New Powertrains: I'm A Believer

[Ghrankenstein]

Powertrains Old and New: I’m A Believer, and Other Ramblings

By Ghrankenstein

I’ve had a bunch of ideas floating around in my head lately, along with several unfinished articles crusting up my hard drive. I’ve been thinking about recent drives and the vehicles I’ve been in, and I’ve been considering the debates I’ve had with the opinionated sales staffers with whom I’m honored to work. This article is a synthesis of several others, and a typically hopeful attempt at a conclusion with mercifully little meandering. Since you all are so gracious in reading my articles all the way through, I’m going to add a few tidbits that haven’t been printed elsewhere (GMC Acadia).

Mostly, though, this is a ramble. As usual, I’m not one to dish out mercy, so you can expect plenty of sidebar editorials and impressions along the way. Ultimately, I’m sorting out the equation of powertrains, the old and the new, and what’s good. We all like things that are good, right?

I finally took my first drive in a 2007 Pontiac G6 GTP today. These things don’t exactly grow on trees, at least in my neck of the woods. Since I’ve already posted one 2007 G6 review, another isn’t really necessary, but there’s still plenty to mention. The one I drove was pretty crazy, and I don’t think a G6 can get any more panoramic or pricey. I can excuse a lot of the interior details in a $21,000 3.5L G6, which I think is a great car for the money, but this GTP needs a black tie radio at the bare minimum. Leather seating that isn’t noticeably less comfortable than the cloth seats is another reasonable request. A nice set of paddle-shifters is only fair. Ghrankenstein’s insistence on using the passive voice: pure drudgery.

I like how the GTP drives. I don’t know if the steering has been tweaked, or if I’m just habituated to it from my time in the 3.9L GTP, but I feel like there’s less liability that I have to excuse as “interesting.” It’s not that different either way, but the steering does feel sharper, the on-center feel seems better, and the mass of the 18” wheels feels less intrusive. On the down side, the 17” 3.5L G6 still has better, more linear steering feel, and the GTP is still not shy about understeer. The GTP still feels very solid and sticky, but it still prefers smoothness and I doubt that the 2007 will take any kindlier to tossing than earlier GTP’s. I need to drive an Aura XR, and see just how much difference there really is, beyond the shift paddles.

I’ve also spent quite a bit of wheel time in the Acadia. Other members have written reviews that are more than adequate, and I’m not going to change any opinions at this point anyway. I went to the GM Training Ride-And-Drive a few weeks ago, and the event was rather underwhelming. Among competitors, we only got a single Durango and a single Pilot to drive. The high point was a peek at the pretty 2008 Saturn VUE that we were allowed to walk past, but not really stand near. GM never lets you forget who’s in charge.

The Acadia is impressive. It’s gorgeous in person, and it does a great job of leveraging GMC’s rugged authenticity against a functional minivan. Despite the ruggedness, the look remains aggressive and sporty, especially in the leopard-like crouch of the front aspect. I still have mixed feelings about a crossover carrying such a thick SUV disguise; if it were my vehicle, I’d take the Enclave or Outlook on the grounds of such meaningless ivory-tower semantics. One of those things I said I’d add: Contrary to other reports, there is no fake aluminum in the Acadia’s interior. The SLE’s trim isn’t brushed, as it is in the SLT, but it’s completely genuine. Since I’m no expert on interiors, I asked the trainer, who was both miffed and adamant about the material’s singular chemical symbol.

The Acadia drives about as well as a 4900 lb eight-seater can drive. The steering effort and response are both linear. The speed-sensitivity in the SLT’s steering is almost unnoticeable, and drivers opting for the SLE won’t be missing much. There isn’t any play in the steering to speak of, but the level of feedback is limited to a drab version of what’s necessary. It’s not bad, but the Cadillac SRX has an amusingly snooty charm in the way it decides what’s “necessary,” and the Acadia just doesn’t. The Acadia’s steering is more of a professional-grade form of sterile.

For such faint praise, the Acadia’s chassis dynamics are good enough that they might even be mistaken for sporty on an import. The big Lambda can be pushed into a corner, and come out flat and composed. It isn’t a serious challenger to the SRX in the switchbacks, as long as you’re one of the first five passengers. The “Active Intelligent” AWD system is nice, and it actually works better than the setup in the SRX, in that it’s less noticeable and more capable. The Acadia’s AWD system keeps at least 1% of the available torque at either end to quicken shifts in power, and it uses two different distribution maps simultaneously: one to maximize traction, the other to maximize performance. Not only does it work, it’s extremely geeky, the kind of thing you can explain in great detail to a completely disinterested passenger who just wants you to turn off the death metal.

I think the driving impressions were worthwhile, but the context here is powertrain, and it’s what the Acadia and G6 GTP have in common. The 3.6L High-Feature V-6 and 6T70E transaxle are GM’s workhorse powertrain of the near future. Like most people reading this, I’m happy to see it, and I’m willing to take it a step further.

First I have to take a step back, to the aging workhorse mechanics: the 3800 V-6 and the 4T65E. Lots of time behind the wheels of the Buicks Lacrosse and Lucerne has left me smiling, and thinking what an enjoyable swan song they represent. Wistfulness aside, this is not the material of a complete article, and a swan song for a 30 year-old powrtrain that’s motivated millions of appliance-caliber vehicles isn’t a major selling point. In 2007, though, it’s a wonder that the combo is still around, much less as pleasant as it is.

The 3800 still feels more powerful than it is, thanks to its hefty torque reservoir; neither vehicle is underpowered. What I appreciate most is the acoustical tuning, and the rich song that I hear in both of these throwback Buicks. Within a comfort-oriented setting, both steer crisply and handle smartly. They also have their faults, and plenty of detractors within our ranks. Sub-Lexus customers are justified in asking for more, but I enjoy appreciating both vehicles for what they are. I have a particular penchant for the Lacrosse, and its world-class seats.

Buick has also tried a couple of intermediates, vehicles pairing the 3.6L V-6 and 4T65E: The Buick Lacrosse CXS and Buick Rendezvous Ultra/CXL 3.6. In my humble opinion, both were failures, and the engine/transaxle pairing was a major part of both. Each is obviously a worthwhile component, but together they were less than optimal. In these early FWD setups, the 3.6L V-6 was tuned for 225 lb-ft of torque, admittedly at a low 2000 rpm, versus 230 lb-ft for the 3800 and its own staunch low end, no real benefit. Furthermore, the broad rev band of the 3.6L V-6 was awkwardly spread over four gear ratios. In the heavy Rendezvous, the transaxle was especially busy, but both vehicles felt less powerful in DOHC form than with the old-school pushrods.

They’re all functionally the same. The 3800 and 3900 with the 4-speed, and the 3600 with the 6-speed, all perform well, behave themselves nicely, and get about the same fuel economy. I’ve often wondered if this whole powertrain issue wasn’t simply change for the sake of change. To me, the proof is in the driving.

The clincher, of course, is having driven the G6 GTP in both 3.9L/4T65E and 3.6L/6T70E incarnations. I still have nothing but positive thoughts for the 3.9L GTP. The 3.9L V-6 is gutsy, and it still makes some of the prettiest music you’ll ever hear from a V-6. Matched with the 4T65E, it never seems to lose a step. Just as in the Grand Prix GXP, the manual shift mode is really well executed, with the smarts to know when to implement a downshift at just the right time in order to minimize torque-converter drama. Comparison with the newer powertrain only reminds me of how good we already had it.

The 3.6L/6T70E duo matches the other combinations every step of the way, and it always outperforms the others by a small but noticeable margin. I like the intangibles of the pushrod V-6/4-speeds, but the 3.6/6-speed has them too, and then some. The fact that a [2008] Chevy Malibu powertrain can propel the Lambda bodies competitively, and with best-in-class fuel economy is a testament, even if it requires some controversially creative software. I had no problem with the performance of the Acadia; I’m even surprised by it. Drivers need to understand that the transaxle is doing a lot of the work, and that it’s not going to hold a gear as long as a four-speed, but that scenario won’t change in a crossover competitor.

In the G6 GTP, and presumably the Aura XR and Malibu LTZ, the setup is unflappable. The 3.6 idles almost silently, and it revs eagerly. The acoustic tuning in the G6 GTP is lovely, better than in the 2007 Cadillac CTS 3.6, whose exhaust note is still vastly improved over the haughty and annoying drone of its 2006 counterpart. The biggest difference is at the higher end of the rev band, where the 3.6 continues to pull strongly and maintain its aristocratic composure. There’s no harshness, no rasp, and no thrash. I believe that a world without thrash would be unlivable, but in my microcosm I prefer to get it from XM radio rather than my V-6.

For all the wrong of the 4T65’s pairing with the 3.6, the 6T70 is right. In the G6 especially, the wide ratio span and shift software lend the combo the same level of competence that I see in the 2007 Yukon Denali and Cadillac Escalade. That’s high praise, in that both vehicles always seem to have the right gear selected before you need it, and that shift quality is both crisp and drama free. I’ll gripe that the addictive PAS and PAL shift algorithms (i.e. CTS) need to be included on a performance-oriented Pontiac, at least in a driver-selectable sport mode.

It’s enough to make me question the premium of the Saab 9-3 Aero automatic over the G6 GTP (I’d still take a manual 9-3 2.0T over either). The clutch-to-clutch Hydra-Matic outclasses the Saab’s Aisin-Warner sourced Sentronic 6-speed by the same narrow (but noticeable) margins by which the 3.6 outpaces the 3.9. With close ratios and outstanding shift quality, it makes me wonder if the electronic twin-clutch DSG arrangement isn’t more of a curiosity and more of an innovation for its own sake. I thought the same about the DSG versus the 4T65E with manual shift mode and Sentronic 6-speed, and I can only agree with that conclusion more strongly now. For the time being, Hydra-Matic is wise to stick to its guns, until electronic clutch vs. torque converter becomes the equivalent of DOHC vs. OHV and cachet takes over.

With all of that in mind, I’m a believer. The DOHC/6-speed combination really is that good. Unless GM fears putting all of its V-6 eggs in one basket, or if an OHV breakthrough is on the approaching horizon, this is GM’s best option for a workhorse powertrain. Optimizing the High Feature family could eliminate three other engine families (HV, 90-degree OHV, and Atlas) from regional economies of scale, and allow for less costly future development of only one engine family. The Buicks especially, would be immeasurably better, and even more “Buick-like,” with the 2008 Malibu’s V-6 and transaxle. Expensive modifications to old, inflexible platforms are the biggest obstacle in the future of Buick’s powertrains.

As much as I like the OHV-VVT “High Value” V-6 engines, I’d be willing to accept their history in favor of newer and sweeter HF V-6’s. Modern midsize sedans simply don’t benefit from the more efficient packaging on an OHV engine; there’s plenty of room for a DOHC. In the biggest volume car markets, OHV just isn’t relevant anymore beyond the diehards and the apathetic. Not when resources can be allocated toward a single V-6 engine family globally.

In this last sidebar, the G6 has its own set of criticisms. The big wheels and long wheelbase have made it stable but oddly unwieldy, despite its respectable cornering limits. With the Saturn Aura and Chevrolet Malibu earning its wheelbase and more acclaim, along with a dominating spread of high-end and low-end, where does that leave the G6? GM’s admirable work at differentiating the Pontiac now seems empty, and it leaves us looking to a future model for the answer. Pontiac’s position as a “damaged” performance brand, with too many “Chevrolet Jr.” aftershocks (G6 becoming Saturn/Chevy notwithstanding) has become diluted to the point that the midsized RWD/AWD Holden Torana concept offers the most promise. Performance and enthusiast appeal are huge factors in brand equity, and the fact that Mazda could gain it so quickly with a well-engineered Ford-powered Mazda6 bodes well. In this case, the 2.8 or 3.6 and the excellent 5-speed Hydra-Matic would be a solid combination, but potentially outstanding driving dynamics would create a demand for manual transmissions that would enhance Pontiac’s sales for both enthusiast drivers and the non-enthusiast drivers that they refer. That’s where Pontiac needs to start.

I’ve editorialized enough. I’ve driven the 2007 G6 GTP, and its powertrain has made me a believer.

Thanks for reading,

Insane W. Ghrankenstein

[Achelous]

Amen. 3800 & 4T65 has been a wonderful companion over the years, but its time has come. Having driven the Aura XR, the successor to this glorious powertrain dynasty is obvious.

[Evo69]

Nice write up Grank' I hear u loud an clear.

[Mikkoo]

Nice thread on powertrains. It's my wish list that GM will install the
six speed automatic in every application that currently uses
the old four speed automatic. This is of course a product of lack
of monetary resources to apply there latest competitive transmissions
across the board. Instead, GM will trickle it out first to the top
version powertrains, with the bottom feeders stuck with an
antiquated old transmission. Too bad GM doesn't has been slow to
react to what the competition has been offering in the powertrain
dept. It's also time to lay old faithful, ( 3800 V6) to sleep permanently,
as it's served it usefullness well, but just doesn't compete in the
NHV category that is demanded in today's market. It's a bit rough
around the edges for me.

[dav305z]

The Aura XR handles much, much better. I like the 3.6L too, but after a week of driving the XR, I' still feel like the 3.8L S/C in my GTP feels faster. One of the great what if's for me has always been what a 3800 S/C would have felt like if GM offered it with a manual. You'd be able to keep it in it's reve range much better than the wimpy 4T65. Anyway, I digress. The 3.6L is a terrific engine, and I hope GM continues to improve and proliferate it.

[regfootball]

nice writeup, but really you have just gotten to the point that many car customers got to a long time ago when shopping cars by engine....the DOHC and more than 4 speeds, well, it just is more pleasing and it makes you wonder why it took GM until the mid 2000's to get this in their lineup.

The OHV tradition was fine and all but GM is now just getting to where they needed to be 5-10 years ago.

[racy]

I was not a fan of Saab's Sentronic. Not that its a brad tranny. I just don't feel anything special about it. The gear ratios are about as perfect as can be. And mated with the 2.8 Turbo, they make a very nice combo that continues to impress me with every drive. However, the shifting quality is just not there. Its not a software issue either. It is as if they made the gear transition *too* smooth. In an effort to achieve comfort, they went too far and lost performance. On a spirited WOT run, the shift transitions will take so long and lose so much torque that the nose will dive and momentum gets lost. The result is that it takes an additiona 2 seconds to get back to good torque and pull.

[sancapguy]

A very accurate report, I'd say right on the money! Having driven both powertrains, the 3800 is good until you drive the 3.6. Have to say though the Lacross is a steal of a car @ $18000 (with rebates).

[mjd1001]

Originally Posted by sancapguy

A very accurate report, I'd say right on the money! Having driven both powertrains, the 3800 is good until you drive the 3.6. Have to say though the Lacross is a steal of a car @ $18000 (with rebates).

I totally agree with what you said. I have had myself GM cars with the 4 speed auto and the 3800, as well as many of my family members. When you drive them, there is nothing wrong with them. The Transmission is smooth, the powertrain is reliable, and the engine has pretty good power without too much noise. -- But then, when you get a chance to drive a car with a 5 or 6 speed auto...that is mated to an engine that is obviously of newer design.....you realize just how old the 3800 and 4 speed auto are. They form a good combo, and if you never experience anything else they are fine...but once you drive something more modern, it is THEN you realize how far GM is behind by still offering this combo.

[cmutt]

Having owned several 3800's over the years, it's hard to complain with their performance: unbelievable torque while delivering outstanding gas mileage. They weren't the most refined of engines (vibration and noise-wise), but they did their job -- and if you've owned one for any length of time, you'd know that at 100,000 miles, these engines were bearing broken in -> when taken care of, they'd last 3 times that. It truly is a workhorse engine. Sad to see it's days are numbered.

That being said, I'm going to switch direction:

GM's powertrain situation is a bit of a mess -- and I'm not sure what their gameplan is for straightening it out.

1) Where is GM's 40mpg 4-cyl? The Aveo & the Cobalt dearly need them. They've got 1.xl engines in Europe. It's long overdue for GM to export a worthy design across the ocean and spend some coin on having it meet US emisions.

2) GM's Ecotec 2.2 and 2.4 aren't as refined as their competition. Compare the 2.4l vs a Honda/Toyota 2.4l and their specs match up quite nicely. Now drive them - and the difference is noise and smoothness is amazing. A majority of Honda Accords and Toyota Camry's are 4cyl's. If you really want to pursue that audience, then GM's going to need to resolve this issue ASAP.

3) GM's Atlas engines. The 5cyl never took root. It didn't deliver the hp/torque or gas mileage. The public want's better. The 4cyl Atlas seems like a capable engine -- I've never seen a bad review of it. The trailblazer is done at the end of this product cycle - and as far as I know, it's the only 'host' vehicle for the inline 6. This may be GM's smoothest engine - and it's going to be without an application. Is GM really going to let this die? Arguably, GM could replace the base Silverado/Sierra 4.3l V6 with the Atlas, but the Atlas I6 puts out comparable power to the 4.8l V8 - so it would end up replacing 2 engines - and more importantly, 2 CHEAPER engines. Would the GM beancounters allow an expensive engine to replace 2 cheaper ones?

4) GM's pushrod V8's. I'm talking about the truck engines (not the 'vette). Toyota's new 5.7l has matched (or slightly bested) GM in terms of balance of hp/torque/gas mileage -- an area where GM has virtually *always* been the leader. Is GM going to let it's foreign rival get a foothold in the market or is GM going to up the ante and tweak these engines for something a bit more than they currently are?

[Ming]

Great write up, Ghank!

The main problem with the 3800 is simple and straighforward. GM stopped any real efforts at improving and keeping it competitive back when Clinton was in office.

Really, not much more needs to be said beyond that. If anyone thinks GM can survive by selling product it has put zero R&D effort into for years, they are living in a dream world, blinded by nostalgia.

The 3.6L is a great engine, and in the right applications it shines even in the fuel economy department. I recall that the weaker 3400 V6 actually got worse fuel economy in the Buick Rendezvous than the 27MPG/HWY 3.6LV6 version. But generally the 3.6L hasn't been known for delivering stellar fuel economy, and that worries me a bit in a time when gas mileage is more important than ever.

The E-85 capable 3500VVT interests me more for a commuter car, and the price is usually right. Difference with the "value" sibling 3800 is that the 3500VVT architecture actually has been updated and improved regularly for the last few years. While the 3800 horsepower has stayed the same, and even declined in the Lucerne to below 200hp, the 3.5LVVT V6 is up to 220+ hp. Just a few years and the 60-degree V6 (3400, 3500-preVVT, 3.5LVVT) has seen a 30+ hp jump from 185-odd hp.

If the 3.6L DOHC engine is set to replace the 3.5LVVT OHV engine, I sure hope that they add things like E-85 capability and tweak at least a car or two in GM's stable that the engine is put into for maximum fuel economy, even if that means losing a little get up & go.

[BlueMontreal]

I think there is too many engine in GM lineup in the 200-250 hp range.

Let's see :
The Chinese 3400 in the equinox
Atlas in line 5
Dohc 2.8
Dohc 3.6
The 3500
The 3900
The 3800


7 engines. GM doesn't have the ressources to keep all those engines up to date.

[howpeculiar]

We have been driving several of the smaller fuel efficient cars looking for a commuter for the wife during the summer months. The 9-3 Aero with 6spd, and G6 GTP are the finalists at this point. We where VERY dissapointed with the CTS (the 5 speed automatic was terrible!), and you get a much better interior and transmission with the G6, for less money. We have not tested the Automatic version of the 9-3, she really wants a stick. We have not had the chance to try the 3.6L with a manual trans, but would really like to. I must say that my biggest complaint with the G6 GTP was torque steer. Nothing too major, and pretty predictable, but I was surprised to find it. Point the car straight and mash the pedal, and you will no longer be going straight. Other than that, I was very impressed with the 3.6L/6speed Auto powertrain. Very smooth, quiet, and you can feel a lot of low-midrange torque. Engine wants to rev to the moon! The 2.8L in the Aero is a bit less fun, low end torque is jumpy, but having that manual really makes up for it. It is sad to see the 3800 go, but it really has done all they could have hoped and more when it was designed. Now we need a twin turbo version of the 3.6L!

[NDH 66]

The 3.6 l in my Aura is a great combination, power ,handling and style. As far as power and fuel mileage it doesn't compare with the 3800 SC in the Regal.Think this will change when they put the Direct Injection on the 3.6 . 08 Caddy CTS will have it , 300 HP I read somewhere .The direct injection should be the next step on all engines for GM. Hate seeing those Tundra commercials beating GM , wonder how we would stack up with DI on our truck engines.

[jwrebholz]

The Acadia was 4,900 pounds?

It didn't feel that heavy when I was driving it. It drove, to me, like a somewhat smaller vehicle.

I do agree with you about the pushrod sixes and 4-speed. They were a great combination for a long time, but that time is past and we need to move on. It isn't like the OHV small-block V8, which has been going for 50 years with no signs of stopping and which the General has no superior engine.

It's time to put the OHV V6 families to pasture.