Honda Power Unit Hardware & Software

[henry]

Is the yellow arrow in this image pointing at a blow off valve? With pressurised air being returned to the compressor intake?


The arrangement of the wastegate valve in this image is very different from the mk1 engine which used two valves, one on either side of the turbine, which widened the PU at that point and was quite likely heavier.

[MrPotatoHead]

Is the yellow arrow in this image pointing at a blow off valve? With pressurised air being returned to the compressor intake?

Yes. More correctly though a Bypass Valve.

[wuzak]

They wouldn't be able to stop me from taking a spanner to it and tearing it apart just to put it back together. I'm grateful for the pictures but sad I can't see in more detail. That they're showing the power unit like this, I imagine it's this engine's last time out.

Honest question, had the engine in the car for this weekend been in the car at the beginning of the season, would there have been more points on the board?

Well, yes. But then If Ferrari, Mercedes and Renault could also have their late season engines at the beginning of the season it would be tougher.

[wuzak]

The turbine is completely shrouded in the Honda engine, that's a very interesting design, probably done to isolate the heat of the turbine from the rest of the engine bay. No wonder they had so many bearing issues, it's certainly impressive they managed to get that working.

No, it is not. It is clearly behind the cylinder bank.

[gruntguru]

By how it works combustion is rapid as i have said above, zguru but rapid cobustion is different from the timing of that combustion. TJI will beat it in that regard. How does one time HCCI anyway?

Isn't HCCI compression ignition of a petrol fueled engine? So the timing would largely be like a Diesel.
Which restricts how fast the engine can operate in that mode.
My understanding of HCCI engines is that they can convert to spark ignition at high rpm.

Ah yes, I know. It was rhetorical question for Guru. But I want to hear why he thinks the HCCI won't be speed limited. Formula 1 engines have a relatively narrow operating band and the lower edge of that band is so high above any Diesel or HCCI engine has reached.. like 8000 rpms.. I can't see why Honda would shoot them self in the foot by not using the more applicable technology which is TJI.

1. (Mainly for the benefit of some other posters) HCCI is nothing like diesel. Air and fuel are pre-mixed and ignition happens whenever the temperature of the mix gets high enough for it to ignite (very difficult to control). Ignition occurs simultaneously at many points across the chamber hence the rapid complete burn without knock. (Knock is when the burn progresses across the chamber at the speed of sound.)
2. Ignition timing can be controlled by varying: Pressure (boost or CR), Charge temperature, AFR or (maybe) turbulence.
3. HCCI is not speed limited. Accurate timing may be more difficult since the window of optimum timing which is only a few degrees wide gets narrower (as measured in milliseconds) as rpm increases. The most common example of HCCI is the "Diesel" model engine with adjustable CR. These things can turn very high rpm.
4. TJI is a step towards HCCI efficiency. It produces very rapid combustion (not quite as rapid as HCCI) but doesn't have the ignition timing accuracy problem (ignition begins with a spark).

[makecry]

Honda is planning to carry over this concept/architecture next year right? Wouldn't it be smart to not display the PU for everyone to see? Kind of confused .

[FW17]

1. (Mainly for the benefit of some other posters) HCCI is nothing like diesel. Air and fuel are pre-mixed and ignition happens whenever the temperature of the mix gets high enough for it to ignite (very difficult to control). Ignition occurs simultaneously at many points across the chamber hence the rapid complete burn without knock. (Knock is when the burn progresses across the chamber at the speed of sound.)

So what does happen in a petrol engine if the mixture is not premixed and injection happens into highly compressed hot air as in a diesel engine, does it detonate or can be useful work?

Auto ignition of petrol happens between 250 - 280 deg C while diesel is at 210 deg C, cannot the temperature of the charge air inside the cylinder be raised to 280 deg C or higher to promote auto ignition of petrol?

Can't the detonation be controlled by multiple injections like in a Diesel?

[gruntguru]

1. (Mainly for the benefit of some other posters) HCCI is nothing like diesel. Air and fuel are pre-mixed and ignition happens whenever the temperature of the mix gets high enough for it to ignite (very difficult to control). Ignition occurs simultaneously at many points across the chamber hence the rapid complete burn without knock. (Knock is when the burn progresses across the chamber at the speed of sound.)

So what does happen in a petrol engine if the mixture is not premixed and injection happens into highly compressed hot air as in a diesel engine, does it detonate or can be useful work?

Auto ignition of petrol happens between 250 - 280 deg C while diesel is at 210 deg C, cannot the temperature of the charge air inside the cylinder be raised to 280 deg C or higher to promote auto ignition of petrol?

Can't the detonation be controlled by multiple injections like in a Diesel?

Detonation only occurs in pre-mixed air/fuel parcels. Injection during combustion does not lead to detonation. Multiple injections prior to ignition still creates pre-mixed parcels which may still detonate.

[GhostF1]

Honda is planning to carry over this concept/architecture next year right? Wouldn't it be smart to not display the PU for everyone to see? Kind of confused .

I feel like what you are seeing in those photos hardly gives anything away anyway.. not enough to be concerned of prying eyes. Mercedes does a video on every engine they've had each year and safe to say they haven't changed architecture.

The trick stuff is all internal, and even with the plenum system, we still can't see any of the inner workings such as trumpet mechanism/runner design.

[godlameroso]

The turbine is completely shrouded in the Honda engine, that's a very interesting design, probably done to isolate the heat of the turbine from the rest of the engine bay. No wonder they had so many bearing issues, it's certainly impressive they managed to get that working.

No, it is not. It is clearly behind the cylinder bank.

I meant there's a very thick heat shield over the turbine.

[63l8qrrfy6]

The bearing housing is most likely a separate component bolted to the turbine housing and probably watercooled. Just because the turbine housing is really well insulated doesn't have to mean that the bearings run extremely hot.

There is of course a tradeoff between how close the bearing can be to the turbine wheel. Too close and it gets hot, too far and the whirl frequency drops.

Bearing issues are due to the rotor operating super-critically and being inadequately balanced and/or insufficiently damped.

[Tommy Cookers]

[quote=gruntguru]
3. HCCI is not speed limited. Accurate timing may be more difficult since the window of optimum timing which is only a few degrees wide gets narrower (as measured in milliseconds) as rpm increases. The most common example of HCCI is the "Diesel" model engine with adjustable CR. These things can turn very high rpm.[/quote]

what tends to make HCCI speed limited is that the gasoline fuel is resistant to self-ignition - the opposite of CI fuel
resistance meaning a delay - measurement of this at various temperatures being the basis of CI fuel rating (Cetane No)

model 'diesel's' fuel 'always' contained the famously potent self-ignition accelerator amyl nitrate
though isopropyl nitrate might be favoured as less suspect to today's authorities
ether is a dominant ingredient and readily self-ignites, having very low boiling and flash points etc relative to the high compression temperatures reached
anyway these model 'diesels' engines are always slower-running than their 'glowplug' competitors and happy in slow running
http://adriansmodelaeroengines.com/cata ... ?cat_id=72
http://www.antiquemodeler.org/sam_new/p ... basics.htm
this http://nvlpubs.nist.gov/nistpubs/jres/3 ... 73_A1b.pdf seems to show that ethers lower ON of alcohol fuel

btw surely HCCI combustion only gives safe peak pressures if the mixture is very lean/EGR'd ie SI throttled operation substitute ?

btw timed DI of self-ignition accelerator was shown pre-WW2 to be a viable replacement for SI

[dren]

It is pretty well known. There is a rule however that forbids K torque fill under a certain speed (100 kph I think?).

Yeah, I think there is a formula dictating torque up to a certain RPM, too.

That'd be the fuel flow formula.

Q = 0.009 * RPM + 5.5 <10,500rpm.

Or maybe you mean the maximum torque specified for the K at 200Nm?

Maybe it was in the original regulations? I remember there being some sort of torque limit for the K from 0 up to a certain RPM, 4000 seems right if I remember. Or maybe I've had too many beers since...

[muramasa]

piping from plenum to cylinders, 2 pipes per each bank, red arrow is regulator for wastegate

https://pbs.twimg.com/media/DLW_uJ5VYAEcAWV.jpg:large

That's wrong.
There are 3 inlet pipes for each bank.

"4" in that pic goes to 2nd cylinder or middle one on the right
"3" in that pic goes to 3rd cylinder or the right rear
ditto for left bank

There is a 3rd inlet pipe below "3" in that pic
of course this goes to 1st cylinder or right front
ditto for left

Not clear from pics because the thing is black and in the dark/shadow but in person it's easy to distinguish. The pipes are bent quite a bit.
btw MGU-H is directly attached/coupled to the compressor, which is also easy to see in person.

[stevesingo]

piping from plenum to cylinders, 2 pipes per each bank, red arrow is regulator for wastegate

https://pbs.twimg.com/media/DLW_uJ5VYAEcAWV.jpg:large

That's wrong.
There are 3 inlet pipes for each bank.

"4" in that pic goes to 2nd cylinder or middle one on the right
"3" in that pic goes to 3rd cylinder or the right rear
ditto for left bank

There is a 3rd inlet pipe below "3" in that pic
of course this goes to 1st cylinder or right front
ditto for left

Not clear from pics because the thing is black and in the dark/shadow but in person it's easy to distinguish. The pipes are bent quite a bit.
btw MGU-H is directly attached/coupled to the compressor, which is also easy to see in person.

As I thought...

My guess is they are the intake runners for cylinders 2,3,5,6, 1&4 being entirely inside the plenum. The runners are not symmetrical. Runner indicated 4 in the picture seems to have the tightest radius and may feed cyl 2, runner 1 is the next tightest radius and i guess that would feed cylinder 5. Runners indicated 2&3 feeding 6&3 respectively due to 3 being slightly further forward.