Are turbo engines more efficient when driven hard?
 

I don't understand how the government can mandate what kind of engine you get in a car, especially a low volume car like a sports car.

Also, is it the case that having a smaller engine with turbos is more efficient when you're actually using the turbos? When you put your foot to the floor and the exhaust gas comes into the cylinder, doesn't it also call for more fuel? Do they test mpg with cars under hard acceleration? Everytime I read about forcing companies like Porsche or Ferrari to put tiny engines with turbos that ruins the sound and throttle input it gets me upset.

Are turbo engines more efficient when driven hard?
 

It's a farce! There is logical understanding of what's happening.

The gov't intrudes on our life more and more every year, even down to what size soda one can buy.

Only more efficient when driving like a grandma to hit these magical feel good numbers. Have you read the parameters which they test cars for MPG and emissions? It's a joke.

Blame the politicians in Europe and here. Europe is even crazier than the kooks here. I know this will snowball into a political debate, but that's the pushing force behind this. No escaping it.

The few reviews on the new engines have not been favorable.

The irony is that Europeans probably drive faster on public highways (and consequently further away from the EU efficiency profile) than any other continent....

I honestly don't see what the government has to do with the question asked by the OP.


My response is that one should not care about MPG when buying a magnificent car as is any Porsche 911! You will not care about MPG when the adrenalin is flowing. Unless you plan to race for a living, these cars deliver more wonderful driving experiences than most owners can handle.

Are turbo engines more efficient when driven hard?
 

OP's first sentence ...

"I don't understand how the government can mandate what kind of engine you get in a car, especially a low volume car like a sports car. "

We are getting turbo engines shoved down our throats. I have nothing else to offer here. Checking out!

Gotta agree with all that The STG writes here. Porsche absolutely would not be building the engines they're building for 991.2s if they weren't trying to target an artificial mileage cycle mandated by the EU. The quest for increased power would be reached via other engineering means, as has been the case since the 911 began as a 130hp sportscar. When the 3.8 was making 380hp in 997.2, it seemed surely to have reached its max. But they created the 408hp powerkit. Then the standard motor jumped to 400, and they produced the 430hp powerkit. Something would be done to keep it NA if the motor were allowed to be developed by the engineers and not have to bow to this mandate.

I'm all for cleaning up the air, but as the central question in the OP points out, does this actually clean up the air given the way people use automobiles?

Point taken. However, I'm sure that Porsche, like all businesses, make decisions that are not necessarily tied to government regulations. I'd be interested in hearing a statement from Porsche. When someone refers to efficiency in the context of cars, I think of two things. Power output for size of engine and MPH which the average consumer is generally focusing on. I responded to the latter.


As for my interpretation of the OP's first statement, I honestly don't have any proof that any government has forced any automaker to use any particular engine in any particular car. Do you? Just curious.

I believe the whole raison d'etre for turbo charging *is* greater (thermal) efficiency of the engine, i.e for a certain "input" (fuel, air mass, temp) the
"output" (tq, bhp) will be (in general) greater than N.A of the same configuration (because of the greater compression hence air mass) the turbo
charger is effectively an energy pump recovering "waste" energy from the
exhaust and re-injecting it back into the engine essentially recovering it
to add it back into the engine input thus overall increasing output efficiency
(reducing loss thru waste).

I suspect that, at least in part, turbo-charging is the result of how fuel consumption and emissions are measured and reported.

What a turbo does is let you run small engines which, driven the way they for official tests, are relatively fuel efficient and low-emission. But that same engine, driven at RPMs higher than usually used in such testing, can claim high horsepower and performance (relative to engine size and reported "green" metrics, anyway), which is what many shoppers are looking for.

were you guys around in 1998? The conversation was nearly the same when Porsche announced the end of the air cooled engines and the next get would be the 996 Water Cooled. The Posrche faithful were ON FIRE about it (and some still are).

Same thing on BMW motorcycles, when the boxer engine has to go water cooled to stay up with power increases and emissions. Harley Davidson won't be far behind.

The one constant in vehicles is change, and they will always be changing. Mostly for the better, too. Look around at oil prices now, they're depressed worldwide as we have begun to fine alternate energy and are vehicles are more fuel efficient. It's all good.

Porsche put a Turbo in their first 911 way back in 1976. They know what they're doing, rest easy.

I absolutely hate having political stuff forced on me when trying to enjoy a hobby, but in this case it's central to the hobby.

Every article I've read about future engines says something like "due to government mandates, the engine will be downsized and getting turbos". Hence why I'm asking about what gives the government the right to tell me what kind of engine I can buy in a car.

This is not a safety issue, like airbags or head restraints, so why is it taken for a surety that car makers must comply with some fuel standards I never asked for? I'm genuinely confused how the automakers all let politicians decide what kinds of vehicles they'd make in the future.

I don't think any of the regulations mandate automakers to put turbos in their engines. It only mandates that they burn less fuel / lower emissions. As I understand it, one way to do this is by reducing engine displacement. However, automakers always need to improve power and performance in order to sell. One way to do that is by turbocharging.

Been lurking around these Porsche forums for a while now. I don't post since I am just here to gather some intelligence on any long term issues with the 991 generation before purchasing one a year or two down the road.

But responses such ones written in this thread is getting a little ridiculous. I get it, we all love fast cars, nice sounding exhaust, and engines with instant throttle response. But downsizing the displacement and emission of internal combustion engines is by all mean necessary given bleak environment issues that we are facing. You can rant all you want, but there is simply no way to make a emission friendly NA engine that can compete with the rest of the cars in this price range.

Truth is, technology moves forward, whether you like it or not. Or else we would all be stuck driving lead burning, carburetor fueled engines with flat tapped valves that needs to be manually adjusted every few thousands miles. Porsche knows what they are doing, putting a pair of turbos on the flat six makes total sense for the non-GT 911, given the much needed torque in the mid range and more linear power delivery than a high stun GT engine. And if you understand the specs for the current NA engines that Porsches uses for their 911 range, you will realize that the development for these engines have truly reached an dead end. There is simply no way to further increase the power output without drastically increasing the displacement (hence the rumor'd flat-8) or going with forced induction, which is the more reasonable choice of the two.

After all, these are still 2.7-3.0 L flat six enigne with a conservative boost pressure (my guess is 10-18 psi, given the expected power output of 420hp), so the so called turbo lag will be nearly indistinguishable to most drivers here on this sub forum, considering very few owners here are actually tracking these cars and have the driving skills to push the chassis and the engine to their limit. And I am not even sure why some people here think the 991.2 will weight hundreds of lbs heavier than the 991.1... A pair of turbos and some extra plumbing for the intercoolers will add 50lbs max., and I bet Porsche will figure out a way to further reduce that number given their expertise in these areas. And really, there is NO WAY you can tell the difference of extra 50lbs in a modern street car that weights +3000lbs.

Sure, exhaust might sound different, and might lack the iconic raspiness of the NA flat 6. But it is a very minor trade off for the extra performance and better emission. And there are aftermarket solutions for these issues if you really care enough. Personally, I am very looking forward to a RWD 991 chassis paired with a potent turbocharged engine and latest PDK that I can enjoy on the street and track, without the harshness and compromises of the last gen GT2s. And honestly, if you want a "pure" 911 experience, just get a old gen like the 964, or the original 911 for god's sake... Even the 993 wasn't a "true 911" by the strictest definition, given the move from the traditional, lift-off oversteer happy, rear trailing arm suspension to the more modern and predictable multi-link setup in the 993.

It's not just mileage requirements, it's carbon emission limits. But regardless, you're correct that government regulations are the reason for the turbo engines.

Are turbo engines more efficient when driven hard?
 

You have to blame the people in Brussels for the change in the motor industry.

No one is forcing the manufacturers to turbo charge. But! At the moment this is the easiest and cheapest way to live up to emission goals set by the EU.
The MPG numbers posted on a for sale sticker in the US is very close to the true consumption. They use a city and Highway average.
In Europe that's not the case. The provided km/l numbers are based on the EU driving test cycle that all cars have to do. And here lies the big problem.
These numbers are far away from real world consumption.
So all manufactures fine tune their cars to get great numbers in the "cycle" and getting :rockon: :thumbup: :thumbup: :thumbup: from Brussels.
In most cases real consumption is 20-50% more than stated.
For the polar bears and us, there is no difference. Just a smaller turbo charged engine that if you don't use the turbos will burn less fuel.