[...]
I would bet that compression ratio is when it’s doing the Atkinson thing, so the exhaust valves are open for a part of that compression stroke, meaning it’s not really 14 parts air, it’s more like 10 parts air but then the fuel explodes and pushes the piston back down to 14 parts, hence the extra efficiency of the Atkinson cycle
>Is it just a gimmick?
No. Its more than just engine, its the whole car design. >why does no company try to copy them?
Most of modern engines already have miller cycle/modified atkinson cycle. So others did copy this one feature.
Yeah but it also combines insanely high compression ratio I think around 14 to 1
Which is way above the standard 10 to 1
I would bet that compression ratio is when it’s doing the Atkinson thing, so the exhaust valves are open for a part of that compression stroke, meaning it’s not really 14 parts air, it’s more like 10 parts air but then the fuel explodes and pushes the piston back down to 14 parts, hence the extra efficiency of the Atkinson cycle
Nah, if you left the intake valves open on the compression stroke, you would be forcing some air back out the intake and create a mess of turbulence. You send that air out the exhaust because air us already flowing that way.
https://i.imgur.com/afVyV2I.png
I don't get it. I used to know how an engine works
It’s an interesting concept. It’s trying to make a little more power out of all the wasted heat that regular engines always have. When you compress 1L of air down to 0.1L on the compression stroke, then add an explosion with the gasoline, it expands it back out to 1L but there’s still more power in there when the piston bottoms out. Atkinson cycle says that burning gas is still expanding and cold push it out to 1.5L+ if the piston didn’t hit its physical bottom. So you do the modified atkinson cycle. Leave the exhaust valve open a little bit on the compression stroke so some air escapes, now you only have 0.5L of air in there being compresed down to 0.1L. You add the fuel with direct injection (except it’s only half as much fuel as before because you only have 0.5L of air to burn with it) and then spark, and that 0.5L of air plus the fuel burns enough to expand the cylinder all the way back to the 1.0L. And the exhaust gasses are cooler by the time they leave the engine because more heat was turned into power on that theoretically longer power stroke
It’s making less power when it runs like that because it’s less powerful explosions, but you get more power out of s given amount of gasoline. And it’s all variable valve timing, so it will run the normal Otto cycle when you want power, and the atkinson when you want efficiency.
2 weeks ago
Anonymous
I'm no engineer but what you're explaining sounds too good to be true
What's the downside?
2 weeks ago
Beppu
Well it wasn’t really possible until direct injection was a thing, otherwise you would be blowing air/fuel mix out the open valves. And it wasn’t really possible until variable valve timing was a thing, or it could be done but you would be getting way less power for a given displacement but now VVT lets them switch between regular Otto Cycle for power and Atkinson for efficiency. Tons of hybrids use it because the electric motor makes up for the lack of power, it’s sort of a standard thing in the auto industry these days.
It’s like cylinder deactivation. It’s all possible and helps efficiency a bit, but it makes the engines more complicated.
?si=0cT1iVtw5G-GSCu0
>Nah, if you left the intake valves open on the compression stroke, you would be forcing some air back out the intake and create a mess of turbulence. You send that air out the exhaust because air us already flowing that way
it definitely isn't the exhaust valve that's opening.
?feature=shared&t=932
Ahh I see, Toyota engineers did something fancy with a “tumble flow”. Maybe it was the original design that left the exhaust valve open. I’ve fallen into too many wikipedia holes.
2 weeks ago
Anonymous
>Nah, if you left the intake valves open on the compression stroke, you would be forcing some air back out the intake and create a mess of turbulence. You send that air out the exhaust because air us already flowing that way
it definitely isn't the exhaust valve that's opening.
from what I understand its mostly just marketing, "skyactiv" is apparently their general philosophy - efficient, powerful (relatively) engines and a chassis that are comfortable but engaging to drive.
Nominally for the engines themselves is means high compression (13:1 in US market) direct injection, factory header, VVT, which all probably sounded a lot more impressive back in 2010 or whenever they first started that branding.
As far as transmissions, their automatic is partially a normal torque converter auto but with a true multi-disc clutch as well.
This guy gets it correct. The goal is also to keep the vehicle weight, real world emissions in check while not joining into stupid trend of downsized forced induction engines. In the past times it was also with reduced amount of electrified powertrains but this part recently changed because of too strict policies from human made climate change propaganda.
tbh it mostly is, every manufacturer has it's own gimmicky marketing name.
and while i don't toyota, because they make boring af cars, their dynamic whatever engines were verified epa not to long ago and they really do have peak 40% thermal efficiency (without hybrid crap)
>its the whole car design. >drinking corporate kool-aid
>>its the whole car design.
corporate kool-aid
we're literally talking about a corporate name here, you dumbfrick
"skyactiv" isn't a specific piece in the engine
Interesting. In many European countries there is Mazda CX-60 with econobox 3.3liter 48volt mild inline6 turbodiesel option with 200hp RWD or 254hp AWD. Mazda 3, CX30 have 2.0liter mild hybrid e-skyactiv X 186hp. Weird if Poland didnt get these options.
The turbos are a high trim option, not standard. The NA already makes at/more than everyone else's turbo I4, so the turbo pushes them into NA V6 levels of power.
Skyactiv-G is nothing special. Skyactiv-X is the innovative system. It uses compression ignition (like a diesel) on a gas engine. In Oz it's only available as an expensive option on the Mazda3. Reason other makers don't use it is that Mazda owns the patents.
Yes,but Sky-X is world first tech. First ever compression ignition gas engine to market. Ready for Euro-7 regs. On another note, look how many Mazda SUV's we get in Oz.
>Ready for Euro-7 regs
but emission limits for gas engines were virtually unchanged in euro7, excluding nox limit lowered by 20mg/km and equalized between gas and diesel
I have a grey import 2015 CX-5 from Japan. What I know:
>14:1 compression ratio on the diesel as well >Exhaust valves stay a little open for part the intake stroke while cold >Auto box locks up super early >Auto rev match down shifts even in "D" >I almost thought it was a dual clutch when I first drove it >If you have a wheel in the air it hardly spins at all before sending power to the rest >Full throttle the first 2 gears are short and make it feel like a rocket >Barely any turbo lag >First KEKV I drove that actually drove well >Pull back to shift up, push forward to shift down like God intended. >Better clearance that most other KEKV's
Problem is that it is still a KEKV. However I think it deserves more praise than it gets, though not as much as that moronic autist that posts about it every other day gives.it.
Definitely put the ND Miata on my bucket list of cars to drive but they don't sell them in my country and I haven't seen one imported yet.
Its more expensive, brings only limited gains in power and mileage, long term reliability is unknown and non-hybrid economy ICE powertrain development is nearly dead.
>long term reliability is unknown and non-hybrid economy ICE powertrain development is nearly dead.
ICE engines arent going anywhere as long as hybrid batteries cost like a used car
Isn’t it a modified atkinson cycle? Lots of other engines do it but call it something else.:. Like VVT
Yeah but it also combines insanely high compression ratio I think around 14 to 1
Which is way above the standard 10 to 1
More like ACKinson cycle
>Is it just a gimmick?
No. Its more than just engine, its the whole car design.
>why does no company try to copy them?
Most of modern engines already have miller cycle/modified atkinson cycle. So others did copy this one feature.
I know the engine stands out because of the compression ratio but what does the gear and suspension have that others don't?
I would bet that compression ratio is when it’s doing the Atkinson thing, so the exhaust valves are open for a part of that compression stroke, meaning it’s not really 14 parts air, it’s more like 10 parts air but then the fuel explodes and pushes the piston back down to 14 parts, hence the extra efficiency of the Atkinson cycle
>exhaust valves
guessing you mean intake valves?
Nah, if you left the intake valves open on the compression stroke, you would be forcing some air back out the intake and create a mess of turbulence. You send that air out the exhaust because air us already flowing that way.
It’s an interesting concept. It’s trying to make a little more power out of all the wasted heat that regular engines always have. When you compress 1L of air down to 0.1L on the compression stroke, then add an explosion with the gasoline, it expands it back out to 1L but there’s still more power in there when the piston bottoms out. Atkinson cycle says that burning gas is still expanding and cold push it out to 1.5L+ if the piston didn’t hit its physical bottom. So you do the modified atkinson cycle. Leave the exhaust valve open a little bit on the compression stroke so some air escapes, now you only have 0.5L of air in there being compresed down to 0.1L. You add the fuel with direct injection (except it’s only half as much fuel as before because you only have 0.5L of air to burn with it) and then spark, and that 0.5L of air plus the fuel burns enough to expand the cylinder all the way back to the 1.0L. And the exhaust gasses are cooler by the time they leave the engine because more heat was turned into power on that theoretically longer power stroke
It’s making less power when it runs like that because it’s less powerful explosions, but you get more power out of s given amount of gasoline. And it’s all variable valve timing, so it will run the normal Otto cycle when you want power, and the atkinson when you want efficiency.
I'm no engineer but what you're explaining sounds too good to be true
What's the downside?
Well it wasn’t really possible until direct injection was a thing, otherwise you would be blowing air/fuel mix out the open valves. And it wasn’t really possible until variable valve timing was a thing, or it could be done but you would be getting way less power for a given displacement but now VVT lets them switch between regular Otto Cycle for power and Atkinson for efficiency. Tons of hybrids use it because the electric motor makes up for the lack of power, it’s sort of a standard thing in the auto industry these days.
It’s like cylinder deactivation. It’s all possible and helps efficiency a bit, but it makes the engines more complicated.
?si=0cT1iVtw5G-GSCu0
Ahh I see, Toyota engineers did something fancy with a “tumble flow”. Maybe it was the original design that left the exhaust valve open. I’ve fallen into too many wikipedia holes.
>Nah, if you left the intake valves open on the compression stroke, you would be forcing some air back out the intake and create a mess of turbulence. You send that air out the exhaust because air us already flowing that way
it definitely isn't the exhaust valve that's opening.
?feature=shared&t=932
I don't get it. I used to know how an engine works
from what I understand its mostly just marketing, "skyactiv" is apparently their general philosophy - efficient, powerful (relatively) engines and a chassis that are comfortable but engaging to drive.
Nominally for the engines themselves is means high compression (13:1 in US market) direct injection, factory header, VVT, which all probably sounded a lot more impressive back in 2010 or whenever they first started that branding.
As far as transmissions, their automatic is partially a normal torque converter auto but with a true multi-disc clutch as well.
This guy gets it correct. The goal is also to keep the vehicle weight, real world emissions in check while not joining into stupid trend of downsized forced induction engines. In the past times it was also with reduced amount of electrified powertrains but this part recently changed because of too strict policies from human made climate change propaganda.
tbh it mostly is, every manufacturer has it's own gimmicky marketing name.
and while i don't toyota, because they make boring af cars, their dynamic whatever engines were verified epa not to long ago and they really do have peak 40% thermal efficiency (without hybrid crap)
>its the whole car design.
>drinking corporate kool-aid
>>its the whole car design.
corporate kool-aid
we're literally talking about a corporate name here, you dumbfrick
"skyactiv" isn't a specific piece in the engine
>why does no company try to copy them?
consoomers don't care
I'm pretty sure this wound up going nowhere. Every Mazda ad I hear or see mentions their turbo engines. I thought they were trying to avoid turbos?
Must be a US thing, I don't think I've ever seen a new turbod Mazda in Poland
They are all either 2.0L or 2.5L naturally aspirated
see
mazda is the only one selling regular everyday commuter cars with "big" engines. Everything else is turbocucked .9l 3 cylinders.
Interesting. In many European countries there is Mazda CX-60 with econobox 3.3liter 48volt mild inline6 turbodiesel option with 200hp RWD or 254hp AWD. Mazda 3, CX30 have 2.0liter mild hybrid e-skyactiv X 186hp. Weird if Poland didnt get these options.
Oh yeah diesels all come with turbos
I was specifically talking about petrol
The turbos are a high trim option, not standard. The NA already makes at/more than everyone else's turbo I4, so the turbo pushes them into NA V6 levels of power.
Skyactiv-G is nothing special. Skyactiv-X is the innovative system. It uses compression ignition (like a diesel) on a gas engine. In Oz it's only available as an expensive option on the Mazda3. Reason other makers don't use it is that Mazda owns the patents.
Even the Skyactiv-G generates 13-14 to 1 compression
Yes,but Sky-X is world first tech. First ever compression ignition gas engine to market. Ready for Euro-7 regs. On another note, look how many Mazda SUV's we get in Oz.
SUVs sell so companies make SUVs
Cant blame them for following the market demands
Hope they sell boatloads of the RWD architecture CX60-CX90's. May pave the way for a new model car.
>Ready for Euro-7 regs
but emission limits for gas engines were virtually unchanged in euro7, excluding nox limit lowered by 20mg/km and equalized between gas and diesel
I have a grey import 2015 CX-5 from Japan. What I know:
>14:1 compression ratio on the diesel as well
>Exhaust valves stay a little open for part the intake stroke while cold
>Auto box locks up super early
>Auto rev match down shifts even in "D"
>I almost thought it was a dual clutch when I first drove it
>If you have a wheel in the air it hardly spins at all before sending power to the rest
>Full throttle the first 2 gears are short and make it feel like a rocket
>Barely any turbo lag
>First KEKV I drove that actually drove well
>Pull back to shift up, push forward to shift down like God intended.
>Better clearance that most other KEKV's
Problem is that it is still a KEKV. However I think it deserves more praise than it gets, though not as much as that moronic autist that posts about it every other day gives.it.
Definitely put the ND Miata on my bucket list of cars to drive but they don't sell them in my country and I haven't seen one imported yet.
Skyactiv-X?
Its more expensive, brings only limited gains in power and mileage, long term reliability is unknown and non-hybrid economy ICE powertrain development is nearly dead.
Too little too late.
>long term reliability is unknown and non-hybrid economy ICE powertrain development is nearly dead.
ICE engines arent going anywhere as long as hybrid batteries cost like a used car