Simple enough to understand especially with the side by side comparison. However, to me it is still the Otto cycle of intake-compression-power and exhaust, delaying the intake valve closure for a split second doesn't alter that. Adding an electric motor and energy storage to overcome its low-end torque just complicates matters, carrying around two propulsion systems basically.
Instead of closing the intake valve late to capture less intake charge, why not close it early? Okay, the piston would have to pull against a partial vacuum during the end of the induction stroke but most of that work would be recovered early in the compression stroke. Wouldn’t this be better than pulling charge in past the inlet valve only to push it out past the same valve again with the pumping losses that that incurs?
I think opening late could be even better, little vacuum would force air faster in to the sylinder and might help with the air-fuel mixing providing better burning, and it would delete need to special manifold for accomodating exess fuel in air. And basically it could be done with separate throttle plate assembly as long they are cylindrical and not plates that shake loose to end up in the engine
@@felixchaus Chrysler MultiAir engines do this. Actually they have several separate intake valves openings during a single intake stroke at low load. You would think there would be large losses as vacuum is made and then broken, but supposedly it gives much better mixing at low load.
Thanks for this description. I found it very good. I have just ordered a hybrid SUV with Atkinson cycle engine coupled with an E-CVT. . Does the VVT allow the engine to select between Otto and Atkinson cycle as required so you can maximise torque when needed. ? Thanks Rob, Melbourne Australia.
No one will know how to work on this..not even the dealership, they can’t even figure out issues with older Otto gasoline only engines. I work with a company with a large fleet of vehicles..they have their own garage and when they have trouble solving issues they send it to the dealership and guess what?… the dealership in most case can’t figure it out either !
Hello sir i have a hyundai car.. Cranking but no start.. we test the compression and the Reading is Zero. We also do the live data and run some test. And DTC is clear.. what do you think is the problem... mechanic says engine needs to Overhaul..
Why does the Ford Atkinson motor have a bunch of equipment in the fuel tank? In other words apparently they are the same fuel tank for the Maverick Hybrid and Maverick Eco boost but the Ecoboost has a 16.5 fuel capacity and the Hybrid only 13.8 gallons. So what takes up 2.7 gallons within the fuel take to run the Atkinson motor?
Everybody has an opinion; here's mine: I think you missed the most important aspect of Atkinson cycle engines. Combustion engine efficiency is directly related to the compression ratio. This is why Diesel engines get such great mileage. Atkinson cycle engines will typically have a higher mechanical compression ratio than an equivalent Otto cycle engine. Detuning the intake valve timing reduces the compressed charge and simulates a smaller intake stroke, thereby managing the pinging and detonation you would otherwise get from that high compression ratio. However, the higher efficiency of the power stroke from that high compression ratio remains. This is more where the fuel efficiency comes from, although the lower compression pressures you described do contribute. Just sayin'...
I think the "designers" NEED to think a bit more about the physics between the two options.. what does the throttle plate do in restricting air IN.. vs blowing excess air back out where it came from.. the intake stroke vacuum.. acts to pull the piston back up in part of the "compression" stroke.. so would actually be MORE efficient than pulling un needed air in then to just push it back out creating even more drag
@@Errol.C-nz - I agree that there are many ways to skin a cat, but I have to assume that the engineers who developed these engines did their homework and verified the design by testing. Valve timing might have been the cheapest (free) way to achieve a reliable max chamber pressure since modulating the throttle might have required to much precision. There are lots of design tradeoffs in every machine, balancing various competing factors. Cost, of course, is often king of the hill. 😁
@@ralphwaters8905 The throttle is inefficient. Vasically it is taking air from a partial vacuum and needs to compress it against the outside air. That is called "pumping losses". (that there is a compression and power stroke in between doesn't change that).
When they use atkinson + force induction . When the piston compresses the intake valve stays open little longe . Then part of air fuel mixture will compress in to the intake manifold. When they use super charger . There is compression from the both sides . Isn’t that a problem ??
I have a 21 Tacoma 3.5 that uses Atkinson cycling at lower power settings and then back to Otto under load. It has dual GDI and Port injection. I believe it uses port under load during Otto. With the delayed intake closing during compression and some of the air/fuel charge going back into the intake I take it that it used again during the intake stroke if the port injectors are used. Could you have some residue fuel in the manifold if the GDI kicks in?
I'm sure it could be possible that there was a little "leftover" when switching modes. Realistically it should be very minor if it ever happens and the engineers likely compensated for it in programming.
You talk about some of the "charge" being forced back into the inlet manifold, that suggests that fuel has been injected or do these engines need to be direct injected? Anthony
On conventional injection, the air-fuel "charge" enters the cylinder during the intake stroke. When the piston starts back up on the compression stroke with Late Intake Valve Closing, part of that charge can be forced back into the intake. If Direct Injection is used, most of the time (U.S. spec vehicles anyway) fuel is injected during the intake stroke, so a small amount of that charge would also be forced out during Late Intake Valve Closing (or "Atkinson Cycling"). Direct Injected vehicles do have a benefit here as they can be programmed to inject during the compression stroke after the valves have closed, but that has some potential emissions ramifications.
The difference here being the Atkinson still takes advantage of the longer stroke on the power stroke (expansion). If displacement is decreased, the stroke is shorter providing less power (less energy transferred to the crankshaft.) But if we drop displacement and add a turbo.....
@@pccastengineperformance7844 thank you for the explanation, i see how Atkinson is saving gas know, but is it worth? I mean is 2.5 Atkinson better than 2.0 Otto? Thx for your time.
There are a couple of issues at play here. Everyone talks about compression ratio, but the other half of this is expansion ratio (as the piston is going back down after crossing TDC). Lower compression ratio effects both, and lowers overall engine efficiency. By increasing the intake duration slightly and late intake valve closing, it only changes the effective compression ratio, but not the expansion ratio. This allows a higher compression ratio to be used, that with the late intake closing ends up at a fairly "normal" effective compression. When moving into the power stroke however, this will be a greater expansion ratio, to gain more power from combustion. Also, as Atkinson cycling is used currently with variable camshaft timing (and sometimes variable valve lift) , during some conditions the late intake closing strategy won't be used, and the engine can benefit from having higher working compression.
@@Errol.C-nz typically defined as (the volume of the cylinder with piston at BTC + the volume of the combustion chamber + volume of head gasket thickness) / (volume of cylinder with piston at TDC + the volume of the combustion chamber + volume of head gasket thickness)
exactly my point.. dependent on.. volumetric efficiency.. what dose a throttle plate do.. now factor your valve/port timing for "corrected" compression ration...and.. what are the true pumping loses.. more important of the pumping loses are damping in the pumping action such as intake air resistance just to expel it again past a valve.. vs.. a rebound bounce effect of a vacuum vs pressure from opposite strokes.. rotate an engine with valves closed.. then rotate the same engine with them open.. which has the most rotational resistance (or energy loses).. flow resistance increases as a square not linear as well & acts as a damper
Got to love that FROCED induction!😂
The Mazda I had in my 20s ran on this engine design. Kind of a neat engine.
Simple enough to understand especially with the side by side comparison. However, to me it is still the Otto cycle of intake-compression-power and exhaust, delaying the intake valve closure for a split second doesn't alter that. Adding an electric motor and energy storage to overcome its low-end torque just complicates matters, carrying around two propulsion systems basically.
Thanks
Instead of closing the intake valve late to capture less intake charge, why not close it early? Okay, the piston would have to pull against a partial vacuum during the end of the induction stroke but most of that work would be recovered early in the compression stroke. Wouldn’t this be better than pulling charge in past the inlet valve only to push it out past the same valve again with the pumping losses that that incurs?
even simpler.. a throttle plate
I think opening late could be even better, little vacuum would force air faster in to the sylinder and might help with the air-fuel mixing providing better burning, and it would delete need to special manifold for accomodating exess fuel in air.
And basically it could be done with separate throttle plate assembly as long they are cylindrical and not plates that shake loose to end up in the engine
I believe if you look at the Miller Cycle engine, that's exactly what it does.
I believe "few" engineers have at some point assessed this argument and considered it a waste of time.
@@felixchaus Chrysler MultiAir engines do this. Actually they have several separate intake valves openings during a single intake stroke at low load. You would think there would be large losses as vacuum is made and then broken, but supposedly it gives much better mixing at low load.
My Lexus 5.0 V8 (2UR-GSE) uses both Otto and Atkinson with both port and direct injection.
Thanks for this description. I found it very good. I have just ordered a hybrid SUV with Atkinson cycle engine coupled with an E-CVT. . Does the VVT allow the engine to select between Otto and Atkinson cycle as required so you can maximise torque when needed. ? Thanks Rob, Melbourne Australia.
No one will know how to work on this..not even the dealership, they can’t even figure out issues with older Otto gasoline only engines. I work with a company with a large fleet of vehicles..they have their own garage and when they have trouble solving issues they send it to the dealership and guess what?… the dealership in most case can’t figure it out either !
Hello sir i have a hyundai car.. Cranking but no start.. we test the compression and the Reading is Zero. We also do the live data and run some test. And DTC is clear.. what do you think is the problem... mechanic says engine needs to Overhaul..
The fuel air mixture pushed back, no problem with fuel air mixture stuck at intake manifold?
Why does the Ford Atkinson motor have a bunch of equipment in the fuel tank? In other words apparently they are the same fuel tank for the Maverick Hybrid and Maverick Eco boost but the Ecoboost has a 16.5 fuel capacity and the Hybrid only 13.8 gallons. So what takes up 2.7 gallons within the fuel take to run the Atkinson motor?
Everybody has an opinion; here's mine: I think you missed the most important aspect of Atkinson cycle engines. Combustion engine efficiency is directly related to the compression ratio. This is why Diesel engines get such great mileage. Atkinson cycle engines will typically have a higher mechanical compression ratio than an equivalent Otto cycle engine. Detuning the intake valve timing reduces the compressed charge and simulates a smaller intake stroke, thereby managing the pinging and detonation you would otherwise get from that high compression ratio. However, the higher efficiency of the power stroke from that high compression ratio remains. This is more where the fuel efficiency comes from, although the lower compression pressures you described do contribute. Just sayin'...
I think the "designers" NEED to think a bit more about the physics between the two options.. what does the throttle plate do in restricting air IN.. vs blowing excess air back out where it came from.. the intake stroke vacuum.. acts to pull the piston back up in part of the "compression" stroke.. so would actually be MORE efficient than pulling un needed air in then to just push it back out creating even more drag
@@Errol.C-nz - I agree that there are many ways to skin a cat, but I have to assume that the engineers who developed these engines did their homework and verified the design by testing. Valve timing might have been the cheapest (free) way to achieve a reliable max chamber pressure since modulating the throttle might have required to much precision. There are lots of design tradeoffs in every machine, balancing various competing factors. Cost, of course, is often king of the hill. 😁
@@ralphwaters8905 The throttle is inefficient. Vasically it is taking air from a partial vacuum and needs to compress it against the outside air. That is called "pumping losses". (that there is a compression and power stroke in between doesn't change that).
its called "corrected compression ratio".. when "compression" begins with valves/ports SHUT!
When they use atkinson + force induction . When the piston compresses the intake valve stays open little longe . Then part of air fuel mixture will compress in to the intake manifold. When they use super charger . There is compression from the both sides . Isn’t that a problem ??
i think they use direct injection, so only air is pushed back
I didn't understand this very well. Low compression is my beetle. But haven't many power.
I have a 21 Tacoma 3.5 that uses Atkinson cycling at lower power settings and then back to Otto under load. It has dual GDI and Port injection. I believe it uses port under load during Otto. With the delayed intake closing during compression and some of the air/fuel charge going back into the intake I take it that it used again during the intake stroke if the port injectors are used. Could you have some residue fuel in the manifold if the GDI kicks in?
I'm sure it could be possible that there was a little "leftover" when switching modes. Realistically it should be very minor if it ever happens and the engineers likely compensated for it in programming.
You talk about some of the "charge" being forced back into the inlet manifold, that suggests that fuel has been injected or do these engines need to be direct injected?
Anthony
On conventional injection, the air-fuel "charge" enters the cylinder during the intake stroke. When the piston starts back up on the compression stroke with Late Intake Valve Closing, part of that charge can be forced back into the intake. If Direct Injection is used, most of the time (U.S. spec vehicles anyway) fuel is injected during the intake stroke, so a small amount of that charge would also be forced out during Late Intake Valve Closing (or "Atkinson Cycling"). Direct Injected vehicles do have a benefit here as they can be programmed to inject during the compression stroke after the valves have closed, but that has some potential emissions ramifications.
99% these atkinson videos are explaned wrong.
the tric is in the exaust phase which allows for a larger expansion, the power stroke, than with an equivalent otto
I destroyed a engine because if something happens to the timing chain than it's over
Ok, why not go for decreasing displacemen? That Atkinson give us less power and better fuel consumption same us the smaller engine
The difference here being the Atkinson still takes advantage of the longer stroke on the power stroke (expansion). If displacement is decreased, the stroke is shorter providing less power (less energy transferred to the crankshaft.) But if we drop displacement and add a turbo.....
@@pccastengineperformance7844 thank you for the explanation, i see how Atkinson is saving gas know, but is it worth? I mean is 2.5 Atkinson better than 2.0 Otto? Thx for your time.
What is the advantage of closing the intake valve late vs just lowering the compression ratio? It seems like the result would be similar.
There are a couple of issues at play here. Everyone talks about compression ratio, but the other half of this is expansion ratio (as the piston is going back down after crossing TDC). Lower compression ratio effects both, and lowers overall engine efficiency. By increasing the intake duration slightly and late intake valve closing, it only changes the effective compression ratio, but not the expansion ratio. This allows a higher compression ratio to be used, that with the late intake closing ends up at a fairly "normal" effective compression. When moving into the power stroke however, this will be a greater expansion ratio, to gain more power from combustion. Also, as Atkinson cycling is used currently with variable camshaft timing (and sometimes variable valve lift) , during some conditions the late intake closing strategy won't be used, and the engine can benefit from having higher working compression.
@@pccastengineperformance7844 thanks for the explanation
define.. compression "ratio".. as at when.. is the "ratio" measured.. or.. is it.. cylinder volume vs intake volume.. that a throttle restricts anyway
@@Errol.C-nz typically defined as (the volume of the cylinder with piston at BTC + the volume of the combustion chamber + volume of head gasket thickness) / (volume of cylinder with piston at TDC + the volume of the combustion chamber + volume of head gasket thickness)
exactly my point.. dependent on.. volumetric efficiency.. what dose a throttle plate do.. now factor your valve/port timing for "corrected" compression ration...and.. what are the true pumping loses.. more important of the pumping loses are damping in the pumping action such as intake air resistance just to expel it again past a valve.. vs.. a rebound bounce effect of a vacuum vs pressure from opposite strokes.. rotate an engine with valves closed.. then rotate the same engine with them open.. which has the most rotational resistance (or energy loses).. flow resistance increases as a square not linear as well & acts as a damper
wrong explanation, and the tric is in the exaust phase which allows for a larger expansion, the power stroke, than with an equivalent otto