You may be reading this and wondering why PHR is doing a story on a four-banger. The answer is simple: this new turbocharged Ecotec makes V-8 power, while retaining four-cylinder fuel mileage. To illustrate the point, let's turn the clock back to 1985, when GM introduced its then fire-breathing 250hp, L98 tuned-port small-block in the new C4 Corvette. At the time, the Corvette was the fastest car you could buy in America; it was the pinnacle of power and performance, and now it's about to be upstaged by a four-cylinder. My, how far we've come.
Many of the technical innovations in the Turbo Ecotec, like variable valve timing and intercooling, have been around for a while, yet it's the unique way these systems are combined with new, cutting-edge, technology that allows this small-displacement engine to churn out a very impressive 260 horsepower and an equal amount of torque. It may not sound like much when compared to GM's 505-horsepower LS7, but at only two liters, it's the highest specific output engine ever built by GM. What's not to love about 2.1 horsepower per cubic inch? We're not suggesting you rip out your 383 stroker motor and toss in an Ecotec, but we invite you to learn about the technology that may eventually find its way into the V-8s that we love. After all, at 2.1 hp per cubic inch, GM's LS7 would be putting out over 896 hp, and that's a number worth shooting for.
Direct InjectionOne key factor in the Ecotec's ability to make big power is the use of direct injection. This system differs from the fuel delivery process of a conventional engine by spraying fuel directly into the combustion chamber, where it's mixed with air drawn into the chamber through the intake. In a conventional fuel-injected engine, air and fuel are mixed in the intake port or intake manifold prior to going into the combustion chamber. Direct injection is an evolution of this process and offers improved control of the fuel by introducing it closer to the point of combustion.
According to Ecotec's Chief Engineer Dean Guard, "Direct injection [Spark Ignited Direct Injection--SIDI as GM calls it] is one of those rare technologies where we get two synergistic benefits from a single technology. Direct injection offers the opportunity to increase the compression ratio due to the charge-cooling effects of in-cylinder fuel vaporization, and therefore helps both improve fuel economy, around 2 percent, and performance with roughly a 5 percent power increase." The way that direct injection precisely delivers the fuel enables a more complete combustion, particularly on cold starts when emissions are higher. Better combustion means fewer emissions and a greater fuel economy benefit from the higher compression. It's a win-win in an industry constantly trying to meet tougher government standards.
Dual-Scroll TurboAnother technology unique to this motor is the use of a dual-scroll turbocharger. Dual exhaust passages from the engine to the turbine move exhaust gas to the turbo more efficiently. This in turn reduces the time needed for the turbo to spool up and cuts the lag time commonly associated with turbocharged engines at low rpm. Guard told PHR: "The engine feels more like a naturally aspirated engine since there is virtually no lag. Throttle response is immediate." Max boost for the intercooled system is about 20 psi and the motor is in boost as low as 1,700 rpm with peak boost at around 2,500 rpm. This turbo design is well-tested and is currently used in boosted Saabs."
According to Ed Groff, assistant chief engineer of the Ecotec turbo: "Direct injection technology works well with turbocharging and helps deliver a great balance of power and economy. The Ecotec 2.0-liter turbo produces the power expected of a V-6, but in a smaller, more efficient package-and the driving response is simply terrific."
We asked Guard why GM chose a turbo over a supercharger and he had this to say: "This engine from day-one was designed as a global engine. Turbos are well-received in Europe, but the same cannot be said for supercharging. The turbo also suffers less from parasitic losses typical of superchargers. Also, the dual-scroll turbo coupled with SIDI resulted in virtually no turbo lag, so a supercharger was even less necessary." Being able to effectively market the engine overseas means that overall costs for the powertrain development can be spread over the international market.
Dual Cam PhasingThe dual camshafts of the turbo Ecotec are equipped with phasers (we will resist the urge to insert a "Star Trek" reference) that allow for the intake and exhaust valve timing to be constantly varied. Through the use of cam position sensors, the engine control module can precisely modulate the timing of the valves and this allows for the combustion process to be optimized. According to Guard it also allows for generous overlap to be used at low rpm levels that in turn decreases the response time of the turbocharger and gives a "more immediate feeling of power." This is yet another technology that works well with the direct injection and dual-scroll turbo to meet the goals of the Ecotec program.
Oil-Cooled PistonsBelow each piston lies an oil cooling jet. These jets spray oil directly into channels that are cast into the bottom of the oil-galley pistons. This helps to reduce piston temperatures by as much as 95 degrees. The system continuously delivers pressurized oil to cool and lubricate. This reduces noise, friction and greatly adds to the durability of the engine at high power levels. The oil pump used in this engine is the same as that found in all other Ecotec engines and it was designed from the onset to support future high-performance applications.
Let the Wrenching Begin!The immediate problem with modifying the new Turbo Ecotec will be the uniqueness of the design. Even though many parts are shared with the other members of the Ecotec family, many of the power-making parts are not. The cylinder head was built specifically for the SIDI fuel injectors so there are no immediate replacement performance heads. The cast pistons are unique due to their internal channels for the oil squirters. If you were to swap in existing aftermarket forged pistons, you would lose much of the benefits of the oil cooling and since the top of the pistons is dished specifically for SIDI, it's doubtful they would work at all. Because of the design of the phasers and variable valve timing, a swap of the cams would be tricky as well. Even the computer, which is based on the new 58-tooth reluctor wheel, is something that the aftermarket is just now starting to figure out how to tune. Like all new technologies, there's a learning curve involved and this engine is all about cutting-edge tech.
Now for the good news. Over the last four years, GM has made good on its promise to turn the Ecotec into the "small-block Chevy" of the compact crowd. GM Performance Parts has successfully built a line of serious speed parts for the First-Generation Ecotec-stuff like blocks, cranks, cylinder heads, camshafts, pistons, and intakes. We're regularly seeing over 800 hp from the First-Generation Ecotec architecture, and it's only going to go higher with the new turbo version, which already has an upgraded block and a forged steel crank.
Based on the engineered-in margin of past turbocharged GM mills such as the 4.3-liter V-6 Syclone/Typhoon and the 3.8-liter LC2 Buick V-6, it's not a stretch to image 350 easy hp out of the turbo Ecotec with only a turbo upgrade, bigger injectors and a computer re-flash. And unlike a naturally aspirated engine, a turbocharged one has the potential to respond to minor tweaks in a big way. Dodge's four-cylinder SRT-4, for instance, is boosted from 225 hp to 355 hp with its stage 3R kit, which consists only of a reprogrammed computer, larger injectors, wastegate actuator, a few new sensors, a larger turbo, and a bigger fuel pump. The two big differences between the Dodge and the Turbo Ecotec is that the Ecotec starts with 35 more hp, and all that power drives the rear wheels for maximum effect. Coupled to a world-class, fully independent suspension and dropped into an easy-to-wrench-on engine compartment, the turbo Ecotec and Solstice GXP already have us salivating.
Bottom LineGM feels this is a "no compromise" package and they have gone through all the validation processes to show it will hold up to real-world use. The folks at GM are understandably proud of their accomplishment with the new turbo Ecotec and the synergy of various technologies employed. "The 2.0-liter turbo is the pinnacle of Ecotec performance to date, with additional growth planned. The groundwork for its capabilities was laid on the drawing table at the very beginning of the Ecotec's development," said Groff. "Prior work and a far-thinking engine design continue to help GM respond to market demands around the globe more quickly and with greater accuracy."
Put all these technologies together and what you end up with is a look at the future of modern high-performance engines. While these technologies help GM's newest four-banger make good power for its diminutive size, just imagine what they could do to pump up the power in the next generation of V-8 mills. As for a crate version of this mighty little mill (GM Performance Parts already offers a 205hp version of the supercharged 2-liter Ecotec, PN 12499466), Guard had this to say: "No decision has been made at this point, but we're proud of this engine and we're always looking for additional ways to get it to the marketplace, so stay tuned."
|Assembly site: ||Spring Hill, Tenn. |
|Application: ||2007 Pontiac Solstice GXP |
|Type: ||2.0-liter DOHC turbocharged I4 |
(cu in/ cc):
|122 / 1998 |
|Bore x stroke |
|(in x mm): ||3.39 x 3.39 / 86 x 86 |
|Block material: ||319 aluminum |
|Cylinder head material: ||356 T6 aluminum |
|Intake manifold: ||cast aluminum |
|Exhaust manifolds: ||cast stainless steel |
|Compression ratio: ||9.2:1 |
|Valve configuration: ||overhead cam; |
four valves per cylinder
|Valve lifters: ||hydraulic lash adjuster, |
roller finger follower
|Firing order: ||1-3-4-2 |
|Fuel system: ||Gasoline high-pressure, |
variable-rail pressure, spark ignition
direct injection (SIDI)
|(hp / kW): ||260/194 @ 5,300 rpm |
(SAE certification pending.)*
|Torque (lb.-ft. / Nm): ||260/353 |
@ 2,500 - 5,300 rpm
(SAE certification pending.)*
|Fuel shut off: ||6,300 rpm |
|Crankshaft: ||forged steel |
|Connecting rods: ||forged steel |
|Additional features: ||air-to-air intercooled |
|dual scroll turbocharger system, variable valve timing, electronic throttle control, pressure-actuated piston cooling jets, extended-life spark plugs, extended-life coolant, GM oil level sensor, extended-life accessory drive belt, Nimonic sodium-filled exhaust valves |