Honda Power Unit Hardware & Software

[henry]

@gruntguru, Yes the multiple flame fronts of TJI do acccess the combustion volume much more quickly than the conventional spark. I was going to try to calculate that but the TJI gets much too complex because there are multiple flame fronts. Also I imagine the actual combustion chamber is nothing like the flat disc in my assumptions, which would only be about 3mm thick.

@godlamerosa. Thanks for the graphs. I’ll need to look at them a few times to get my head round them. One thing that leaps out is the peak jet speed which is much higher than I imagined, I’d assumed around 200 m/sec.

"with a 3mm disc", i am assuming you mean on top the piston, the big part of the combustion sapce is in the pistons 4 valve clearance indentations, the pistons gets much closer then that at TDC. the NA engines were struggling to get past a comprssion ratio of 13 because of said valve indantations in the pistons running a valve lift well past 17mm and marks of valves hitting pistions was common.

The regulations limit the geometric compression ratio to 18:1, I assume this limit suggests that the engine makers were potentially going to go higher. As you say in the normally aspirated engines the pistons had pockets to cope with the valve lift. A question would be whether with forced induction such extreme lifts are necessary or desirable. If the pockets can be reduced or dispensed with the chamber can be created to be more suitable for the combustion.

[ADC]

Looking at the last races Honda still has a massive hill to climb over winter regarding reliability in that spec 3 engine...

So is. But the engine did not break, they had an oil leak. They stopped as a precaution.

Is there a source on this, because I’m not totally buying it. What precaution do they need to take at the last race of the season? It’s not like they’ll take a grid penalty in testing or something...

[HPD]

Looking at the last races Honda still has a massive hill to climb over winter regarding reliability in that spec 3 engine...

So is. But the engine did not break, they had an oil leak. They stopped as a precaution.

Is there a source on this, because I’m not totally buying it. What precaution do they need to take at the last race of the season? It’s not like they’ll take a grid penalty in testing or something...

Tanabe: Pierre had to retire, when running in the top ten, because of an oil leak, the cause of which we are currently investigating.
https://en.hondaracingf1.com/races/2018 ... racereview

[PhillipM]

An oil leak into the cylinder looking at how it rocketed down the straight while burning it (and it was much worse on throttle than off it). Still a failure, no matter how it's worded.

[saviour stivala]

An oil leak into the cylinder looking at how it rocketed down the straight while burning it (and it was much worse on throttle than off it). Still a failure, no matter how it's worded.

Yes most probably, an oil leak can mean leaking oil out the engine as well as leaking oil into engine cylinders or into exhaust manifold such as from a leaking turbo bearing.

[saviour stivala]

@gruntguru, Yes the multiple flame fronts of TJI do acccess the combustion volume much more quickly than the conventional spark. I was going to try to calculate that but the TJI gets much too complex because there are multiple flame fronts. Also I imagine the actual combustion chamber is nothing like the flat disc in my assumptions, which would only be about 3mm thick.

@godlamerosa. Thanks for the graphs. I’ll need to look at them a few times to get my head round them. One thing that leaps out is the peak jet speed which is much higher than I imagined, I’d assumed around 200 m/sec.

"with a 3mm disc", i am assuming you mean on top the piston, the big part of the combustion sapce is in the pistons 4 valve clearance indentations, the pistons gets much closer then that at TDC. the NA engines were struggling to get past a comprssion ratio of 13 because of said valve indantations in the pistons running a valve lift well past 17mm and marks of valves hitting pistions was common.

The regulations limit the geometric compression ratio to 18:1, I assume this limit suggests that the engine makers were potentially going to go higher. As you say in the normally aspirated engines the pistons had pockets to cope with the valve lift. A question would be whether with forced induction such extreme lifts are necessary or desirable. If the pockets can be reduced or dispensed with the chamber can be created to be more suitable for the combustion.

It is not like you said so, but a forced induction system/turbo boost does not increase compression ratio. It is the combustion chamber space above the piston that does. But you are right, a forced induction/turbo engine does not need as extreme a valve lift as an NA engine and also much less need of valve overlap to avoid turbo boost going right through the exhaust. It is valve overlap that mostly necessitates valve pockets in pistons. In turn valve pockets in pistons is driven by the need to keep combustion chamber space above the pistons as small as possible to obtain high compression ratios.

[Sieper]

An oil leak into the cylinder looking at how it rocketed down the straight while burning it (and it was much worse on throttle than off it). Still a failure, no matter how it's worded.

It did not really rocket (I at first thought so too, quicker then the RBR) as Max at that point of the race in Total lost like 8 seconds to Vettel apparently, the pace of the RBR was gone. In Any case, If oil leaked into a cilinder and was being burnt in the engine, wouldn’t the smoke have come out of the exhaust? It came from under the rear body work. Right hand side. In the FIA race highlight video you can clearly see it back If you would like to.

[Tommy Cookers]

.......But you are right, a forced induction/turbo engine does not need as extreme a valve lift as an NA engine and also much less need of valve overlap to avoid turbo boost going right through the exhaust. It is valve overlap that mostly necessitates valve pockets in pistons. In turn valve pockets in pistons is driven by the need to keep combustion chamber space above the pistons as small as possible to obtain high compression ratios.

Gilles Simon wrote that there would be a conflict between adequate valve size/lift and adequate compression ratio
and boost isn't free in a turbocompound engine - pressure lost at the valves is work recovery denied to the turbine

we might also think that overlap would be needed to cool the exhaust valves
the exhaust mass-specific heat is unusually low but it's volume-specific heat is unusually high
and in these engines overlap loses no fuel and most of its flow work is recovered

could there even be some weird valve timing to use exhaust backpressure variations ?
sometimes overlap overscavenge and at other times underscavenge for internal exhaust retention and super-lean mixture

[Snorked]

Oil was leaking from the connection point, it wasn't tight enough. A simple mistake.

https://headlines.yahoo.co.jp/hl?a=2018 ... ports-moto

Saw listing on Amazon for the magazine that does the end of season Honda feature, releases Dec 27th.

[gruntguru]

X scale is ms not °

You're right - thanks tok-tokkie.

Having trouble making sense of that graph. Even at a slow 2,000 rpm, 10ms = 120*. Please someone point out my mistake?

[godlameroso]

.......But you are right, a forced induction/turbo engine does not need as extreme a valve lift as an NA engine and also much less need of valve overlap to avoid turbo boost going right through the exhaust. It is valve overlap that mostly necessitates valve pockets in pistons. In turn valve pockets in pistons is driven by the need to keep combustion chamber space above the pistons as small as possible to obtain high compression ratios.

Gilles Simon wrote that there would be a conflict between adequate valve size/lift and adequate compression ratio
and boost isn't free in a turbocompound engine - pressure lost at the valves is work recovery denied to the turbine

we might also think that overlap would be needed to cool the exhaust valves
the exhaust mass-specific heat is unusually low but it's volume-specific heat is unusually high
and in these engines overlap loses no fuel and most of its flow work is recovered

could there even be some weird valve timing to use exhaust backpressure variations ?
sometimes overlap overscavenge and at other times underscavenge for internal exhaust retention and super-lean mixture

That's a good question, I often wonder if teams are using valve timing as a way to get away with high geometric compression ratios? A sort of Miller Atkinson combination, I wonder how much experimentation they've done with with valve timing. If it's gotten to the point that they're squeezing water out of stones, or if it's still a soggy sponge dripping with potential.

[Zynerji]

Odd question, but do the rules prohibit a much slower cam rotation so a single cam lobe could have more than one profile?

[gruntguru]

Odd question, but do the rules prohibit a much slower cam rotation so a single cam lobe could have more than one profile?

Probably permissible but there are a number of problems eg the lobes would need to be much bigger (my gut feel guess says double the base circle diameter to get the the same profile twice on the same lobe).

[saviour stivala]

All four cycle four stroke internal combustion engines except radials and rotary type no matter the configuration and number of cylinders will have the camshaft rotating at one half crankshaft speed. Variable valve timing or variable lift will not effect crank/cam rotation ratio.
I do not believe variable compression system is allowed in F1.
Gilles Simon has designed and was responsible for many engines produced, as such if there is a man that know that an engine design is a complete series of compromises that is him. He will for sure tell you that how good the final package turns out to be depends on how good were the design compromises.

[saviour stivala]

.......But you are right, a forced induction/turbo engine does not need as extreme a valve lift as an NA engine and also much less need of valve overlap to avoid turbo boost going right through the exhaust. It is valve overlap that mostly necessitates valve pockets in pistons. In turn valve pockets in pistons is driven by the need to keep combustion chamber space above the pistons as small as possible to obtain high compression ratios.

Gilles Simon wrote that there would be a conflict between adequate valve size/lift and adequate compression ratio
and boost isn't free in a turbocompound engine - pressure lost at the valves is work recovery denied to the turbine

we might also think that overlap would be needed to cool the exhaust valves
the exhaust mass-specific heat is unusually low but it's volume-specific heat is unusually high
and in these engines overlap loses no fuel and most of its flow work is recovered

could there even be some weird valve timing to use exhaust backpressure variations ?
sometimes overlap overscavenge and at other times underscavenge for internal exhaust retention and super-lean mixture

If there is a man that knows that turbocompounding is not allowed in formula 1 that will be Giles Simon.