Large naturally aspirated engines are more efficient than small turbos

[niky]

Given a mixed fleet with mixed drivers and mixed styles and conditions, the results are obviously... mixed.

Unless they drive the cars on the same route back-to-back with the same set of drivers (rotating), then the figures should be taken with huge grain of salt.

I semi-agree with the premise... as when I drove the Explorer EcoBoost, the economy I got was not really that much better than the V6... and the EcoBoost was only 2WD... but this needs controlled testing.

[RobertISaar]

Originally Posted by oil pan 4

A Turbo gasoline engine need 20% fuel to make the same horsepower as a N/A motor.

But on the other hand a turbo diesel gets better fuel milage with a turbo. I have done the N/A to turbo diesel thing and picked up 2mpg on my diesel suburban.

exhaust restrictions are the devil. and so are engines that need exceedingly rich AFRs to keep cylinder temps down.

diesels love air.... and lots of it. not surprising to see a bump in fuel economy when pressurizing them.

[razor02097]

I think the point of their testing was putting a tiny engine in a land yacht doesn't necessarily net you better fuel economy.

For instance in their road test of the fusion the 1.4 turbo didn't perform well in the city, In the video of the road test the lady described the engine seemed to have to work hard to get the vehicle up to speed. I'm sure if you used hypermiling techniques you could boost the numbers but their city tests are pretty straight forward...Stop and go, corners, low speeds, etc. They put in a fuel flow meter and drive the same course for every vehicle. All the performance data is collected on a closed test track.

I'm pretty sure they don't use data collected from their employees driving them around every day. That test is for "how is the car to live with". I wouldn't ignore their experience but I wouldn't take it as gold either. However if you are shopping for a new car it's pretty valuable info. When you go in you have data from an independent source and know better what to look for.

I'm in no way affiliated with CR... In fact I have my own gripes about them... such as buying $50k to $100k cars and not testing the new smaller eco cars... Also they are more and more reviewing pre production or borrowed cars where before they kept saying how they "pride" themselves on how they buy the car just like you and me then do unbiased testing...

[cRiPpLe_rOoStEr]

I've already seen some engines with the same displacement of a N/A delivering better fuel-efficiency, since in a large vehicle a small underpowered engine would have a higher effort to move it while either a bigger N/A or a turbocharged in the same size would be more suitable. After all, turbocharging is not the only factor influencing the fuel-efficiency - but in a turbocharged one the cam profiles can be set-up for higher torque without significant prejudices to power, for example...

And optimizing the gearing to match either the advantages or to overcome some disadvantages of the engine is also essential...

[gone-ot]

CR "sells" magazines, not technically correct information.

[tjts1]

Hyundai, Los Angeles Times and Consumer Reports in fuel economy skirmish?

http://www.latimes.com/business/auto...,1092336.story

[oil pan 4]

Originally Posted by razor02097

I think the point of their testing was putting a tiny engine in a land yacht doesn't necessarily net you better fuel economy.

Yes GM tried this in the early 1980s. They put 2.8L V6 engines in chevy blazers.
You gained like 1 MPG over the V8 and had no towing ability and little to no get up and go.

[ciderbarrel]

All their tests were done in automatics. They kept complaining that the turbos "kept downshifting too much." I can not understand the point of an automatic turbo that was not meant for drag racing.

[RobertISaar]

Originally Posted by oil pan 4

Yes GM tried this in the early 1980s. They put 2.8L V6 engines in chevy blazers.
You gained like 1 MPG over the V8 and had no towing ability and little to no get up and go.

V8? you're referring to the K5 blazers then? because the smallest engines those got were the 4.1 straight six...

[rmay635703]

Read the consumer report on the Citicar.

Boiling exploding batteries blow acid all over occupants.

Can't say I ever experienced that.