Gen IV Ecotec -- an opportunity for change

[dwightlooi]

4^th Generation Ecotec (circa 2017)

The 4^th Generation Ecotec represents a significant architectural shift in GM’s High Feature engines and a significant reduction in the number of different engines in the lineup. There is no longer Family 0, 1 and 2 Ecotecs, and the total number of concurrently produced variants goes from 24 to just 5 for all applications. The following summarizes the key features of the Ecotec⁴:-

• All engines are turbocharged and utilize air-to-water intercooler(s)
• All engines sport a 79 mm (bore) x 81.5mm (stroke) with a 10.8:1 compression ratio
• The valvetrain transitions to a SOHC layout with concentric cams
• 2-stage cam profile switching and dual independent VVT are standard
• Direct gasoline injection is standard
• Pistons, rods, valves, springs, lifters, rockers and most parts are fully interchangeable
• Vee configuration engines feature reverse flow heads and a single turbocharger
• Ecotec⁴ engines are available in Inline-3, Inline-4, V-6 and V-8 configurations

The Ecotec⁴ family seeks to achieve class leading refinement, superior fuel efficiency and performance equivalent to or exceeding the engines it replaces. Unlike previous GM turbocharged engines, the static compression ratio is kept at a lofty 10.8:1, while boost pressures are reduced by about 33%. High off-boost compression promotes reduced fuel consumption during cruise. The incorporation of independent VVT and a cam switching system allows the engine to manage compression under load by selecting between two intake periods and dialing in either overlap or keeping the intake valves open into the compression stroke. This allows 87 octane fuel to be used without the risk of denotation although output may be reduced. Because the boost levels are lower the engines do not make as much torque as the previous generation. The turbochargers are not actually smaller and, featuring 3D aerodynamics, are actually more efficient. Combined with the extremely small pressurized volume afforded by air-to-water charge coolers, boost rise is radically quick and maximum torque is maintained over the widest range in the industry. Most of the Ecotec⁴ engines stretches their torque peak over a 4000 rpm range – amounting to a 1000 rpm wider plateau than the previous generation. Maximum engine speed is capped at 6200 rpm allowing very light valve springs to be used reducing valve train drag, which along with using a single cam design provides superior fuel efficiency over competing DOHC offerings.

The Ecotec⁴ family also replaces the previous 3.0 and 3.6L engines with a 2.4L boosted V6 and a 3.2L V8. These engines are very low in displacement for their cylinder count and offers a unique level of refinement and efficiency over the competition. The 2.4L turbo V6 is roughly equivalent to the outgoing 3.6L naturally aspirated engine, while the 3.2L V-8 matches the output of the outgoing 3.6L Twin-turbo engine. Both engines are about 6~12% more fuel efficient and 30% lower in NVH compared the engines they replace. Unlike the previous generation 3.6L bi-turbo V6, the new 2.4T V6 and 3.2T V8 do not drive like turbocharged engines. The combination of very light reciprocating mass, high compression and relatively modest boost allows it to mimic the driving characteristics naturally aspirated engines of 50% greater displacement. The low displacement of these power plants also allow GM to offer 6 cylinders against competing fours and V8s against competing V6 offerings in markets which imposes a displacement tax.

1.2T Ecotec⁴ (LV3)

Configuration---Inline-3 Aluminum Block & Heads w/ single balance shaft

Displacement---1198 cc

Aspiration--------Honeywell MGT1544 turbocharger @ 14.7 psi w/ air-to-water intercooler

Power-------------160 bhp @ 6000 rpm

Torque------------140 lb-ft @ 2600~6000 rpm

Fuel Cut----------6200 rpm

Fuel Type--------91 Octane recommended; 87 Octane (min) required

Transmission----Hydramatic 6T40 6-speed automatic

Applications-----Replaces all 1.4, 1.4T, 1.6 and 1.8 Ecotec engines

1.2T Electra (LVE)

Configuration---Inline-3 Aluminum Block & Heads w/ single balance shaft (Miller Cycle)

Displacement---1198 cc

Aspiration-------- Honeywell MGT1544 turbocharger @ 14.7 psi w/ air-to-water intercooler

Power-------------160 bhp @ 6000 rpm + 40 bhp @ 6000 rpm (Electric; via Flywheel Integrated Motor-generator)

Torque------------140 lb-ft @ 2600~6000 rpm + 120 lb-ft @ 0 rpm (Electric; via Flywheel Integrated Motor-generator)

Fuel Cut----------6200 rpm

Fuel Type--------91 Octane recommended; 87 Octane (min) required

Transmission----Electramatic 6E40 6-speed automatic

Applications-----1.4L Voltec Drive, 2.4L eAssist

1.6T Ecotec⁴ (LV4)

Configuration---Inline-4 Aluminum Block & Heads w/ Dual balance shafts

Displacement---1598 cc

Aspiration--------Honeywell MGT2056 Dual Scroll turbocharger @ 14.7 psi w/ air-to-water intercooler

Power-------------214 bhp @ 6000 rpm

Torque------------186 lb-ft @ 2200~6000 rpm

Fuel Cut----------6200 rpm

Fuel Type--------91 Octane recommended; 87 Octane (min) required

Transmission----Hydramatic 6T50 6-speed Automatic

Applications-----Replaces all 2.0, 2.0T, 2.4 and 2.5 Ecotec engines

2.4T Ecotec⁴ (LV6)

Configuration---Reverse Flow 90° V-6 Aluminum Block & Heads w/ single balance shaft

Displacement---2397 cc

Aspiration--------Honeywell MGTX2863R Dual Scroll turbocharger @ 14.7 psi w/ air-to-water intercooler

Power-------------320 bhp @ 6000 rpm

Torque------------280 lb-ft @ 2000~6000 rpm

Fuel Cut----------6200 rpm

Fuel Type--------91 Octane recommended; 87 Octane (min) required

Transmission----8T50 6-speed Automatic, 8L50 6-speed Automatic

Applications-----Replaces 2.0T (high output), 3.0, 3.6 Ecotec engines

3.2T Ecotec⁴ (LV8)

Configuration---Reverse Flow 90° V-8 Aluminum Block & Heads

Displacement---3196 cc

Aspiration--------Honeywell MGTX3067R Dual Scroll turbocharger @ 14.7 psi w/ air-to-water intercooler

Power-------------428 bhp @ 6000 rpm

Torque------------375 lb-ft @ 2000~6000 rpm

Fuel Cut----------6200 rpm

Fuel Type--------91 Octane recommended; 87 Octane (min) required

Transmissio-----Hydramatic 8T70 8-speed automatic, Hydramatic 8L70 8-speed automatic

Applications-----Replaces 3.6 TT engine

Edited February 2, 2014 by dwightlooi

[carguy10101010]

Would this approach really net any gains over simply using an IBC design for all of the V6 and V8 engines? It seems to me if one is going to the trouble to make a high compression boosted V6 that you may as well crank everything up more and add methanol/ethanol injection to the whole setup to get much bigger efficiency and/or power gains. I know with diesels they can tie a methanol injection setup directly into the windshield washer fluid. I assume the same could be done on a gasoline engine. Perhaps gasoline could be port/throttle body injected as well as direct injected while the methanol/ethanol could be direct injected only? Keeps things cool and burning efficiently, which should allow somewhat higher boost and/or compression ratios. I suppose you would want more compression ratio with the above proposal since the idea would be to use little boost.

[carguy10101010]

I guess the overarching question would be is there a true performance reason to run an engine line based upon lower displacement boosted engines, or would it be simpler/easier/more effective to stick with an L86 or L83, and either lop off a set of cylinders and/or add boost to hit certain power/performance goals? An I4 would be needed as well I suppose.

[dwightlooi]

I guess the overarching question would be is there a true performance reason to run an engine line based upon lower displacement boosted engines, or would it be simpler/easier/more effective to stick with an L86 or L83, and either lop off a set of cylinders and/or add boost to hit certain power/performance goals? An I4 would be needed as well I suppose.

No, it won't actually be lighter than a large displacement IBC engine. That's because a pushrod small block so extremely compact, lightweight and efficient it's not even funny... It may or may not be more fuel efficient, but if so it won't be a hellof a lot more fuel efficient. The main advantages are really the ability to skirt the higher displacement tax brackets in some markets and the lighter reciprocating masses resulting in somewhat improved vibrations and NVH. Those and also because there is nothing like it on the market -- a 2.4L V6 or a 3.2L V8 will be relatively unique.

There are two ways you can make big power on a small displacement engine. By making a lot of boost (hence torque) or by spinning the engine really fast (hp = torque x rpm / 5252). Here we are doing a moderate amount of both -- using some boost and maintaining it higher than usual. This approach avoids the lag and poor cruise efficiency of a low compression, high boost engine. It also avoids the low end drivability of a stratospherically revving naturally aspirated engine.

Methanol-Water injection will not work for a production car. Firstly, you can't get methanol at gas stations or grocery stores. Methanol is in fact a toxic substance which causes blindness and a bunch of other acute health issues when ingested or breathed in. Nitrous Oxide is illegal for use on public roads in most states and similar supply infrastructure issues exists. Ethanol or water or some mixture thereof is better but still... anything short of a factory rally car for the street is not going to resort to "Emergency Power" susbtance injection systems. Fact of the matter is that no factory production car is going to resort to a system which has enough fluid or gas to give just a few minutes of increased power, and cannot be easily refilled anywhere and everywhere. If you are after very high octane ratings running on E85 will get you most of the benefits of running an alcohol-water injection system. I think that a factory car with a "GM-1" or "MW-50" switch -- ala WWII Luftwaffe Fighters -- in the cockpit will be interesting but ultimately impractical.

Edited February 5, 2014 by dwightlooi

[G. David Felt]

I see the value of it for a global market since so many counteries especially the Socialist Euro Union seems to love to tax size. My hate point is the weight and low torque these engines have. Just to beat the tax man you end up building a engine that is not really the best solution.

I will say that I do love this idea especially for reducing the number of engines being built to simplify and increase the profit of GM which would allow you to have special niche vehicles with big block engines.

[dwightlooi]

I see the value of it for a global market since so many counteries especially the Socialist Euro Union seems to love to tax size. My hate point is the weight and low torque these engines have. Just to beat the tax man you end up building a engine that is not really the best solution.

I will say that I do love this idea especially for reducing the number of engines being built to simplify and increase the profit of GM which would allow you to have special niche vehicles with big block engines.

Yes, yes, I get that. But the idea is that this may be more interesting and advantageous compared to building 2.5L and 3.6L DOHC fours and V6es.

Given the power demands and desired rev range of today's "passenger" cars -- by that I mean the Cruzes and Corollas of the world -- the most efficient engine in the 140 hp class is actually a 2.5~2.7 liter four cylinder with a SOHC, 2-valves per cylinder, direct injection, about 15:1 compression and an Atkinson Cycle cam. Specific output will be in the low-to-mid 50hp/L range, with an effective operating displacement of about 1.7~1.9 liters, but it'll have lower brake specific fuel consumption than any DOHC-4v 1.4T of the same 140hp output you can put together. But, such an engine is not without it's flaws. For one, it's BIG meaning some markets will penalize it with a BIG tax even if it allows the Cruze to get say 30/45 EPA mpg. Secondly, it's big meaning it is heavier than an aluminum block engine of a much smaller size. Finally, it's BIG meaning it has big slugs going up and down and that generates more vibrations and NVH -- although potentially not any worse than the 2.5 GM engine or the 2.7L Toyota I4 in the cute-Utees.

Look.... DOHC is bad for fuel economy, 4-valves are bad for economy, turbos (consequently low compression) is bad for economy. Unfortunately, stupid law makers don't get it or don't care!

Edited February 7, 2014 by dwightlooi

[Drew Dowdell]

Is there any official displacement measurement system with regards to the law? Do they have to measure to bottom dead center in each cylinder or can the say "the effective displacement is X.X liters"?

[dwightlooi]

Is there any official displacement measurement system with regards to the law? Do they have to measure to bottom dead center in each cylinder or can the say "the effective displacement is X.X liters"?

Swept volume -- 0.5 x bore_size x stroke_length x Number_of_cylinders. They don't care about effective displacement. Now, Mazda did pull a fast one and called their 3.0 Miller Cycle V6 a 2.3 Miller Cycle V6 based on the fact that about 24% of the intake charge is kicked back out the cylinder because the intake valves stay open during first 24% of the compression stroke. But that's for the US Market, and the US has no displacement tax, so whatever they call it has no regulatory consequence whatsoever.

[loki]

do "we" know when GM will add DI to the 1.8L and 1.4L turbo in the cruze and sonic.....?

slightly off topic....

[Drew Dowdell]

I think they'll go to the newer 1.6T with DI instead. The 1.4 is getting rather dated....

[dwightlooi]

do "we" know when GM will add DI to the 1.8L and 1.4L turbo in the cruze and sonic.....?

slightly off topic....

The current word is never... both will be retired.

[dwightlooi]

The point here is that you actually get the best fuel economy for any given power output with large displacement + low specific output. Try beating the fuel economy of a 140hp 2.5L SOHC 8-valve Atkinson cammed engine with a 140 hp 1.4L DOHC 16-valve or 20-valve turbo. You won't beat it -- save yourself the trouble and don't even try.

But, low displacement engines have an interesting role in beating displacement taxes and if you are going that route one thing that is worth exploring is to go really small and really high output. Doing any less really isn't worth the expense and effort.