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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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You may want to read page 53 of said document. :AH-HA_wink:

The related presentation is also interesting reading.

Edited by thegriffon
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You may want to read page 53 of said document. :AH-HA_wink:

I'd love to... looks like the page has been taken down already.

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The PDF has, yes, but you don't have to read the pdf version. :AH-HA_wink:

If you still can't find page 53 the presentation(s) is on a different site and has even more info.

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The PDF has, yes, but you don't have to read the pdf version. :AH-HA_wink:

If you still can't find page 53 the presentation(s) is on a different site and has even more info.

It sure does!

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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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I was merely pointing out further interesting info on GM programs, if you know how to find the documents, in some format.

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Are 'canisters' stricitly a diesel thing or are they used in modern gasoline engines too?

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'Gen V' 6.2-liter dual overhead cam (DOHC) V8 engine

i just grew a tree with a tent over it.

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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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how great would it be for the 5.X to be a new 5.7 make it 10hp less than the yota but better on gas and about the same in torque. being outdone by someone with less is always good for pissin somebody off.

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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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6.2 liters is rather big though, that could use up a lot of gas.

:rotflmao:

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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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Are 'canisters' stricitly a diesel thing or are they used in modern gasoline engines too?

Well, whatever "canister" refers to, apparently they'll be on the Camaro, Impala, Lucerne and DTS.

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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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Last time I checked, GM's OHVs didn't regurgitate camshafts.

P.S. if you believe anyone besides once-a-month Lowe's guy will demand DOHC from a truck, you don't know truck customers.

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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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