Turbo 2.0L 4cylinders - Beat V6s? (Ecoboost, etc.)

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I was down pretty hard on Ford's Ecoboost effort, labelling them as largely failed. However, that whole approach may have a future. Its a partial success, half-failure, trying to gain fuel economy while delivering power using a smaller blown 4.

Anyway, to get a look at what that ubiquitous 2.0L turbo 4, various designs of that size/type, can do, take a look at the list below, from CarAndDriver archives. All cars listed have 2.0L turbo 4's unless they say "v6", for comparison (arranged by city EPA MPG number):

2014 Audi A3 24/33 220 hp 5.4 sec
2014 Audi A4 24/32 220 hp 5.6 sec
2014 Mercedes CLA250 24/32 208 hp 6.1 sec
2013 BMW 228i 23/36 240 hp 4.9 sec
2012 BMW 528i 23/34 240 hp 5.9 sec
2012 Hyundai Sonata 22/34 274 hp 6.5 sec
2014 Ford Fusion 22/32 240 hp 6.6 sec
2014 Ford Focus ST 22/32 252 hp 6.0 sec
2013 Nissan Altima v6 22/31 270 hp 6.1 sec
2013 Honda Accord v6 21/34 278 hp 5.6 sec
2014 Hyundai Sonata 21/32 274 hp
2012 Toyota Camry v6 21/30 268 hp 5.8 sec
2014 Chevy Malibu 21/30 259 hp 6.2 sec
2014 Cadillac ATS 21/31 272 hp 6.0 sec
2013 Buick Verano 20/31 250 hp 6.4 sec
2014 Cadillac CTS 20/30 272 hp 6.2 sec
2012 VW Passat v6 20/28 280 hp 6.3 sec
2015 Chrysler 200 v6 19/32 295 hp 6.3 sec
2011 Chevy Camaro v6 19/30 312 hp 6.0 sec
2014 Kia Cadenza v6 19/28 293 hp 6.2 sec
2014 Cadillac CTS v6 18/29 321 hp 6.0 sec
2014 Chevy Impala v6 18/28 305 hp 6.0 sec
2014 Cadillac ATS v6 18/28 321 hp 5.4 sec
2014 Corvette Stingray17/29 460 hp 3.9 sec
2011 Chevy Malibu v6 17/26 252 hp 6.3 sec
2014 Cadillac CTS v6Turbo 17/25 420 hp 4.4 sec
2014 Chevy SS v8 14/21 415 hp 4.5 sec
2011 Cadillac CTS-V 12/18 556 hp 3.9 sec

Too slow:
2014 VW Passat (1.8T) 24/34 170 hp 7.5 sec
2013 Ford Taurus 22/32 240 hp 7.4 sec
2014 Mazda6 2.5L no-turbo 26/38 185 hp 7.0 sec
 
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You can get good fuel economy out of an eco-boast engine. However, they are geared TOO TALL for good fuel economy. The slightest hill or headwind, and your foot starts to get in it - causing it to start overfueling to prevent detonation.

The 2.0EB / 6F35 combination - somewhat ubiquitous (Escape, Fusion, Taurus, Explorer) has 3.07 "rear end" ratio. That's too tall. I have found that I get better mileage by engaging the select shift and dropping it down to 5 whenever I have a small hill or headwind start. Otherwise it will start pulling timing and overfueling. That keeps the boost PSI down (turbo is still forcing a lot of air in) and keeps it from running rich.

Fuel econ concerns aside, the low end torque is nice ... and they will go like stink (for a 4 cylinder) on demand!
 
The two that really stand out at me for being fast with high fuel economy, are the BMW turbo 4 and the Honda V6, yet its almost a tie when you compare mid-priced v6 cars to blown-4's here.
 
Originally Posted By: Miller88
You can get good fuel economy out of an eco-boast engine. However, they are geared TOO TALL for good fuel economy. The slightest hill or headwind, and your foot starts to get in it - causing it to start overfueling to prevent detonation.


I'd like to see instantaneous MPG comparing a 2.0L turbo4 Fusion to a Honda Accord V6 climbing the same hill here in the Rockies on I-70. Both would have to gear down.
 
The data above is flawed because EPA figures aren't always attainable in real-world driving, particularly with turbo engines. This is about a year old but the point remains.

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Originally Posted By: FetchFar
Originally Posted By: Miller88
You can get good fuel economy out of an eco-boast engine. However, they are geared TOO TALL for good fuel economy. The slightest hill or headwind, and your foot starts to get in it - causing it to start overfueling to prevent detonation.


I'd like to see instantaneous MPG comparing a 2.0L turbo4 Fusion to a Honda Accord V6 climbing the same hill here in the Rockies on I-70. Both would have to gear down.


They would both have to gear down and would probably be running the same RPM (flat torque curve on the EB 4 cylinders) but my money would be on the Honda v6 for fuel economy.

On the flat - ecoboost hands down.
 
Originally Posted By: gofast182
The data above is flawed because EPA figures aren't always attainable in real-world driving, particularly with turbo engines.

The EPA MPG numbers are simply a way to compare vehicles using the same test, thats all. Sure, you can get better or worse depending on how you drive. ... I've seen the federal test procedures used and they explore a lot of different city/hiway RPM & load ranges, idling, etc., a mixed bag.
 
Originally Posted By: Miller88
They would both have to gear down and would probably be running the same RPM (flat torque curve on the EB 4 cylinders) but my money would be on the Honda v6 for fuel economy. ...On the flat - ecoboost hands down.

From the city MPG numbers, the turbo-4's have less internal engine friction, increasing their city MPG over a V6. Maybe the take-away here is if you do more city-type driving, its hard to beat the idling (start/stop systems like what the BMW has helps too) fuel economy of a smaller 4.
 
Originally Posted By: Clevy
Am I to understand that the 2014 corvette has a turbo 4 cylinder engine.
Pretty good power though
corrections:
2014 Corvette Stingray v8 17/29 460 hp 3.9 sec
2011 Cadillac CTS-V v8 12/18 556 hp 3.9 sec
 
Originally Posted By: FetchFar
Originally Posted By: Clevy
Am I to understand that the 2014 corvette has a turbo 4 cylinder engine.
Pretty good power though
corrections:
2014 Corvette Stingray v8 17/29 460 hp 3.9 sec
2011 Cadillac CTS-V v8 12/18 556 hp 3.9 sec



Those cars have displacement-on-demand, so they do function as 4-cylinder motors sometimes.
smile.gif
 
I'd rather have a 6 over a turbo 4 any day. Mainly because I've had 4 (inc turbo) and 6 cylinder cars and I prefer the smoothness of the 6s. Also the 6 cylinder will always be more reliable (for most makes at least)
When turbos kick in it's a good feeling for sure but in a straight line the 6 I own now is quicker and has power from a breath on the pedal without the turbo lag
There are a lot of turbo 4s out now that use more fuel than their 6 cylinder brothers because of the way they get driven, i.e. Keeping the revs up to keep the turbo working
 
Originally Posted By: 19jacobob93
I'd rather have a 6 over a turbo 4 any day. Mainly because I've had 4 (inc turbo) and 6 cylinder cars and I prefer the smoothness of the 6s. Also the 6 cylinder will always be more reliable (for most makes at least)
When turbos kick in it's a good feeling for sure but in a straight line the 6 I own now is quicker and has power from a breath on the pedal without the turbo lag
There are a lot of turbo 4s out now that use more fuel than their 6 cylinder brothers because of the way they get driven, i.e. Keeping the revs up to keep the turbo working


Drive one of the new ecoboost engines. I always thought it would be hard to get something with the torque curve of an old I6 - other than a split second of turbo lag, the 2.0 EB I4 just feels MUCH better than my AMC I6.

I'll still take an I6 over anything.
 
I don't think that Ford's slogan "Power of a V6, MPG of 4" is right a lot of the time. It does depend on the comparison, true sometimes, not in others. Notice the big Taurus with a 2L Ecoboost 4 actually gets great MPG with reasonably 0-60 times. ... This discussion of "how you drive" is interesting. For the EPA city/highway particular mix & variety of driving, we have the answer. If you don't have hills or heavy city driving/idling, the turbo4 seems the one.
 
Originally Posted By: Miller88
I'll still take an I6 over anything.


BMW did the opposite of that. My 07 530xi has the venerable normally aspirated N52 inline6, yet for a couple of years now you get a turbo4 in its place, or they insist on a turbo on the current 6.
 
One comparison above, the VW 1.8T and the Mazda non-turbo 2.5L, really stands out as why you might not accept the "u gotta have a turbo" crowd:
2014 VW Passat (1.8T) 24/34 170 hp 7.5 sec
2014 Mazda6 2.5L no-turbo 26/38 185 hp 7.0 sec
Better fuel economy AND power in a normally aspirated 4 over the 1.8T. This tech race is far from over, yet I'd currently take a Mazda6.
 
A turbo 4 is definitely in the same power/torque zone as a V6, and will ALLOW (key word!) the driver to get better mileage if they choose to keep their foot out of it. Turbo lag is pretty well eliminated these days, too. The current crop even has fairly good vibration suppression compared to 10 years ago, but an inline 4 will *never* have good inherent balance and will produce more vibration without bigger fluid-filled or elastomeric engine mounts than a similar powered v6 (which in turn has less ideal balance than an I6) and balance shafts. They're fine for appliance cars, but I can't stand the feel/sound of most inline 4-bangers. I'm not a member of the Church of Subaru, but the boxer 4 is definitely the best way to go if you're limited to four cylinders.
 
Are any of the recent motors very different in lbs of fuel burned per hp? Put your foot into anything, and it burns gas to get the job done.
 
Originally Posted By: supton
Are any of the recent motors very different in lbs of fuel burned per hp? Put your foot into anything, and it burns gas to get the job done.


There's still a slight penalty to pay for each extra cylinder (not so much per cubic inch- that's on a flatter curve). Pumping losses, frictional losses. But overall I think you're right- the shape of the vehicle makes a bigger difference (aero), and then comes weight, rolling resistance, and then number of cylinders. The fact that the same power is available with a turbo 4 or a v6 (or a turbo 6 vs. an eight) just means the driver has to work harder NOT to use the power.

When I'm careful with my SRT, it will get 25 on the highway pretty easily. Use the power whenver I want to: it'll get 23 highway. The v6 Challengers with the new 8-speed auto trans are rated in the low 30s mpg highway. So there's your penalty for 170 additional horsepower on tap and two extra cylinders (and all the cylinders are larger)- around 5-7 mpg. Granted, its a heavy vehicle and the difference might be more pronounced with a lighter car.
 
The fuel economy can vary greatly on higher powered, turbo'ed 4's. Those CR EPA averages are a bit low based on how they were probably driven. The Fusion with the 2.0 averaged 22MPG.

Our Focus ST weighs 400lbs less and is geared without really caring about MPG and it brings 24-26MPG averages with all around town driving. It's rated 23/32.

You can drop MPG on the ecoboosts down to horrific numbers or keep things looking good, these engines vary a lot on how you drive them. I feel something like a new V6 will bring more consistent MPG's on each fill-up, but if you drove both trying to get the best mileage I feel the ecoboosts would surprise a few people.
 
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