushrod 6.2 liter. They could reduce to 5.5, which is still big, and have the power they need.

Switching to DOHC is a good idea, because people are going to demand it in trucks, just like they do with cars. The Tundra has a DOHC V8 with 380 hp, everyone else is going to have to do a similar engine. Just like the Camry and Accord's DOHC V6s made all the pushrod American sedans almost no factor, the Tundra is going to promote DOHC in trucks, and the F150 has OHC too, so GM might as well jump on board.

It just seems like your tirade against Pushrods is only because you hate and the name not like the idea of saying "DOHC" better.

I remember when DOHC started coming ricers used to put huge 24-Valve DOHC decals on their 4-cylinder cars which showed how much depth they had in their knowledge of engines. May be GM should have put OHV on their trucks, so that people like you would have not hated it that much.

Let me say it again, other than the disadvantage of displacement to power ratio, there is nothing wrong with a OHV and with DI OHV will just be better. The LS7 is as technologically advanced as any other motors coming from M division, or AMG division. Tell me which 500-hp beats the gas guzzler tax. Even the MB 381-hp CLS550 comes with a gas guzzler tax, the last time I saw.

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I think a lot of people here are missing the point that these engines are designed against a MOVING TARGET.

Sure the OHV engines are debatably competitive now. They won't be in five years. Toyota will improve their 5.7 by the time this is released. When every other company has four valve per cylinder DOHC engines making more power per displacement with fewer emissions and better milage in 2015, pushrod engines will hamper sales. They probably are already, with those people who go to lowes once a week, which constitute a large segment of the truck buying market.

Some people don't like change, but this is a no brainer. The same arguments were made when fuel injection made it's way into trucks.

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I think a lot of people here are missing the point that these engines are designed against a MOVING TARGET.

Sure the OHV engines are debatably competitive now. They won't be in five years. Toyota will improve their 5.7 by the time this is released. When every other company has four valve per cylinder DOHC engines making more power per displacement with fewer emissions and better milage in 2015, pushrod engines will hamper sales. They probably are already, with those people who go to lowes once a week, which constitute a large segment of the truck buying market.

Some people don't like change, but this is a no brainer. The same arguments were made when fuel injection made it's way into trucks.

This is a good point. They have to do a DOHC engine for the Escalade and GMC trucks at least, offering it as a top end in Chevy is a good idea. They should still have a pushrod like the 5.3 liter for a mainstream engine for lower cost. A good diesel will give them a big advantage also. 6-speed automatic is needed most on the Silverado though. They can't hold back on what they put into the Silverado and expect buyers to keep buying from loyalty. They laughed at the Camry and Accord 20 years ago, now look at GM's midsize cars. They can't underestimate the Tundra, it will get better, they have to keep the Silverado ahead of it.

What will stop Toyota from using the Lexus V10 they are working on in the Tundra? They already use the Lexus LS V8 in it, and have the hybrid V8 planned. GM needs to plan ahead and have stuff ready to go, so they don't get caught behind the 8 ball.

Edited by smk4565
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^^^

That argument is a bynch of BS considering that pushrod powered v8s in GM products lead the truck and SUV segments in terms of milage over comparable DOHC engines. The displacment is irrellevant, what matters is

A- power produced

B- fuel eco.

C- reliability

The pushrods LEAD all current pickup DOHC v8s in fuel econemy, are fully competitive in terms of power and tend to be far more reliable and deffinetly easier to maintain and cheaper to fix because they are an inherently cheaper design.

How gives a sh!t about who has more better hp/displacment if the bigger just as powerful motor is both lighter and gets better fuel econemy.

End of argument, thanks and come again...

...That being said I have every confidence in GM powertrain and if they decided they want to build a range topping monster of a DOHC v8 I'm all for it, I'm sure it won't eat cam shafts.

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I think a lot of people here are missing the point that these engines are designed against a MOVING TARGET.

Sure the OHV engines are debatably competitive now. They won't be in five years. Toyota will improve their 5.7 by the time this is released. When every other company has four valve per cylinder DOHC engines making more power per displacement with fewer emissions and better milage in 2015, pushrod engines will hamper sales. They probably are already, with those people who go to lowes once a week, which constitute a large segment of the truck buying market.

Some people don't like change, but this is a no brainer. The same arguments were made when fuel injection made it's way into trucks.

Your missing the point. GM has been ahead with their V8s as long as I can remember. In 99, GM offered a 285 hp 5.3L. Whenever the Titan came out (04?), they finally made more power than GM, with 305 hp. GM already has the 6.2 in the Escalade, 403hp. How much power does a truck need? GM already gets the best gas mileage out of any full size truck. GM is already working on a diesel to fit in the 1/2 tons, which is more of an acheivement than Toyota offering 380hp. GM will be offering a 330hp hybrid truck with over 20mpg in the city. The target is moving, that target is GM.
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^^^

That argument is a bynch of BS considering that pushrod powered v8s in GM products lead the truck and SUV segments in terms of milage over comparable DOHC engines. The displacment is irrellevant, what matters is

A- power produced

B- fuel eco.

C- reliability

The pushrods LEAD all current pickup DOHC v8s in fuel econemy, are fully competitive in terms of power and tend to be far more reliable and deffinetly easier to maintain and cheaper to fix because they are an inherently cheaper design.

How gives a sh!t about who has more better hp/displacment if the bigger just as powerful motor is both lighter and gets better fuel econemy.

End of argument, thanks and come again...

...That being said I have every confidence in GM powertrain and if they decided they want to build a range topping monster of a DOHC v8 I'm all for it, I'm sure it won't eat cam shafts.

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The target is GM. Only on this forum! You have me in stitches!

Keep in mind Toyota has direct injection already developed for this engine line, but haven't implemented it on the 5.7 yet. It's a stroke of the pen away. They don't need it, they already have the horsepower and torque advantage. With the new mpg ratings, the two will probably be a wash.

This is the first generation of this engine. It will improve. GM's pushrod technology won't be good enough forever. They know it (obviously).

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The target is GM. Only on this forum! You have me in stitches!

Keep in mind Toyota has direct injection already developed for this engine line, but haven't implemented it on the 5.7 yet. It's a stroke of the pen away. They don't need it, they already have the horsepower and torque advantage. With the new mpg ratings, the two will probably be a wash.

This is the first generation of this engine. It will improve. GM's pushrod technology won't be good enough forever. They know it (obviously).

GM has plenty of V8s, that make big power, and get good gas mileage, and that's even before DI and the rest of the technology GM is working on. Toyota is merely catching up. Toyota has had their 5.7 out less than a year, and already you think they are the standard for trucks? GM has been on top for years and years. If the Toyota's are so great, why does it need to much cash on the hood to move compared the GM's trucks? Isn't the take rate for the 5.7 low compared to the 4.7? Maybe, just maybe, truck buyers care about more than drag racing. Edited by CaddyXLR-V
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The target is GM. Only on this forum! You have me in stitches!

Keep in mind Toyota has direct injection already developed for this engine line, but haven't implemented it on the 5.7 yet. It's a stroke of the pen away. They don't need it, they already have the horsepower and torque advantage. With the new mpg ratings, the two will probably be a wash.

This is the first generation of this engine. It will improve. GM's pushrod technology won't be good enough forever. They know it (obviously).

What's to keep GM from putting the 403hp 6.2 litre pushrod in other trucks? All it requires is a "stroke of the pen".

Toyota's top truck engine is 380hp. GM's is 403hp. GM is still the target.

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What's to keep GM from putting the 403hp 6.2 litre pushrod in other trucks? All it requires is a "stroke of the pen".

Toyota's top truck engine is 380hp. GM's is 403hp. GM is still the target.

And, why all this complaining, in a thread about GM's next gen engines, where power figures aren't even released?

Toyota will be chasing GM with their trucks, yet again.

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The target is GM. Only on this forum! You have me in stitches!

hehe well if you scroll up the header does say gms biggest fans... the majority are going to trumpet gm's success of course. but heres what i like about the whole thing Gm has 4 engines to choose from while yota only got 2. theres 4 choices between the 5.3 alone so 7 if you want to get technical. i dont see a need for the 4.3 but the 4.8 is standard except work trucks, 5.3 is general duty, then 6.0 for stump pulling. kinda limited when you go to the circle T ranch in my opinion.

hopefully the 5.x will be the 5.7 and will be a notch above whatever japan can throw at it. the 6.2 will be hands down but thats kinda being bullyish pitting them against each other.

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I've had conversations with 'truck' guys that think they need to have the latest technology and think DOHC engines are the latest greatest thing and therefore they need to buy a Toyota or Nissan. I've explained that GM's OHV engines are not 60's technology but they just don't get it. GM's protecting it's market share by developing engines that these kinds of people will think is market leadership.

Real pickup guys know pushrods can get the job done. I've seen lots of GM and Ford pushrod engines last for 300-400K. I've never seen a DOHC engine do this so I'm pretty interested in how the imports hold up especially in pickups that are working. I hope GM can keep the same formula for longevity in new DOHC's.

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AFM shuts down half the cylinders during steady state running for improved fuel economy – a feature not currently available for the i-Force. Up until this point, it’s been conventional wisdom that implementing cylinder deactivation on OHC engines is impractical for reasons of cost and complexity.

It took two gin and tonics before this hit me.

The Northstar has had cylinder deactivation since 1993... it just wasn't used for fuel saving purposes. For those of you playing at home, the Northstar is DOHC.

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I've had conversations with 'truck' guys that think they need to have the latest technology and think DOHC engines are the latest greatest thing and therefore they need to buy a Toyota or Nissan. I've explained that GM's OHV engines are not 60's technology but they just don't get it. GM's protecting it's market share by developing engines that these kinds of people will think is market leadership.

Real pickup guys know pushrods can get the job done. I've seen lots of GM and Ford pushrod engines last for 300-400K. I've never seen a DOHC engine do this so I'm pretty interested in how the imports hold up especially in pickups that are working. I hope GM can keep the same formula for longevity in new DOHC's.

well, you can allways tell them DOHC originated in ...what... the 1910's? and if the nailhead and similar can be called OHV , those came out in the 30's, right? so which one is "newer tech"...
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nothing wrong with gm working on a dohc truck motor to hedge their bets in case it become neccessary in trucks. 1- you put it in the escalade to amortize and pay for it, 2- look what happened when gm waited to long with dohc v6's.....

any dolt who thinks gm never should have developed ohc v6's have not drove a 3.6 nor read any new cts reviews.

in the end though, my guess is this is primarily emissions and fuel economy driven.

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