Honda Power Unit Hardware & Software

[godlameroso]

So, what is your theory on the combustion process Honda is using?

My theory= a supposition of a system of ideas based on general principles, cannot be any more and cannot be any less. as long as what is being used by the respective four is such a highly guarded secret. maybe when time passes and this present combustion development is Superseded by a more advanced development we will get not only to know but also see with our own eyes like what happened with the “write-up” permission of the FERRARI 2000 winning car publication, the first of its kind in such a secretive technical matters.

So you have no theory that you think is good enough to contribute but you're 100% sure they're not using TJI because a third party translator doesn't know anything about a specific engineer at Honda?

Do you have any experience in prototype engine development or advanced combustion technologies to back up your claims? Any real evidence that they're using something other than what they're publishing? Any reason to believe Honda is lying to all of us through these publications? Anything at all?

TJI as used by Mahle with the injector and spark plug in one housing isn't being used, HCCI isn't being used. Those are his only claims, which don't require much to verify. Now whether his claim that a diesel style pre-chamber isn't being used, probably not too far out there. There's plenty of ways to skin a cat(ie improve the speed and power of combustion), fuel chemistry being a biggie.

[godlameroso]

....

None, our descriptions are in agreement in how flame jet ignition, and combustion in general work. It's more than just spark flame, heat. There's thousands of steps involving radicals formed at the spark gap, which create further radicals, and as these radicals interact with the hydrocarbons, new bonds are formed, which release heat, and some are broken which absorbs heat. During the combustion process, partially unburned hydrocarbons further release free radicals which again create and break bonds in the A/F mixture. Understanding and modeling these radicals are key to making improvements to both fuel and the combustion process itself.

Elemental nitrogen is a radical by the way, and the fact that these engines have high combustion temperatures and they produce plenty of NOx, perhaps the process makes use of elemental nitrogen to some extent.

No doubt the actual combustion processes are very complex. But surely in a discussion of TJI that’s not the key issue.

In a TJI solution there is a small chamber in which combustion is initiated by a spark and then the combustion products are ejected in a controlled manner into a larger chamber where those combustion products cause ignition. The process is spark, burn, eject, burn.

In your post above you seem to agree with this characterisation and show a shrouded plug, with a small chamber and ejection holes.

Whilst it is obviously important that the actual chemistry supports this, and there are almost certainly some specifics that are beneficial to the differing fuel-air ratios in the two chambers, as far as I can see the chief difference for a TJI concept is how the spark chamber is formed and how the air movements and injection patterns form the two environments in which the combustion processes operate.

The alternative to TJI is that the differing fuel-air ratios are generated within the space of the combustion chamber by some form of stratification. It seems unlikely that at the extreme air-fuel ratios used reliable ignition could happen in a homogenous charge.

Possibilities that "differing fuel-air ratios are generated within the space of the combustion chamber" I personally believe that there is very little possibility if any of therec being 'differing fuel-air ratios' inside a formula 1 engine cylinder when as i belive the fuel is being injected at a pressure of 500bar and at least 60 degrees BTDC and before being fully compressed.

60 degrees? That's an insane amount of crank angle before the combustion event. Most road cars top out at 30 degrees BTDC for ignition timing.

If there is such a huge window to inject fuel, then it logically follows that stratification is altered by multiple injection pulses during the compression stroke.

[henry]

....

None, our descriptions are in agreement in how flame jet ignition, and combustion in general work. It's more than just spark flame, heat. There's thousands of steps involving radicals formed at the spark gap, which create further radicals, and as these radicals interact with the hydrocarbons, new bonds are formed, which release heat, and some are broken which absorbs heat. During the combustion process, partially unburned hydrocarbons further release free radicals which again create and break bonds in the A/F mixture. Understanding and modeling these radicals are key to making improvements to both fuel and the combustion process itself.

Elemental nitrogen is a radical by the way, and the fact that these engines have high combustion temperatures and they produce plenty of NOx, perhaps the process makes use of elemental nitrogen to some extent.

No doubt the actual combustion processes are very complex. But surely in a discussion of TJI that’s not the key issue.

In a TJI solution there is a small chamber in which combustion is initiated by a spark and then the combustion products are ejected in a controlled manner into a larger chamber where those combustion products cause ignition. The process is spark, burn, eject, burn.

In your post above you seem to agree with this characterisation and show a shrouded plug, with a small chamber and ejection holes.

Whilst it is obviously important that the actual chemistry supports this, and there are almost certainly some specifics that are beneficial to the differing fuel-air ratios in the two chambers, as far as I can see the chief difference for a TJI concept is how the spark chamber is formed and how the air movements and injection patterns form the two environments in which the combustion processes operate.

The alternative to TJI is that the differing fuel-air ratios are generated within the space of the combustion chamber by some form of stratification. It seems unlikely that at the extreme air-fuel ratios used reliable ignition could happen in a homogenous charge.

Possibilities that "differing fuel-air ratios are generated within the space of the combustion chamber" I personally believe that there is very little possibility if any of therec being 'differing fuel-air ratios' inside a formula 1 engine cylinder when as i belive the fuel is being injected at a pressure of 500bar and at least 60 degrees BTDC and before being fully compressed.

So you think that there is a homogenous fuel-air mixture in the combustion chamber and it is ignited by a single spark plug, and runs at 45% BTE.

With TJI the differing fuel-air ratios are in two physically separate parts of the combustion chamber. One is very much smaller than the other. Obviously getting these right with a single injector is tricky. However:

There is nothing in the regulations that requires a single injection event. Peak pressure before combustion is, I guess, less than 100 bar. So an injector at 500 bar would be able to inject at any point in the compression cycle, and multiple points to help generate differing fuel-air mixtures.

[saviour stivala]

OK, a lot of this is way above me, however, SS, dont get hung up on the 10500 rpm as being max rpm. You will see for instance that during a race, the Merc is getting up to 12000 rpm. I am not sure if this spoils your calculations, but certainly 10500 rpm is no longer a maximum in use.

"Combustion that starts at one place and continue at another place as a pre-chamber system is in my opinion not conductive to a 10500 rpm MAX POWER SPEED system of operation".
I have no doubt whatsoever that up-shift gear change takes place above 'max power speed rpm ', that was always the way to go racing and not lose speed. during the NA engines formula the max RPM was always 500 RPM above what is called the LOVELL factor point (max power speed). On todays forced induction engine the RPM band above the max-power-speed-RPM used is most probably X 3 times that used on an NA engine. But be assured that in both types of engines no more additional power can be produced above their respective max-power-speed-RPM.

[saviour stivala]

No doubt the actual combustion processes are very complex. But surely in a discussion of TJI that’s not the key issue.

In a TJI solution there is a small chamber in which combustion is initiated by a spark and then the combustion products are ejected in a controlled manner into a larger chamber where those combustion products cause ignition. The process is spark, burn, eject, burn.

In your post above you seem to agree with this characterisation and show a shrouded plug, with a small chamber and ejection holes.

Whilst it is obviously important that the actual chemistry supports this, and there are almost certainly some specifics that are beneficial to the differing fuel-air ratios in the two chambers, as far as I can see the chief difference for a TJI concept is how the spark chamber is formed and how the air movements and injection patterns form the two environments in which the combustion processes operate.

The alternative to TJI is that the differing fuel-air ratios are generated within the space of the combustion chamber by some form of stratification. It seems unlikely that at the extreme air-fuel ratios used reliable ignition could happen in a homogenous charge.

Possibilities that "differing fuel-air ratios are generated within the space of the combustion chamber" I personally believe that there is very little possibility if any of therec being 'differing fuel-air ratios' inside a formula 1 engine cylinder when as i belive the fuel is being injected at a pressure of 500bar and at least 60 degrees BTDC and before being fully compressed.

60 degrees? That's an insane amount of crank angle before the combustion event. Most road cars top out at 30 degrees BTDC for ignition timing.

If there is such a huge window to inject fuel, then it logically follows that stratification is altered by multiple injection pulses during the compression stroke.

It is my personal opinion that fuel is injected directly at least 60 degrees BTDC before being fully compressed, fully agree that most road-cars tops out at 30 degrees BTDC for ignition timing advance, most probably it is very much the same gnition timing advance used in F1 engines.

[henry]

OK, a lot of this is way above me, however, SS, dont get hung up on the 10500 rpm as being max rpm. You will see for instance that during a race, the Merc is getting up to 12000 rpm. I am not sure if this spoils your calculations, but certainly 10500 rpm is no longer a maximum in use.

"Combustion that starts at one place and continue at another place as a pre-chamber system is in my opinion not conductive to a 10500 rpm MAX POWER SPEED system of operation".
I have no doubt whatsoever that up-shift gear change takes place above 'max power speed rpm ', that was always the way to go racing and not lose speed. during the NA engines formula the max RPM was always 500 RPM above what is called the LOVELL factor point (max power speed). On todays forced induction engine the RPM band above the max-power-speed-RPM used is most probably X 3 times that used on an NA engine. But be assured that in both types of engines no more additional power can be produced above their respective max-power-speed-RPM.

However that max power speed is unlikely to be 10500 but roughly half way between that and max RPM. around 11200 RPM.

[HPD]

Q: You mentioned the upgraded Honda engine there. How much of an improvement is that? Is it something you can actually feel in the cockpit?
BH: It’s a tricky one to answer because these Formula One cars are very light and you have close to 1,000hp.
https://www.formula1.com/en/latest/arti ... ieoQs.html

I believe that Mercedes and Ferrari have already broken the barrier of 1000hp.. (personal opinion)

[subcritical71]

So you have no theory that you think is good enough to contribute but you're 100% sure they're not using TJI because a third party translator doesn't know anything about a specific engineer at Honda?

There may be some confusion, or a coincidence, as hasika is a forum member here who did some of the early translations of the article. I don't believe he ever claimed to be a honda engineer.

[Craigy]

OK, a lot of this is way above me, however, SS, dont get hung up on the 10500 rpm as being max rpm. You will see for instance that during a race, the Merc is getting up to 12000 rpm. I am not sure if this spoils your calculations, but certainly 10500 rpm is no longer a maximum in use.

"Combustion that starts at one place and continue at another place as a pre-chamber system is in my opinion not conductive to a 10500 rpm MAX POWER SPEED system of operation".
I have no doubt whatsoever that up-shift gear change takes place above 'max power speed rpm ', that was always the way to go racing and not lose speed. during the NA engines formula the max RPM was always 500 RPM above what is called the LOVELL factor point (max power speed). On todays forced induction engine the RPM band above the max-power-speed-RPM used is most probably X 3 times that used on an NA engine. But be assured that in both types of engines no more additional power can be produced above their respective max-power-speed-RPM.

However that max power speed is unlikely to be 10500 but roughly half way between that and max RPM. around 11200 RPM.

For the record, max RPM on the Merc last year was circa 13K. (obviously the regs state 15K, but that's not where the limiters are...)

Force India routinely ran higher RPM than seemed sensible; possibly either they got some sums wrong, or more likely they had compromised their gear selection toward tracks I wasn't looking at their revs at, so I was looking at the worst case. I miss the old pre-halo graphics.

[63l8qrrfy6]

Isn't that too late for ignition?

It wouldn't necessarily have to be at TDC. The pre-chamber piston can start to seal into the spark plug shroud before TDC.

combustion that starts at one place and continues at another place such as a pre-chamber system is in my opinion not conductive to a 10500 RPM max power speed system of operation.

How do you then justify the use of passive pre chamber spark plugs in 1500 RPM natural gas engines ?

[gruntguru]

A couple of questions;

- Why can't you have injection in a pre-chamber, the pre-chamber is located between the intake and exhaust valves?

- Are you saying the appendix makes a multi stage injector a no go?

- I found an article in which the author thought that a standard injector might be what is used;

When the injector was fully open, its spray pattern was a fairly narrow cone that reached the main chamber, but when the injector had nearly closed, the spray pattern became radial, fueling only the pre-chamber.

I don't think this would be multistage as the spray pattern is what is changing in its single stage of operation.

The pre-chamber is in between the intake and exhaust valves but then how would you inject into the main chamber? Unless you have 1 injector feeding both(extremely improbable), you can't use a pre-chamber. You aren't allowed to have an injector which houses a pre-chamber and also a separate nozzle for the main chamber. Now, you can have an injector with multiple spray patterns, also the precision of the injector is up for grabs. Unfortunately you're limited by the 500 bar injection pressure which, unless you get creative, limits the fuel droplet size and in turn atomization.

If there is a "chamber", combustion isn't originating from it, more likely attenuating some acoustic frequency, in other words resonance tubes are being used to improve fuel atomization beyond the 500bar injection limit. Probably in conjunction with shrouded spark plug.

I don't think you should state this as fact. There is at least one paper out there (by Attard) that describes the use of a "TJI" pre-chamber without internal injector - port injectors only. Granted this engine ran at stoichiometric mixtures. However with the benefit of DI and its ability to stratify the charge distribution, I am very confident that this is the strategy used by the F1 teams. Early injection (intake stroke thru to early compression stroke) producing a relatively homogeneous lean mixture and late injection (middle of the compression stroke) producing a richer mixture in the region of the pre-chamber. The richer mixture is pushed into the pre-chamber during the later part of the compression stroke and provides the lambda 1.0 - 1.2 required for Jet Ignition from the pre-chamber.

[gruntguru]

5.11.1 would be almost impossible to police though. I'm not saying I think HCCI is being used, I'm just saying that detonation can and does happen. The FIA would need to prove the detonation was being used as the main source of ignition, how could they prove that without an admission from the team? Even if they look at knock/cylinder pressure sensors I don't think they could prove controlled detonation was the intent, especially if the plug is firing.

I do wonder would there be any advantage to using controlled detonation during slow speed/part throttle operation? Would it be a viable way to save fuel? Of course you have to make sure the ICE doesn't kill itself in the process...

HCCI is not "controlled detonation". It is auto ignition at multiple points throughout the combustion chamber. Combustion is completed by flame propagation from these points.

[gruntguru]

because the technical rules stipulates a 'direct injection' as the system to be used.

This is the part I don't get. I've searched all instances of 'direct' and none apply to the fuel injector. What I do find is the following, none of which says it must be directly injected into the combustion chamber;

1.31 Fuel injector :
Any device or component that delivers fuel into an oxidiser.

5.10 Fuel systems :
5.10.1 The pressure of the fuel supplied to the fuel injectors may not exceed 500bar. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.
5.10.2 There may only be one fuel injector per cylinder and no fuel injectors are permitted upstream of the intake valves or downstream of the exhaust valves. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.

I can't seem to find the relevant 'direct injection' rule, can you tell me what paragraph of the rules specify it?

That’s a change for 2019. The 2018 regs say this:

5.10.2 There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.

So it looks like the FIA realised that the term direct didn’t add anything of value.

More to the point, they probably realised that the word "direct" was creating confusion by some folk who might interpret it in the same sense as Diesel terminology where "direct" means "not into a pre-chamber".

This is probably moot anyway - with only one injector allowed I am sure they inject into the "main" chamber but "towards" the pre-chamber.

[gruntguru]

That’s a change for 2019. The 2018 regs say this:
So it looks like the FIA realised that the term direct didn’t add anything of value.

Are you sure , I double checked the 2018 rules, and just re-downloaded from the FIA site. The change is in the 2018 regs also.... (dated 2017-12-19)

Ok my copy of the 2018 regs is dated 21 September 2017 , I didn’t spot the later version. The paragraph I quote is unchanged since the 3 July 2013 version of the regs.
So this year they have, for the first season, been able to use an injector that isn’t direct ...

. . as long as it isn't "port". I don't think the intent of the rule has changed - only the wording. They didn't anticipate someone might inject into a pre-chamber and wouldn't want to exclude that. They only ever intended to eliminate port injection.

[gruntguru]

What is it that informs your opinion about the dis-usage of "TJI?" (Genuinely curious.)

How would you initiate combustion inside the pre chamber if the injector has to be outside of said chamber? There is a technical appendix to the regulations that specifies which types of injectors are allowed. What if in this appendix it is stated that the kind of multi stage injector needed to have a pre-chamber is not allowed?

We know the injectors are side mounted on the exhaust valve side on the Honda engine, and that the coil pack for the spark plug indicates it's mounted in a conventional way.
The most plausible method of having any kind of flame jet ignition with the current regulations is with the shrouded spark plug type.

When this has been discussed, it's been suggested that the mixture "compresses into" the pre-chamber. I, myself, struggle a bit with this and also with how it's cleared well enough post ignition. But I certainly want to believe/ understand it.

At the beginning of the compression stroke the density in the cylinder (including the pre-chamber) is about 3 times atmospheric. At the end of the compression stroke the density in the combustion chamber (including the pre-chamber) is about 15 times that i.e. 45 times atmospheric. (assuming 15:1 CR). This means that 14/15 ths (93%) of the contents of the pre-chamber have flowed into it during the compression stroke and almost all of this 93% is fresh charge. The very worst case scenario where all the exhaust remaining in the pre-chamber at the end of the exhaust stroke stays there throughout the intake stroke, would still only allow 7% residual exhaust in the pre-chamber.