Honda Power Unit Hardware & Software

[PlatinumZealot]

I find it amazing, how Honda thinks they can make PU much smaller than other 3 competitors. Mercedes went radical with split turbo to allow for better packaging (and cooler air for ice), Newey has surely pushed Renault hard with regards to packaging and yet Honda thinks they can do much better job. It just seems they want something that can't be done and I wouldn't be surprised at all if they hit troubles. However, it is a good thing they are pushing the boundaries and at least they will learn something.

But it was done, wasn't it?

[godlameroso]

We can argue until we're blue in the face about who knows what. Look at what actually works, and then tell me why it's wrong?

https://www.youtube.com/watch?v=UxVqWfQZeOQ

Listen to the engine when it's halfway down the straight, does it not sound like it's turbo is stalling?

Radial compressor is almost impossible to stall under a normal working. In the case where even if you slam the throttle shut - and even if there is no blow off, the system is designed for these events by use of the MGUH. Also the pressure ratio is so small when compared to axial compressors.. it's only a few bar haha. I don't think the compressor is stalling at all - even if it were stalling it is only one stage with passages only a few centimeters in length - nothing detrimental will happen like in a multistage axial compressor with rows of blades....

I'm not saying it's a catastrophic stall(the engine wasn't sputtering or backfiring), I'm saying partial stalling, as in the compressor is unable to deliver enough boost pressure to the cylinders(because it's a small turbo that requires high rotational speed to achieve the desired pressure). This would only happen on full throttle, down a long straight, when the MGU-H does most of it's harvesting(reducing turbine, and compressor rpm, unless there's some other way the MGU-H harvests that I'm not aware of), and made worse by the fact Honda was running out of battery power half way through the lap. If you notice in the low speed stuff, the engine actually has good response and drivability, the problem comes on the long straights, right when MGU-H should be in generator mode.

[taperoo2k]

I find it amazing, how Honda thinks they can make PU much smaller than other 3 competitors. Mercedes went radical with split turbo to allow for better packaging (and cooler air for ice), Newey has surely pushed Renault hard with regards to packaging and yet Honda thinks they can do much better job. It just seems they want something that can't be done and I wouldn't be surprised at all if they hit troubles. However, it is a good thing they are pushing the boundaries and at least they will learn something.

Honda could have played it relatively safe and gone with the conventional wisdom "Mercedes split turbo design is the best", but they've gone down a radical and somewhat experimental route. It could yet pay off for Honda, if they can get it working properly and the most important thing of all - fast and reliable.

I think some people underestimate the technical challenges of these PU's. We simply don't know for sure how many teething issues Mercedes had during it's R&D phase before they hit the ground running in 2014.

[hurril]

I think the, let's call it, mercedes model is getting way too much credit here. Having a split turbo configuration and having the best complete package are correlations and we all know that story about correlation and causation.

Saying something to the effect of: "why aren't everybody just Doing It Like Mercedes. They're stupid!1." is not a whole lot different from saying: Mercedes have it easy; they just stumbled upon the right solution, or in fact: however they compiled their solution is inconsequential - there's no real substance to it. Now that we know that they run a split turbo, the cat is out of the bag. Split thein turbos, people, and you shall run as fast as the W0x-models. Nothing more to it really.

Mercedes' way of doing it is just as radical. We don't know about the problems it has because they haven't disintegrated all over the place for all to see like Renault and Honda have.

[godlameroso]

There's a lot we don't know about the power units, a lot of things we can't really see. There's certain advantages to putting the MGU-H in the way Renault have done. It's really a compromise, putting the MGU-H sandwiched between the turbo, puts more heat into the electric motor, putting it in front of the compressor makes cooling the MGU-H easier, but penalizes you with other things like packaging, and forces you into requiring more cooling for the engine itself.

I think Honda's reliability is going to be rock solid next year(the Pirelli tests already hinted at this). With an engine so strong it could practically run off pure detonation. I'm sure they learned a lot in dealing with 2015's live grenade.

[Per]

We can argue until we're blue in the face about who knows what. Look at what actually works, and then tell me why it's wrong?

https://www.youtube.com/watch?v=UxVqWfQZeOQ

Listen to the engine when it's halfway down the straight, does it not sound like it's turbo is stalling?

Radial compressor is almost impossible to stall under a normal working. In the case where even if you slam the throttle shut - and even if there is no blow off, the system is designed for these events by use of the MGUH. Also the pressure ratio is so small when compared to axial compressors.. it's only a few bar haha. I don't think the compressor is stalling at all - even if it were stalling it is only one stage with passages only a few centimeters in length - nothing detrimental will happen like in a multistage axial compressor with rows of blades....

I'm not saying it's a catastrophic stall(the engine wasn't sputtering or backfiring), I'm saying partial stalling, as in the compressor is unable to deliver enough boost pressure to the cylinders(because it's a small turbo that requires high rotational speed to achieve the desired pressure). This would only happen on full throttle, down a long straight, when the MGU-H does most of it's harvesting(reducing turbine, and compressor rpm, unless there's some other way the MGU-H harvests that I'm not aware of), and made worse by the fact Honda was running out of battery power half way through the lap. If you notice in the low speed stuff, the engine actually has good response and drivability, the problem comes on the long straights, right when MGU-H should be in generator mode.

Your stubbornness is frustrating. It's already been mentioned three time in the last few pages that MGU-H harvesting does *not* necessarily reduce RPM. Rather, it harvests all the power that is generated by the turbine and not used by the compressor. The MGU control unit is perfectly capable of keeping the MGU-H at the desired RPM and taking just the amount of power that is available.

[godlameroso]

Quote from Yasuhisa Arai
"Let me put this concept of the domino effect into a technical example: if you try to harvest energy using the MGU-H, it puts a strenuous workload on the turbo. When the turbo is under stress, it cannot do what it is supposed to do, which is to force more air into the engine, thus leading to decreased power output. This is the result of one component working against the others, instead of working together."

* http://www.racecar-engineering.com/inte ... nda-f1-qa/

I'm the stubborn one, yes, if you point at the sky and ask me what color it is in the middle of a clear day, I'm going to keep saying blue. If you keep asking me how much hair I have on my head I'm going to stubbornly keep saying I'm bald, because it's the truth and it's plain to see.

[gruntguru]

Which has nothing to do with "stalling".

When you say "stall" I assume you mean compressor surge which is a condition which occurs when boost is high but discharge flow from the compressor is restricted (due to throttling or low rpm). Surge is not caused by slowing the compressor in fact the opposite is true - slowing the compressor will move the operating point out of the surge region.

[godlameroso]

Ok I admit it was a poor choice of word to say stall/surge what else could it be, dragging turbo, inefficient? The shaft doesn't stop spinning all together, but it is slowed down enough to not generate enough boost for the engine, and thus it loses power.

[Postmoe]

His stubborness is just giving us more and more of this awesomely hypnotic avatar.

Think about it.

Ps: couldn't we agree that a turbo with resonance problems working at a rpm's way lower than expected could be somehow impairing an already problematic energy harvesting? I mean... Call it stall or not, I think this discussion has been more problematic because of the words used than for anything else.

[gruntguru]

Grunt, it appears that Honda did have that very issue. As did Ferrari in 2014.

Wuzak could you expand on that? I find it impossible to believe that two engine teams both overlooked the need to run the PU as a pure TC (turbine -> MGUH -> MGUK -> transmission).

[gruntguru]

Ok I admit it was a poor choice of word to say stall/surge what else could it be, dragging turbo, inefficient? The shaft doesn't stop spinning all together, but it is slowed down enough to not generate enough boost for the engine, and thus it loses power.

In the normal operating region, boost has a direct relationship to compressor speed. Any change in speed will change the boost. Boost is a variable which is critical to the tune of these engines. The tune (AFR, air mass etc) has a dramatic effect on the crankshaft power. They are not likely to compromise the crankshaft power for the sake of a small increase in turbine/MGUH power.

As a matter of fact - if you take X kW away from the compressor because you want to feed those KW into the MGUH instead, the resulting loss of airflow through the engine will reduce the turbine power by approximately X KW - you gain nothing. I have done the calculations previously and posted them elsewhere in the forum.

[Per]

Exactly, which is why no engine manufacturer would harvest more than what is available (i.e. work taken from exhaust by turbine, minus work done by compressor). Or at least, not in the middle of the straight.

If they try to harvest more than what is available, then yes it will affect compressor performance. It is not a condition that can be sustained because the at some point the turbine can't deliver the work anymore.

On the other hand of the spectrum, if they don't harvest the available power, it will cause the turbine/compressor to spin up to a higher RPM, up to the 125k limit at which point the wastegate will have to be opened.

So.... the MGU-H is there to keep the turbine and compressor at the desired RPM. It's simple physics, isn't it?

"As a matter of fact - if you take X kW away from the compressor because you want to feed those KW into the MGUH instead, the resulting loss of airflow through the engine will reduce the turbine power by approximately X KW - you gain nothing."

What if they WANT to reduce the turbine power... because at full capacity the MGU-H is overheating? Simplest way to prevent overheating would be to clutch the MGU-H and open the waste gate, but perhaps that's even less efficient than what you described? So instead you use the MGU-H to keep the turbine/compressor RPM at a lower-than-optimum speed and have a bit less performance from the ICE but a bit more harvesting?

[gruntguru]

. . . What if they WANT to reduce the turbine power... because at full capacity the MGU-H is overheating? Simplest way to prevent overheating would be to clutch the MGU-H and open the waste gate . . .

Reduce MGUH power and open the WG.

[wuzak]

Grunt, it appears that Honda did have that very issue. As did Ferrari in 2014.

Wuzak could you expand on that? I find it impossible to believe that two engine teams both overlooked the need to run the PU as a pure TC (turbine -> MGUH -> MGUK -> transmission).

It was rumoured that Ferrari could not operate the MGUK directly from teh MGUK in 2014, that the recovered energy from the MGUH had to be routed through the ES.

The symptom of this method is that they would run out of energy at the end of straights, as happened to Ferrari in 2014 and Honda in 2015. It was a case of only being able to use 4MJ per lap, instead of, quite possibly, 6+ MJ that Mercedes and Renault could use.

Ferrari also increased the size of the turbine for the 2015 season and, maybe, also the compressor. Using the bigger turbine and adjusted control electronics to allow the direct linking of MGUH and MGUK has transformed the Ferrari performance. From what I recall, the only track at which they struggled with running out of ES allowance was Spa, but the loss wasn't the 160hp Honda were having, but probably less than half and for much less of the lap than Honda and Ferrari's 2014 PU.

If you had vision of the rain lights of the cars you could probably do an analysis of the ERS usage. The flashing light is said, by some, to mean the ES is being charged, but I believe it is fundamentally to show that the MGUK is no longer adding power to the ICE. In most cases it will be charging.

Most cars seem to have the flashing light in the last section of a straight, which probably means that the MGUH is feeding the ES at that point, rather than the MGUK.