Honda Power Unit Hardware & Software

[GoranF1]

https://twitter.com/F1sMyDrug/status/860559252800360449

[etusch]

I want to share a video link about mercedes diesel engine pre chamber. A bit out of topic.
https://www.youtube.com/watch?v=8uTuk1RZRjk

[godlameroso]

If there is a pre chamber, it's formed over the spark plug, similar to a spark plug defouler/spacer, the injector injects petrol at least more than once during intake and compression strokes.

If there is combustion instability, and they have to run rich in order to control it, then it stands to reason that the flame jets are not being produced as precisely or in the time frames as they'd like or need. It seems like a band aid fix, run less timing so you don't have combustion before TDC, and run rich to gain more power from having to fire so far after TDC than what you could if the jet precision was higher.

Not to mention a richer mixture will produce more defined jets as well as there's more fuel to burn, but that's probably an afterthought.

[ollandos]

JA: "Behind the scenes Mercedes engineers have been working hard in a rare show of sporting camaraderie, helping the Japanese manufacturer..... to speed up the recovery process, to stabilise the parts that keep going wrong and to maximise the integration with the McLaren chassis"....

i say this some post behind ...the honda go for mercedes clone engine ..with mercedes hands....and this is on media some time ago ...and today wazari say ..that work its his work with honda ????......if i understand correct.... =D> =D> =D>

[PlatinumZealot]

Rumours and Alternative facts.. Wazari will confirm in due time.

[McHonda]

The more I look at the TJI injection scheme, the more I doubt it is actually implemented like the pictures in the Mahle explanations of it.

https://www.google.com/patents/US20120103302

I think what ever gains you could get from the pre-chamber combustion, would be eliminated by what would seem to me be, really poor atomization and homogeneous distribution in the rest of the main part of the combustion chamber...

What happens to the spray from the injector, impinging on the internal surfaces of that little "pre-chamber" to eventually leaking out the rest of the holes in that extra part? I think the losses from that, would be greater than the pre-chamber. How could the injector spray not just "leak out" of that tiny chamber? How does fuel not build up in the pre-chamber and completely soak the spark plug creating a fouling concern? ? I think a fine atomization from the injector, and a great deal of tumble leading to a high value of overall turbulent kinetic energy right around a normal parkplug would be better in this racing application than the TJI.

All the pressure and velocity of fuel particles, I'd bet, would be gone by the time the fuel leaves the injector and builds up in the pre-chamber. Could the rapidly rising pressure in the combustion chamber cause an even higher likely hood that fuel coming out of the pre-chamber would not be well atomized.....

Until I see real pictures from an F1 engine with that system. I don't think any team has actually implemented it (in the fashion shown in mahle patents and websites.) , and this is a red-hearing...

The pictures are misleading because it's not technically TJI being used, it's an adapted form of TJI to fit F1 requirements so there are no pictures.

And it's why Renault and Honda are struggling to make the same gains. Mercedes and Ferrari used some of the same people, engineers who came up with the solution split and some went to Brixworth(Merc) and some went to Mahle. Mahle a few years later then wen't to Ferrari(2015) who had already signed the Mercedes combustion expert Cedric Cornebois in the summer of 2014 and started in Jan 2015.

It's not an accident that the two systems that work the best have shared history of engineers who have detailed knowledge of both the TJI system and it's adapted form for F1.

[gruntguru]

I think frictional losses are to some extent cancelled out by less heat loss due to faster combustion. So maybe thermal efficiency does not improve overall but power output does.

Could you clarify that for me? When you say "overall thermal efficiency" I assume BTE and power is inextricably locked to BTE. i.e.

Brake Power = BTE x Fuel Flow x HV

Flow and HV are constants.

[gruntguru]

it's interesting to me that Wazari asks here the question that I asked 5 years ago - why not design around systematically higher rpm ?

eg I suggested that 13000-14800 rpm had some advantages over 10500-12100
mainly 'boost' pressure would be lower ie the supercharging power reduced in greater proportion (eg 23000 would be NA)
the recoverable energy is at least the same at this lower boost
and much less ES energy is used in 'spooling up'

ok at that time I was assuming a mildly lean AFR not very lean
clearly if the very lean TJI or similar suffers at these higher rpm then higher rpm is not on

I actually remember the discussion; doesn't seem that long ago! Less boost demand with similar MGUH recovery would certainly be more efficient?

It would, but it is unlikely that thermal recovery could be maintained. If you assume exhaust mass flow stays the same you would need the same EBP also which would mean a less favourable pressure differential across the engine.

There could be something in the higher CR argument. Raising rpm by 10% would reduce fuel/cycle by 10% so peak cylinder pressure would reduce significantly if AFR is maintained (lower boost).

[gruntguru]

İsn't there any company good on direct injection pre-chamber ignition? When I googled I can see that Mann uses this tech on its engines. Toyota were partner with Mann when they were in F1. I think these kind of heavy industiry companies good on big powers and reliability. So Honda also can work with Mann, Caterpiller etc. Mahle is just an example and not matter who is its owner.

The combustion tech currently used in F1 is cutting-edge. There are no companies out there (except Mahle) with more knowledge than the F1 engine teams.

Respectfully, plenty of knowledge, and numerous companies have patents or improvement patents on ignitors and/or prechamber geometry for multiple fuel types. eg Federal Mogul, Borg Warner, Caterpillar, GM. These cover prechamber in the piston bowl, prechamber swirl characteristics etc etc. This search link is a start, remove assignee to get others.

Agreed - there is more knowledge out there. It just isn't applicable to the combustion regime currently operating in an F1 engine. No one has pushed this limit before.

[J.A.W.]

& especially given the oddly archaic technical constraints mandated by the FIA, such as bans on laser, &/or plasma ignition..

[gruntguru]

I think wazari is hinting at the fact that higher piston speeds raise the knock limit.
It was said that v8 engines did not knock and CR was only limited geometrically.

Less time spent at said compression?

Not sure how it works really. Kevin Hoag from SWRI mentioned this several times and it was later confirmed by an ex F1 engineer.

Turbulence and rate of combustion. The faster combustion occurs/completes the less likelihood of knock.

[63l8qrrfy6]

I think frictional losses are to some extent cancelled out by less heat loss due to faster combustion. So maybe thermal efficiency does not improve overall but power output does.

Could you clarify that for me? When you say "overall thermal efficiency" I assume BTE and power is inextricably locked to BTE. i.e.

Brake Power = BTE x Fuel Flow x HV

Flow and HV are constants.

As PZ pointed earlier I overlooked the fact that fuel flow is limited.
You are absolutely right.

[63l8qrrfy6]

Less time spent at said compression?

Not sure how it works really. Kevin Hoag from SWRI mentioned this several times and it was later confirmed by an ex F1 engineer.

Turbulence and rate of combustion. The faster combustion occurs/completes the less likelihood of knock.

Does the combustion rate increase with respect to crank angle with speed ?
Or does it only increase with respect to time ?

[gruntguru]

The more I look at the TJI injection scheme, the more I doubt it is actually implemented like the pictures in the Mahle explanations of it.

https://www.google.com/patents/US20120103302

I think what ever gains you could get from the pre-chamber combustion, would be eliminated by what would seem to me be, really poor atomization and homogeneous distribution in the rest of the main part of the combustion chamber...

The presence of a pre-chamber has no effect on the ability to achieve correct atomisation and homogeneity in the main chamber.

What happens to the spray from the injector, impinging on the internal surfaces of that little "pre-chamber" to eventually leaking out the rest of the holes in that extra part? I think the losses from that, would be greater than the pre-chamber. How could the injector spray not just "leak out" of that tiny chamber?

The pre-chamber is charged during the compression stroke and airflow is inwards to the pre-chamber only.

How does fuel not build up in the pre-chamber and completely soak the spark plug creating a fouling concern?

If we knew what they are doing inside an F1 engine we wouldn't need all the experts here on this forum. The Mahle system works - no question. How they do it with one injector is conjecture. You can be pretty sure the injector is not in the pre-chamber.

I think a fine atomization from the injector, and a great deal of tumble leading to a high value of overall turbulent kinetic energy right around a normal parkplug would be better in this racing application than the TJI.

The object is to burn a very lean mixture at a high rate. This can't be done the way you are suggesting.

All the pressure and velocity of fuel particles, I'd bet, would be gone by the time the fuel leaves the injector and builds up in the pre-chamber. Could the rapidly rising pressure in the combustion chamber cause an even higher likely hood that fuel coming out of the pre-chamber would not be well atomized.....

Its not fuel coming out of the pre-chamber. It is hot jets of partially burned combustion products. The idea of the pre-chamber is to provide an environment where the mixture is rich enough to burn rapidly and consistently, then use this energy to ignite a wide area of the main chamber where the mixture is too lean to burn rapidly and reliably with a conventional spark.

Until I see real pictures from an F1 engine with that system. I don't think any team has actually implemented it (in the fashion shown in mahle patents and websites.) , and this is a red-hearing...

I believe there has been official confirmation from at least one team that they are using this technology.

[gruntguru]

Not sure how it works really. Kevin Hoag from SWRI mentioned this several times and it was later confirmed by an ex F1 engineer.

Turbulence and rate of combustion. The faster combustion occurs/completes the less likelihood of knock.

Does the combustion rate increase with respect to crank angle with speed ?
Or does it only increase with respect to time ?

According this this paper http://ltces.dem.ist.utl.pt/lxlaser/lxl ... 12.2_6.pdf (Thanks JAW) Combustion speed increases in proportion to piston speed/rpm.