Six Points: Twin-Scroll Turbo Tech In The 2015 Ford Edge

March 13, 2015

The 2015 Ford Edge, for which we posted our first driving impressions this past week, has been fully redesigned to fit right in with Ford’s latest lineup of cars and crossovers, and reengineered to have a far more refined yet responsive freel from the driver’s seat.

Two of the three engines in the 2015 Edge are new, and they make a significant contribution to this model’s concerted improvement and world-class aspirations.

ALSO SEE: Nissan Murano Vs. Ford Edge: Compare Cars

One of those is the new twin-turbocharged, 2.7-liter V-6 that’s offered exclusively in the Edge Sport. It adds quicker performance than the previous 3.7-liter naturally aspirated V-6 in the Sport, and offers a relatively lag-free, strong, and remarkably engaging yet smooth-and-silent driving experience—save for the off-cadence thrum that we found sounded a lot like a five-cylinder.

2.0-liter twin-scroll EcoBoost engine, debut in 2015 Ford Edge

2.0-liter twin-scroll EcoBoost engine, debut in 2015 Ford Edge

But the one that will make the most difference is what Ford anticipates will soon be the most popular engine in the lineup—a 2.0-liter turbocharged four-cylinder engine, making 245 horsepower and 275 pound-feet of torque.

You might notice that power and torque numbers are both up by five versus Ford’s other models to offer the 2.0-liter EcoBoost. That’s because it’s the first model from the automaker to get this new, ‘second-generation’ version of that engine, with a twin-scroll turbocharger setup that helps gain some of the same advantages of a twin-turbo setup.

READ: 2015 Ford Edge: First Drive

It follows the 2.3-liter twin-scroll EcoBoost engine that’s already now offered in the 2015 Ford Mustang, Lincoln MKC, and Ford Explorer.

Click on to see six observations on what makes this engine, its technology, and its pedigree so noteworthy.

EcoBoost badge

EcoBoost badge

EcoBoost now comes standard

As a show of confidence, Ford is making this version of the EcoBoost far more widely available on the 2015 Edge than it was before. While it was only offered with front-wheel drive before, the new version is available with all-wheel drive, and is approved to tow up to 3,500 pounds.

While the turbo four was optional last year, for $995, you now need to pay $425 extra to get the V-6.

 

Turbocharger housing - 2.0-liter Ford EcoBoost engine

Turbocharger housing - 2.0-liter Ford EcoBoost engine

Turbo lag is (almost) a thing of the past

In the outgoing four-cylinder EcoBoost engine, exhaust-manifold runners come from the two middle cylinders and the two outer ones and converge into one flow into the turbocharger. Yet in a twin-scroll turbo, you cut the runner in half. And those two cylinder flows stay distinct all the way down to the turbo, so you keep the individual exhaust pulses distinct.

The benefit, as we confirmed on our test drive this past week, is less turbo lag or, as automotive engineers call it, “time to torque” for the turbocharger. It’s already in fractions of a second, but with the twin-scroll setup, it’s a small fraction of what it was with the single-scroll version.

“You relieve the traffic jam and basically, you’ve added another lane,” said engineering manager Scott Slimak. “In customer terms, or what I would tell my neighbor, there’s quicker response, there’s not that initial delay...so ultimately, there’s improved responsiveness and better performance.”

Exhaust runner for Ford 2.0-liter twin-scroll EcoBoost engine

Exhaust runner for Ford 2.0-liter twin-scroll EcoBoost engine

You gain efficiency and reduce emissions

That reduced turbulence, and a better delivery of exhaust pulses to the turbocharger means that you capture more energy with the turbo—which pays off with more power and better fuel economy.

Peak turbocharger boost is the same as the previous version, so that output gain largely comes from the longer exhaust cam that twin-scroll setups enable. You have to close that exhaust valve before the turbo housing pushes air back into the cylinders. Since the paths are closed off in a twin-scroll setup, you can leave the valve open longer, reducing the amount of work the piston has against a closed valve.

The exhaust-valve change alone is good for a one-percent gain in fuel efficiency, as well as better emissions performance, Ford claims.

Gasoline prices in California, August 2012 [photo: Brenda Priddy]

Gasoline prices in California, August 2012 [photo: Brenda Priddy]

Higher MPG and power? There are definitely some asterisks.

If that's too much geekery, and you're just interested in mileage ratings, so far there are no great gains to report. The new engine hasn’t produced any boost in EPA fuel economy numbers; while the 2014 Ford Edge with the single-scroll turbo and front-wheel drive earned estimates of 21 mpg city, 30 highway, the 2015 model with the dual-scroll version earns 20/30 mpg. There’s also the issue that Ford rates the engine for power and torque with 93-octane gasoline.

Since it’s a base engine, in a mass-market model, we think it’s only fair to point out that while torque would stay the same on lower-octane (87 is common) gasoline, power ratings would be about ten percent lower, or around 220 horsepower.

Chrysler Engine Stop-Start (ESS) technology - slated for 2015 Jeep Cherokee

Chrysler Engine Stop-Start (ESS) technology - slated for 2015 Jeep Cherokee

Better chances for real-world mileage improvements?

As before, the engine has an aluminum engine block and cylinder heads, as well as a dual overhead cam design and four valves per cylinder. It gets new pistons, and its cylinder head has been redesigned somewhat. Also, the manifold is now cast as part of the cylinder head. All of these traits, but especially the latter, allows better, uniform cooling and more importantly, faster warmup that may improve real-world mileage.

Furthermore, the engine will be available with Auto Start-Stop, which will turn the engine off, to save fuel, at stoplights when it makes sense, and then restart it momentarily when you lift off the brake pedal.

American flag

American flag

EcoBoost fours now Made in America

And there’s one other change that will reduce Ford’s manufacturing footprint on these EcoBoost vehicles. Previously, 2.0-liter EcoBoost engines were built in Spain, then shipped to the U.S. for vehicle assembly. But the new 2.0-liter is also supplied from the automaker’s engine plant in Cleveland, Ohio—much closer than before to the Edge’s assembly in Oakville, Ontario.

Look for the new twin-scroll 2.0-liter EcoBoost engines to be phased in for other models in the near future.

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