spwolf

i think you have problem reading the charts because you want them to be different :-).
There is nothing misleading there.

BTW, As to the BMW, it says it is the same as their I6 3.0l in X3, not better... and for VW, they say their NA engines suck so cant be compared, as they do :-).

We all knew what is written there is true because we read those comparo tests.

Only where small turbo's are better is under 2.5l 4cly... because NA engines under 2.5l are simply weak.

gengar

Uh what? How can you make that accusation? His post doesn't address volumetric efficiency because that's immaterial to his point. Turbocharging increases air density, but fuel density needs to be raised as well to match the increased air density - that's his point. You don't get free energy efficiency gain. Energy efficiency is independent of volumetric efficiency.

Droid13

I'm going to have to side with the other two on this point. The fuel air ratio is something that's precisely as possible controlled for optimal power, efficiency, emissions, and catalytic converter life. Gasoline just doesn't burn without air, and air just doesn't burn without gasoline. The two have to be in a fairly tight balance. In theory, what you say is true that forcing extra air into the cylinder without adding fuel will be more efficient to a point, but dangerously impractical for a turbo boosted engine. Leaner mixtures burn more efficiently, but much, much hotter. The more or longer you push the leaner mixture, the greater chances of misfire causing increased emissions and cat failure, or even a catastrophic engine failure. How is this solved in practice, more fuel.

ST430

You guys keep arguing that a 290hp FI engine is less efficient than a 140 I4, which is completely irrelevant to the argument. I've been saying that with the same A/F with a NA and FI engine, which do you think makes more power? Or lets ask it another way, if your Supra NA is making 220hp and you detune your 2JZGTE Supra engine to only 220hp, which one do you think would get better gas mileage?

ST430

Having self-tune not only my 600hp EVO, but quite a number of other cars as well, your thinking cannot be more incorrect. Most modern day vehicles are not tuned necessarily for optimum power (if it was guys like Dinan / Vishnu / Cobb would be out of business), but with worse case safety in mind to guardband the variations in engines and vehicles produced. Secondarily, with today's intercooling/DI technologies, FI applications are more safe then ever before. The key to avoiding preignition (detonation) on FI vehicles is yes, sloppy/lazy fuel mapping (which i absolutely detest and could actually lead to loss of power) or 2 optimizing the charge density via high octane (E85 does wonders), lowering the intake charge temps accordingly (DI), or decreased timing. It's interesting that ya'll are debating this when billions of R&D of the biggest companies in the world have done their own research to conclude this already. Anyhow, I;m going to stop deliberating this and let you guys discover the magic of FI yourselves. Given that Lexus/Toyco will introduce their own in the coming years, I think it will turn many of you guys into believers when it is done right!

SteVTEC

http://news.consumerreports.org/cars...my-claims.html

The Dodge Dart is flagged and bolded for "not meeting mileage expectations", yet it still performs much better and gets better fuel mileage than its NA counterpart. Why is that? Because turbo engines are less efficient? That's a bit misleading. Half of the other NA cars also didn't meet mileage targets in their testing. Rather than singling out turbos they should have just said that half of the cars don't meet mileage targets. It's not just a turbo thing.

spwolf

they are comparing turbo's to NA engines and find that they perform worse instead of performing better, look at the chart in first post.

instead you are generalizing, doesnt make sense... they made specific claims and compared the cars there.

but again, it is nothing we didnt discuss before in various comparo reviews... very few turbo engines ended up being top of the class.

gengar

When did I ever argue that? In this thread you have accused someone of not understanding something that they didn't even talk about and then claiming someone said something they never said. You need to chill out.

SteVTEC

na-ah you are.

You're cherry-picking the examples where they perform poorer and get better mileage while completely ignoring the ones that do perform better AND get better mileage, just as you always have.

I was very specific in my longer post that when turbo engine are done properly as mainly the Germans seem to know how to do at this point, their promises become true. There are many ways to go wrong, as I also explained and which you have once again completely ignored in favor of one-liners.

ydooby

Interesting rebuttal today from Hyundai, which claims that its EPA fuel economy estimates, old or new, are clearly above average in terms of being closer to Consumer Reports' "real world" test results. Although its argument is weak IMO because its chart aggregates all models and not separated by the turbo'd and non-turbo'd models (which was the main point of the CR article), the chart is still an interesting one to draw some comparisons from. It also shows that the American makes are generally worse than average (or "better" at gaming the EPA estimates).

http://www.autoblog.com/2013/02/07/h...er-reports-in/

spwolf

i am referring to the article in OP, hows that cherry picking, it has +10 different cars compared? Which are the ones that do better in performance and mileage? BMW has the same... and VW doesnt have a valid 4cly to compare with.

Aron9000

Last time I went new car shopping was back in October 2011 with my mother, looking to replace her 2000 Avalon with 220k miles on it. Knowing how she liked to get her "worth" out of a car, that meant a VERY long ownership of the new car. With her new job, that meant putting about 25k miles a year on the car just driving to work, not to mention any road trips, which might entail another 2-5k miles a year.

I told her to steer clear of any of these new "turbocharged 4 cylinders"(Hyundia/Kia seem to be the only people selling this type of powertrain at the time) IMO you are going to have more problems and repairs with turbo motors as the miles stack on. I don't doubt manufacturer's claims to have these motors perform flawlessley for the first 100k, but what about when you roll that odometer to 150k, 200k, 250k???? I know for a fact you are going to encounter some very expensive repairs like turbo replacement, wastegate replacement, etc.

Granted these turbo cars might make it to 150k or 200k before requiring expensive repairs, but a damn v6 Camry(which she bought) will just keep running, running, and running with no such bs problems, all the while getting similar fuel economy, similar peak horsepower ratings, and much much much better throttle response.