Honda Power Unit Hardware & Software

[godlameroso]

The Kernel near the spark plug does not apply the same in jet ignition. Remember now, that the jets are igniting the bigger mixture. That means the spark plug can be in a different position or even location than the norm if required.

No way dude. The kernel near the spark plug always follows the same rules. It doesn't just start behaving differently because PZ needs to win on the interwebz. When a sparky goes off, it always makes that pop noise. That's the sound of air clapping with one hand. The sparky is the prime mover of combustion in a spark ignition engine whether it has a pre chamber or not.

That spark pushes air in a certain direction, it has to, or it wouldn't make that popping noise.

An ill informed answer.

We are both discussing TJI right? The effets surrounding the kernel does not affect the combustion of the mixture in the main chamber the same way as in an engine without TJI. That is a fact.
The kernel has an important influence in especially lean mixtures, but in the pre-chamber the mixture is not lean at all. But anyway, once that body of fuel is ignited the main ignition is carried out by the jets created from there.

On the other Plasma ignition is a type of ignition where the kernel characteristic is an extremely important differentiator and what is used to allow very lean combution. In TJI we are not as extreme becsuse the fuel is not lean in the pre-chamber.

I'm just keeping it playful and somewhat serious, it's more fun that way.

[Zynerji]

Deleted

[gruntguru]

I will try to answer a few of the questions and comments without quoting them all individually.

1. The pre-chamber is the ignition source for the main chamber. The best location is in the centre between the valves where the spark plug usually is. This gives the jets the shortest path to all points in the main chamber.
2. During ignition the swirl type pre-chamber has almost identical function to one with radial jets - the jets fire towards the perimeter. It is during compression while the pre-chamber is filling, the swirl may (or may not) produce better mixing within the chamber. (more likely stratification when compared to the radial jet pre-chamber)
3. Re - injection timing.
- If injection occurs early in the intake stroke, the result will be similar to port injection (homogeneous mixing) resulting in uniform lean charge throughout the main chamber and pre-chamber.
- Later injection (say end of intake stroke) the charge will be more stratified and will depend on spray shape. AFR in the pre-chamber will depend on main-chamber AFR in the vicinity of the pre-chamber during compression stroke - particularly the latter part.
- Very late injection can put a rich kernel in the vicinity of the pre-chamber, right at the time when it is filling rapidly. This is how the pre-chamber AFR can be adjusted richer.
4. Purging the pre-chamber is not necessary. At BDC exhaust it has 1 or 2% of the total cylinder volume. Even if all that exhaust stayed in the pre-chamber for 540* (3 strokes) until TDC compression it will have contain less than 10% exhaust residual (CR is ~ 18:1) representing less than 1% overall EGR.

[Zynerji]

I will try to answer a few of the questions and comments without quoting them all individually.

1. The pre-chamber is the ignition source for the main chamber. The best location is in the centre between the valves where the spark plug usually is. This gives the jets the shortest path to all points in the main chamber.
2. During ignition the swirl type pre-chamber has almost identical function to one with radial jets - the jets fire towards the perimeter. It is during compression while the pre-chamber is filling, the swirl may (or may not) produce better mixing within the chamber. (more likely stratification when compared to the radial jet pre-chamber)
3. Re - injection timing.
- If injection occurs early in the intake stroke, the result will be similar to port injection (homogeneous mixing) resulting in uniform lean charge throughout the main chamber and pre-chamber.
- Later injection (say end of intake stroke) the charge will be more stratified and will depend on spray shape. AFR in the pre-chamber will depend on main-chamber AFR in the vicinity of the pre-chamber during compression stroke - particularly the latter part.
- Very late injection can put a rich kernel in the vicinity of the pre-chamber, right at the time when it is filling rapidly. This is how the pre-chamber AFR can be adjusted richer.
- purging the pre-chamber is not necessary. At BDC exhaust it has 1 or 2% of the total cylinder volume. Even if all that exhaust stayed in the pre-chamber for 540* (3 strokes) until TDC compression it will have contain less than 10% exhaust residual (CR is ~ 18:1) representing less than 1% overall EGR.

Brilliant. Thank you.

I have guessed at several of those, and I'm glad that my understanding is in line with reality. I'm reading through this link of a TJI doctorate study, and she gives timing, sizing, orifice nuance as well as visuals to explain the system.

To your last point, however. If the prechamber flushing isn't that big of a deal, why did Honda patent a rotary-type valve to handle it?
viewtopic.php?t=29552

I'd recommend it for anyone wanting to try some TJI shenanigans in their garage.

https://scholar.google.com/citations?us ... AAAJ&hl=en

An annotated view of the pressure, which correlates to the experimental images of the issuing hot
jet appears in Figure 6-2. This plot shows that the hot jet dynamics occur when the pressure in both
chambers is close to the TDC pressure (15-20 bar). Numerical studies of the TJI system [23, 128]
have shown that a relatively cold jet of unburned prechamber mixture issues into the main chamber
82
prior to the hot jet of combustion products. This colder non-reacting jet cannot be seen in the
chemiluminescence imaging. The cold jet has a strong effect and both increases the turbulent
intensity and the mixing rate in the main chamber. Figure 6-2 shows that the initial 15% of the
pressure rise is due to the issuance of the hot combusting jet. The influence of the TJI concept on
the burn rate compared to direct SI combustion was investigated by Gentz et al. [19]. Detailed
images of the issuing jets are provided in the next section.

Pre-jet? Didn't see that coming...

[godlameroso]

Bosch saw it in the 80's, the spark displaces air because the plasma is very hot, the fact the pre-chamber is a small partially enclosed volume means the disturbance on airflow caused by the sparky is magnified.

[Zynerji]

Bosch saw it in the 80's, the spark displaces air because the plasma is very hot, the fact the pre-chamber is a small partially enclosed volume means the disturbance on airflow caused by the sparky is magnified.

So, if doing the stoichiometry inside the pre-chamber, one needs to calculate 15% of the mixture getting blown into the cylinder before igniting?

The more I read about the intricacies of this tech, the more I become fascinated by the complexity of setting air on fire.

[etusch]

Can it be something like that roughly

[gruntguru]

I don't think that injector location is likely. This view is supported by reports (looking at engine photos) that the injector sits in the side of the cylinder.

[godlameroso]

I don't think that injector location is likely. This view is supported by reports (looking at engine photos) that the injector sits in the side of the cylinder.

On the exhaust side no less. Given that Honda mentioned the spark plugs have a ~550km life span, I'm guessing the pre-chamber is built into the spark plug and they use a passive pre-chamber. 550km is too low for material abrasion on the electrode. So I'm guessing it's carbon build up on the pre-chamber orifices that limits their lifespan.

[PlatinumZealot]

Can it be something like that roughly

https://i.ibb.co/mBBXRF0/Ekran-Resmi-20 ... -56-34.png

https://i.ibb.co/drrzSkZ/Ekran-Resmi-20 ... -56-06.png

Bring the angle of the injector more horizontal si that it sits below the exhaust ports then see where she goes from there.

[Big Tea]

I don't think that injector location is likely. This view is supported by reports (looking at engine photos) that the injector sits in the side of the cylinder.

On the exhaust side no less. Given that Honda mentioned the spark plugs have a ~550km life span, I'm guessing the pre-chamber is built into the spark plug and they use a passive pre-chamber. 550km is too low for material abrasion on the electrode. So I'm guessing it's carbon build up on the pre-chamber orifices that limits their lifespan.

Could the life limit be due to the shape and definition of the 'holes' or jets?
It is after al quite close to a plasma cutter shooting through them up to 100 times a second?

Once the passages lose definition the jet may lose shape?

[ispano6]

Interview with Marko had some information on the Honda PU.

Interestingly, they feel the MGU-K issues which Mercedes are facing, could be beneficial to Red Bull as Honda had been reliable mostly in 2020. The engine part is linked to the signing of Perez on a one-year deal, where the team is looking to use his expertise.

Perez has been driving the Mercedes engine for the last seven years and even though he gets the customer spec, he has sound knowledge which Red Bull wishes to use in 2021 in the fight against the German manufacturer in the last year of Honda.

“It was a relatively short contract negotiation,” said Marko on Servus TV. “It’s a one-year contract, but we have an option, we can step in if he gets other offers. The reason for it is where you have to bring Max in. Since he’s been with us, the second car, except with Ricciardo, has always dropped off. Now we are looking at how a driver who was very fast in a Mercedes copy will perform.

“Perez has an incredible tyre management and he brings a lot of know-how about how the Mercedes engine works, the drivability. After they [Racing Point] terminated the contract with him, he was naturally very attentive to everything Mercedes does, so we are hoping for a lot of input,” summed up Marko, as he added on the Honda/Mercedes engine.

The Austrian updated on the negotiations with regards to having Honda IP. “The Honda engine will gain significantly in power,” said Marko. “Mercedes has durability problems, they need to look at fixing the MGU-K errors. And what Honda has promised us is also coming. We also see a significant gain in driveability and clipping.

“As for the negotiations, it’s a complex topic, but I would say we are 85%/90% close to the target. Honda has been very helpful. This means that we can continue to use the engine, also with technical help from Honda. But we need a freeze on development.

“The development is the most expensive thing and needs technical capacities that we cannot afford in this form. But the rest looks good. We might be able to finalise it by the end of the year or shortly into the new year,” summed up Marko.

https://formularapida.net/marko-verstap ... 2021-more/

[godlameroso]

Interview with Marko had some information on the Honda PU.

Interestingly, they feel the MGU-K issues which Mercedes are facing, could be beneficial to Red Bull as Honda had been reliable mostly in 2020. The engine part is linked to the signing of Perez on a one-year deal, where the team is looking to use his expertise.

Perez has been driving the Mercedes engine for the last seven years and even though he gets the customer spec, he has sound knowledge which Red Bull wishes to use in 2021 in the fight against the German manufacturer in the last year of Honda.

“It was a relatively short contract negotiation,” said Marko on Servus TV. “It’s a one-year contract, but we have an option, we can step in if he gets other offers. The reason for it is where you have to bring Max in. Since he’s been with us, the second car, except with Ricciardo, has always dropped off. Now we are looking at how a driver who was very fast in a Mercedes copy will perform.

“Perez has an incredible tyre management and he brings a lot of know-how about how the Mercedes engine works, the drivability. After they [Racing Point] terminated the contract with him, he was naturally very attentive to everything Mercedes does, so we are hoping for a lot of input,” summed up Marko, as he added on the Honda/Mercedes engine.

The Austrian updated on the negotiations with regards to having Honda IP. “The Honda engine will gain significantly in power,” said Marko. “Mercedes has durability problems, they need to look at fixing the MGU-K errors. And what Honda has promised us is also coming. We also see a significant gain in driveability and clipping.

“As for the negotiations, it’s a complex topic, but I would say we are 85%/90% close to the target. Honda has been very helpful. This means that we can continue to use the engine, also with technical help from Honda. But we need a freeze on development.

“The development is the most expensive thing and needs technical capacities that we cannot afford in this form. But the rest looks good. We might be able to finalise it by the end of the year or shortly into the new year,” summed up Marko.

https://formularapida.net/marko-verstap ... 2021-more/

That's good news, all that's left to see is how Ferrari and Renault develop if they can be relatively competitive mid 2021, then I see no reason for all 4 OEMs to not agree to an engine freeze. All 4 can continue to develop their 2022 power units until the end of 2021 and then they can run them for 2 further seasons with the new style cars. Having 4 competitive power units and a close field is good for the sport. Imagine if the midfield fight was shifted towards the front of the grid.

[PlatinumZealot]

They should allow more dyno time in 2021 if they do the wngine freeze. I for one do not agree with it one bit just to let you know. Engines should be free to keep things exciting. The others should not be punished because F1 isn't attractive to Honda board room anymore.

Back in the TJI matter I have been doing some reading on injection methods. The sideways injector suggests that the piston is beign used to guide the fuel spray... In what fashion... And wher to.. Nobody but Honda engineers know.

It could guide it up as in a second rich stratified injection. But does this go through the holes of of the pre-chamber fast enough to get to where tge spark plug is?



I think i see that the rotating chamber that is in the cbr tji bike engine... Can be used! It makes sense now.. Even with one injector. If the comrpession ratio is not altered by doing this it should be legal...

[gruntguru]

Back in the TJI matter I have been doing some reading on injection methods. The sideways injector suggests that the piston is beign used to guide the fuel spray... In what fashion... And wher to.. Nobody but Honda engineers know.

I think most of the injection occurs with the piston down the bore - no guiding.