Burning lean: Pre-chamber combustion tech

[MatsNorway]

Hi guys, sorry about the caps.

I am unsure about the level this forum is at. Either way this read is a decent one about the current generation of motors.

https://drivetribe.com/p/f1-burning-lea ... ce=network

Lets talk engine combustion.

[MrPotatoHead]

A very dumbed down description of a very complex process sadly.
The part saying Honda Civics used the same technology in the 70s made me shake my head.

[MatsNorway]

I did not know anything about civics but i do know Mercedes had Pre chamber Diesels back in the day and probably still use the techicue to this day.

What i really hope for F1 is for them to free up the rules regarding these engines. Say open up the Bore and stroke ratios and flatten the fuel curve. That way you get a better shot at making more efficient engines and they might sound better in the process which is something many fans would enjoy. It is a win win if true.

[NL_Fer]

I believe the author "Scarbs" is a regular in this forum.

And yeah, how they constructed a single-injector-prechamber is something we all want to know here.

[toraabe]

I did not know anything about civics but i do know Mercedes had Pre chamber Diesels back in the day and probably still use the techicue to this day.

What i really hope for F1 is for them to free up the rules regarding these engines. Say open up the Bore and stroke ratios and flatten the fuel curve. That way you get a better shot at making more efficient engines and they might sound better in the process which is something many fans would enjoy. It is a win win if true.

The last mercedes pre chamber diesel is the famous OM606. In stock the engine easily can be tuned to well above 400 hp https://www.youtube.com/watch?v=YlwTxw-027o

[Dazed1]

A very dumbed down description of a very complex process sadly.
The part saying Honda Civics used the same technology in the 70s made me shake my head.

I did own a 1975 Civic CVCC (Orange, we called it the pumpkin) and it consistently got 35 MPG while scooting along at traffic speeds. "Compound Vortex Controlled Combustion". I was impressed with it.

[stevesingo]

A very dumbed down description of a very complex process sadly.
The part saying Honda Civics used the same technology in the 70s made me shake my head.

I believe the author "Scarbs" is a regular in this forum.

That explains it.

There are many other posters on this forum whose word I would take before this "Author".

[MrPotatoHead]

I actually didn't realize Scarbs wrote the article when I skimmed it earlier and made my comment.
Knowing it was Scarbs if it was dumbed down it was intentional as he certainly understands how the technology works.

My apologies if you are reading this for my overly harsh words!

[riff_raff]

I did own a 1975 Civic CVCC (Orange, we called it the pumpkin) and it consistently got 35 MPG while scooting along at traffic speeds. "Compound Vortex Controlled Combustion". I was impressed with it.

The most impressive aspect of the Honda CVCC engine was that they got it to work fairly reliably using a carburetor.

[dren]

I did own a 1975 Civic CVCC (Orange, we called it the pumpkin) and it consistently got 35 MPG while scooting along at traffic speeds. "Compound Vortex Controlled Combustion". I was impressed with it.

The most impressive aspect of the Honda CVCC engine was that they got it to work fairly reliably using a carburetor.

Those things were a vacuum hose nightmare! Impressive none the less.

[johnny comelately]

Hi guys, sorry about the caps.

I am unsure about the level this forum is at. Either way this read is a decent one about the current generation of motors.

https://drivetribe.com/p/f1-burning-lea ... ce=network

Lets talk engine combustion.

Very important subject in it contribution to the "new" F1 efficiencies.
Pure pre-combustion chambers (flame ignition) are discussed here without any conjunctive fuel injection.
i think F1 rules limit the ignition source to one per cylinder which is unreasonable and an inhibition of good development, it should relate to the bore size and at 80mm two igniters would probably be an advantage.
but anyway the advantage in what can be called flame ignition is enormous.
the flame shooting out across the combustion chamber igniting a large tract of mix is such an advantage over a single point electrical spark.
One of the benefits from this large source area is the inhibition of knocking, a serious danger with such high compression pressures.
From the pre-combustion chambers i have seen, they only need room for a 3mm to 4mm hole to exit into the chamber proper.
The important dimensions are the ratio of the volume where the sparkplug point is to the volume of the barrel and then the barrel diameter, the larger the diameter the less distance the flame travels across the chamber.

[Tommy Cookers]

the inhibition of knocking is inherent to lean mixtures - because the fuel heat is spread over a greater mass of air
called heat dilution - its main benefit is a big reduction in the relatively great amount of heat needing dumping to coolant

ok the prechamber allows more leaning
but it's a pity we don't also know more about the creditable performance of the erstwhile non-prechamber competition

the benefits of heat dilution depend on high boosts (relatively downsizing) and so rely on compressor motorising and efficiency
but turbine recovery is independent of leaning

[blueytoo]

but it's a pity we don't also know more about the creditable performance of the erstwhile non-prechamber competition

More than likely improved ICE efficiency of the pre-chamber jet ignition is a key reason Mercedes have been dominant for so long. Nobody else knew and they have spent years chasing marginal gains from ERS and split turbo.

How they manage this with a single injector is the great unknown. Patents must exist. Wazari-san said he has filed several in the process of developing Honda's F1 engine.

This one describes 2 different mixtures from one injector.
https://patents.google.com/patent/DE19530072A1/en

But that is different from 2 different chambers being fuelled by one injector.

[godlameroso]

There's really only one way to do it with one injector and one spark plug, and the side injector is the big hint. It takes an injector with variable spray pattern. One spray pattern injects fuel in the main chamber, the other directs it at the pre-chamber. The intake system, and the MGU-H aid this process by controlling back pressure and cylinder filling, along with varying the fuel temperature. With the injectors on the exhaust side, they could more easily have more range to precisely control the fuel temperature which is also critical in the combustion process.

Different fuel temperatures change the properties of the fuel, perhaps the primary injection is at a different temperature than the pre-chamber injection.

[rgava]

Different fuel temperatures change the properties of the fuel, perhaps the primary injection is at a different temperature than the pre-chamber injection.

I don't see this happening because of the short time between primary and pre-chamber injection trough the same injector and the short volume of the pre-chamber injection compared to the main one.