Honda Power Unit Hardware & Software

[godlameroso]

Because what some users are correcting are conflicts of opinion and not facts. That there is an ideal point in the piston stroke where you want maximum cylinder pressure if the goal is efficiency is a fact. The analogies or methods used to convey this information takes many shapes, and because our understanding is ours we tend to weigh it abnormally high. Thus, any difference in understanding(by nature of our hierarchical brain) tends to be seen as a lower form of understanding; particularly when there's a lack of social cues that gives away that person's status(high status individuals tend to be believed more often even if what they say is utter rubbish, and the inverse is also true).

[trinidefender]

Because what some users are correcting are conflicts of opinion and not facts. That there is an ideal point in the piston stroke where you want maximum cylinder pressure if the goal is efficiency is a fact. The analogies or methods used to convey this information takes many shapes, and because our understanding is ours we tend to weigh it abnormally high. Thus, any difference in understanding(by nature of our hierarchical brain) tends to be seen as a lower form of understanding; particularly when there's a lack of social cues that gives away that person's status(high status individuals tend to be believed more often even if what they say is utter rubbish, and the inverse is also true).

And this point changes as combustion speed increases.

That is supported by the graphs and papers that were cited earlier in this thread. To say 14 degrees is the only number and doesn't change based on combustion speed is demonstratedly untrue

[godlameroso]

Because what some users are correcting are conflicts of opinion and not facts. That there is an ideal point in the piston stroke where you want maximum cylinder pressure if the goal is efficiency is a fact. The analogies or methods used to convey this information takes many shapes, and because our understanding is ours we tend to weigh it abnormally high. Thus, any difference in understanding(by nature of our hierarchical brain) tends to be seen as a lower form of understanding; particularly when there's a lack of social cues that gives away that person's status(high status individuals tend to be believed more often even if what they say is utter rubbish, and the inverse is also true).

And this point changes as combustion speed increases.

That is supported by the graphs and papers that were cited earlier in this thread. To say 14 degrees is the only number and doesn't change based on combustion speed is demonstratedly untrue

It does not change, what changes is ignition point of the A/F charge. If the goal is to achieve maximum cylinder pressure during the power stroke, ~14 degrees ATDC +/- is the ideal place for it to happen slightly varying depending on the variables we have discussed(rod ratios etc).

If maximum pressure is created exactly at TDC it is the same as a misfire, asymptotically after TDC is the area where CR of the CC is highest, however the piston is still in the process of reversing it's momentum from the up-stroke. Sure this isn't very significant from a purely mechanical point of view(as the piston has already overcome it's pumping losses and is starting it's downstroke), but from an inertial and thermodynamic point of view it is.

If it only takes 9 degrees of crank rotation, then the ignition point would be ~5 degrees ATDC, if it takes 30 degrees of crank rotation then ignition point would be ~16 degrees BTDC.

[trinidefender]

Because what some users are correcting are conflicts of opinion and not facts. That there is an ideal point in the piston stroke where you want maximum cylinder pressure if the goal is efficiency is a fact. The analogies or methods used to convey this information takes many shapes, and because our understanding is ours we tend to weigh it abnormally high. Thus, any difference in understanding(by nature of our hierarchical brain) tends to be seen as a lower form of understanding; particularly when there's a lack of social cues that gives away that person's status(high status individuals tend to be believed more often even if what they say is utter rubbish, and the inverse is also true).

And this point changes as combustion speed increases.

That is supported by the graphs and papers that were cited earlier in this thread. To say 14 degrees is the only number and doesn't change based on combustion speed is demonstratedly untrue

It does not change, what changes is ignition point of the A/F charge. If the goal is to achieve maximum cylinder pressure during the power stroke, ~14 degrees ATDC +/- is the ideal place for it to happen slightly varying depending on the variables we have discussed(rod ratios etc).

If maximum pressure is created exactly at TDC it is the same as a misfire, asymptotically after TDC is the area where CR of the CC is highest, however the piston is still in the process of reversing it's momentum from the up-stroke. Sure this isn't very significant from a purely mechanical point of view(as the piston has already overcome it's pumping losses and is starting it's downstroke), but from an inertial and thermodynamic point of view it is.

If it only takes 9 degrees of crank rotation, then the ignition point would be ~5 degrees ATDC, if it takes 30 degrees of crank rotation then ignition point would be ~16 degrees BTDC.

Have anything to back up your statements? Because they disagree with what was shown a few posts before yours.

In case you missed it, this;

"Based on test data, it has been found that the peak cylinder pressure usually occurs around 15* ATDC at MBT timing. The 50% mass fraction burned point generally occurs from 8* to 10* ATDC when MBT timing is achieved, see [4]. The algorithm published in [3] controls PR(10) (normalized pressure ratio of incylinder and motoring pressure at 10* ATDC) around 0.55 to obtain the MBT timing. Because these criteria are solely based upon observations and may change at different operating conditions, each algorithm still requires some calibration effort. It is clear that the combustion process has to be matched with the engine cylinder volume change to attain the best torque. However, there is no sound theory to support the rationale that peak cylinder pressure must occur around 15* ATDC or that 50% burned must happen around 9* ATDC for the MBT timing conditions."

Zhu, G.G., Daniels, C.F., & Winkelman, J. (2004). MBT Timing Detection and its Closed-Loop Control Using In-Cylinder Ionization Signal.

Disagrees with your statement that it doesn't change.
(Thanks to GG for the original post)

[godlameroso]

And this point changes as combustion speed increases.

That is supported by the graphs and papers that were cited earlier in this thread. To say 14 degrees is the only number and doesn't change based on combustion speed is demonstratedly untrue

It does not change, what changes is ignition point of the A/F charge. If the goal is to achieve maximum cylinder pressure during the power stroke, ~14 degrees ATDC +/- is the ideal place for it to happen slightly varying depending on the variables we have discussed(rod ratios etc).

If maximum pressure is created exactly at TDC it is the same as a misfire, asymptotically after TDC is the area where CR of the CC is highest, however the piston is still in the process of reversing it's momentum from the up-stroke. Sure this isn't very significant from a purely mechanical point of view(as the piston has already overcome it's pumping losses and is starting it's downstroke), but from an inertial and thermodynamic point of view it is.

If it only takes 9 degrees of crank rotation, then the ignition point would be ~5 degrees ATDC, if it takes 30 degrees of crank rotation then ignition point would be ~16 degrees BTDC.

Have anything to back up your statements? Because they disagree with what was shown a few posts before yours.

In case you missed it, this;

"Based on test data, it has been found that the peak cylinder pressure usually occurs around 15* ATDC at MBT timing. The 50% mass fraction burned point generally occurs from 8* to 10* ATDC when MBT timing is achieved, see [4]. The algorithm published in [3] controls PR(10) (normalized pressure ratio of incylinder and motoring pressure at 10* ATDC) around 0.55 to obtain the MBT timing. Because these criteria are solely based upon observations and may change at different operating conditions, each algorithm still requires some calibration effort. It is clear that the combustion process has to be matched with the engine cylinder volume change to attain the best torque. However, there is no sound theory to support the rationale that peak cylinder pressure must occur around 15* ATDC or that 50% burned must happen around 9* ATDC for the MBT timing conditions."

Zhu, G.G., Daniels, C.F., & Winkelman, J. (2004). MBT Timing Detection and its Closed-Loop Control Using In-Cylinder Ionization Signal.

Disagrees with your statement that it doesn't change.
(Thanks to GG for the original post)

The analogies or methods used to convey this information takes many shapes, and because our understanding is ours we tend to weigh it abnormally high. Thus, any difference in understanding(by nature of our hierarchical brain) tends to be seen as a lower form of understanding; particularly when there's a lack of social cues that gives away that person's status(high status individuals tend to be believed more often even if what they say is utter rubbish, and the inverse is also true).

Because these criteria are solely based upon observations and may change at different operating conditions, each algorithm still requires some calibration effort.

The author is being careful to not say that ~15 degrees ATDC is a constant because it isn't. However the value will always be around that number and influenced by a variety of reasons. I made a note of this when I said

If the goal is to achieve maximum cylinder pressure during the power stroke, ~14 degrees ATDC +/- is the ideal place for it to happen slightly varying depending on the variables we have discussed(rod ratios etc).

However, there is no sound theory to support the rationale that peak cylinder pressure must occur around 15* ATDC or that 50% burned must happen around 9* ATDC for the MBT timing conditions."

When the author(s) say this we have to understand what is meant. Let's look at the words used. When I say there's no sound theory to support my understanding of why something happens, it doesn't mean that the phenomena doesn't exist. Merely that I lack an adequate method of explaining it that satisfies scientific rigor. In other words I fail to see the causal pattern that makes the phenomena so.

[PlatinumZealot]

It is just the wayt it is.... Like the sweetspot when you are cranking on that bicycle pedal. When the energy gets that large window to transfer but not too early or too late to cause missdirection/dissipation /loss.

[saviour stivala]

Modern electronics and their control abilities has relegated centrifuge and vacuum advance mechanisms and old ways of doing things and controlling of said things to the scrap heap, the development of reliable in-cylinder pressure sensors plus crankshaft position sensors and torque sensors allows modern ignition point to be set at maximum MBT produced under all conditions and be retarded at knock limit. This modern day capability can be likened to playing with fire with a big chance of not burning your fingers.

[saviour stivala]

Because what some users are correcting are conflicts of opinion and not facts. That there is an ideal point in the piston stroke where you want maximum cylinder pressure if the goal is efficiency is a fact. The analogies or methods used to convey this information takes many shapes, and because our understanding is ours we tend to weigh it abnormally high. Thus, any difference in understanding(by nature of our hierarchical brain) tends to be seen as a lower form of understanding; particularly when there's a lack of social cues that gives away that person's status(high status individuals tend to be believed more often even if what they say is utter rubbish, and the inverse is also true).

And this point changes as combustion speed increases.

That is supported by the graphs and papers that were cited earlier in this thread. To say 14 degrees is the only number and doesn't change based on combustion speed is demonstratedly untrue

It does not change, what changes is ignition point of the A/F charge. If the goal is to achieve maximum cylinder pressure during the power stroke, ~14 degrees ATDC +/- is the ideal place for it to happen slightly varying depending on the variables we have discussed(rod ratios etc).

If maximum pressure is created exactly at TDC it is the same as a misfire, asymptotically after TDC is the area where CR of the CC is highest, however the piston is still in the process of reversing it's momentum from the up-stroke. Sure this isn't very significant from a purely mechanical point of view(as the piston has already overcome it's pumping losses and is starting it's downstroke), but from an inertial and thermodynamic point of view it is.

If it only takes 9 degrees of crank rotation, then the ignition point would be ~5 degrees ATDC, if it takes 30 degrees of crank rotation then ignition point would be ~16 degrees BTDC.

“It does not change, what changed is ignition point” Thank you and prosit.

[gruntguru]

It does not change, what changes is ignition point of the A/F charge. If the goal is to achieve maximum cylinder pressure during the power stroke, ~14 degrees ATDC +/- is the ideal place for it to happen slightly varying depending on the variables we have discussed(rod ratios etc).

As I said previously, the ideal place for peak pressure is at TDC but only if combustion starts and finishes at TDC.

14* ATDC does not have any value of its own. That's what I mean when I say its not a "magic number" It is merely where PCP happens to fall when the timing is adjusted for MBT in a typical conventional engine ie one where the 10% - 90% combustion duration occupies about 20* - 30* of crank rotation.

[saviour stivala]

So we are now agreed that 14 degrees ATDC is were PCP/PPP happens. that point produces maximum MBT, it also produces the best power stroke duration. for all that to happen ignition point is set to happen at a certain point BTDC and thereafter it is constantly on the move according to engine needs. the ignition point is set at maximum MBT and retarded at knock limit.

[trinidefender]

So we are now agreed that 14 degrees ATDC is were PCP/PPP happens. that point produces maximum MBT, it also produces the best power stroke duration. for all that to happen ignition point is set to happen at a certain point BTDC and thereafter it is constantly on the move according to engine needs. the ignition point is set at maximum MBT and retarded at knock limit.

Pretty sure, they and others don't agree.

Their previous posts indicated that with faster combustion that ignition point will move later and that PCP will move closer to TDC.

GG please correct me if I'm wrong.

[gandharva]

Looking at the last races Honda still has a massive hill to climb over winter regarding reliability in that spec 3 engine...

[HPD]

Looking at the last races Honda still has a massive hill to climb over winter regarding reliability in that spec 3 engine...

So is. But the engine did not break, they had an oil leak. They stopped as a precaution.

[ian_s]

So we are now agreed that 14 degrees ATDC is were PCP/PPP happens. that point produces maximum MBT, it also produces the best power stroke duration. for all that to happen ignition point is set to happen at a certain point BTDC and thereafter it is constantly on the move according to engine needs. the ignition point is set at maximum MBT and retarded at knock limit.

Pretty sure, they and others don't agree.

Their previous posts indicated that with faster combustion that ignition point will move later and that PCP will move closer to TDC.

GG please correct me if I'm wrong.

The thinking that 14 degrees is the PCP/PPP is 100% inside the box of a port injection spark ignition engine.

These engines are not like that. In cylinder injection alone will change that, and pre chamber ignition will change it even more.
With these engines, everything learned about traditional combustion goes completely out the window.

[saviour stivala]

So we are now agreed that 14 degrees ATDC is were PCP/PPP happens. that point produces maximum MBT, it also produces the best power stroke duration. for all that to happen ignition point is set to happen at a certain point BTDC and thereafter it is constantly on the move according to engine needs. the ignition point is set at maximum MBT and retarded at knock limit.

Pretty sure, they and others don't agree.

Their previous posts indicated that with faster combustion that ignition point will move later and that PCP will move closer to TDC.

GG please correct me if I'm wrong.

The thinking that 14 degrees is the PCP/PPP is 100% inside the box of a port injection spark ignition engine.

These engines are not like that. In cylinder injection alone will change that, and pre chamber ignition will change it even more.
With these engines, everything learned about traditional combustion goes completely out the window.

Can you please provide a link that proves that a pre-chamber (a system that splits combustion into two parts) is being used by F1 engines?.