• Feb 22, 2006

No, that's not some sort of captured alien - it's Toyota's rather unique way of showing off its latest 2GR-FSE direct-injection V6. We're going to take a look at this engine, which is interesting primarily for the means that it introduces fuel into intake air. We'll also check out what's going on with GM's so-called "High Feature" DOHC V6 that currently sees use in the Cadillac CTS and Buick LaCrosse, and will soon be available under the hood of the upcoming Saturn Aura.

Sorry, Lexus fans - the poor lighting combined with the acrylic walls of the display enclosure to result in a terrible environment for photography. You'll have to take my word that the bottom end of this engine is, well, rather mundane when compared to what's going on in the intake manifold and cylinder heads.

If you look at the first picture, you can see that Toyota has avoided the usual cutaway techniques and instead takes a slice from the middle of the block. This chunk o' engine is motorized, and runs up and down while the engine is on display. It makes it difficult to see what's going on in the bottom end, but does an excellent job of showing off the top end.

Check out the vertical intake runners; this looks more like velocity stacks on a race engine than something we'd find in a luxury automobile.

 

Check out the cool little roller rockers that are used to transfer motion from the cam lobes to the valves. They add a bit of packaging height, but they also multiply valve lift and therefore require smaller cam lobes. There's the benefit of reduced friction as well.

We can also see the coil-on-plug (COP) assembly tucked between the two camshafts. It's extremely slender, and allows a narrow "included valve angle". This is important for two reasons: 1) Quite simply, it reduces packaging bulk; and 2) Narrower valve angles lend themselves to better intake and exhaust port geometry. The size of this coil is one of those "little details" that impacts so much of the engine's design.

The real story, though, lies just above and below the intake runner. You can see that there are actually two injectors for each cylinder - the top one is a standard port fuel injector, while the bottom one injects fuel directly into the combustion chamber. The two injection systems are used together to optimize the fueling over the engine's operational envelope.

As described in the January 2006 issue of SAE Automotive Engineering International, the system primarily relies on the port injection system when low engine speeds are combined with high loadings. Under these conditions, a direct injection scheme cannot properly atomize the fuel, and so approximately 60% of the fuel is provided by the port injector. As engine speed increases, the direct injection system takes over more of the fueling responsibility, until eventually it provides 100% of the necessary go-juice. Obviously, there some complex calculations going on to determine the optimum fueling over the engine's operating range, and that has led to over 300 patents being issued to Toyota concerning the design of this system.

There's a 7 increase in torque from the system, some of which comes from the 11.8:1 compression ratio that's enabled by the use of direct injection. Better yet, the benefits apply to the entire powerband, so this is a feature that will be useful to most any driver.

The dual injection system also reduces cold-start emissions. The port injection system dumps a bit of fuel on the back of the closed intake valve; when that valve opens, the fuel is evenly distributed throughout the cylinder. As the piston approaches the top of its travel, the direct system injects a bit more fuel into the cavity on top of the piston. The total air/fuel mixture in the combustion chamber is slightly lean, but the mixture is significantly richer in the area around the spark plug, making it easier to ignite in a cold engine. The result is quicker warm-up and smoother operation when cold.

The engine produces 306 HP at 6400 RPM, and 277 lb-ft at 4800 RPM; a remarkable accomplishment for a luxury-car V6. 

Next we'll take a look at GM's "High Feature" V6. Where as GM's V6 lineups have previously involved more players than the average football team, the company is moving forward with plans to use only two V6 engine architectures from here on out - the updated pushrod design that is being sold as the 3.5L and 3.9L, and this DOHC design.

 

Like every other modern engine, it's apparently necessary to cover this one in a large, non-descript plastic shroud. I'd always figured that hoods were the part of the car designed to cover up engines. Seriously, such covers are as much about reducing noise as they are about decreasing visual clutter.

Here's the left rear of the engine. GM did a nice job of minimizing the packaging height, as can be witnessed by how closely the decorative cover hugs the cam covers. There's the now-typical swooping exhaust manifold as well. Just to the left of the manifold in the photo, we see what appears to be the oil filter. The up-top positioning of it is probably nice for service, but I'm guessing that there's a bit of a mess upon removal.

There's the chain drive for the camshafts, as well as variable-valve-timing (VVT) actuators on both cams.

This appears to be a well-designed intake tract (255 HP at 6200 RPM and 252 lb-ft at 3200 RPM doesn't come by accident). The intake manifold features a shorter path that what we've seen on other engines; some of that is likely due to a bit of bias towards higher-RPM power, while there were probably also tradeoffs made to minimize packaging volume (let the intake manifold guys have their way, and we'll be driving around with all manners of bumps sticking up through the hood).

The intake path into the head isn't quite as vertical as other engines, but it shows a considerable improvement over the Northstar V8 (which has its roots in the original Quad 4). Note that this engine also uses roller rockers to actuate the valves, and there's some nice beehive valve springs in there as well.

I mentioned the compactness of Toyota's coil assembly; compare it to the slightly larger unit used here on the GM engine. This relatively minor increase in packaging volume results in the cams being pushed out slightly, which affects the intake and exhaust tracts while slightly increasing the size of the head.

The flat-top pistons contribute to a 10.2:1 compression ratio. And, yes, that's another crankshaft position sensor setup there, just ahead of the flywheel.

This is yet another example of a "deep-skirt" block, where it extends well below the centerline of the crankshaft. Also take notice of the amount of material in the valley of the block (above the crank and between the cylinders). Presumably, all that webbing is there to stiffen the block and reduce NVH (noise/vibration/harshness).



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    • 1 Second Ago
  • 28 Comments
      • 8 Years Ago
      Why is the GM 3.6 engine a so-called high tech engine. It may not be pushing 300 HP but it is a high tech engine and it is quite a piece of work.

      And if you think a .1 increase in displacement should make 50 HP you are crazy. Modify this engine for direct-injection and then we can compare Japanese to American.
      critter
      • 2 Years Ago
      i have the2012 camaro v6 323 hp-6speed manual; icommand the road - nuff said- wait'n for the twin turbos- 440hp-
      • 8 Years Ago
      "American" is out to lunch with his comments.

      Some of the generalizations might be slightly more applicable to Honda engines, but in this specific comparison they do not apply.

      If you read the article, it states that the GM motor is optimized for peak power, having shorter runners etc.

      Yes, premium is preferred for the Lexus motor, but a point and a half CR will easily make up any fuel price difference by providing significant fuel consumption reductions. The high CR is all about extracting as much energy from a given amount of fuel as is possible. It is "free" power/efficency that is available as a result of the unique injection system configuration.

      The benefits of the Lexus motor are all across the rev range, it is far from a peaky motor. Also, it strikes me as strange, you seem to be comparing HP to torque.
      In the case of the Lexus engine, +90% of peak torque is available at 2000 RPM. Follow the link provided by Aegis if you don't believe this.

      The simple fact is that both motors are quite good, however the Lexus one is a step above.
      • 8 Years Ago
      I have a 3.6 in my STS and had one in my CTS. You couldn't ask for a smoother, quieter engine. That and the fact that it returns 20 MPG around town all the time.
      • 8 Years Ago
      hmmm...Dodge 2.4L World Engine 300 HP and 260lb/ft of torque...4 cylinders of American Muscle. I'm not exactly sure, but I believe that engine will be produced in Illinois
      • 7 Years Ago
      I read the article and specs on the chevy and japanese V6 motors and agree with ` proud japanese` #8 , but hopefully there are upgrades to improve and increase the numbers for both motors - remember more power = more pleasure.
      • 8 Years Ago
      Direct injection is not new by any means. I think Mitsubishi pioneered mass market direct injection with their GDI engines. Renault in Europe has been offering it for years. The Alfa/Fiat JTS was a pioneer of high revving direct injection engines (the previous efforts only used lean burn at part throttle or at lower rpms), using very high fuel delivery pressures and very high compression to deliver the benefits over a wider power band. Mercedes offers a form of direct injection similar to the VW/Audi system via CGI - although they did offer one of the first forms of direct injection on the original 300SL.

      One of the reasons direct injection and high pressure injection has been slow to arrive in North America, is that our higher sulphur fuel is not always compatible with these systems and so the lean burn feature has to be disabled to enhance longivity of the car and components. With the gradual switch to lower sulphur gas and diesel, we should see more and more choices.

      • 8 Years Ago
      "agree. the american auto companies are losing engineers and it shows in their products. america cant import enough asian engineers to meet demand because home grown students would rather study basket weaving. even then the asian engineers would be nuts to work for an american company."

      Homegrown engineers would rather work for high paying defense contractors such as Northrop-Grumman and McDonald-Douglas. Those undergrads who can't master the shift key take basket-weaving.
      • 8 Years Ago
      I think that's a fuel filter on the Caddy engine. It looks like one, and it also looks like the oil filter mount is on the first picture, toward the back of the engine under the exhaust manifold.

      However, if it is an oil filter, well, that's just retarded.
      • 8 Years Ago
      MY LINCOLN TOWN CAR GETS APPROXIMATELY 10 CITY MILES PER GALLON. I GUESS I WON THE COMPETITION.
      :)
      • 8 Years Ago
      #17. Read the god damn article before you spew out rubbish from your hole. Only 305hp? Compare it with your 3.6L american engine,hat only gives you 255hp. No torque? The 3.5L gives you 277lb-ft @ 4800rpm while your bigger american engine gives only 252 @ 3200rpm. So no, you don't have to rev the shit out of it to get anything.
      • 8 Years Ago
      it's a 4.7 liter, and I drive it like it wants to be driven...no babying from me. #8, why are japanese engines all torqueless boat anchors? 305 hp and only 277lb/ft of torque??? sounds weak...you'd have to rev the shit out of it to get anything out of it
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