Honda Power Unit Hardware & Software

[jesa7271]

good read ...

http://www.grandprix.com/ns/ns32991.html

hope Arai is right en don't fools us like the Spa update

[Wazari]

This is the whole interview with the questions asked included. The translation is very good and I know the reporter who is very objective and fair.

http://asia.nikkei.com/Business/Compani ... rough-year

[turbof1]

This is the whole interview with the questions asked included. The translation is very good and I know the reporter who is very objective and fair.

http://asia.nikkei.com/Business/Compani ... rough-year

I readed it earlier. Fantastic and very insightful interview.

[gruntguru]

Its easy to say something is obvious, especially when you have 2 years of knowledge on what was the best solution.

"MGUH -> MGUK -> Wheels" was obvious to me the day the new formula was rumoured. If it was obvious to me, it would have been obvious to at least some of the engineers in a multi-million dollar design team.

I think that's very hugely simplified. Of course they will have considered the possibility, but you are forgetting that we are talking about rule sets back in 2011 that was changing by the day and which was not visible for the public. These guys do not deal with rumors.
Anyway, Arai mentioned this on the upcoming second generation Honda PU:http://www.motorsport.com/f1/news/analy ... 16-670525/

If you read everything Arai says in that article there is no hint of Honda overlooking the need to operate in "MGUH -> MGUK -> Wheels" mode. In fact it is obvious that they were always able to run a direct turbocompounding mode.

[PlatinumZealot]

OK. This is called compressor surge. Stall is the opposite. Surge is when the compressor hit its peak mass flow and it cannot push out any more flow. This is at the far right of the graph and the pressure is very low. The momentum forces of the gas take over. I am not sure if this happens much if at all in F1... because at full throttle your map is still set to deliver power so there would be still a moderate level of boost. I think what you are hearing is just compressor noises as the compressor speed swings up and down.

No. Surge is the low-flow-limit of the compressor. It occurs when the discharge flow is restricted (low engine revs or downstream throttles closed) and boost (compressor speed) is elevated.

The high-flow-limit of a compressor is called the "choke" limit. The compressor itself is restricting the flow.

That is correct. And i know this too.. haha.

[PlatinumZealot]

Merc will probably send some people to viry ( like they did last year with ferrari ) to sort things up...
And is is as I have said before, it is in Merc intrest that Renault becomes competitive...

Well if Adrian has confirmed that a few Mercedes people moved to Ferrari to work on the 2015 engine we can expect some more to move if the money is right.

[toraabe]

Merc will probably send some people to viry ( like they did last year with ferrari ) to sort things up...
And is is as I have said before, it is in Merc intrest that Renault becomes competitive...

Well if Adrian has confirmed that a few Mercedes people moved to Ferrari to work on the 2015 engine we can expect some more to move if the money is right.

Exactly. Since these engines are so expensive, they have to be in F1 as long as possible. To avoid them to be illegal, the manufacturers have to cooperate and at last, make them more or less equal

[turbof1]

If you read everything Arai says in that article there is no hint of Honda overlooking the need to operate in "MGUH -> MGUK -> Wheels" mode. In fact it is obvious that they were always able to run a direct turbocompounding mode.

I think I phrased that rather poorly. My second paragraph with the link to the article had nothing to do with my reply on your comment, although I can definitely see it gave that impression. Sorry about that!

[Per]

I think there maybe a confusion of terminology regarding compressor surge and stall. To simplify things, compressor surge is when the air pressure after is higher than what the compressor can maintain. This can sometimes cause the compressor to "back up" can cause to slow the compressor down and cause a "stall". This can lead to catastrophic of the compressor itself. The most common cause of this is when the compressor itself is too large for the ICE. I am sure this phenomenon is not occurring with the current F1 PU's.

The first line in your post is definitely correct. From my perspective (working for a jet engine manufacturer), compressor stall is the aerodynamic stall of one or more blades (just like wing stall) and is a local phenomenon. Surge is what you call "backing up" of the compressor, i.e. a complete loss of compressor flow. Stall can be a precursor for surge. In jet engines, surge can be catastrophic while stall can sometimes be so insignificant you can barely measure it.

I have little knowledge about radial compressors and automotive applications, so it may be that the terminology there is different. It does make discussing on a forum like this very difficult.

In any case, you have to get your compressor design quite wrong for it to systematically misbehave under normal operating conditions. However, if Honda were running it at a different RPM than initially intended, maybe weird stuff can happen. But running it at different RPM is a free choice, so the question remains what element could cause them to do this, which they did not see coming during dyno testing before the start of 2015. Leads me again to MGU-H running too hot when installed on the car.

[godlameroso]

If your turbo is small and it's dependent on high revs to maintain adequate boost, it makes the compressor more sensitive to changes in compressor speed. Arai even said as much, now if you have a compressor that makes max boost at say 80k rpm, it will have a larger efficiency island than one that can only make max boost pressure at the 125k rpm limit. You can over-rev the former compressor slightly and use MGU-H harvesting to slow it down and bring the compressor into it's peak efficiency island. On the other hand, you cannot employ the same strategy with a turbo that makes max boost at the peak rpm limit, any reduction in compressor rpm could bring you out of the peak efficiency island as well as lower boost pressure, which reduces exhaust gases, engine power, and lessens MGU-H recovery.

It would be even worse if your MGU-H runs hot because then you can't use it as effectively to control boost pressure.

[ringo]

I do not beleive Honda's turbo is stalling to the point that we are hearing it from outside. They can't be that bad at engineering. it's not like they fitted a turbo that was on the shelf. They had it designed, so it can't be a case that they design something so poorly.

[Wazari]

The efficiency "island" of a particular turbocharger's compressor map actually has very little to do with at which RPM maximum boost is achieved for that compressor wheel.

[wuzak]

If your turbo is small and it's dependent on high revs to maintain adequate boost, it makes the compressor more sensitive to changes in compressor speed. Arai even said as much, now if you have a compressor that makes max boost at say 80k rpm, it will have a larger efficiency island than one that can only make max boost pressure at the 125k rpm limit. You can over-rev the former compressor slightly and use MGU-H harvesting to slow it down and bring the compressor into it's peak efficiency island. On the other hand, you cannot employ the same strategy with a turbo that makes max boost at the peak rpm limit, any reduction in compressor rpm could bring you out of the peak boost island, which reduces exhaust gases engine power, and lessens MGU-H recovery.

It would be even worse if your MGU-H runs hot because then you can't use it as effectively to control boost pressure.

The turbo doesn't have a maximum rpm, the MGUH does. But the MGUH can be geared to the turbo's shaft.

The MGUH should be able to balance the turbo such that the desired rpm and boost levels are met without needing to slow it down. All it does, in fact, is stop it from speeding up.

[godlameroso]

My poorly worded point is that perhaps the mgu-h can work better at controlling boost and generating energy when the compressor has a wider window of operation. One that isn't so sensitive to going over or under its ideal speed, instead of a peaky one that requires high rpm.

But ultimately what creates electrical energy is the turbine. The million dollar question is what is the best turbine size? Too small and it'll have too much backpressure, but will be great at charging the mguh, too large and response will be too slow and will drain the ERS trying to maintain boost until all but the highest rpm.

Choosing the right combination must be a nightmare even with all their facilities. And we haven't even started to discus how to make a more powerful mguh.

[hurril]

My poorly worded point is that perhaps the mgu-h can work better at controlling boost and generating energy when the compressor has a wider window of operation. One that isn't so sensitive to going over or under its ideal speed, instead of a peaky one that requires high rpm.

But ultimately what creates electrical energy is the turbine. The million dollar question is what is the best turbine size? Too small and it'll have too much backpressure, but will be great at charging the mguh, too large and response will be too slow and will drain the ERS trying to maintain boost until all but the highest rpm.

Choosing the right combination must be a nightmare even with all their facilities. And we haven't even started to discus how to make a more powerful mguh.

I'm going out on a limb here but I don't think you can say that; are you referring to the housing or the actual impeller when you refer to »the turbine?»