Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
In europe when BMW changed the 330 engine to direct injection that can run in the lean burn mode, the horspower went from 258 to 272 but more significantly, the milage went from 32.5 ( combined european cylce) to 39.5, a 22% increase. If they did the same to our 328, the milage would go from 28 to 34. Why would BMW not ditch the 335 turbocharged engine and instread increase the displacement of the 330 to 3.4 liters. The horspower would be a little over 300, the milage would remain very close the the 34 mpg ( Honda, Toyota etc did not see their milage decline at all when they went from 3 liters to 3.5 liters.) BMW would then have an engine that put out the same horsepower (albeit less torque) as the 335 but the milage would go from 26 in the 335 to 34 mpg in this direct injected engine. I realize their could still some fuel quality issues to run the lean burn in the United States.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
In europe when BMW changed the 330 engine to direct injection that can run in the lean burn mode, the horspower went from 258 to 272 but more significantly, the milage went from 32.5 ( combined european cylce) to 39.5, a 22% increase. If they did the same to our 328, the milage would go from 28 to 34. Why would BMW not ditch the 335 turbocharged engine and instread increase the displacement of the 330 to 3.4 liters. The horspower would be a little over 300, the milage would remain very close the the 34 mpg ( Honda, Toyota etc did not see their milage decline at all when they went from 3 liters to 3.5 liters.) BMW would then have an engine that put out the same horsepower (albeit less torque) as the 335 but the milage would go from 26 in the 335 to 34 mpg in this direct injected engine. I realize their could still some fuel quality issues to run the lean burn in the United States.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Well, to be fair Turbocharging allows a car manufacturer to use an existing engine platform, improve on power output, match the efficiency of larger engines with similar power figures and makes packaging (based on vehicle) less of an issue.
All of this is achieved without having to design a new engine from the ground up, without jumping to V6 or V8s to get the power and keeps you from having to bump displacement. the former is done without having the cost associated with the latter.
plus...you get great gains with a more compact engine. it a way to save money IMHO.
It is expected that highway millage would improve because boost doesn't come into effect until higher rpm's. So, basically, when you're doing 60mph at 2000rpm's you're running a naturally aspirated 4cyl. motor which will be lighter than a 6 and more efficient. In the real world, however, I see little benefit except for marketing, cost and packaging to manufacturers.
They charge more on the RDX because it uses Castrol Synthetic oil. If you buy the 5 quarts and bring them to a Honda dealership it will cost about $45 total.
On the fuel efficiency of the engine....I used to have an X3 3.0 that normally averaged about 15mpg's, only on the hgwy I was getting about 20-21mpg's. On my RDX now I normally average between 20-22 mpg's daily. With higher numbers when cruising in the highway. And I don't feel too much the differences in power, liking more the Turbo rush once it kick ins. Very few situations you will fill the turbo lag at all, its kept to a minimum very well.
Low-pressure turbocharging allows one to improve the area under the torque curve, which may mean less downshifting and therefore can improve efficiency. It's basically the principle used in the Diesels in big rigs.
The same logic can be applied to a lazy, low-stressed V8, which is why some yank tanks, driven carefully, can achieve surprisingly good results.
It's the "driven carefully rider" that f ucks it all up. Absolute power corrupts absolutely and I tend to redline whatever I'm given. In my case, I get surprisingly good results out of Honda's VTEC engines.
Ultimately, a car of a given size and mass requires a given amount of energy to move it around.
Lower the mass and the frontal area and you'll get better results. Ever heavier, taller, wider cars are gonn a require more squirt, take more cornering requiring more tyre drag and more stopping, needing heavier brakes.
If you wanna increase FE, just add lightness and compact dimensions - length is less of a problem, so build it like an old low-scuttle Honda. You win in all areas by creating a virtuous circle.
To my knowledge turbo charging does not change the fuel consumption of the engine (g/KWh). it DOES alter the BSFC map, however, by lowering the engine load at which peak BSFC occurs. So say an engine takes 260 grams of fuel to make a kilowatt of energy for an hour straight (typical efficiency minded Ford engine). Naturally aspirated, that engine will only be that efficient at 90% throttle load (almost full throttle) and about 2-3k RPM. This is not where we spend most of our time when driving. Now apply a turbocharger. the same peak efficiency may now be available from 75% throttle load, making it slightly more likely that the driver will spend some time in the peak efficiency area of that engine.
Now take an NA Toyota engine, 230g/KWh max efficiency (2010 Prius has a small potato shaped island on its BSFC map that gets 220g/KWh, but after taking the drag of their planetary geared transmission it isn't all that efficient after all). Then, take a Honda engine with several 200g/KWh islands dotted directly over the path of where a driver spends time when accelerating (high fuel maneuvers).
So, all of this is to say that yes, turbocharging can move the most efficient area of the engine to a throttle load and RPM that is more often used. However, even so, Honda engines are so far the most efficient gasoline engines, without turbocharging.
And a quick note to diesel fans: diesel fuel weighs about 12% more than gasoline per "gallon", so measuring diesel fuel consumption based on miles per gallon and calling a gallon of diesel the same as a gallon of gasoline is biased to diesels- they are getting 12% more fuel (by weight) per gallon. Even so, some may say VW gets 197g/KWh with diesel fuel, a full 3g/KWh BETTER than a Honda gasoline engine. But then we look at the efficiency of the drivetrain and find the Honda STILL gets more WHP per gram of fuel consumed. Honda engines really are over-engineered amazing pieces of machinery.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
In europe when BMW changed the 330 engine to direct injection that can run in the lean burn mode, the horspower went from 258 to 272 but more significantly, the milage went from 32.5 ( combined european cylce) to 39.5, a 22% increase. If they did the same to our 328, the milage would go from 28 to 34. Why would BMW not ditch the 335 turbocharged engine and instread increase the displacement of the 330 to 3.4 liters. The horspower would be a little over 300, the milage would remain very close the the 34 mpg ( Honda, Toyota etc did not see their milage decline at all when they went from 3 liters to 3.5 liters.) BMW would then have an engine that put out the same horsepower (albeit less torque) as the 335 but the milage would go from 26 in the 335 to 34 mpg in this direct injected engine. I realize their could still some fuel quality issues to run the lean burn in the United States.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
In europe when BMW changed the 330 engine to direct injection that can run in the lean burn mode, the horspower went from 258 to 272 but more significantly, the milage went from 32.5 ( combined european cylce) to 39.5, a 22% increase. If they did the same to our 328, the milage would go from 28 to 34. Why would BMW not ditch the 335 turbocharged engine and instread increase the displacement of the 330 to 3.4 liters. The horspower would be a little over 300, the milage would remain very close the the 34 mpg ( Honda, Toyota etc did not see their milage decline at all when they went from 3 liters to 3.5 liters.) BMW would then have an engine that put out the same horsepower (albeit less torque) as the 335 but the milage would go from 26 in the 335 to 34 mpg in this direct injected engine. I realize their could still some fuel quality issues to run the lean burn in the United States.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Notyper has talked about this fairly extensively recently too. There are some advantages to turbo efficiency in gas engines, but what is happening right now is slightly different.
1) The US government has dictated a minimum level of performance on their test.
2) Their test involves light load throttle and slow speed driving conditions, which is naturally going to favor a smaller engine, as it can run closer to its peak efficiency and has a lower overall fuel burn by virtue of the fact there is less displacement.
So, this test will clearly favor a smaller engine over a larger one. Since a 100HP 1.3L 4 cylinder isn't going to work in a 4,000lb barge in the real world, we must figure out a way to still provide adequate real world acceleration.
The solution? Turbocharging. It allows a small engine to have the output of a bigger one.
It allows a company to take a small engine that performs well (off boost) on the EPA cycle, and then also provide the area under the curve required to actually accelerate a vehicle.
Unfortunately, as the boost, and thus displacement increase, the total fuel consumption increases drastically. So, what you end up with is an engine that performs well on the EPA cycle, but doesn't deliver anywhere near that in the real world, because in the real world, it must rely on its additional boost in order to perform adequately, and thus there is a big skew between on boost real world peformance and off boost EPA performance. People are still arguing that boosted engines don't operate under boost all the time, which is partly correct. The problem is that in order to improve throttle response, OEM's have had to size the turbos to provide boost just off idle, which means there is probably some boost available or happening at very low RPM's. Also, the smaller turbos are breathing restrictions compared to larger ones, which further compromises efficiency in certain areas.
I don't really blame the OEM's for doing it, because it is more or less dicated by a government entity that knows nothing about engines, or how they work (Congress/the President), and thus arbitrarily creates numbers that look good on paper, but don't occur in the real world. It is a very clear case of intended results versus actual results, and the law of unintended consequences. It is a prime example of the government trying to create one outcome, but in fact, creating something else. The OEM's are going to do what they can to meet the laws they are given, even if it means subpar real world results. The fact that we have divergent requirements makes it even worse. On the one hand, we have a set of laws that dictates increase MPG performance on paper, but on the other we have constantly increasing "safety" requirements that add weight and bulk, which are directly divergent from efficiency. I say "safety" because in this country we focus on reactive safety versus proactive safety, and thus it is not really safety at all, it is protection. But that is another topic entirely.
A good example of this is the Taurus Ecoboost. It is argueable whether a HO NA V8 would in fact get worse MPG, as most numbers I have seen put the Taurus Ecoboost in the mid teens, real world, while providing overal performance that would be similar to that same NA V8. The V8 would be cheaper and if it were high tech in materials construction, it is debateable whether it would even be significantly heavier, not to mention the additional mechanical complexity and reliability issues associated with additional thermal stresses and component count. The fact is that modern comparisons of V8 versus boosted V6 power aren't as comparable IMO, because engines like the small block Chevy and Ford V8 have low VE for what is possible in this day and age. Hyundai's Tau is a good example of this, as for the price point, it provides adequate power and decent efficiency compared to those other V8, which were designed to be cheap.
As long as OEM's have to pursue the path of compromising the technology in favor of a horribly unrealistic lab test, we will continue to see the fallacy of improved gas mileage.
Allow me to provide a brief primer on modern turbocharged engine fueling techniques.
1) Traditionally, once you're into boost, you must run a much richer mixture than a naturally aspirated engine, even when said NA engine is operating at full throttle. For example:
Any engine operating in vacuum - 14.7:1 A/F ratio
Naturally Aspirated engine at or near full throttle - 12.0-13.0:1
Turbo (historically) engine at full throttle - 10-11:1
Expressed in terms of BSFC (we normally use lbs fuel/hp-hr) this will yield (with variations for engine tech and combustion chamber) this will get us:
Vacuum - 0.38-0.42 lbs/hp-hr
NA full power - 0.45-0.5 lbs/hp-hr
Boost - 0.5-0.55 or higher (I swear my Evo is at about 0.6 on pump gas)
The reason that a boosted engine must run richer is due to increased cylinder pressure and heat which increases detonation potential, especially on poor quality pump gasoline. Additionally, those higher temps can be hard on engine components, so even if detonation isn't an issue (race gas), it is still a good idea to run richer than what you'd see on an NA engine.
So, what this yields then is an interesting interrelationship. A small displacement boosted engine can operate very efficiently off-boost, but once you start making power and have to go into power enrichment mode, your efficiency drops dramatically. In contrast, a larger displacement NA engine will lose less efficiency as it transitions into full power operation. Furthermore, on a typical modern turbo engine you will transition into boost at anything above half the rated power output (for a given rpm). By comparison, a large displacement NA engine will operate at stoichiometric up to 80% or more of rated power.
2.) The big change that has skewed things in favor of turbo charged engines lately has been direct injection. To a lesser extent, modern engine management and advanced knock control strategies have also aided the 2nd coming of gasoline turbocharging.
Starting with the less significant change, we see that modern engine management systems allow turbocharged engines to run leaner at full load for short periods of time, especially at lower rpms before peak boost and torque are reached. This requires reduced timing (and puts an upper limit on how much boost/torque you can produce regardless of timing), but it works very well for government fuel economy testing, and it helps some drivers maintain good economy since they rarely get into boost for more than a few seconds at a time. Of course, modern NA engines will also run stoichiometric for a few seconds, but since they ran leaner to begin with, the fuel consumption improvements are much larger for the turbo cars. My EVO X goes rich pretty quickly, but something like the Subaru WRX or STI stay at stoich up to 3000 rpm or sometimes even higher.
Secondly, direct injection and its late stage injection and charge cooling benefits allow turbo charged engines to run leaner for far, far longer. The clearest example in modern engines that I've seen is the BMW N54 twin turbo engine. This engine will run stoichiometric at full throttle up to and even beyond 4000 rpm. Considering that it is making significant torque and boost by 1500 rpm, this is along time, and most folks will rarely go over 4000 rpm. This is probably one reason why N54 cars return excellent fuel economy for their relative performance.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following...
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Let me take a crack at this... one thing to keep in mind when you start comparing the performance and efficiency of different cars is that it is important to make an apples to apples comparison. Let's take your first comparison, the Hyundai Genesis 4.6 vs the Ford Taurus Ecoboost. The Taurus is all-wheel drive, the Hyundai drives its rear wheels only. The Taurus also weighs almost 300 pounds more. Despite these disadvantages the Taurus is significantly faster (5.2 vs 6.0 to 60 mph according to C&D). So if they get the same mileage I would say that the Taurus is far more efficient. The Acura RDX is also a bad example. For reasons known only to Honda they chose not to use Direct Injection on this engine (or any other for that matter) and because of it the RDX is simply not as efficient as most modern, turbo-charged mills. The BMW 335 and the Infiniti G37 is a better comparison. They are similar in weight and are both rear drivers. But take a look at the numbers. The 335 is quite a bit faster (4.9 vs 5.4 to 60 MPH according to C&D) despite the horsepower disadvantage. Which brings me to another point. You can't just look at horsepower when comparing engines. Direct Injected, turbocharged engines produce lots of torque over a very wide range and torque is just as important as horsepower, maybe more so. The 335 produces its peak torque starting at only 1400 RPM.
The best argument I can give you for small displacement, direct injected, turbocharged engines (which I believe are the future for internal combustion engines, in 10 years there will be nothing else) is a true apples to apples comparison... the same car. Take a look at the naturally aspirated Audi A4 3.2 V6 Quattro vs. the 2.0 Turbocharged version of the same car. The 3.2 produces 265 horsepower and goes from 0-60 in 5.7 seconds. The 2.0 turbo matches the 0-60 time of the 3.2 with 54 less horsepower thanks to superior torque over a wider range. The 2.0 turbo also gets 21/27 MPG with the auto while the 3.2 gets 18/26. So lets see... equal performance with better fuel economy and lower weight (and hence better weight distribution and handling) sounds like a winner to me. Is it any wonder that for the 2010 model year Audi stopped making the 3.2. Consumers did the math and realized the 2.0 was the better engine. Audi was having trouble selling the 3.2.
canoman wrote: They charge more on the RDX because it uses Castrol Synthetic oil. If you buy the 5 quarts and bring them to a Honda dealership it will cost about $45 total.
I have an 09 RDX and it uses "Mobil 1 synthetic 5W30 or oil meeting Acura spec HTO-06". That comes directly from my owner's manual. Castrol Synthetic may meet that spec too. There can be quite a difference in synthetics from the same company. Its best to check the small print.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Your comparing vehicles with very different specs. A Genesis weighs 4015lbs and is rwd vs a Taurus SHO that weighs 4285 and is awd. The turbocharged v6 SHO(0-60 5.2) is still quicker then the v8 Genesis(0-60 5.5) despite being heavier, awd, and having less hp then the Genesis and still achieves similar gas mileage which does show the strengths of turbocharging.
The BMW 335 with 300 turbocharged hp is quicker(0-60 4.8) then the G37 with 328-330NA hp(0-60 5.2-5.4). The G does weigh more and is larger but it has more gears and a bigger engine that makes more power. There is no way the real world gas mileage of the VQ is the same as the BMW I6. Real world the VQ gets terrible gas mileage and much worse then the twin turbo BMW unit. The VQ is also rough and thrashy compared to the very smooth BMW inline 6.
In many cases turbo engines usually outperform their NA rivals in acceleration and mpg if you compare very similar powered cars that weigh roughly the same.
The WRX when it first came out had around 227hp and awd yet could accelerate 0-60 under 6 seconds. I have never seen a NA sedan with 227hp, awd or fwd, and weighed the same that could come anywhere close to its performance.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Your comparing vehicles with very different specs. A Genesis weighs 4015lbs and is rwd vs a Taurus SHO that weighs 4285 and is awd. The turbocharged v6 SHO(0-60 5.2) is still quicker then the v8 Genesis(0-60 5.5) despite being heavier, awd, and having less hp then the Genesis and still achieves similar gas mileage which does show the strengths of turbocharging.
The BMW 335 with 300 turbocharged hp is quicker(0-60 4.8) then the G37 with 328-330NA hp(0-60 5.2-5.4). The G does weigh more and is larger but it has more gears and a bigger engine that makes more power. There is no way the real world gas mileage of the VQ is the same as the BMW I6. Real world the VQ gets terrible gas mileage and much worse then the twin turbo BMW unit. The VQ is also rough and thrashy compared to the very smooth BMW inline 6.
In many cases turbo engines usually outperform their NA rivals in acceleration and mpg if you compare very similar powered cars that weigh roughly the same.
The WRX when it first came out had around 227hp and awd yet could accelerate 0-60 under 6 seconds. I have never seen a NA sedan with 227hp, awd or fwd, and weighed the same that could come anywhere close to its performance.
Allow me to provide a brief primer on modern turbocharged engine fueling techniques.
1) Traditionally, once you're into boost, you must run a much richer mixture than a naturally aspirated engine, even when said NA engine is operating at full throttle. For example:
Any engine operating in vacuum - 14.7:1 A/F ratio
Naturally Aspirated engine at or near full throttle - 12.0-13.0:1
Turbo (historically) engine at full throttle - 10-11:1
Expressed in terms of BSFC (we normally use lbs fuel/hp-hr) this will yield (with variations for engine tech and combustion chamber) this will get us:
Vacuum - 0.38-0.42 lbs/hp-hr
NA full power - 0.45-0.5 lbs/hp-hr
Boost - 0.5-0.55 or higher (I swear my Evo is at about 0.6 on pump gas)
The reason that a boosted engine must run richer is due to increased cylinder pressure and heat which increases detonation potential, especially on poor quality pump gasoline. Additionally, those higher temps can be hard on engine components, so even if detonation isn't an issue (race gas), it is still a good idea to run richer than what you'd see on an NA engine.
So, what this yields then is an interesting interrelationship. A small displacement boosted engine can operate very efficiently off-boost, but once you start making power and have to go into power enrichment mode, your efficiency drops dramatically. In contrast, a larger displacement NA engine will lose less efficiency as it transitions into full power operation. Furthermore, on a typical modern turbo engine you will transition into boost at anything above half the rated power output (for a given rpm). By comparison, a large displacement NA engine will operate at stoichiometric up to 80% or more of rated power.
2.) The big change that has skewed things in favor of turbo charged engines lately has been direct injection. To a lesser extent, modern engine management and advanced knock control strategies have also aided the 2nd coming of gasoline turbocharging.
Starting with the less significant change, we see that modern engine management systems allow turbocharged engines to run leaner at full load for short periods of time, especially at lower rpms before peak boost and torque are reached. This requires reduced timing (and puts an upper limit on how much boost/torque you can produce regardless of timing), but it works very well for government fuel economy testing, and it helps some drivers maintain good economy since they rarely get into boost for more than a few seconds at a time. Of course, modern NA engines will also run stoichiometric for a few seconds, but since they ran leaner to begin with, the fuel consumption improvements are much larger for the turbo cars. My EVO X goes rich pretty quickly, but something like the Subaru WRX or STI stay at stoich up to 3000 rpm or sometimes even higher.
Secondly, direct injection and its late stage injection and charge cooling benefits allow turbo charged engines to run leaner for far, far longer. The clearest example in modern engines that I've seen is the BMW N54 twin turbo engine. This engine will run stoichiometric at full throttle up to and even beyond 4000 rpm. Considering that it is making significant torque and boost by 1500 rpm, this is along time, and most folks will rarely go over 4000 rpm. This is probably one reason why N54 cars return excellent fuel economy for their relative performance.
SC
Thanks for that, Shawn - it really helps explain a lot.
Even if it clearly went over most peoples' heads at a great height.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Your comparing vehicles with very different specs. A Genesis weighs 4015lbs and is rwd vs a Taurus SHO that weighs 4285 and is awd. The turbocharged v6 SHO(0-60 5.2) is still quicker then the v8 Genesis(0-60 5.5) despite being heavier, awd, and having less hp then the Genesis and still achieves similar gas mileage which does show the strengths of turbocharging.
The BMW 335 with 300 turbocharged hp is quicker(0-60 4.8) then the G37 with 328-330NA hp(0-60 5.2-5.4). The G does weigh more and is larger but it has more gears and a bigger engine that makes more power. There is no way the real world gas mileage of the VQ is the same as the BMW I6. Real world the VQ gets terrible gas mileage and much worse then the twin turbo BMW unit. The VQ is also rough and thrashy compared to the very smooth BMW inline 6.
In many cases turbo engines usually outperform their NA rivals in acceleration and mpg if you compare very similar powered cars that weigh roughly the same.
The WRX when it first came out had around 227hp and awd yet could accelerate 0-60 under 6 seconds. I have never seen a NA sedan with 227hp, awd or fwd, and weighed the same that could come anywhere close to its performance.
A key factor to those early WRX 0-60 times were AWD. If you look at the acceleration curves from those early 2.0 WRX's, they trailed off pretty significantly in the top end.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Your comparing vehicles with very different specs. A Genesis weighs 4015lbs and is rwd vs a Taurus SHO that weighs 4285 and is awd. The turbocharged v6 SHO(0-60 5.2) is still quicker then the v8 Genesis(0-60 5.5) despite being heavier, awd, and having less hp then the Genesis and still achieves similar gas mileage which does show the strengths of turbocharging.
The BMW 335 with 300 turbocharged hp is quicker(0-60 4.8) then the G37 with 328-330NA hp(0-60 5.2-5.4). The G does weigh more and is larger but it has more gears and a bigger engine that makes more power. There is no way the real world gas mileage of the VQ is the same as the BMW I6. Real world the VQ gets terrible gas mileage and much worse then the twin turbo BMW unit. The VQ is also rough and thrashy compared to the very smooth BMW inline 6.
In many cases turbo engines usually outperform their NA rivals in acceleration and mpg if you compare very similar powered cars that weigh roughly the same.
The WRX when it first came out had around 227hp and awd yet could accelerate 0-60 under 6 seconds. I have never seen a NA sedan with 227hp, awd or fwd, and weighed the same that could come anywhere close to its performance.
A key factor to those early WRX 0-60 times were AWD. If you look at the acceleration curves from those early 2.0 WRX's, they trailed off pretty significantly in the top end.
the original WRXs were 0-60 heros but absolutely DEAD as soon as you got into 3rd gear. I mean FREAKING DEAD. I forget the actual numbers but I want to say they ran low-mid 14's at 92ish. The ET was pretty impressive but the trap speed was terrible considering the sub 6.0 0-60 times. These cars were a hoot around town but out on open roads, only having 2 fun gears grew old VERY quickly for me. I despised driving the WRX on the freeway. The aerodynamics must absolutely suck because there was basically zero acceleration from 75mph.
lexusgs wrote: ....Your comparing vehicles with very different specs. A Genesis weighs 4015lbs and is rwd vs a Taurus SHO that weighs 4285 and is awd. The turbocharged v6 SHO(0-60 5.2) is still quicker then the v8 Genesis(0-60 5.5) despite being heavier, awd, and having less hp then the Genesis and still achieves similar gas mileage which does show the strengths of turbocharging.
If all you are gaining is .3 sec on a drag race, I'll take the smooth as silk V8 for my daily driver on public roads. Instead of the overly complex intercooled, turbocharged, direct injected V6 that probably weighs as much as the simple V8.
You make very strong and technical arguments concerning the theoretical benefits of turbo charging. They do not however translate to the real world. The EPA highway rating of the BMW 335 is 26 MPG highway, no different than Acura TL etc etc. It seems as though to make a fair comparison, the na engine will need to produce an additional 10% horsepower in the same vehicle to produce similar performance levels, due to lower torque levels. I would bring you back to the original post, If BMW took their european direct injected 330 ( 272 BHP)( .6 slower to 60 than the 335), and now increased the displacement to 3.6 liters, the horsepower would be in the 325 range and offer comperable levels of performance to the 335. Remember that the combined european cycles for the 335 is 32.5 highway and the 330 in 39.5 highway. Let say this larger 3.6 liter engine had a 1.5 mpg penalty, netting 38 mpg versus 32.5 of the 335. This is a 17% increase. The percentages are constant no matter what milage method you use. So once again, it appears the only benefit is to the car manufacturers. I believe this to be a valid comparison because you are comparing the same car, same tranmission, drive line losses etc.
The only way I could possibly see turbocharging delivering improved milage with comperable performance would be it can potentially also run in the lean burn mode (over 20:1). Does anyone now if this is possible.
The new Ford Miustang NA 3.7 liter with 305 BHP return 30 MPG highway, another example of the efficiancy of NA engines.
RAV wrote: Car companies keep preching the milage benefits of turbocharging, but they simply to not pencil out. Please look at the following:
1.Hyundai 4.6 liter Gensis sedan with 368 HP( regular fuel ) V8
gets 25 mpg and the ford Tarus with eccoboost with 355 hp gets 25 mpg running premium ( essentally worse milage because of the premiuim penatly).
2. Acura RDX get 22 mpg highway ( premium ) and thre Maxda CX7 with a 271 hp V6 gets 22 mpg running regular.
3. BMW 335 with 300 hp gets 26 mpg and the Infiniti G37 with 328 hp gets the same 26 mpg.
I could go on with more examples but I'm certain everyone gets the point.
So what gives with the manufacturers feeding us this BS. Is turbocharging just a cheap way for them to make horsepower ? Ever since they combined turbocharging with direct injection and eliminated the lag, evryone is jumping on the bandwagon.
Can someone please englighten me as to the reason for this shift. It just appears to be cost savings to me.
Your comparing vehicles with very different specs. A Genesis weighs 4015lbs and is rwd vs a Taurus SHO that weighs 4285 and is awd. The turbocharged v6 SHO(0-60 5.2) is still quicker then the v8 Genesis(0-60 5.5) despite being heavier, awd, and having less hp then the Genesis and still achieves similar gas mileage which does show the strengths of turbocharging.
The BMW 335 with 300 turbocharged hp is quicker(0-60 4.8) then the G37 with 328-330NA hp(0-60 5.2-5.4). The G does weigh more and is larger but it has more gears and a bigger engine that makes more power. There is no way the real world gas mileage of the VQ is the same as the BMW I6. Real world the VQ gets terrible gas mileage and much worse then the twin turbo BMW unit. The VQ is also rough and thrashy compared to the very smooth BMW inline 6.
In many cases turbo engines usually outperform their NA rivals in acceleration and mpg if you compare very similar powered cars that weigh roughly the same.
The WRX when it first came out had around 227hp and awd yet could accelerate 0-60 under 6 seconds. I have never seen a NA sedan with 227hp, awd or fwd, and weighed the same that could come anywhere close to its performance.
A key factor to those early WRX 0-60 times were AWD. If you look at the acceleration curves from those early 2.0 WRX's, they trailed off pretty significantly in the top end.
the original WRXs were 0-60 heros but absolutely DEAD as soon as you got into 3rd gear. I mean FREAKING DEAD. I forget the actual numbers but I want to say they ran low-mid 14's at 92ish. The ET was pretty impressive but the trap speed was terrible considering the sub 6.0 0-60 times. These cars were a hoot around town but out on open roads, only having 2 fun gears grew old VERY quickly for me. I despised driving the WRX on the freeway. The aerodynamics must absolutely suck because there was basically zero acceleration from 75mph.
The aero on those bug eyed WRX's was horrendous. I am not sure they are much better now, but they have a lot more power, and more gears, so that probably helps.
Those numbers for the 1/4 mile performance seem about consistent with what I have seen/heard.
I love my v8 and love v8s, don't get me wrong the smoothness and sound is great but I would still prefer the twin turbo inline six available in the Japanese GS because of how easily and relatively cheaply it is tuned for more power. V8s still have a place and are important in this segment. I think Acura still desperately needs a v8 option for the RL to be taken seriously but I think it is great if people can have the option of a FI engine that gets better fuel economy and still perform roughly the same as the v8. FI engines have their advantages over larger NA engines and you can see it when looking at some of these comparisons, for smaller cars FI might be the better option in many cases.
I was just reading Automobile comparing the new S4 to 335i and you cannot ignore how much more efficient the supercharged v6 is to the old v8. The supercharged v6 is 37 pounds lighter then the v8 and can sit further back in the chassis for better weight distribution. The supercharged v6 makes 333hp and 325tq that is available across a wider rev range where the v8 made 340hp and 302tq. 0-60 is pretty much the same at 5.2 seconds. The best thing is the gain in efficiency. The v8 got 13mpg city 20mpg highway compared to the new supercharged v6 that gets 18/27 which is a huge jump, the v6 also does not get the gas guzzler tax either like the v8.
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