8 ms·

Turbochargers Will Keep Getting Better

38 points by dmmalam 11y ago

deleted 11y ago
[deleted]
iaw 11y ago
We're heading in a good direction with turbochargers. I suspect we're getting close to the Carnot limits for gasoline engines [1]. Next steps would be adapting the regenerative braking technology, like that on the Porsche 918, into regular vehicles. There's a lot of kinetic energy wasted in brakes and we're soon going to be able to recapture it. [1] https://en.wikipedia.org/wiki/Carnot_cycle#Efficiency_of_real_heat_engines https://en.wikipedia.org/wiki/Carnot_cycle#Efficiency_of_rea...
- maxerickson 11y ago
  Is there something notable about the brakes in the Porsche? Regenerative brakes are a big win in many of the hybrids that have been brought to market.
  - drcross 11y ago
    It's a significant car because it currently holds the lap record in Nürburgring for a supercar.
    - maxerickson 11y ago
      That doesn't make the brakes interesting in comparison to the system on a Prius (or whichever earlier car you want to pick).
    - Grazester 11y ago
      There is nothing notable about the regenerative brakes in the Porsche 918. Other hybrids have been using regenerative brakes for years and years now. As for a Nürburgring "record" I dont see the relevance in this conversation
  - iaw 11y ago
    So there are a few components interesting in the Porsche 918's braking system that I'll speak to. 1) The brakes slow the car down through a combination of electric generation and traditional brake pads, just like the hybrids you're familiar with. Unlike the Prius, the brakes escalate in a predictable a familiar fashion. Most regenerative braking systems do not scrub speed from the car in the same linear fashion as the 918. This is a major accomplishment because it makes the transition from regular brakes to regenerative brakes seamless and allows for spirited driving. 2) The batteries are not designed to store a substantial amount of charge, instead they are designed to provide a large chunk of the acceleration power that would normally come from a gasoline engine in a hybrid. Instead of designing the car to utilize batteries for long-ranges, Porsche designed the car to utilize batteries for sprints. 3) The net result is a car that is as spirited as a traditional sports car but with greatly increased efficiency. People that wont buy a Prius or BMW Hybrid right now because of the ride quality issues would be willing to purchase a car with the 918 style system. The school of thought behind the Prius to squeeze every drop of efficiency out of the electric side, the school of thought behind the 918 is to support spirited driving with the electric side. Both lead to increases in efficiency but only the latter is something people that consider themselves 'drivers' would buy. You can see this with Turbochargers as they are just now starting to trickle onto sport vehicles such as the BMW M4 and Ferrari has acknowledged that they will be pursuing the technology in their road cars in the near future.
- creshal 11y ago
  > Next steps would be adapting the regenerative braking technology, like that on the Porsche 918, into regular vehicles. Virtually all hybrids already do that…
  - iaw 11y ago
    Yes but you have to buy a car with a huge battery pack and crap performance (including the i8). I drive an M3, I'm not going to give up fast vehicles until self-driving cars are mandatory. Regenerative braking (with a small battery pack) could double the fuel efficiency I obtain. The existing regenerative braking systems available are horrible (in a number of ways) and not comparable to what's in existence for F1 and the 918. Regenerative braking for most cars now is where turbochargers were pre-1990s. The system I'm talking about can run only a few miles in full electric but gives a substantial boost in fuel economy because it's utilized for most acceleration below ~100 MPH.
- ssmoot 11y ago
  The Mazda 3 has an option for a regenerative braking system. I'm not really sure how that works in a non-hybrid TBH. Just used to charge for accessories, electric compressor, steering, etc so you can use a clutched alternator and minimize accessory loads? Just a guess.
  - ollie87 11y ago
    I believe the BMW 1 Series is the same.
- sliken 11y ago
  As mentioned in the article. Turbos don't help MPG much. Several examples in the article who larger engines with on turbos having similar MPG to smaller turbo engines. Sure they increase peak HP, but they also increase exhaust backpressure. Seems like the main achievement of turbos is cheaper/smaller engines.
  - Shivetya 11y ago
    most of the efficiency benefits we stand to gain with forced induction and other improvements is routinely lost because people cannot drive properly. the race to the next red light does nothing but wreck your mileage. some have suggested regenerative braking as if this isn't on many cars, but it has been in use but it does not necessarily have to be with large battery packs to make a difference. When combined with auto start/stop it can keep a slightly larger battery charged enough to extend engine off time.
  - bluedino 11y ago
    You can only make so much power with a certain amount of gasoline - whether it's by a larger displacement engine, higher RPM, or using turbochargers to fill the cylinders with air. If you make 300hp, it's going to take around the same amount of gasoline to do so whether you do it with a 5 liter V8 or a 2 liter turbocharged 4 cylinder. Sure, the smaller engine is going to get better gas mileage when idling and such, and it's amazing how efficient the larger engines are these days. But in a heavy vehicle with the aerodynamics of a brick, the EcoBoost engines aren't seeing much better gas mileage numbers than the GM V8's.
donkeyd 11y ago
I keep seeing more cars with tiny engines and turbos, which have decent performance and very good fuel economy.
- arethuza 11y ago
  Yeah - we have a 1.2 turbo ŠKODA Yeti which is a great wee car. Had a couple of VW's before that had the 1.4 twin charged engine (turbo and a supercharger as well) which I liked as well. [NB I have had cars with much bigger engines in the past (e.g. 4.4 BMW) and I honestly don't miss them].
  - ollie87 11y ago
    I have the same engine in the SEAT Ibiza. 1.2 8v only a single overhead cam, but direct injection and a turbo. Makes 105 PS and 175Nm in the model I have, but in the larger cars they tune it to 110 PS. Most of the time it feels alright, about on par with a 1.6 16v engine but sometimes I miss the power of my old RenaultSport Clio.
    - arethuza 11y ago
      I certainly don't miss the speeding tickets! I used to speed regularly - the last time I got a ticket I decided to stop speeding completely (I literally never go above the marked speed limits). So no worries about speeding tickets, use much less fuel, I find driving less stressful and it turns out that it doesn't seem to make a huge difference to how long it takes to get anywhere. Edit: I find it amusing that when I look into the engine bay of our Yeti that I can actually see the road in the gap behind the engine - probably makes it much easier to service!
      - ollie87 11y ago
        The funniest thing about the 1.2 TSI is the oil filter pointing straight at you. Looks like you could change it in seconds.
  - donkeyd 11y ago
peterwwillis 11y ago
Wouldn't the development of turbochargers naturally direct itself toward special industry/heavy duty applications, as climate change and new technology spurs more investment in electric & autonomous vehicles? In five years, once one in four (i'm pulling that number out of my ass) of every new car is a hybrid, will the efficiency of turbos matter?
- maxerickson 11y ago
  Those applications don't have the huge volumes that the vehicle market does. Ford is going to sell 1 million turbos this year, what industrial market for engines approaches that? As to the relevance of turbos in the future, they increase peak power more than anything else, so I would expect them to continue to be useful in parallel hybrid configurations (if it enables a smaller ICE, it's probably a win).
- arethuza 11y ago
  Small high-performance turbo engines seem pretty appropriate for hybrids - look at the 1.5L 3 cylinder engine in the BMW i8.
fulafel 11y ago
> While smaller turbocharged engines have improved EPA scores, in many of our road tests, we haven't seen such radical mileage swings compared with naturally aspirated engines. Ford's EcoBoost 2.7-liter and 3.5-liter V-6 engines, for example, return mileage on par with Chevy's larger 6.2-liter V-8. Are these really standard fare in the US? In Europe the norm is more like 1.0-1.6 liter turbo engines in new cars.
- isaacdl 11y ago
  My Hyundai Accent has a 1.6L engine, and that's considered very small by most people in this country.
- jguimont 11y ago
  Ford 2.7 Ecoboost and 3.5 V6 are used on the F-150, which is not your regular car. It is however one of the most popular truck in north america (1st I believe), outselling cars in most states.
  - chrisBob 11y ago
    Careful with that statistic. People might think that we have more trucks on the road than cars which is far from the truth. Its mostly that there are really only about 10 models of trucks and probably closer to 100 cars.
    - jcoby 11y ago
      The F-series outsells any other single car by at least double. 65192 units in November vs 30945 Camrys [1]. And trucks/SUVs/minivans/crossovers (all "light-duty trucks") as a whole outsell cars by about a 50% margin. But if you just compare pickup trucks to cars, it's ~200k trucks vs ~500k cars. So, you can skew the stats however you want depending on how you want to look at it. Overall cars are actually the lesser-selling segment in the US. 1. http://online.wsj.com/mdc/public/page/2_3022-autosales.html#autosalesC http://online.wsj.com/mdc/public/page/2_3022-autosales.html#...
- peterwwillis 11y ago
mtgx 11y ago
This is like trying to improve the buggy whips when the cars first appeared. Make them faster, cheaper, lighter - and ultimately pointless. EVs will dominate new car sales within 10-15 years. And that's the more pessimistic view.
- onesun 11y ago
  Not if big oil has any say in the matter. I try not to be a conspiracy theorist, but after watching "Who Killed the Electric Car?" I'm convinced that the interests of the oil industry are why EV's don't dominate the auto industry today.
- ssmoot 11y ago
  I think that's a very optimistic view. Full EVs are a drop in the bucket right now. The Model 3 isn't even released, probably won't be widely available for another couple years, will likely cost around $50K comparably equipped, and even then Tesla likely couldn't make enough to make a dent in the overall market. The Leaf is a great car (IMO), but even in a major metro (DFW) spot-charging is really impractical. There are NO DC quick-chargers in North or North East Dallas last I looked, and you at minimum have to have a subscription just to have the option to pay to use them. There's a reasonable number of Blink Network chargers around, but no one who's actually used those would suggest they're a viable way to maintain a charge without major compromises. Using a Leaf to commute to the suburbs is an experience fraught with stress as well. Maybe in a couple years the Leaf will have kicked the range-anxiety issue to the curb. And the Chevy Beat looks very promising. 2 cars in the range of the average new car purchase price does not make for domination though. My prediction is that it's realistically going to be at least 3 car generations before that has a chance of happening, and most manufacturers haven't even released a full EV yet. That's a good 15 to 20 years as a best case scenario. That doesn't address the Truck and family SUV market either. These things are made for hauling. They're going to suck down a lot more power. "Work Trucks" aren't going to convert for much longer Though I think there's a good chance many will go hybrid in ~10 years. There's got to be a ton of utility in a series-hybrid truck for towing, site power, etc. Just my 2c. I've actually owned a Leaf. I think EVs are great. A lot more so than people even realize. Instant torque and acceleration response makes them really fun to drive. That doesn't mean I think they'll somehow become dominant in the same timespan that it took Nissan to come out with a massively compromised diesel truck nobody is going to buy. That's beyond optimistic IMO.
acd 11y ago
You can possibily prespool turbo chargers so that the turbo pressure is already there from start RPMs. Techniques to do that is either electric or compressed air. https://en.wikipedia.org/wiki/Hybrid_turbocharger https://en.wikipedia.org/wiki/Hybrid_turbocharger http://www.motorauthority.com/news/1094807_volvo-reveals-450-hp-four-cylinder-with-electrically-driven-turbo-video http://www.motorauthority.com/news/1094807_volvo-reveals-450...
hencq 11y ago
With the direction this seems to be moving in with ever bigger turbos on smaller engines, I wonder how long it will take before we simply remove the piston engine altogether and just switch to (turbine) generators. It seems this would work quite well as part of a hybrid setup.
- Gravityloss 11y ago
  Large industrial processes can be analyzed by looking at flows of hot, warm and cold fluids etc. They can then be optimized mathematically so you lose the least energy while producing the same useful output. Often people with already basic knowledge of thermodynamics can spot the large inefficiency sources in many of the currently common processes. This stuff has been known since the 1800s. It's just that the implementation has been too expensive (payoff is too slow), or politically inconvenient (the technology is in another department/company). There might be some reliability or emissions or noise issues etc... The world is full of massive technical inefficiencies and thus, great business opportunities. You can look at the car as an industrial process as well. Intercoolers, capacitor energy recovery, heat pumps for heating (and not just for air conditioning). Most of the mechanical technology is 100+ years old. The turbocharger was patented in 1905. With batteries and capacitors and control electronics there's some fairly new stuff. You could for example skip the piston engine and instead have just a turbine and then a bottoming engine with CO2 cycle recovering the waste heat. Ships run with turbocharged diesel engines, but GE is championing precisely this turbine + bottoming for them. So why not cars? There are some big operational differences of course (heating the working fluid in an external combustion engine takes a while). But there could be some big benefits too, like if you don't have reciprocating machinery at all, the noise is different and there's no vibration.

38 points by dmmalam 11y ago

deleted 11y ago

[deleted]

iaw 11y ago

We're heading in a good direction with turbochargers. I suspect we're getting close to the Carnot limits for gasoline engines [1]. Next steps would be adapting the regenerative braking technology, like that on the Porsche 918, into regular vehicles. There's a lot of kinetic energy wasted in brakes and we're soon going to be able to recapture it. [1] https://en.wikipedia.org/wiki/Carnot_cycle#Efficiency_of_real_heat_engines https://en.wikipedia.org/wiki/Carnot_cycle#Efficiency_of_rea...

maxerickson 11y ago
Is there something notable about the brakes in the Porsche? Regenerative brakes are a big win in many of the hybrids that have been brought to market.
- drcross 11y ago
  It's a significant car because it currently holds the lap record in Nürburgring for a supercar.
  - maxerickson 11y ago
    That doesn't make the brakes interesting in comparison to the system on a Prius (or whichever earlier car you want to pick).
  - Grazester 11y ago
    There is nothing notable about the regenerative brakes in the Porsche 918. Other hybrids have been using regenerative brakes for years and years now. As for a Nürburgring "record" I dont see the relevance in this conversation
- iaw 11y ago
  So there are a few components interesting in the Porsche 918's braking system that I'll speak to. 1) The brakes slow the car down through a combination of electric generation and traditional brake pads, just like the hybrids you're familiar with. Unlike the Prius, the brakes escalate in a predictable a familiar fashion. Most regenerative braking systems do not scrub speed from the car in the same linear fashion as the 918. This is a major accomplishment because it makes the transition from regular brakes to regenerative brakes seamless and allows for spirited driving. 2) The batteries are not designed to store a substantial amount of charge, instead they are designed to provide a large chunk of the acceleration power that would normally come from a gasoline engine in a hybrid. Instead of designing the car to utilize batteries for long-ranges, Porsche designed the car to utilize batteries for sprints. 3) The net result is a car that is as spirited as a traditional sports car but with greatly increased efficiency. People that wont buy a Prius or BMW Hybrid right now because of the ride quality issues would be willing to purchase a car with the 918 style system. The school of thought behind the Prius to squeeze every drop of efficiency out of the electric side, the school of thought behind the 918 is to support spirited driving with the electric side. Both lead to increases in efficiency but only the latter is something people that consider themselves 'drivers' would buy. You can see this with Turbochargers as they are just now starting to trickle onto sport vehicles such as the BMW M4 and Ferrari has acknowledged that they will be pursuing the technology in their road cars in the near future.
creshal 11y ago
> Next steps would be adapting the regenerative braking technology, like that on the Porsche 918, into regular vehicles. Virtually all hybrids already do that…
- iaw 11y ago
  Yes but you have to buy a car with a huge battery pack and crap performance (including the i8). I drive an M3, I'm not going to give up fast vehicles until self-driving cars are mandatory. Regenerative braking (with a small battery pack) could double the fuel efficiency I obtain. The existing regenerative braking systems available are horrible (in a number of ways) and not comparable to what's in existence for F1 and the 918. Regenerative braking for most cars now is where turbochargers were pre-1990s. The system I'm talking about can run only a few miles in full electric but gives a substantial boost in fuel economy because it's utilized for most acceleration below ~100 MPH.
ssmoot 11y ago
The Mazda 3 has an option for a regenerative braking system. I'm not really sure how that works in a non-hybrid TBH. Just used to charge for accessories, electric compressor, steering, etc so you can use a clutched alternator and minimize accessory loads? Just a guess.
- ollie87 11y ago
  I believe the BMW 1 Series is the same.
sliken 11y ago
As mentioned in the article. Turbos don't help MPG much. Several examples in the article who larger engines with on turbos having similar MPG to smaller turbo engines. Sure they increase peak HP, but they also increase exhaust backpressure. Seems like the main achievement of turbos is cheaper/smaller engines.
- Shivetya 11y ago
  most of the efficiency benefits we stand to gain with forced induction and other improvements is routinely lost because people cannot drive properly. the race to the next red light does nothing but wreck your mileage. some have suggested regenerative braking as if this isn't on many cars, but it has been in use but it does not necessarily have to be with large battery packs to make a difference. When combined with auto start/stop it can keep a slightly larger battery charged enough to extend engine off time.
- bluedino 11y ago
  You can only make so much power with a certain amount of gasoline - whether it's by a larger displacement engine, higher RPM, or using turbochargers to fill the cylinders with air. If you make 300hp, it's going to take around the same amount of gasoline to do so whether you do it with a 5 liter V8 or a 2 liter turbocharged 4 cylinder. Sure, the smaller engine is going to get better gas mileage when idling and such, and it's amazing how efficient the larger engines are these days. But in a heavy vehicle with the aerodynamics of a brick, the EcoBoost engines aren't seeing much better gas mileage numbers than the GM V8's.

donkeyd 11y ago

I keep seeing more cars with tiny engines and turbos, which have decent performance and very good fuel economy.

arethuza 11y ago
Yeah - we have a 1.2 turbo ŠKODA Yeti which is a great wee car. Had a couple of VW's before that had the 1.4 twin charged engine (turbo and a supercharger as well) which I liked as well. [NB I have had cars with much bigger engines in the past (e.g. 4.4 BMW) and I honestly don't miss them].
- ollie87 11y ago
  I have the same engine in the SEAT Ibiza. 1.2 8v only a single overhead cam, but direct injection and a turbo. Makes 105 PS and 175Nm in the model I have, but in the larger cars they tune it to 110 PS. Most of the time it feels alright, about on par with a 1.6 16v engine but sometimes I miss the power of my old RenaultSport Clio.
  - arethuza 11y ago
    I certainly don't miss the speeding tickets! I used to speed regularly - the last time I got a ticket I decided to stop speeding completely (I literally never go above the marked speed limits). So no worries about speeding tickets, use much less fuel, I find driving less stressful and it turns out that it doesn't seem to make a huge difference to how long it takes to get anywhere. Edit: I find it amusing that when I look into the engine bay of our Yeti that I can actually see the road in the gap behind the engine - probably makes it much easier to service!
    - ollie87 11y ago
      The funniest thing about the 1.2 TSI is the oil filter pointing straight at you. Looks like you could change it in seconds.
- donkeyd 11y ago

peterwwillis 11y ago

Wouldn't the development of turbochargers naturally direct itself toward special industry/heavy duty applications, as climate change and new technology spurs more investment in electric & autonomous vehicles? In five years, once one in four (i'm pulling that number out of my ass) of every new car is a hybrid, will the efficiency of turbos matter?

maxerickson 11y ago
Those applications don't have the huge volumes that the vehicle market does. Ford is going to sell 1 million turbos this year, what industrial market for engines approaches that? As to the relevance of turbos in the future, they increase peak power more than anything else, so I would expect them to continue to be useful in parallel hybrid configurations (if it enables a smaller ICE, it's probably a win).
arethuza 11y ago
Small high-performance turbo engines seem pretty appropriate for hybrids - look at the 1.5L 3 cylinder engine in the BMW i8.

fulafel 11y ago

> While smaller turbocharged engines have improved EPA scores, in many of our road tests, we haven't seen such radical mileage swings compared with naturally aspirated engines. Ford's EcoBoost 2.7-liter and 3.5-liter V-6 engines, for example, return mileage on par with Chevy's larger 6.2-liter V-8. Are these really standard fare in the US? In Europe the norm is more like 1.0-1.6 liter turbo engines in new cars.

isaacdl 11y ago
My Hyundai Accent has a 1.6L engine, and that's considered very small by most people in this country.
jguimont 11y ago
Ford 2.7 Ecoboost and 3.5 V6 are used on the F-150, which is not your regular car. It is however one of the most popular truck in north america (1st I believe), outselling cars in most states.
- chrisBob 11y ago
  Careful with that statistic. People might think that we have more trucks on the road than cars which is far from the truth. Its mostly that there are really only about 10 models of trucks and probably closer to 100 cars.
  - jcoby 11y ago
    The F-series outsells any other single car by at least double. 65192 units in November vs 30945 Camrys [1]. And trucks/SUVs/minivans/crossovers (all "light-duty trucks") as a whole outsell cars by about a 50% margin. But if you just compare pickup trucks to cars, it's ~200k trucks vs ~500k cars. So, you can skew the stats however you want depending on how you want to look at it. Overall cars are actually the lesser-selling segment in the US. 1. http://online.wsj.com/mdc/public/page/2_3022-autosales.html#autosalesC http://online.wsj.com/mdc/public/page/2_3022-autosales.html#...
peterwwillis 11y ago

mtgx 11y ago

This is like trying to improve the buggy whips when the cars first appeared. Make them faster, cheaper, lighter - and ultimately pointless. EVs will dominate new car sales within 10-15 years. And that's the more pessimistic view.

onesun 11y ago
Not if big oil has any say in the matter. I try not to be a conspiracy theorist, but after watching "Who Killed the Electric Car?" I'm convinced that the interests of the oil industry are why EV's don't dominate the auto industry today.
ssmoot 11y ago
I think that's a very optimistic view. Full EVs are a drop in the bucket right now. The Model 3 isn't even released, probably won't be widely available for another couple years, will likely cost around $50K comparably equipped, and even then Tesla likely couldn't make enough to make a dent in the overall market. The Leaf is a great car (IMO), but even in a major metro (DFW) spot-charging is really impractical. There are NO DC quick-chargers in North or North East Dallas last I looked, and you at minimum have to have a subscription just to have the option to pay to use them. There's a reasonable number of Blink Network chargers around, but no one who's actually used those would suggest they're a viable way to maintain a charge without major compromises. Using a Leaf to commute to the suburbs is an experience fraught with stress as well. Maybe in a couple years the Leaf will have kicked the range-anxiety issue to the curb. And the Chevy Beat looks very promising. 2 cars in the range of the average new car purchase price does not make for domination though. My prediction is that it's realistically going to be at least 3 car generations before that has a chance of happening, and most manufacturers haven't even released a full EV yet. That's a good 15 to 20 years as a best case scenario. That doesn't address the Truck and family SUV market either. These things are made for hauling. They're going to suck down a lot more power. "Work Trucks" aren't going to convert for much longer Though I think there's a good chance many will go hybrid in ~10 years. There's got to be a ton of utility in a series-hybrid truck for towing, site power, etc. Just my 2c. I've actually owned a Leaf. I think EVs are great. A lot more so than people even realize. Instant torque and acceleration response makes them really fun to drive. That doesn't mean I think they'll somehow become dominant in the same timespan that it took Nissan to come out with a massively compromised diesel truck nobody is going to buy. That's beyond optimistic IMO.

acd 11y ago

You can possibily prespool turbo chargers so that the turbo pressure is already there from start RPMs. Techniques to do that is either electric or compressed air. https://en.wikipedia.org/wiki/Hybrid_turbocharger https://en.wikipedia.org/wiki/Hybrid_turbocharger http://www.motorauthority.com/news/1094807_volvo-reveals-450-hp-four-cylinder-with-electrically-driven-turbo-video http://www.motorauthority.com/news/1094807_volvo-reveals-450...

hencq 11y ago

With the direction this seems to be moving in with ever bigger turbos on smaller engines, I wonder how long it will take before we simply remove the piston engine altogether and just switch to (turbine) generators. It seems this would work quite well as part of a hybrid setup.

Gravityloss 11y ago
Large industrial processes can be analyzed by looking at flows of hot, warm and cold fluids etc. They can then be optimized mathematically so you lose the least energy while producing the same useful output. Often people with already basic knowledge of thermodynamics can spot the large inefficiency sources in many of the currently common processes. This stuff has been known since the 1800s. It's just that the implementation has been too expensive (payoff is too slow), or politically inconvenient (the technology is in another department/company). There might be some reliability or emissions or noise issues etc... The world is full of massive technical inefficiencies and thus, great business opportunities. You can look at the car as an industrial process as well. Intercoolers, capacitor energy recovery, heat pumps for heating (and not just for air conditioning). Most of the mechanical technology is 100+ years old. The turbocharger was patented in 1905. With batteries and capacitors and control electronics there's some fairly new stuff. You could for example skip the piston engine and instead have just a turbine and then a bottoming engine with CO2 cycle recovering the waste heat. Ships run with turbocharged diesel engines, but GE is championing precisely this turbine + bottoming for them. So why not cars? There are some big operational differences of course (heating the working fluid in an external combustion engine takes a while). But there could be some big benefits too, like if you don't have reciprocating machinery at all, the noise is different and there's no vibration.