GM applying new intake valve lift control technology in 2.5L Ecotec for 2014 Impala; up to 1 mpg fuel economy boost
18 September 2012
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| IVLC enables variable intake valve lift, duration and timing over a range of operation. Click to enlarge. |
GM is applying a new advanced valvetrain technology on the Ecotec 2.5L four-cylinder engine used in the 2014 Impala, due next year. Chevrolet’s redesigned flagship sedan will use 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. GM estimates the fuel savings at up to one mile per gallon, according to Mike Anderson, GM global chief engineer for Ecotec engines.
The engine achieves variable valve lift using a 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, GM says. 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 (6.7 l/100 km) 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. All models also feature an electric variable-assist steering system that helps save fuel by drawing energy only when the steering wheel is turned.
Another mini step for GM's PR department?
Posted by: HarveyD | 18 September 2012 at 08:04 AM
See Honda VTEC for comparison. I wonder if GM is paying royalties to Honda.
Posted by: Nick Lyons | 18 September 2012 at 08:48 AM
Nick Lyons
The effect of the GM system is the same as the Honda VTEC but the mechanism is not. It may be closer to the FIAT MultiAir but FIAT developed this when they were majority owned by GM. Also the GM engines are direct injection while the Honda engines are port injected.
It seems popular for the readers of this site to knock GM and GM may have had some management problems in the past but GM is also responsible for much of the automotive research work that has been done at least since the 1930's. Back when Honda had the CVCC system for emissions control, GM pushed for unleaded fuel and catalytic convertors which was a far better solution.
Posted by: sd | 18 September 2012 at 12:09 PM
I don't know if this is an infinetely variable, or only two position, valve lift. If only two position, it is a compact and useful attempt at valve lift control, that secures a significant portion of variable valve lift benefits.
If infinitely variable, it is a much more compact variant of Fiat's MultiAir. Infinite variable valve lift may be needed for the precise flow control that is needed to provide proper conditiions for HCCI operation; and no-throttle losses on OTTO ICE engines. Such HCCI, and PMCI, operation reaches the theoretical limit for all ICE efficiency.
In either case, it is technological progress. Well done GM.
Posted by: D | 18 September 2012 at 12:33 PM
Harvey,
Why are you downgrading and minimizing a significant accomplishment; and also a possible stage setter for introducing the long sought highest theoretical efficiency of an ICE engine with HCCI operation?
Does your background education preclude any recognition of what is genuinely important, and what is merely controversial?
Yes I know, that the 57 Chevys and 58 Fords that you see on your annual pilgrimmage, to worship in Castro's Cuban paradise, don't have the feature; but as any Socialist propagandist knows, the proletariat masses don't need it. Such things are better reserved for the Nomenklatura aristocracy.
Have a nice day.
Posted by: D | 18 September 2012 at 12:47 PM
@sd: Using an oil pressure activated mechanism to switch between two cam profiles is essentially what VTEC has been doing all these years, that's all I'm saying. I see this as a positive development--increasing part-load efficiency has always been one of the big challenges for Otto-cycle engines. And I have nothing against GM, am glad we bailed them out, and hope they continue to improve their cars.
Posted by: Nick Lyons | 18 September 2012 at 01:46 PM
G...you sound a lot like the current R-Candidate gentleman who is driving down the 47% because they do not think like him or the 3%. Do you really think that by selling their mis-information you will one day become one of them (the 3%)?
Too many posters look in a mirror and see GM (boats) on wheels. The truth is that GM did so badly for decades that it would/should have gone Chapter 11 (years ago) without USA's, Canada's, Ontario's taxpayers (or borrowed) $$B. I own 5 GM cars and the last two were so badly built that I'll never get close to another one. My wife converted me to made in Japan Toyotas and we are very satisfied.
Sorry D..one day, in not too distant future, the 47% may become the 97% and the 3% will not be there to help.
Posted by: HarveyD | 18 September 2012 at 02:26 PM
D, GM had many technical research breakthroughs and used this info to disrupt world transportation advances, whether it be planned obsolescence(superficial model year changes), closing existing non-polluting metro electric trolleys(convicted), multi-ton finned vehicles(mpg waste), the EV1(crushed), the NiMH EV battery(patents stolen/shelved), SUVs(more mpg waste), etc, etc, ..
Posted by: kelly | 18 September 2012 at 02:50 PM
And speaking of "..current R-Candidate gentleman who is driving down the 47% because they do not think like him.." - is he an earthling?
If our President had made just 10% of the 'R-Candidate's screw-ups - Obama would be declared 'out of the race'.
The 'R-Candidate' is unemployed, trying to get by on $54,000 A DAY, evaded $millions(if not $billions) in taxes, and bankrupted dozens of US businesses - while charging $m/billions for his takeover 'services'.
Even his Wall Street buddies recognize the Bain/Mob "bust out" - overpowering a business, running it into massive debt(which Bain/'management' pockets), and then moving on as the workers lose job, pension, and benefits.
And if anyone thinks $54,000 A DAY 'return' was honestly earned - they are mistaken.
If the money is 'offshore', send the depositor there as well.
Posted by: kelly | 18 September 2012 at 03:14 PM
Posted by: Engineer-Poet | 18 September 2012 at 05:48 PM
@EP
Well, if you find a source, I would like to see it. If you want to find great similarities, CVCC and PROCO are not the concepts to look at. Both aimed at reducing fuel consumption (and emissions, to some extent) but in much different ways.
Posted by: Peter_XX | 19 September 2012 at 10:57 AM