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2014 Impala engine gets a high-tech lift - car fanatics - 09-17-2012 09:10 AM

General Motors
Photo credit: General Motors

[Image: 7996247622_7e6beb5460_b.jpg]

Drivers of the 2014 Chevrolet Impala coming early next year can get improved fuel economy over the competition due in part to a new advanced valvetrain technology on the Ecotec 2.5L four-cylinder engine.

Chevrolet’s redesigned flagship sedan uses new Intake Valve Lift Control (IVLC) technology that enables variable intake valve lift, duration and timing over a wide range of engine operation. When the technology operates in low-lift mode, the engine pumps only the air it needs to meet the driver’s demand. The system switches to high-lift mode at higher speeds or under heavy loads, providing the full output capability of the engine.

“Intake Valve Lift Control works so seamlessly drivers aren’t likely to notice it at all,” said Mike Anderson, GM global chief engineer for Ecotec engines. “What they will notice is a fuel savings of up to one mile per gallon.”

The engine achieves variable valve lift using an innovative all-new rocker arm that switches between low and high lift intake cam profiles. The mechanism is actuated by an oil control valve through a dual-feed stationary hydraulic lash adjuster. It is the first of its kind for low friction roller-type finger-follower valvetrains in gasoline engines. The engine’s computer continuously selects the optimal lift profile based on conditions such as engine speed and load.

Impala’s three powertrains all feature fuel-saving direct injection and lightweight components.
  • Impala’s Ecotec 2.4L engine works with the eAssist system to provide electrical assist in certain conditions to help save fuel. It is GM-estimated at 182 horsepower (134 kW) and 35 mpg on the highway.
  • The Ecotec 2.5L is one of a new family of four-cylinder engines developed with increased efficiency and greater refinement. Output is estimated at 195 horsepower (145 kW).
  • Output for the 3.6L V-6 is estimated at 303 horsepower (226 kW).

All of Impala’s engines are matched with six-speed automatic transmissions.

The powertrains are the force behind Impala’s responsive driving experience, tuned for a spirited yet comfortable performance. A MacPherson-strut front suspension and four-link rear suspension underpin the Impala with an isolated front cradle and hydraulic ride bushing that help deliver a smoother, quieter ride. All models feature an electric variable-assist steering system that helps save fuel by drawing energy only when the steering wheel is turned.





RE: 2014 Impala engine gets a high-tech lift - REVolution - 09-17-2012 09:16 AM

That is pretty cool. I would love to see this work in a slow motion diagram or something. I'm curious as to how the oil gets fed into it.

RE: 2014 Impala engine gets a high-tech lift - car fanatics - 09-17-2012 10:04 AM

RevOver9000;231238 Wrote:That is pretty cool. I would love to see this work in a slow motion diagram or something. I'm curious as to how the oil gets fed into it.





RE: 2014 Impala engine gets a high-tech lift - RougeRiver - 09-17-2012 10:13 AM

I would like to see details in order to determine how this is different from VTEC. VTEC has two lifters riding on distinct cam profiles with an oil pressure actuated switch that locks the low profile finger to high when VTEC kicks in..... please insert humor here.


Anyhow, this system looks like it uses the hydraulic lash adjuster to be a means to enable distinct profile.

I have see this mentioned in the printed patent publications dealing with the next generation small block V8.

One of the big arguments against pushrod engines is that the high lift requires spring rates that are much higher than an equivalent OHC. Well, if one can change lift, then the loss of stiffer valve springs would only be seen at full throttle.

If I remember correctly, the hydraulic lifter rode on both cam profiles with oil pressure control "collapsing" the system to the low profile.

Please do not tell any of this to MT.

Their members are convinced that OHC is a very hard to understand technology beyond the capability of Americans so any consideration of OHV merely proves our intellectual inferiority.

RE: 2014 Impala engine gets a high-tech lift - RougeRiver - 09-17-2012 10:19 AM

I saw the video. This is a bit different from what they propose for an OHV engine. In that system the control is in the block where the pushrod rides on the hydraulic actuator.

What is shown in the video is close to VTEC, but not the same.

RE: 2014 Impala engine gets a high-tech lift - REVolution - 09-17-2012 10:30 AM

Yea, V-Tec uses 3cam lobes, 2 of them being the same. When the oil gets passed through the 3rd cam which is in the middle of the other two, it locks all of them together. The middle cam has the higher duration and longer stroke so it stays open longer and allows more air in. This seems to use only one cam, and lightens up the system by using only one rocker arm to do both low level and high level work. I guess complexity can be argued, but I like how it really cuts down weight.

RE: 2014 Impala engine gets a high-tech lift - RougeRiver - 09-17-2012 11:04 AM

A hydraulic lash adjuster can be used as a lift control by the degree of oil pumping. The simplest use is in DOD systems where the lash adjuster is drained with complete collapse of the system which closes the cylinder.

If this is the case, then it is not really VTEC. VTEC has two distinct profiles wherein one has more lift than the other.

What I saw for the small block did have two cam profiles.

This technology is also close to Fiat's multiair.

RE: 2014 Impala engine gets a high-tech lift - REVolution - 09-17-2012 11:07 AM

I'm trying to wrap my head around the small block use of this. I'm trying to picture in my head how the push rods would actuate the different profile.

RE: 2014 Impala engine gets a high-tech lift - RougeRiver - 09-17-2012 11:35 AM

RevOver9000;231273 Wrote:I'm trying to wrap my head around the small block use of this. I'm trying to picture in my head how the push rods would actuate the different profile.



In a pushrod engine, the lash adjuster (lifter) rides on the cam deep in the block. I believe that the bottom end of the lifter has two parts with one engaging the steep profile and the other the economy profile. Three operating conditions can be satisfied:

A. engage the steep profile = performance

B. engage the low profile = economy

C. collapse the entire system = DOD

I posted the patent application number about two years ago on this site.

RE: 2014 Impala engine gets a high-tech lift - jspookss - 09-17-2012 12:05 PM

RougeRiver;231288 Wrote:
RevOver9000;231273 Wrote:I'm trying to wrap my head around the small block use of this. I'm trying to picture in my head how the push rods would actuate the different profile.



In a pushrod engine, the lash adjuster (lifter) rides on the cam deep in the block. I believe that the bottom end of the lifter has two parts with one engaging the steep profile and the other the economy profile. Three operating conditions can be satisfied:

A. engage the steep profile = performance

B. engage the low profile = economy

C. collapse the entire system = DOD

I posted the patent application number about two years ago on this site.

Absolutely correct. The adjuster sits between the cam and the rods.

RE: 2014 Impala engine gets a high-tech lift - REVolution - 09-17-2012 12:16 PM

Ok, I'm probably going to sound etremely stupid.

The cam, sits inside the block, in the lower part of the engine. The pushrods run inside the block up to the heads and push the lifters up to lower the valves on the other side of the lifters. When you say the lifter is in the block, is the new generation of the small block different in that regard and everything is moved around?

RE: 2014 Impala engine gets a high-tech lift - jspookss - 09-17-2012 12:21 PM

No. We may have confused you by calling the adjuster a lifter..

There was a pic I had in a brochure from gm away back when.. it illustrated the system quite well.

Its really simple as hell she you see it. I'm gonna Google hunt right now

RE: 2014 Impala engine gets a high-tech lift - REVolution - 09-17-2012 12:22 PM

Yea, any help would be great, dude! beer

RE: 2014 Impala engine gets a high-tech lift - jspookss - 09-17-2012 12:31 PM

[Image: gm_dod1.png]

RE: 2014 Impala engine gets a high-tech lift - jspookss - 09-17-2012 12:34 PM

Now that's the old version for DOD. But its similar in concept. Since this iteration they have a variable fluid ratio that acts like this newer multi profile system.

Before it was just kind of an on and off switch for cylinder deactivation. Now its currently used to vary timing as well.

I haven't seen any leaks on what the system will look like for the new gen V8's