Gotcha! 'Gen V' Engine Details... DOHC!

[LSxcellent]

Via several links eventually ending up at www.pickuptruck.com:

http://www.pickuptruck.com/html/news...eunionuaw.html

"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 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."




Um, this is unbelievable news if it is indeed true (which it looks like it is)... This means we might get a DOHC, 6.2L, V8 capable of big power AND good mpg! I have to breath, this is crazy...

~LSx

[Eisenhower]

If it makes it into the Camaro; that'll be a hot ride.

[acscamarochick06]

Good find!

[Mindz]

Which has more potential for power LS3 or that? I know which is better for mpg, but are the power potentials similar?

[Mr. Wyndham]

It seems that that Gen V engine thing I found a while back wasn't a one hit wonder...check this out, from the same post of mine a while back -- it sort of integrates both articles together...

Fortunately, timing is on the auto maker’s side. The recent introduction of the ’08 Corvette’s 430-hp LS3 V-8, along with the release later this year of the ’08 Chevrolet Tahoe Hybrid’s 6.0L V-8, represent the last editions of the Gen IV engine family, Stephens says.
All subsequent introductions will be of the Gen V architecture and could have DIG fueling integrated from the ground up, especially considering the refinement of the current test engine’s operation. The greater specific output provided by DIG also would allow for greater engine downsizing, thereby improving fuel economy even further.
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The new Camaro, which originally was shown at the 2005 North American International Auto Show in Detroit, is expected to appear later next year as an ’09 model, with the all-new RWD Impala taking form sometime early in the next decade. Revisions for future generations of the Corvette and Chevrolet Silverado/GMC Sierra pickups are expected in the same timeframe, Wolkonowicz says.

I never had anything against DOHC...just thought it was neat that GM managed to keep up with their pushrods, (sigh)...Hopefully, now we'll see some increased rpms, too!


EDIT: I skimmed that entire pdf...and there are numerous mentions to "zeta" and many if not all parts are going to be made HERE. There were multiple references to Gen V...but none that slated production to start before 2010-1/2. And nobody would happen to know what the GMT/GMX reference is to the Camaro, would they? cause there could be some useful deciferable info if we knew that....(groans) I'm gonna get stuffed in a suburban for this...

[TAG UR IT]

The Gen V 6.2 motor will use variable valve timing (VVT) like the Gen IV 6.2,

This is something that has me interested as well. If the 09 is offered w/ the LS3, I'm guessing that we can expect VVT???...according to the article, right?

And this is GREAT news! GM makes some, and pardon my language, BAD ASS engines. That is one area that has always impressed me. To think...that it's possible to walk up to your new 450hp Camaro and see the window sticker that says, "City = 25mpg : HWY = 38mpg"... (of couse this is me...dreaming...)


heck...why not make it 30/40!!!

[Power Junkie]

Originally Posted by TAG UR IT

To think...that it's possible to walk up to your new 450hp Camaro and see the window sticker that says, "City = 25mpg : HWY = 38mpg"... (of couse this is me...dreaming...)


heck...why not make it 30/40!!!

Why not... imo there's no reason why they can't make an engine efficient... we've seen diesels that have claimed (90mpg) and even big engined versions... One episode of Top Gear showed J.C going from London to Scotland and back on a single tank of fuel in a 4.0 Litre V8 Diesel... with 2 turbos i might add.... ok granted he was driving as efficiently as he could but still 800miles on one tank, Not Bad.

I don't think 35mpg is out of reach for a modern V8.. of course as soon as you mash the loud pedal.. that figures going to disappear faster than a bottle of whiskey at an alcoholics support group

[JeepinMatt]

OHC... Bleh. I want my pushrod engine.

[Mr. Wyndham]

Originally Posted by TAG UR IT

This is something that has me interested as well. If the 09 is offered w/ the LS3, I'm guessing that we can expect VVT???...according to the article, right?

Though it's possible...I'd be willing to bet that they were referring to the Gen IV L92...it, too is a 6.2, and it has VVT...my thinking is, if the LS3 is the last iteration of Gen IV...why improve it? Sorry if I squashed any dreams of yours, I really didn't mean to.:p

Okay...there is an interesting note here:

like I said before, nothing Gen V that's mentioned is slated for production before 2011...but there are numerous gen IV parts, i.e. Cyllinder deac., that will be continuing production well after the start of Gen V production...thought it was a worthy mention...


:eek:YAO! Okay, I'm typing as I'm reading, so excuse my outbursts...Sandusky? I'm not sure what that is, or where in regards to GM's plants, but it'll be making the Zeta front and rear (starting late 2008 -page 66), for GMX 511/521/551.
Saginaw steering will also be taking care of that aspect (at least columns, and half-shafts) for GMX511/521/551...also listed as starting production in late 2008.

I'm assuming that GMX551 is the G8....but, why group it with the Camaro? there's something fishy going on...

The 2008 thing, that's the biggest part. I mean, we've all heard the rumors, and official stuff. But this is an official document between GM, the UAW, and Delphi...sooooo


EDIT: ugh, I'm definitely going to be chased down suburban-style....

[JeepinMatt]

I just hope that the General doesn't abandon the OHV as a performance engine. Yeah, I know all the advantages and drawbacks of pushrods and OHC/DOHCs, but I still always liked the fact that GM was able to compete with their OHVs. It's sort of their calling card, or one of them.

[JeepinMatt]

Originally Posted by Dragoneye

EDIT: ugh, I'm definitely going to be chased down suburban-style....

OT but it got me thinking. If we were talking about Toyota, would you still be hauled off Suburban style?

[Mr. Wyndham]

Really! hmm, interesting. Because everything Camaro (511, 521) in that document is paired with the Impala....

If you don't mind me asking - how did you know that GMX511,521 was the Camaro? I hadn't seen it anywhere, ao I was just asking a question I never expected to be answered . I was extremely surprised when you responded!

[Mr. Wyndham]

You know...since this design isn't coming out full-production untill 2012...I don't know if I can wait that long...

I want a Camaro ASAP, and ASAP for me is summer of 2010...I know that I MUST have E85 capablitly. Don't ask why - I just do...I don't need the SIDI, or the AFM, or the VVT(if I must)...but ugh, I can't wait untill 2012...

[Justcallme61]

i hear ya man, and the more i think about it, the more i realize im gonna have to wait longer to get mine. i wont be getting one anytime soon, probably have to wait till around 2012-13 sadly.

[LSxcellent]

More info:

In the new issue of Motortrend there is an article on the new Corvette, and on the first page of this article, they reference something interesting:

"A mid-engine C7 would get a version of GM's upcoming "high-feature" V8, expected to be an efficient, direct-injection 5.0L+ gas engine with quad-cams and four valves per cylinder and due to launch in 2009 to replace the Northstar V-8"

This is VERY intersting, in that it moves the timeline for this "high-feature" V8 up quite a bit to the year when the Camaro is due to launch! IF this is true (and MT is usually full of **it) then it presents an interesting possibility...

If The General wanted to, he could easily bring this engine over to the Camaro Z28 as the high-feature engine.

For those that are unfamiliar with these technologies, the major advantage to a Quad-Cam engine is that the engine is capable of revving much higher than a pushrod V8 which allows it to make more power.

This is just one possibility... and pure speculation, but it fits in nicely with the image and product range.

~LSx

[LSxcellent]

Originally Posted by Mindz

Which has more potential for power LS3 or that? I know which is better for mpg, but are the power potentials similar?

Hmmm. There seems to be some confusion about this so I will clarify...

Engine Power is the (Torque x RPM)/5250

You can increase engine power by either increasing torque, OR increasing RPM, or both.

The limit to RPM is usually 'valve float' which is when the valve is opened so forcefully, that it actually floats away from the rocker arm, and then valve motion is not controlled accurately, and bad things happen.

On a pushrod engine, the weight of the pushrods themselves actually factor into this equation, and their additional weight lowers the RPM where the valves begin to float. In a DOHC engine, the valvetrain is effectively lighter, allowing higher RPM, and thus more power.

The premier example of this technology is the new BMW M3 which has a 4L V8 that can rev to 8450rpm!!! In doing so it makes ~425hp!

If GM creates this sort of engine, it has two options:
1) Maintain output around 400hp while decreasing engine size (and weight)
2) Maintain engine size and make the proverbial 'A$$Load' of power.

Either way, its a smart move for GM, they need this engine technology.

~LSx

[Mr. Wyndham]

Nice Find, LX...now that's the second mention of the Gen V being offered in 2009. Interesting, indeed.

I'll be a little sorry to see the Pushrod tech finally take a dirt nap if this works, but I'll get over it quickly.

On top of all that power, there is another equation to use, not literally , but Fuel Economy. SIDI (Spark Ignition, Direct Injection) will help, and "quad", or "dual cams" alike (OHC) will make VVT easier to do, and offer even better fuel economy gains. Then add AFM to that, and you're getting tremendous increases in fuel economy for the power it's creating...

So my point is, "LS3 vs 'this' "? 'This' gives better fuel economy - and as LSexcellent stated above - AND more power!

^= see why I'm so excited about this?

[TAG UR IT]

Originally Posted by LSxcellent

If GM creates this sort of engine, it has two options:
1) Maintain output around 400hp while decreasing engine size (and weight)
2) Maintain engine size and make the proverbial 'A$$Load' of power.

~LSx

I'll take option #2, please!!! VERY good find! Two mentions of the engine possibly being offered in 09??? Hmmmmm......

Originally Posted by Dragoneye

I'll be a little sorry to see the Pushrod tech finally take a dirt nap if this works, but I'll get over it quickly.
So my point is, "LS3 vs 'this' "? 'This' gives better fuel economy - and as LSexcellent stated above - AND more power!

^= see why I'm so excited about this?

I'm happy to say goodbye to the pushrod in favor of more power and less weight....fine by me. And fuel economy? We'll be saving lots of cash in the long run getting the great mpg's this engine could offer. This is great news!

[LSxcellent]

Originally Posted by Dragoneye

Nice Find, LX...now that's the second mention of the Gen V being offered in 2009. Interesting, indeed.

I'll be a little sorry to see the Pushrod tech finally take a dirt nap if this works, but I'll get over it quickly.

We'll I wouldn't worry too much about that... I am pretty sure GM isn't going to ditch pushrod V8's anytime soon. They offer way to much 'bang for the buck' and can be used all over the place with ease. I think they'll be around for a while longer...

Originally Posted by Dragoneye

On top of all that power, there is another equation to use, not literally , but Fuel Economy. SIDI (Spark Ignition, Direct Injection) will help, and "quad", or "dual cams" alike (OHC) will make VVT easier to do, and offer even better fuel economy gains. Then add AFM to that, and you're getting tremendous increases in fuel economy for the power it's creating...

So my point is, "LS3 vs 'this' "? 'This' gives better fuel economy - and as LSexcellent stated above - AND more power!

^= see why I'm so excited about this?

We'll, let's take a moment for reality here... all of the technologies you stated will certainly help fuel economy, but the reality is that you won't see 40mpg in this car. Its just not going to happen. The physics of internal combustion are at work, and all of these technologies are eeking out the last one or two percent... I would expect the Camaro (with a V8 containing 'the works') to max out around 27-30mpg (highway) if we are lucky. That's about it... not that its anything to sneeze at, but not 40mpg.

But yes Dragoneye, I DO see why you are excited!

~LSx

[Justcallme61]

that's all i have to say...

[JeepinMatt]

Originally Posted by TAG UR IT

I'll take option #2, please!!! VERY good find! Two mentions of the engine possibly being offered in 09??? Hmmmmm......


I'm happy to say goodbye to the pushrod in favor of more power and less weight....fine by me. And fuel economy? We'll be saving lots of cash in the long run getting the great mpg's this engine could offer. This is great news!

Pushrods weigh less than OHC and DOHC engines and are more compact

[Mr. Wyndham]

LSX, I know that - I'd be foolish to expect 40mpg...not that it isn't possible. Just not now.

I'm betting a little higher, though - around 30-32 hwy

[LSxcellent]

Originally Posted by JeepinMatt

Pushrods weigh less than OHC and DOHC engines and are more compact

This is true... the LS7 in the Corvette weighs almost 200lbs less than the 500hp engine in the M5. Keep It Simple Stupid!

Pushrods have less parts, and are simpler overall.

The problem is that I think they are reaching their performance limit... I don't think they are capable of keeping up with other modern engine designs. At least not in an economical way... The major issue is emissions and engine RPM.

Here's the logic train...

Engine Power = engine speed * engine torque

If Engine Speed is fixed (by design, since pushrods are limited) then engine torque must increase to compensate.

The problem is greater engine torque = greater engine emmisions (torque can be achieved either by greater stroke (which limits RPM = bad) or greater bore (which hurts idle emmisions=bad). Either way, increasing torque hurts emmisions, and so cannot be used as a solution.

In the end, GM really doesn't have a choice. It can't change physics, and thus has to find a way around this problem... The LS7 is one of the highest revving production pushrod V8's EVER, and it has titanium connecting rods, sodium valves, forged pistons, etc. It's VERY expensive. I don't think they could use these technologies for an 'average' engine.


~LSx

[LSxcellent]

Originally Posted by Dragoneye

LSX, I know that - I'd be foolish to expect 40mpg...not that it isn't possible. Just not now.

I'm betting a little higher, though - around 30-32 hwy

True. Who knows what technology may be available... the problem for GM is that you won't get to 40mpg in a car like this without (A) Hybrid Drivetrain or (B) Diesel Engine.

Most folks don't realize that your gasoline engine has a HARD limit on its efficiency that depends on compression ratio.

At a compression ratio of about 10:1 the theoretical limit is ~60%... but this assumes perfect compression and expansion with no heat gain/loss. In reality the limit is somewhere closer to 30% or less.

This is one of the big reasons why diesels are so popular, their theoretical efficiency limit is higher, providing designers more room to improve.


Personally, I'd love to see how a diesel-Camaro would drive... I think it would actually be pretty awesome. LOTS of torque, with plenty of power for the road... Oh, and THEN I could see it reaching 40mpg... but only JUST.

~LSx

[Mr. Wyndham]

Bob Lutz did an interview, for the GM blogs saying something along the lines of Diesels and gas-engines becoming more and more alike, (in terms of emmisions.) Which is why GM hasn't undertaken a widespread use of diesel powertrains. It'd be cheaper(maybe not), and simpler just to continue advancing gasoline engines.

Now, he's not God, and I know that, but he's close

I guess what I'm saying is that pushrods have had their day...they'll be around for some time to come, but very generally speaking, the age of the pushrod is over. and I'm confident (knowing what GM could do with pushrods) that we're in for a wild ride with these Overhead Cammers!