3.6L DOHC V-6 Ward’s 10 Best Engines Winner
 

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SOURCE: http://wardsauto.com/reports/2008/te...s/gm_3-6l_v-6/



Not that we didn’t like General Motors Corp.’s “high-feature” 3.6L DOHC V-6 when it launched in the Cadillac CTS for the ’05 model year.

Its initial output was 255 hp and 255 lb.-ft. (346 Nm) of torque, and there were several competing similar-displacement V-6s already making in the neighborhood of 300 hp.

Although we sometimes find ourselves wishing everyone would dial back a bit on premium V-6 output, 300 hp is the new 250 hp, just like 60 years old is the new 40.

Thanks to a decade of horsepower wars, 300-hp V-6s now are the price of entry in the premium market.

To get fully in the game for the critical new ’08 Cadillac CTS (and to upgrade the larger standard engine on the STS), GM powertrain engineers looked to gasoline direct injection, a technology quickly sweeping through powertrain-development departments on several continents.

Strap on the high-pressure (1,740-psi/120-bar) GDI hardware and fair-to-middlin’ 255 hp becomes 304 horses. And just as important, torque also is boosted by about 8%.

Just like that, the new, direct-injected variant (internal code LLT) solves probably the most noticeable shortcoming of the original variable-valve-timing 3.6L DOHC V-6: the fizzy low- and midrange torque and resultant soft throttle response. The new GDI-equipped 3.6L V-6 has torque that gets your attention at any engine speed, and the throttle pedal no longer thinks rapidly increasing its proximity to the floor is a request that should be pondered at length.

“Solid midrange pull,” says Associate Editor Mike Sutton. “Just pulls and pulls,” echoes Best Engines judge Byron Pope.

And the 3.6L DOHC V-6 likes to pull to the redline, too, and running to the 6,400-rpm power peak is a pleasure to be repeated, underscoring how essentially right GM Powertrain engineers got the noise, vibration and harshness.

We did note – and others have mentioned it, too – a boomy, low-frequency thrum at low rpm. We hear engineers were aware of the matter and are working out a fix that already may be penciled in by the time you read this.

And as we’ve noted with the latest crop of high-performance V-6s, fuel economy is not a strong suit. Despite the fact GM says GDI improves brake-specific fuel consumption by 3%, the rated 17 mpg (13.8 L/100 km) city and 26 mpg (9 L/100 km) highway figures aren’t going to get anybody too far down the road toward the new 35-mpg (6.7 L/100 km) standard in 2020. A huge points-winner with us, however: The big power can be had using regular unleaded gasoline.

But we’re talking the here and now, and GM’s latest 3.6L DOHC V-6 is a world-class engine we’d stack up against any V-6 – and it adds serious credibility to Cadillac’s goal of reclaiming its reputation for technology leadership.

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That chart brings a smile to my face. This engine has to be what made the 6 speed manuel camaro stand out in the test drive last weekend.

When was the last time an American company made an engine you would:

1. Feel comfortable pulling the revs up to red line.... and

2. Actually enjoy it?????

This engine is by far the best V6 GM has ever built. And it seems pretty solid and reliable (so far haven't heard of any issues with them since they first debuted 5 years ago).

This makes the Camaro even more appealing to the import crowd to prefer the "high technology" of DOHC, 24V, VVT, DI, and all the other initials over pushrod power.

I may just give the V6 a chance if it's as good as the disciples who drove the V6 manual Camaro say it is.

Aweseome job GM. Way to give the V6 a whole new reputation :w00t:

Gotta start changing terminology a bit. I'm pretty sure the DI engine doesn't HAVE a throttle, and that's part of why it's more efficient -- a closed throttle introduces lots of pumping loss. I think "gas pedal" would be the more accurate term.

What? You mean the outrageously flat torque curve? :bow: :bow: :bow:
I knew there was a reason I liked this engine...;) Nice find, Camaro5. Great read!

This is going to sound dumb (just a forwarning), but don't ALL engines HAVE to have a throttle? Throttle, as in that little flap that turns and lets more air in?:iono:

Yes. I think he just had things mixed up a bit. Most modern engines have done away with the throttle cable, hence the term "drive by wire" technology. The actual throttle still exists, and will untill the 4 stroke internal combustion engine is completely extinct.

The way they've eliminated the throttle cable is by using a computer controled motor on the throttle flap and a potentiometer (or rheostat) on the gas pedal. As you push the pedal down, instead of mechanically pulling a steel cable, the pedal turns what is essentially the same thing as the volume control on your stereo receiver. This sends a specific voltage signal to the car's ecm and other computers in engine management, controlling everthing from the throttle itself to the throttle position sensors, fuel injection, timing, spark and everything else. Since electricity travels at the speed of light, any engine with drive by wire technology will have faster throttle response than the exact same engine with an old fashioned throttle cable.

Ya, that blue line on the chart is the "it just pulls and pulls" part. Totally linear horsepower delivery. No peaks, no valleys, ideal. :thumbup:

On the other hand, it will kind of suck when the camaro is the new car to get for the ricers, and they destroy a beautiful car with 15 different unpainted bodymods.

Then we will be the ones going, "Yeah but we liked it before everyone else did."

:seesaw:

Yes and not many imports or domestics have DI (direct injection) right now.

Those chart lines are what all engines strive for as far as linearity :)

Thank you, sir!:D

The fact that I know this will expose me for the car geek I am. My brother had a BMW Z4 and he explained to me that there was no throttle, that the valves were computer controlled to open more or less acting just as the old throttle plate has forever. The Infiniti G37 engine (new in 07) uses this same technology - there is no throttle plate, no throttle body, not actuated by a cable or by wire and servo. All engine valve controlled. Welcome to the future! :thumbup:

I like cars, I really really do! :sm0:

No throttle plate. The intake is wide open at all times. It's kinda like a diesel engine with spark plugs and lower compression. The gas pedal operates the fuel injectors, not an intake restriction. According to http://en.wikipedia.org/wiki/Gasoline_direct_injection it can run as lean as 65:1 (hooray for gas savings!). It doesn't say how rich it can run.

Diesel engines, which I'm pretty sure qualify as "4 stroke internal combustion engines", also do not have a throttle plate or throttle body.

You say that most modern engines are drive-by-wire? I thought it was still relatively uncommon, though I don't know that. My VW is DBW and I don't like it.

This is news to me. I hope it's not true and the engine really does operate by enriching or leaning the mixture. Restricting the intake (whether at the intake manifold with a throttle, or at the intake valves as described) is an unnecessary energy loss for a DI engine.

Camaro5, I think your brother was misled or confused by the salesman. I've read that BMW claims that their newest NA engines can run without a throttle, but the idle quality and emissions at idle are unacceptable so they use one.

The LLT also has a normal throttle body. You will probably have to wait for HCCI or electrically actuated valves before you can get rid of it.

On the bright side, I believe that when a DI engine goes into its ultra-lean-burn mode the throttle is open pretty wide relative to the load. So while the LLT still has a throttle, it spends more time open that it would on an LY7 (the same engine with port injection).

The DIs ultra-lean-burn mode is a great illustration of the need for drive-by-wire.