Honda Power Unit Hardware & Software

[GhostF1]

After @godlameroso's post I started to think these
During braking they can cease combusting in the cylinder and injecting fuel later than normal time to send fuel to exhaust and burn there. May be burning can start in exhaust stroke. I don't know. Hope someone come up with good explanation.

Sounds like Honda can afford to waste a lot of fuel while on track.

Actually etusch makes a good point.
If Honda were to burn fuel in the exhaust, it would be partially recovered by the turbine.
Unlike using the MGUK to harvest at part load, the MGUH energy recovery is not limited.

SS, the only waste is not using the maximum allowable fuel flow rate as much as possible.
Once the MGUK has harvested its 2MJ the only other mechanism to harvest at part load would be to burn fuel in the exhaust and carry on with MGUH recovery.

Exactly, so as suggested, if they are efficient enough on the ICE that they have plenty of excess fuel, gains could be found using max fuel flow at all times even if it isn't combusted and the turbo/MGU-H could recover the energy from the fuel burnt in the exhaust. Also abides by the regulation that stipulates all fuel once pumped from the tank must directly enter the engine.

[gruntguru]

A couple of general comments.
1. The popping/crackling sound is not "skipfire". It is definitely either combustion occurring in the exhaust or combustion in the cylinder with exhaust valve open.
2. It is not likely to be for the purpose of aero "blowing". (seems to be happening during decel/downshift, not low-speed corners)
3. The only reason I can see for doing this deliberately is to spin the turbomachinery to save or generate electric energy. You would only do this if fuel use was lower priority AND there was no way to circumvent the fuel->ICE->MGUK->ES per-lap-limits (which we think is possible using "extra harvest")

[PlatinumZealot]

Just found this article related to the current discussion.

https://it.motorsport.com/f1/news/test- ... o/4706019/

Ok.. Im gonna ramble on here. Read at your own peril..

This article suggests that on braking when ICE propulsion is not needed, the igntion and fuel is disabled on four (or three?) cylinders and the throttle is opened. The working cylinders sole purpose is to drive the turbocharger.


Then the aticle states the excess compressed air is passed through the non-firing cylinders to drive the turbine (MGUH). I do not agree with this part as is. i think is redundant and not necessary. You can see the "perpetual motor/generator enegry problem here.


I do not believe the non-firing cylinders act as a "relief or pass thru" for "excess" compressed air. it is just coincidence. The throttle is opened to power only three cylinders because this poses less throttling loss, less thermydnamic loss, less fuel losses than firing all six cylinders at low throttle low load out of their designed efficiency range.
So three efficient firing cylinders power the MGUH.

Because the MGUH loads the turbine, I presume the wheel is slightly over-sized (for racing conditions especially) than one without MGUH.It is a compromise for qualifying actually. However, this is compensated for by the variable inlet guide vanes on the compressor. Anyway, in a good design the turbine wheel mass flow is balanced to the compressor wheel mass flow. There is no such thing as excess air. Each cylinder is getting the same amount of air if they are all firing. Except now the non-firing cylinders do not have a strong scavenging effect. To help this, the equal length exhaust manifold is designed to have a sort of eductor effect at the collector. The firing cylinders still consume most of the intake because of this and the non-firing cylinders consume slightly less air.

Erm. So with that ramble... The skip-firing is basically an efficient way to work the MGUH at low torque demand.

I am now going to suggest "COLD SKIP-FIRING" and "HOT SKIP-FIRING"

The burbbling or the farting noise is the "Cold skip firing" done before the " hot-skip" firing is summoned.... Yes.. This could mean its not anti-lag anymore! We dont need anti-lag with MGUH right. The cold skip is done to blow out hot carbon particles out exhaust runners of the non-firing cylinders. To prevent premature back-fire

And....then the popping noises is fuel.. from the non- firing cylinders being injected into the exhaust stream. HOT SKIP FIRING

This fuel is ignited when it meets the hot particles from the firing cylinders downstream of the collector. Combustion, pressure peak, BANG! Cheap power to the MGUH with
less associated cylinder losses.

[GhostF1]

A couple of general comments.
1. The popping/crackling sound is not "skipfire". It is definitely combustion occurring in the exhaust or combustion in the cylinder with exhaust valve open. Correct, that is not skip-fire, don't think anyone is suggesting that noise is. There has even been clear distinction made between the skip-fire noise (the noise everyone attributes to Honda mid corner and at partial or zero throttle input) and then the more recent behaviour that sounds like an anti-lag system (combustion occurring in the exhaust, ie popping/crackling) See prev. posts.
2. It is not likely to be for the purpose of aero "blowing". (seems to be happening during decel/downshift, not low-speed corners)
3. The only reason I can see for doing this deliberately is to spin the turbomachinery to save or generate electric energy. You would only do this if fuel use was lower priority AND there was no way to circumvent the fuel->ICE->MGUK->ES per-lap-limits (which we think is possible using "extra harvest") Please see previous posts where this exact idea discussing ICE efficiency has improved to the point an excess of fuel is available which can be utilised as an anti-lag type setup. Also discussed at length.

[GhostF1]

Well the rattattataattaa sound is the ICE firing only 3 cylinders under breaking. The deactivated cylinders could be pumping just air, cooling the turbocharger.

Also, the F2 cars are spitting real flames almost half of all their races. The turbo’s are much more durable and antilag more controlled nowadays.

Yeah I would agree, the "rattattatatata" noise definitely sounds like skip fire operation which allows for varying combinations of cylinders to be cut off with the exhaust valves still open, significantly reducing pumping losses, increasing efficiency. And varying combinations of cylinder cuts would affect how "intense" the operation would be.
Doing this, reduces natural spark ignition engine braking, BUT, they could be using the MGU-K to compensate.

So let's think, if we assume skip fire (the "Honda noise") is to reduce pumping losses, there is a gain there in overall efficiency, what you do lose though is natural engine braking but this would allow the programming of the MGU-K, in full generation mode, to recover much more energy in slowing the engine down when off throttle or braking as it would not be competing with spark engine overrun resistance.. Ingenious.

Then add that to this new behaviour which has been prevalent since Spec 4 and the new Mobil fuel was brought in, it seems clear they are efficient enough ICE side to have excess fuel to play with and as such have introduced what is sounding like an antilag system by dumping fuel into the switched off cylinders while skip fire is active (the big bangs and pops). This would have two benefits:
1. Piston/Cylinder cooling from cool fuel injection
2. Causing backfires when it passes into the exhaust unburnt, keeping the turbo spooled without requiring electrical energy use on the MGU-H to do so, the saved energy can then be stored for use by the MGU-K during maximum power modes.

The negative to antilag is turbine damage, however this could be something HondaJet is assisting with on designing impellers that can withstand the shock damage and the sudden heat rise.

Hmm. I think the skip fire the farting noises. The other cars have this farting noise too. The sort of noise you here when you turn over an engine without ignition. (take the spark plugs out and)

Probably miscommunication somewhere, but I'm referencing the two noises in that post. Blue skip-fire, Red anti-lag type popping/crackling
And just to clarify, skip fire reduces the engine braking effect on found on all spark combustion engines.Hence why the K could take advantage and recover more than usual.

[GhostF1]

Just found this article related to the current discussion.

https://it.motorsport.com/f1/news/test- ... o/4706019/

Ok.. Im gonna ramble on here. Read at your own peril..

This article suggests that on braking when ICE propulsion is not needed, the igntion and fuel is disabled on four (or three?) cylinders and the throttle is opened. The working cylinders sole purpose is to drive the turbocharger.


Then the aticle states the excess compressed air is passed through the non-firing cylinders to drive the turbine (MGUH). I do not agree with this part as is. i think is redundant and not necessary. You can see the "perpetual motor/generator enegry problem here.


I do not believe the non-firing cylinders act as a "relief or pass thru" for "excess" compressed air. it is just coincidence. The throttle is opened to power only three cylinders because this poses less throttling loss, less thermydnamic loss, less fuel losses than firing all six cylinders at low throttle low load out of their designed efficiency range.
So three efficient firing cylinders power the MGUH.

Because the MGUH loads the turbine, I presume the wheel is slightly over-sized (for racing conditions especially) than one without MGUH.It is a compromise for qualifying actually. However, this is compensated for by the variable inlet guide vanes on the compressor. Anyway, in a good design the turbine wheel mass flow is balanced to the compressor wheel mass flow. There is no such thing as excess air. Each cylinder is getting the same amount of air if they are all firing. Except now the non-firing cylinders do not have a strong scavenging effect. To help this, the equal length exhaust manifold is designed to have a sort of eductor effect at the collector. The firing cylinders still consume most of the intake because of this and the non-firing cylinders consume slightly less air.

Erm. So with that ramble... The skip-firing is basically an efficient way to work the MGUH at low torque demand.

I am now going to suggest "COLD SKIP-FIRING" and "HOT SKIP-FIRING"

The burbbling or the farting noise is the "Cold skip firing" done before the " hot-skip" firing is summoned.... Yes.. This could mean its not anti-lag anymore! We dont need anti-lag with MGUH right. The cold skip is done to blow out hot carbon particles out exhaust runners of the non-firing cylinders. To prevent premature back-fire

And....then the popping noises is fuel.. from the non- firing cylinders being injected into the exhaust stream. HOT SKIP FIRING

This fuel is ignited when it meets the hot particles from the firing cylinders downstream of the collector. Combustion, pressure peak, BANG! Cheap power to the MGUH with
less associated cylinder losses.

I agree with your paragraph about skip-fire not not being about compressed air pass through. But I think we are misinterpreting or going a little sideways with skip-fire terminology.

I am pretty convinced now that driver torque demand (accelerator pedal position) is controlled via skip-fire on Honda powered cars, zero throttle/s. Varying cylinder cut-off/fired combinations can provide all sorts of torque values from 0-100%. I honestly think this is the system they've been trying to employ perfected for some time now and they've gotten there. So just for clarity, it's employed solely a torque demand function and would boost ICE efficiency greatly and again, because it would neutralise engine braking, the MGU-K would now be the sole pathway for engine braking and the potential energy available for harvest would be higher.

Your "hot skip firing" terminology is a bit odd, and although I'm understanding you, you then mention "It's not anti-lag anymore, we don't need anti-lag with the MGU-H right?" Although this WAS probably true early on for these PU's. I think we've gotten to the point where anti-lag has become useful again.

Here's a super basic/simplified example I'm thinking of.
Say at racetrack X they are used to running with 85kg of fuel for the entire race distance and that amount/weight does not hinder the car's dynamics in comparison to the competition. What if with the introduction of an improved ICE, they can run the same distance at the same (or higher) power but only use 80-83kg (note: numbers are abitrary placeholders to prove a point).
So they now have an ICE efficient enough they can spare fuel.So you would think, "ok take that fuel out and save the couple kg's of weight"... but what if there is a second option now. What if Honda has now suggested to you, keep the fuel load as usual, we can use that left over fuel, pass it into the engine, as per regulations, and inject it into a cylinder that is not currently firing and the fuel will enter the exhaust unburnt and then detonate and create an anti-lag effect on the turbine (This would only be available to manufacturers using skip-fire in the manner Honda is)
The gain would be, they do not need to expend electrical energy from the battery on the MGU-H to keep the turbo spinning at that point in time but in fact have the MGU-H in harvest mode while dumping the fuel and it would spin the turbo for desired boost pressure but also drive the MGU-H to generate more electrical energy.
If the amount recovered is great enough to warrant keeping the extra fuel, then definitely, why not use it. Or at least have this as an engine mode that is a higher power sustained race mode where you have more electrical energy to use for a longer period of laps without over-draining the battery.

I'm sure this could use some refining but initial idea seems sound. Open to critique haha

[amho]

Hi, does anyone know how valves in these engines are controlled? Are valves exactely depend on crank position or possible to be controlled by kind of active control?
Some of you mentioned of reducing pumping losses when tps is zero.

[saviour stivala]

Just found this article related to the current discussion.

https://it.motorsport.com/f1/news/test- ... o/4706019/

Ok.. Im gonna ramble on here. Read at your own peril..

This article suggests that on braking when ICE propulsion is not needed, the igntion and fuel is disabled on four (or three?) cylinders and the throttle is opened. The working cylinders sole purpose is to drive the turbocharger.


Then the aticle states the excess compressed air is passed through the non-firing cylinders to drive the turbine (MGUH). I do not agree with this part as is. i think is redundant and not necessary. You can see the "perpetual motor/generator enegry problem here.


I do not believe the non-firing cylinders act as a "relief or pass thru" for "excess" compressed air. it is just coincidence. The throttle is opened to power only three cylinders because this poses less throttling loss, less thermydnamic loss, less fuel losses than firing all six cylinders at low throttle low load out of their designed efficiency range.
So three efficient firing cylinders power the MGUH.

Because the MGUH loads the turbine, I presume the wheel is slightly over-sized (for racing conditions especially) than one without MGUH.It is a compromise for qualifying actually. However, this is compensated for by the variable inlet guide vanes on the compressor. Anyway, in a good design the turbine wheel mass flow is balanced to the compressor wheel mass flow. There is no such thing as excess air. Each cylinder is getting the same amount of air if they are all firing. Except now the non-firing cylinders do not have a strong scavenging effect. To help this, the equal length exhaust manifold is designed to have a sort of eductor effect at the collector. The firing cylinders still consume most of the intake because of this and the non-firing cylinders consume slightly less air.

Erm. So with that ramble... The skip-firing is basically an efficient way to work the MGUH at low torque demand.

I am now going to suggest "COLD SKIP-FIRING" and "HOT SKIP-FIRING"

The burbbling or the farting noise is the "Cold skip firing" done before the " hot-skip" firing is summoned.... Yes.. This could mean its not anti-lag anymore! We dont need anti-lag with MGUH right. The cold skip is done to blow out hot carbon particles out exhaust runners of the non-firing cylinders. To prevent premature back-fire

And....then the popping noises is fuel.. from the non- firing cylinders being injected into the exhaust stream. HOT SKIP FIRING

This fuel is ignited when it meets the hot particles from the firing cylinders downstream of the collector. Combustion, pressure peak, BANG! Cheap power to the MGUH with
less associated cylinder losses.

“Variable inlet guide vanes on the compressor”. Are variable inlet guide vanes allowed by the rules?.

[3jawchuck]

Hi, does anyone know how valves in these engines are controlled? Are valves exactely depend on crank position or possible to be controlled by kind of active control?
Some of you mentioned of reducing pumping losses when tps is zero.

The technical regulations is where you may find the answers to that question. §5 I think.
As far as I remember there is no specific regulation on how to control the valves, but there is regulation that states that variable valve timing and lift is not permitted. So probably it isn't too fancy a system?

[godlameroso]

You just need to time the injection pulse to happen when the EV opens. You don't need variable valve timing or lift.

[Juzh]

Please see previous posts where this exact idea discussing ICE efficiency has improved to the point an excess of fuel is available which can be utilised as an anti-lag type setup. Also discussed at length.

Let's not forget increase in maximum fuel allowance over the years going up from 100 kg to 105 kg and then finally to 110 kg. Mainly to counteract extra drag and to avoid lift & coast, but maybe nowadays 110 kg is more than enough for most tracks, thus this kind of fuel burning for electrical energy generation has become viable again.

[PlatinumZealot]

“Variable inlet guide vanes on the compressor”. Are variable inlet guide vanes allowed by the rules?.

Yes. Photos are around.

[MtthsMlw]

“Variable inlet guide vanes on the compressor”. Are variable inlet guide vanes allowed by the rules?.

Yes. Photos are around.

FYI

[gruntguru]

You just need to time the injection pulse to happen when the EV opens. You don't need variable valve timing or lift.

Thats right. Maybe fire the spark plug when the EV opens. Need to inject earlier to ensure there is fuel in the pre-chamber (where the spark plug is).

The intriguing part of all this is why? If you have fuel to spare the sensible thing to do is convert it to ES charge. The most efficient way to do that is to drive the MGUK with the ICE. There are per-lap limits on K harvesting but we have been lead to believe they can circumvent that with the "extra harvest" (ICE>K>H>ES) trickery. Combusting fuel after the ICE to drive the H directly is a MUCH LESS EFFICIENT conversion method and makes no sense - unless the "extra harvest" has limitations we don't know about. Its not about anti-lag either - H motoring can do that perfectly well, so backfiring for anti-lag is really only another way of conserving ES energy.

[etusch]

I think using turbo like a jet engine to produce more energy is a way of using fuel flow limit for more gain when the ice not need full fuel flow. So you can use extra fuel for storing more energy to help ice, by using fuel which could not be used if not used during braking. So if you want more power and you ready to burn more fuel for that but fuel flow limit limiting you then it is way to store more fuel during engine braking as electiricity.
I remember that Hasegawa san was complaining that when ice efficiency enhanced they were loosing h power. Now they have more mature and efficient engine and can get by this assumed way more heat and more gas in the h system.