Honda F1 project leader Yusuke Hasegawa has outlined a number of reasons why Honda has been struggling so badly in the beginning of the 2017 Formula One season. He confirmed that lots of problems were not discovered while running on the dynamo meter.
(With regards to friction)The interplay between the main and second compression rings is very important. The top ring is the one that does most of the sealing, but the pressure pocket between the top and second ring is important. The second ring also shears oil off the cylinder walls, it's not all done by the oil control rings.
I don't quite follow this talk about the blow through. Blow through happens from the combustion chamber and into the crankcase, not the other way around. So how could high compression or creativity here be the cause of the hidden burning of oil?
I don't quite follow this talk about the blow through. Blow through happens from the combustion chamber and into the crankcase, not the other way around. So how could high compression or creativity here be the cause of the hidden burning of oil?
Late to this discussion, but why burn oil to then replace it with fuel, which is just as restricted?!? I don't get it...
“Strange women lying in ponds distributing swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony!” Monty Python and the Holy Grail
Increasing compression does not guarantee blowby increase. Rings are pressure energized, the higher the pressure the better they seal. Reducing tension on the other hand is guaranteed to reduce contact pressure and decrease friction.
But what if you create pressurized oil when piston reaching BDE, your ring would not stiff enough to resist oil entering piston, and the ring would be reenergize in TDC. Higher CR lead to stronger sealing power but weaker also in BDE. What is ring material allowed?
I don't think there is a restriction on the piston rings, at least not that I've seen.
5.17.7 Reciprocating and rotating components : a) Reciprocating and rotating components must not be manufactured from graphitic matrix, metal matrix composites or ceramic materials, this restriction does not apply to the clutch and any seals.
I'm guessing piston rings classify as seals of a reciprocating component(ie pistons)?
Last edited by godlameroso on 07 Mar 2018, 18:38, edited 2 times in total.
Some thoughts on the recent responses that were triggers by Wazari’s recent posts. More specifically around lubrication and impact upon MGU-H.
I very much enjoy the insight provided by Wazari, but I would say that maybe even by his own admission he occasionally need to clarify his own comments. Sometimes even allowing others to provide their own estimation in which he approve (or not) of their understanding. And dare I say, even those clarifications may need additional clarification!
Given we hang upon every word of his posts, any slight unintended error creates gnashing of teeth and arguments as the puzzle pieces seem to not fit. For example, in a recent post of his, he said “Cavitation in the oil tank caused the problem.”
My (untrained) understanding is that cavitation is not something that would happen in the tank? You may have issues in which an air pocket may form (via the much discussed slosh mechanics), or that air/oil separation is poor. All of which would be what I believe is an “Aeration” issue (air being pulled into the pump) and not “Cavitation”. That cavitation itself is more of an oil pump phenomenon? My point (assuming my logic is correct), is that he is capable of making an unintended error when explaining details of topics in which he may be intently familiar with. Then the forum obsesses on any resulting inconsistencies.
I think we may currently be hung up on the topic of how the MGU-H is lubricated, how that oil from the oil tank made its way back up scavenging air lines and ultimately how did that cause bearings to fail.
Recent posts by Wazari talk about what I suspect might be two different things happening at the same time with the oil tank issue being the ultimate trigger. The first is that due to the tank design, the pump was picking up a mixture of air/oil. This created a lack of lubrication somewhere in the MGU-H and damaged those bearing that were lubricated/cooled by engine oil. I think someone has already said that they would expect the main journal bearings to feel the effects first. My comment is to say that who knows what is going on inside the Honda engine from a lubrication perspective. I would leave the door open for taking what is said at face value. That oil starvation somehow damaged one or more bearings in the MGU-H.
Second is the issue with over filling the oil tank in an attempt to stop the aeration/starvation issue and this inadvertently causing problems with oil migrating back up the scavenge lines in the wrong direction. The recent posts are hyper focused on the thought that it was fuel contaminated oil. Especially given Wazari gave a thumbs up to that speculation. I wonder if he was giving the thumbs up more to the fact that engine oil was washing over a bearing and causing failure and less about it being “contaminated oil”. Are we focusing too much on the “contamination” part?
Overall, the scavenge line scenario somewhat reminds me of the issue in the M96/M97 Porsche engine used in the 911 a few years ago. It had a design in which an intermediate shaft bearing (used to drive the camshafts if I remember correctly) used a sealed bearing that had its own internal lubricant. However, over time a wash of engine oil would break down the seal on the bearing and would then wash away the intended lubricant and would eventually cause the bearing to fail.
In one of Wazari’s posts, he talks about the bearing in question being a sealed bearing. Maybe there was no expectation that this bearing would ever come into contact with engine oil (contaminated or otherwise). And that the migration of engine oil back through a scavenge path may have introduced oil into an area in should never have been, but making contact with the sealed bearing, breaking down the seal on the bearing, washing away the desired lubricant and ultimately triggering its failure.
Lastly… given the significant expertise here (of which I am not) and the ease in which theories are aggressively shot down, I am hesitant to post on a regular basis. I feel it may result in less people trying to contribute to the discussion (i.e. don't post unless you know what you are talking about). But I am willing to take the risk as I think common sense and a general engineering knowledge might occasionally provide something of interest (I can only hope).
Richard
To paraphrase Mark Twain... "I'm sorry I wrote such a long post; I didn't have time to write a short one."
They probably tried to fix the problem by using a ceramic bearing but the bearing rollers would shatter under resonant loads? I guess it was a combination of using different seals and bearing lubrication that ultimately solved the issue.
Honda sounds a lot diferent than the other engines. It's only due to cylinder deactivation at middle throthle, or its "that" combustion process you were talking about...
