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Re: Honda Power Unit
Posted: 13 Sep 2015, 20:17
by bergie88
godlameroso wrote:bergie88 wrote:
Seriously? A normal turbo engine without a MGU-H the turbine would be sized to efficiently produce the required power for the compressor to produce the required boost for the fuel flow. The rest of the exhaust is sent through the waste gate. To efficiently harvest energy for the MGU-H you will require a bigger turbine to make use of all the exhaust gases. This doesn't effect the compressor in any way at all as the fuel flow is fixed and so the boost required for it. As such to extract more energy for the MGU-H you require a large turbine Not a larger compressor.
Therefore Ferrari's problem last year of not being able to get enough energy from the MGU-H come down to having a too small turbine and has nothing to do with the size of the compressor.
You could have ultra lean running if you design your combustion chambers, and DI system to have a type of stratified charge, so you can burn at or a little bit above stochiometric in part of the chamber, as long as you can control and precisely burn fuel at the right amount, and introduce boost pressure without making the overall AF mixture too lean, I don't see the downside to running as much boost pressure as possible given the PU configuration.
Maybe knock is a problem?
Re: Honda Power Unit
Posted: 14 Sep 2015, 14:29
by tuj
It was said that when Mclaren was running the Merc unit, they were down 40hp just because of lubricants and specifically the fuel. I believe Mclaren couldn't run as high of boost using their contracted Mobil fuel as opposed to the factory teams specifically designed Petronas fuel.
Re: Honda Power Unit
Posted: 14 Sep 2015, 14:57
by godlameroso
bergie88 wrote:godlameroso wrote:bergie88 wrote:
Seriously? A normal turbo engine without a MGU-H the turbine would be sized to efficiently produce the required power for the compressor to produce the required boost for the fuel flow. The rest of the exhaust is sent through the waste gate. To efficiently harvest energy for the MGU-H you will require a bigger turbine to make use of all the exhaust gases. This doesn't effect the compressor in any way at all as the fuel flow is fixed and so the boost required for it. As such to extract more energy for the MGU-H you require a large turbine Not a larger compressor.
Therefore Ferrari's problem last year of not being able to get enough energy from the MGU-H come down to having a too small turbine and has nothing to do with the size of the compressor.
You could have ultra lean running if you design your combustion chambers, and DI system to have a type of stratified charge, so you can burn at or a little bit above stochiometric in part of the chamber, as long as you can control and precisely burn fuel at the right amount, and introduce boost pressure without making the overall AF mixture too lean, I don't see the downside to running as much boost pressure as possible given the PU configuration.
Maybe knock is a problem?
Again it all depends on the fuel you're using, and how your combustion concept works. If you have no pre-chamber and just straight up DI fuel with air charge you're 101% correct, knock is a big problem. But if you design your chamber in a certain way you can run very lean without knocking because the fuel is being burned at the correct ratio in the pre-chamber and the flame front expands into the main chamber, so although the overall charge that is acting on the piston is rather lean, combustion itself is at or near stochiometric.
Re: Honda Power Unit
Posted: 14 Sep 2015, 19:06
by tuj
godlameroso wrote:If you have no pre-chamber and just straight up DI fuel with air charge you're 101% correct, knock is a big problem. But if you design your chamber in a certain way you can run very lean without knocking because the fuel is being burned at the correct ratio in the pre-chamber and the flame front expands into the main chamber, so although the overall charge that is acting on the piston is rather lean, combustion itself is at or near stochiometric.
By "pre-chamber" do you mean before the intake valves? Injection in the intake plenum is not allowed any more, is it?
Re: Honda Power Unit
Posted: 14 Sep 2015, 19:12
by alexx_88
He's probably referring to how a DI system with suitable piston design allows to have a stratified charge with different lambda values across the chamber.
Re: Honda Power Unit
Posted: 15 Sep 2015, 09:21
by Abarth
I don't think they use wall- or air guided combustion. With these high pressures, I think they have adopted for a spray guided combustion, giving more freedom for optimized piston crown and chamber design.
Re: Honda Power Unit
Posted: 15 Sep 2015, 10:31
by taperoo2k
Interesting article about the power unit, with a rumour about Honda using a test mule -
http://www.somersf1.co.uk/2015/09/mclar ... n-and.html
Re: Honda Power Unit
Posted: 15 Sep 2015, 14:33
by Thunder
This is a short new Honda movie. Maybe something can extracted out of it. They show some PU Parts and drawings.
https://www.youtube.com/watch?v=MRDluXz ... e=youtu.be
Re: Honda Power Unit
Posted: 15 Sep 2015, 14:38
by sectionate
https://twitter.com/F1___Talk/status/643764655349977089
One of their CAD drawings from the video.
(I always take these with a pinch of salt, I expect the drawing model is a good 6 months out of date)
Re: Honda Power Unit
Posted: 15 Sep 2015, 14:55
by Thunder
The Exhaust / Turbo arrangement in that Picture has nothing to do with the actual PU. Looks more like a test setup from the earliest days.
Re: Honda Power Unit
Posted: 15 Sep 2015, 14:59
by Facts Only
Thats a dyno set-up, probably an early test engine from years ago before the turbo was integrated into the PU properly.
Apart from the seperated turbo the probe bosses all over the exhaust and the fact that thre is room for the actual dynamometer underneath the turbo are the giveaways.
I managed to pause on a couple of the quickly flashing drawings and it looked like single cylinder stuff.
We can also tell that they are using CATIA V5 and that whoever has done the CAD hasn't been hiding there planes in the model.
Re: Honda Power Unit
Posted: 15 Sep 2015, 15:10
by Sixbarboost
I still believe the Honda PU began as this, a hobby-design which Honda took way too serious;
Re: Honda Power Unit
Posted: 15 Sep 2015, 19:57
by dero
frame with telemetry/graphs from the video, dont know how to get embeddable link from google drive files.
https://drive.google.com/file/d/0BzJbWV ... sp=sharing
Re: Honda Power Unit
Posted: 16 Sep 2015, 07:49
by Abarth
Very interesting, thanks.
I don't even know how to extract frames from a video, go figure....
Are there more frames of this telemetry? I remember an older video, but this seems much better readable.
Re: Honda Power Unit
Posted: 16 Sep 2015, 08:28
by FW17
Someone previously wanted to know the exhaust pressure
Intake pressure 1.24 bar
Exhaust pressure L 1.16 bar
Exhaust pressure R 1.19 bar
Oil temp - 79 deg
water temp - 95 deg
Looks like fuel is heated to about 70deg c, would have expected it to be at ambient temp.