The 2014 Corvette Stingray Forum
News / Blog Register Community Calendar Today's Posts Search

Go Back   Chevrolet Corvette Stingray C7 Forum > Members Area > General Automotive + Other Cars Discussion

Reply
 
Thread Tools
Old 05-26-2012, 05:55 AM   #15
FenwickHockey65
General Motors Aficionado
 
FenwickHockey65's Avatar
 
Drives: 2023 GMC Canyon, 2023 Expedition
Join Date: Aug 2008
Location: Florida
Posts: 37,375
Send a message via AIM to FenwickHockey65
It's an older version of the Equinox's Theta platform.

And the upcoming Buick Encore is on Gamma-II, not Theta.
__________________
2023 GMC Canyon Elevation
2023 Ford Expedition SSV (State-Issued)
FenwickHockey65 is offline   Reply With Quote
Old 05-26-2012, 08:11 AM   #16
JamesNoBrakes


 
JamesNoBrakes's Avatar
 
Drives: 2SS 1LE
Join Date: Oct 2011
Location: AK
Posts: 2,377
Quote:
Originally Posted by fielderLS3 View Post
I climbed that about 3 years ago in early March in a Ford Edge, and its 265hp V6 was breathing pretty hard (about 70-80% throttle and around 4500 RPM). 4-cylinder SUV in summer Arizona heat must have been wide open and nearly red-lined the whole way. Sounds like less a recipe for efficiency than a recipe for short engine life.

Disagree on the V6 is a waste of fuel argument. Yes, in a small car, or at low speeds in city traffic, a 4-cyl is more efficient than a V6. But as the need for power increases, and the load on the engines increase, the efficiency gain gets smaller and you run into a point of diminishing returns. Once you're at the point of having to run the little 4-cyl almost constantly in lower gears just to cruise, you'd probably be better off efficiency wise with a V6 that can handle higher gears.

And turbocharging isn't the answer either. Small turbo engines of similar power of a larger NA engine really don't have an efficiency advantage (Maybe a little on the EPA cycle, but not really in the real world). And in a heavy load situation like the above where the turbo would be constantly spooled, a turbo 4 would probably be thirstier than a NA V6 of similar power. Turbo = lower compression ratio = lower thermodynamic efficiency.
Hmm, well my 2.0L turbo engined car (280-300hp) would stay at around 2800 or so RPM up that grade and simply up the pressure to about 13" or so to maintain 80mph, this is within the range where the engine makes the most torque. No downshifting. I'd say a small turbo engine is far more efficient than a big NA engine, especially if you know how to drive it for efficiency. The turbo would be a little "thirstier" while it makes more power (the additional fuel to cool the engine), but less during all the other cruise scenarios. The engine is also significantly lighter, and turbos generally increase efficiency, unless you are using it to make massive power and accelerate massively faster than equivalent vehicles and engines. I never met many vehicles that could match my AWD turbo for power and efficiency at the same time. Yes, I'd be a little concerned about heat soak during the summer, but you know what, these cars are designed adequately these days usually (well, there are still some idiot-moves out there). This is what they're designed to do. It even had a built in "protection mode" that reduce the engine power , but I never ran into that on "the hill", I'd surmise that's due to airflow through the engine, even when hot, at those speeds that should take care of heat-soak pretty well. In traffic, possibly not. And of course, if you're dealing with high altitude(Flagstaff, White Mountains, Colorado, etc)...well, lets just agree that a turbo makes a huge amount of sense

My big V8 camaro on the other hand doesn't do so well on that climb, in the sense that it's geared so tall I have to downshift and spin more RPMs than my normal cruise in the top-gear. I can't just cruise with "nary a care in the world", as I could with the turbo-engined car that would simply make up the difference in "boost" when faced with a hill.

And yes, having more power is fun (or I wouldn't own a camaro), but, I had a friend a few months back drive a rental Focus up from Phoenix, she said it was plenty adequate for getting up that hill. The rental people were trying to push her to rent a "V6" for "the hill". Hell, my old Neon would do the 80mph in 4th gear up that.

In the end, you don't really need 300+ horsepower to climb that or pretty much any other hill. It's nice to have power, but it's not very practical, especially when you consider those hills are such a small part of your driving, even if you're spending most of your time on the highway. If I were looking at a vehicle such as the one pictured above, I wouldn't be worrying about getting it as a "V6". It's not why I'd get such a vehicle in the first place.

Last edited by JamesNoBrakes; 05-26-2012 at 09:19 PM.
JamesNoBrakes is offline   Reply With Quote
Old 05-26-2012, 09:12 AM   #17
DaBears
 
Drives: 2014 Subaru Forester, 2010 Equinox
Join Date: Nov 2011
Location: South Bend, IN
Posts: 560
Equinox is wayyyy better.
__________________
DaBears is offline   Reply With Quote
Old 05-26-2012, 10:02 AM   #18
Ringo64
Forever Pontiac
 
Drives: 2012 Black 2SS/RS
Join Date: Oct 2010
Location: Naples, FL
Posts: 1,389
Something that has always gotten me w/ 4-cyl engines and why I will never willingly own one is because you have to mash the pedal to get into the higher revs to get any power out of them and you're stuck waiting till it kicks in. Living in Florida I deal with no hills but I test drove and have driven my sister's 4 cyl SUV. It just feels like to get it out in traffic and accelerate I'm wasting more gas than needed because I'm raping the accelerator. Then I get in my mom's Terrain w/ the 6 cyl and that thing flies! (Of course nothing on my Camaro )

Just seems to me that any gains of having a 4 cyl are reduced when you actually need the power. Which yes if you change driving styles then you can take advantage of that but I'd rather have the ease of mind knowing I have the power to get out of a situation rather than not.

Why unless I get a small roadster, the smallest engine I will go is a V6.
Ringo64 is offline   Reply With Quote
Old 05-26-2012, 02:40 PM   #19
DGthe3
Moderator.ca
 
DGthe3's Avatar
 
Drives: 05 Grand Am GT
Join Date: Jul 2007
Location: Niagara, Canada
Posts: 25,366
Send a message via MSN to DGthe3
Let be pre-face this with ...

sorry for writting a small book

Quote:
Originally Posted by fielderLS3 View Post
So exactly how similar is this to an Equinox? Does it share a platform, or is it an older version of a platform? Basically, if one was looking for 1-2 year old Equinox, would this be close enough to look at instead once they start reselling them?

They're more or less equivelent to a ~5 year old Equinox, Vue, or Torrent. I believe the current Equinox/Terrain are a little bigger (yet more efficient) and are overall better vehicles. So while they both fill the same spot in GM's line up (small crossover) you'd notice a not-insignificant difference if you compared them directly as a customer. On the other hand ... I bet you could save quite a bit of money picking up a used Captiva vs a similar used Equinox.


It have to respectfully disagree. The 2.4L 170hp Ecotec in a 3700 lb SUV is quite weak. That puts it in line with the Vulcan Taurus, except the Vulcan had more torque, and likely had less drag to overcome.

In my opinion, you have to take today's horsepower numbers with a grain of salt, because not all horsepowers are necessarily created equal. 170hp today is not the same as 170hp was even 10 years ago. Most of today's engines do have impressive specific horsepower numbers, but specific torque has not increased so much. Newer engines tend to make their power by revving high. So yes, an Ecotec 2.4L will make the same 170hp as the 3.4L in my Alero, but the Ecotec has a narrower power band, and has to be whipped a lot harder to force it out.

Another big difference between cars of today & those of 10 or 20 years ago is that 6 speed transmissions are pretty much the norm these days. By having more gear options, the engine can stay in its optimal RPM range better for the current situation. And yes, this sometimes means downshifting to keep the revs (and power) up. But a few seconds or even a couple minutes of that isn't going to hurt the engine. It was built to handle those sorts of situations on a regular basis. Its use, not abuse.


Same goes for all the modern 300+ horsepower V6s every manufacturer seems to have now. I've driven several of them, and honestly, they just don't feel like it. Run any of those 300hp V6s against a bigger displacement 300hp engine from 10-15 years ago in a similar weight car, and I bet you the older one wins almost every time.

Because when you were driving them, chances are you weren't using their 300 hp. Same with the 300 horse V8s from the late 90s. You were probably more likely to encounter their mid-range, moderate to heavy throttle power -which would be more in the older V8s. But, and this is the important bit, 300 hp is 300 hp. If you lined up 2 cars at the drag strip where the only major difference is that one makes about 50 ft-lbs more peak torque (at a lower RPM), it will be a very close race & probably be decided in the first hundred feet or so. The older car would have the advantage, but only early on. Once the cars get to their upper RPM range at full throttle, they're making the same power and are going to accelerate at pretty much the same rate. In the end, I'd say its more of a drivers race than anything.

Maybe it's just me, and maybe I'm making myself sound a bit crazy, but the philosophy of saying "good enough," and engineering for the bare minumum of adequacy was a major contribuing factor to GM's and Chrysler's market share losses and bankruptcies, and I'm worried about them heading in that same direction again.

GM's problems were deeper than that. They planned on being competetive with what was currently out on the market, then they cheapened their cars further becase cost to the company was seen to be more important than value to the customer. Consequently, when the new car was launched some 4 years after the initial product planning they had a product that was generally worse than the previous generation of its competition In retrospect, its astonishing that Detroit managed to keep moving along as well as they did (afterall, all 3 of them were doing the same thing). But I'm pretty sure they've learnt their lesson: when the bean counters calling the shots, they lost money & marketshare. With product development in charge, they made money & gained marketshare.
See bold

To bring it back to 'a 4 banger isn't enough for a kinda big crossover' I think its important to note that GM can't build enough 4 cylinder Equinoxes these days, and recently had to initiate an incentive program to try and shift the production mix to include more V6s. And thats ~3 years after the vehicle was launched when overall demand should be dying down. So its pretty clear to me that the overwhelming majority of buyers are just fine with their underpowered CUVs.


Quote:
Originally Posted by Ringo64 View Post
Something that has always gotten me w/ 4-cyl engines and why I will never willingly own one is because you have to mash the pedal to get into the higher revs to get any power out of them and you're stuck waiting till it kicks in. Living in Florida I deal with no hills but I test drove and have driven my sister's 4 cyl SUV. It just feels like to get it out in traffic and accelerate I'm wasting more gas than needed because I'm raping the accelerator. Then I get in my mom's Terrain w/ the 6 cyl and that thing flies! (Of course nothing on my Camaro )

Just seems to me that any gains of having a 4 cyl are reduced when you actually need the power. Which yes if you change driving styles then you can take advantage of that but I'd rather have the ease of mind knowing I have the power to get out of a situation rather than not.

Why unless I get a small roadster, the smallest engine I will go is a V6.
But to merge with traffic or pass another car, you are only on the gas hard for a few seconds at a time. The amount of fuel consumed in that time is minimal. With a bigger, more powerful engine you might complete the manuever a little quicker, but durring that time you've also burned a lot more fuel. Remember that it takes X amount of gasoline to produce Y amount of power. So if you want twice the power, you need to burn twice the gas. Simple as that. Now it is true that a more powerful car would take less time to merge into traffic but durring that time its consuming more fuel. Your argument would work if and only if the more powerful car could make the pass in less than half the time -but the laws of physics say that it would always take more than half the time. So in the end the net result is that when you use more power you consume more gasoline.

If things were the other way around, sports cars would be more efficient than sub compacts. And I'm not even talking about say a Z06 vs a Corolla. How about a Mazda 2 vs Miata? They weigh about the same, both have 4 bangers, both are made by the same company, and you can get either of them with a 5 speed manual transmission. They're about as similar as you can get, with the main difference being the engine. But the much less powerful Fit (with the smaller engine) is substantially more efficient than its sporty counterpart.
__________________
Note, if I've gotten any facts wrong in the above, just ignore any points I made with them
__________________
Originally Posted by FbodFather
My sister's dentist's brother's cousin's housekeeper's dog-breeder's nephew sells coffee filters to the company that provides coffee to General Motors......
........and HE WOULD KNOW!!!!
__________________

Camaro Fest sub-forum
DGthe3 is offline   Reply With Quote
Old 05-26-2012, 04:46 PM   #20
Ringo64
Forever Pontiac
 
Drives: 2012 Black 2SS/RS
Join Date: Oct 2010
Location: Naples, FL
Posts: 1,389
Quote:
Originally Posted by DGthe3 View Post
But to merge with traffic or pass another car, you are only on the gas hard for a few seconds at a time. The amount of fuel consumed in that time is minimal. With a bigger, more powerful engine you might complete the manuever a little quicker, but durring that time you've also burned a lot more fuel. Remember that it takes X amount of gasoline to produce Y amount of power. So if you want twice the power, you need to burn twice the gas. Simple as that. Now it is true that a more powerful car would take less time to merge into traffic but durring that time its consuming more fuel. Your argument would work if and only if the more powerful car could make the pass in less than half the time -but the laws of physics say that it would always take more than half the time. So in the end the net result is that when you use more power you consume more gasoline.

If things were the other way around, sports cars would be more efficient than sub compacts. And I'm not even talking about say a Z06 vs a Corolla. How about a Mazda 2 vs Miata? They weigh about the same, both have 4 bangers, both are made by the same company, and you can get either of them with a 5 speed manual transmission. They're about as similar as you can get, with the main difference being the engine. But the much less powerful Fit (with the smaller engine) is substantially more efficient than its sporty counterpart.
The way I'm seeing it is that I can stay in the lower revs with a 6 cyl or 8 cyl which in theory I'm not over exerting the engine thus using more gas. The 4 cyl to get any power you're in the higher revs and over exerting the engine and using more gasoline. Granted yes that the 4 cyl will be more efficient in other areas it just seems with it's loss in power and my current driving style that I wouldn't get the estimated mpg value of the car which would be my only reason for getting one so to me I'd have to change my driving style thus already would be more beneficial to do in my current DD in my Pontiac G6 w/ a Lx9 V6 than spend more money and buy a 4 cyl.

I guess I'm not really stating that the 4 cyl will get less mpgs compared with the V6 or V8, just wouldn't fit the reason why I would get one

I guess my point is mute in this thread carry on
Ringo64 is offline   Reply With Quote
Old 05-26-2012, 09:25 PM   #21
JamesNoBrakes


 
JamesNoBrakes's Avatar
 
Drives: 2SS 1LE
Join Date: Oct 2011
Location: AK
Posts: 2,377
Quote:
Originally Posted by Ringo64 View Post
Something that has always gotten me w/ 4-cyl engines and why I will never willingly own one is because you have to mash the pedal to get into the higher revs to get any power out of them and you're stuck waiting till it kicks in.
Idk, a turbo 4 can rev VERY fast, way faster than my big V8. Having a "fast revving" engine is pretty darn fun, having it hit the high RPMs (fast) is all that much more fun. In fact, mashing the pedal with a turbo car can be a recipe for disaster as many drivers are not ready for the massive power that hits hard and fast, messing up shifts and so on. Virtually no waiting and building power quickly at lower RPMs is what these engines do well, rather than waiting until 5000rpm till the power really kicks in, like with my V8. I can always downshift it 3 gears with my V8, but again, I think a turbo-4 makes sense for most vehicles out there, with the exception of trucks that usually need a big bigger displacement for the torque and very high powered sports cars that for practical design and production purposes can't produce 400-500hp from a small 2.0L turbo 4, even though it's easily attainable from an engineering standpoint.

The places where you "need power" are few and far between in my experience. I often drive rentals or cars at airports due to my job, and things like the 2.5 altimas are very nice, plenty fast with their CVT autos (can you say "INSTANT" acceleration?), I know that when I'm driving these things all it takes is mashing the pedal to really pick it up, even when it's not some huge engine. The thing is that we're not accelerating from 70-120 or 80-140, and since we're dealing more with 0-40, 30-60 and 30-70, it's hard to get into a situation where you "need a whole bunch of power" where you are limited by revs and can actually utilize it.
JamesNoBrakes is offline   Reply With Quote
Old 05-26-2012, 09:31 PM   #22
JamesNoBrakes


 
JamesNoBrakes's Avatar
 
Drives: 2SS 1LE
Join Date: Oct 2011
Location: AK
Posts: 2,377
Quote:
Originally Posted by Ringo64 View Post
The way I'm seeing it is that I can stay in the lower revs with a 6 cyl or 8 cyl which in theory I'm not over exerting the engine thus using more gas. The 4 cyl to get any power you're in the higher revs and over exerting the engine and using more gasoline.
That's really not the way it works. Staying in the low rpms and not "lugging" the engine is how you get the best mileage, no doubt, but you are forgetting the smaller displacement, lesser amount of oxygen and fuel that go into those smaller cylinders, and so on. They will have that same range, but at a different RPM, more like 1800 for my boxxer vs 1000-1200 for my V8, but since the cylinders are much smaller, there's far less fuel and air going in than if the bigger engine was at the same RPM. There seems to also be some sort of misconception that the engine is being "overexerted", they have pretty good protections against that these days. All of what you said changes anyway if you turbo the 4, then it makes a lot more torque down lower at 2500-3000rpm and can accelerate like it got kicked in the rear at those RPMs (then drop off at the high ones).

Where you're killed in mileage is that the bigger engine has more power and can accelerate just a bit faster, which takes quite a bit more power. It's not a linear relationship where if you go twice as much power you accelerate twice as fast, nowhere near that. And of course you're turning bigger cylinders all the time and causing more drag on the system (lubrication for more and bigger cylinders, fuel pump supplying fuel to bigger and more cylinders, air being compressed, water pump circulating more coolant through engine, etc), not to mention the fuel going in there that powers all those parasitic losses. And then there's everything that comes with the bigger engine/more power, bigger drivetrain components, bigger brakes, the heavier engine, and so on.
JamesNoBrakes is offline   Reply With Quote
Old 05-27-2012, 01:35 AM   #23
fielderLS3


 
fielderLS3's Avatar
 
Drives: 2016 Mazda6, 2011 Mustang 5.0
Join Date: Mar 2010
Location: Portage, Wisconsin
Posts: 4,049
Quote:
Originally Posted by JamesNoBrakes View Post
I never met many vehicles that could match my AWD turbo for power and efficiency at the same time.
I still disagree on the fuel efficiency of a turbo. Adding a turbo forces a reduction in compression ratio, which lowers efficiency. Taking a 4-cylinder and adding a turbo will reduce its economy compared to the original NA 4-cylinder. And compared to a NA engine of similar power, there is generally not much if any real world gain.

You say not much can match your combo of efficiency and power. You say you're at about 280-300hp...Just curious what your mileage numbers are. For comparison, a 3.6L V6 Camaro, which is a bigger car, is good for low 30s on the highway. My 412hp V8 does about 28-29 mpg on the interstate.

Quote:
Originally Posted by JamesNoBrakes View Post
And of course, if you're dealing with high altitude(Flagstaff, White Mountains, Colorado, etc)...well, lets just agree that a turbo makes a huge amount of sense
I will agree with you there. FI shines best at high altitude.

Quote:
Originally Posted by JamesNoBrakes View Post
My big V8 camaro on the other hand doesn't do so well on that climb.
Understood, but you are kinda comparing apples to oranges. The Camaro is heavier, so it takes more move it up the hill. It also runs at about 1800-1900 RPM at 75 in 6th, where as you indicate your turbo runs at 2800-3000RPM. That is a big difference.

Also, the way I look at it, 13 psi of boost at that altitude effectively makes your engine at least a 4.0L, if you really think about it. Turbocharging is just a special form of displacement. The engine may measure 2.0L, but at that level of boost, you are forcing ~4L of air through it.

Quote:
Originally Posted by JamesNoBrakes View Post
I had a friend a few months back drive a rental Focus up from Phoenix, she said it was plenty adequate for getting up that hill.
I never said those cars were underpowered. (And to cover all my bases, I never said a turboed 4 couldn't make serious power). I'm talking about a 3700 lb SUV. The NA 4-cylinders you mention do just fine moving those small, light cars. In a larger SUV, not so much.

Quote:
Originally Posted by DGthe3 View Post
Another big difference between cars of today & those of 10 or 20 years ago is that 6 speed transmissions are pretty much the norm these days. By having more gear options, the engine can stay in its optimal RPM range better for the current situation.
Those transmissions can be a two edged sword, though. With car makers clawing for CAFE averages, too many of them try to keep the car in a super tall overdrives as slow as possible, and up to as heavy of a load as possible. So in theory, you can stay in your power band better, but in practice, they end up lugging them even slower in most normal driving situations despite having less torque down there than the larger engines they are replacing. To actually get a downshift, you really have to step down on the gas, so when the downshifts finally do occur, the power comes on suddenly, not smoothly. As a driver, I find this very irritating.

Admittedly, this is more a failure of transmission programming than the engines. Also, my main experience with 6-speed autos is with Ford, since that is what my family has been buying lately. Ford, at least, has done a very poor job of making their engines and transmissions get along. Maybe GM and others have done better, and it's not as big of problem as I think.

Quote:
Originally Posted by DGthe3 View Post
Because when you were driving them, chances are you weren't using their 300 hp. Same with the 300 horse V8s from the late 90s. You were probably more likely to encounter their mid-range, moderate to heavy throttle power
That's kinda the point I was trying to make. Horsepower is for racing. For just driving around normally on public roads, what you really need is torque. They can keep their 170 hp Ecotec. I'd rather have my Alero's 170 hp 3.4L. Its power curve is flatter, wider, and lower in the rev range, which is exactly what I'm looking for in a daily driver. I don't run at 7000RPM just driving from point A to B, so why would I want an engine that only makes power there?

A great example....A couple of months ago, my mother was looking to replace her Ford Edge, originally with another Edge. I recommended a VW wagon diesel, and ultimately, she took my advice. Now, having had some good seat time driving both, I can tell you that 140hp VW is much better. The Edge had no torque and always wanted to run below 2000 RPM anyway. Despite having 125 more horsepower than the VW, it felt like a total dog, whereas the VW feels surprisingly athletic.

Quote:
Originally Posted by DGthe3 View Post
So its pretty clear to me that the overwhelming majority of buyers are just fine with their underpowered CUVs.
Just because it is selling doesn't necessarily make it a good vehicle. You know how many Mustang IIs Ford sold, or how many Vegas GM sold? I'm certainly not comparing those cars to the Equinox, just making a point.

The average "motorist" is not a "driver" if that makes sense. I'm looking at it strictly from the point of view of someone who really enjoys driving, and is not just interested in transportation.

Quote:
Originally Posted by DGthe3 View Post
If things were the other way around, sports cars would be more efficient than sub compacts. And I'm not even talking about say a Z06 vs a Corolla. How about a Mazda 2 vs Miata?
Mazda 2 and Miata are more different than you think. The Miata is actually heavier, and probably less aerodynamic. Miata's also have crazy low gearing, certainly has higher rolling resistance tires, and an engine with about 60% more power than a Mazda 2.

I'm not sure if that was at me or a different post, but I'm not saying that smaller displacement isn't more efficient than large displacement. However, the efficiency benefit of small engine vs. large engine is larger the smaller the car, and diminishes as the vehicle gets larger, and the need for power increases. Eventually, there is a point of diminishing returns where the power you give up no longer nets enough of an efficiency improvement to be worth it.
__________________
2022 1SS 1LE (Arrived 4/29/22)
"The car is the closest thing we will ever create to something that is alive."
. 2022 1SS 1LE (Coming Soon)
fielderLS3 is offline   Reply With Quote
Old 05-27-2012, 11:28 PM   #24
JamesNoBrakes


 
JamesNoBrakes's Avatar
 
Drives: 2SS 1LE
Join Date: Oct 2011
Location: AK
Posts: 2,377
Quote:
Originally Posted by fielderLS3 View Post
I still disagree on the fuel efficiency of a turbo. Adding a turbo forces a reduction in compression ratio, which lowers efficiency.
The compressor does some of the compressing, which is why the turbo engine is relatively (usually not excessively) low compression, it's a combined effect. You can't compare NA engine compression ratios because all of the compression occurs in the cylinder in those cases. Otherwise, why would you need to use high octane fuel in a turbo?



Quote:
Taking a 4-cylinder and adding a turbo will reduce its economy compared to the original NA 4-cylinder. And compared to a NA engine of similar power, there is generally not much if any real world gain.
I don't think anyone is suggesting anything of the sort, they are suggesting replacing that big inefficient V6 with a smaller engine that has the same displacement capability (or even better) via a turbo. This is what improves efficiency, you can also get some amazingly flat torque "curves" these days as well. Those 4cyl are adequate and I don't really see why we'd need to get a "V6", but if you HAVE to have more power, a turbo-4 would be a better way than a 6cyl V6, technology and especially design are to the point where it can be done reliably over thousands and thousands of miles.
JamesNoBrakes is offline   Reply With Quote
Old 05-28-2012, 03:49 PM   #25
jrc1122

 
Drives: 2012 Mustang GT
Join Date: May 2009
Location: Abilene, TX
Posts: 1,358
Not a fan, US sales or not. It's blah, and the interior is extra Blah.
__________________
2012 Mustang GT Premium
Performance White
6-speed Manual
jrc1122 is offline   Reply With Quote
Old 05-28-2012, 04:44 PM   #26
FenwickHockey65
General Motors Aficionado
 
FenwickHockey65's Avatar
 
Drives: 2023 GMC Canyon, 2023 Expedition
Join Date: Aug 2008
Location: Florida
Posts: 37,375
Send a message via AIM to FenwickHockey65
Quote:
Originally Posted by jrc1122 View Post
Not a fan, US sales or not. It's blah, and the interior is extra Blah.
It's a rental/corporate fleet car. It doesn't have to be flashy or have a nice interior.
__________________
2023 GMC Canyon Elevation
2023 Ford Expedition SSV (State-Issued)
FenwickHockey65 is offline   Reply With Quote
Old 05-28-2012, 05:11 PM   #27
fielderLS3


 
fielderLS3's Avatar
 
Drives: 2016 Mazda6, 2011 Mustang 5.0
Join Date: Mar 2010
Location: Portage, Wisconsin
Posts: 4,049
Quote:
Originally Posted by JamesNoBrakes View Post
The compressor does some of the compressing, which is why the turbo engine is relatively (usually not excessively) low compression, it's a combined effect. You can't compare NA engine compression ratios because all of the compression occurs in the cylinder in those cases. Otherwise, why would you need to use high octane fuel in a turbo?
From an efficiency standpoint, it doesn't matter if the air is already partially pressurized before entering the cylinder as long as the volume ratio between TDC and BDC is reduced. While you may achieve similar initial pressure and temperature at ignition by having the same total mass of fuel and air, just in two difference sized cylinders with differing CR, during the power storke, the expanding gases will expand more in the engine with the higher CR, and less in the engine with lower CR. Thus in the lower CR (Turbo) engine, the same amount of fuel burned does less work.

By doing some of the compression externally, turbo engines in a sense have a reverse Atkinson cycle. Efficiency is being traded for power.

Quote:
Originally Posted by JamesNoBrakes View Post
I don't think anyone is suggesting anything of the sort, they are suggesting replacing that big inefficient V6 with a smaller engine that has the same displacement capability (or even better) via a turbo. This is what improves efficiency, you can also get some amazingly flat torque "curves" these days as well. Those 4cyl are adequate and I don't really see why we'd need to get a "V6", but if you HAVE to have more power, a turbo-4 would be a better way than a 6cyl V6, technology and especially design are to the point where it can be done reliably over thousands and thousands of miles.
I'd argue that those V6s really aren't that inefficient. Most of today's V6 cars exceed 30 mpg on the highway. Smaller fours boosted to the point of similar power of larger V6s just aren't putting up real world numbers better than that.

I completely agree on the torque curve benefit of a turbo engine. If you're looking for a nice flat torque curve, a turbo is the way to go, particulalry as today's NA engines seem to be getting less and less low-end torque for their power with every new upgrade. All I'm arguing is that if you're doing it purely for efficiency, you are wasting your money.

Since turbos usually require premium fuel anyway, instead of downsizing and turbo charging, more car makers should be doing what Mazda is doing with their SkyActive engines....Direct Injection on a NA engine, and take the compression ratio up to about 14:1...or 12.5:1 to run on regular. That'll make power and increase efficiency, but for less cost than turbocharging.
__________________
2022 1SS 1LE (Arrived 4/29/22)
"The car is the closest thing we will ever create to something that is alive."
. 2022 1SS 1LE (Coming Soon)
fielderLS3 is offline   Reply With Quote
Old 05-28-2012, 06:17 PM   #28
JimmyDeanSausage
Banned
 
Drives: GM
Join Date: May 2012
Location: Nevada
Posts: 76
There are so many misconceptions and simple lack of mechanical understanding in this thread I don't even know where to start.
JimmyDeanSausage is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:04 PM.


Powered by vBulletin® Version 3.8.9 Beta 4
Copyright ©2000 - 2026, vBulletin Solutions, Inc.