So do I understand this correctly? For next years engine they'll be using the fuel heater and trick-injectors
to inject fluid at a super critical state (more homogeneous), and then use TJI for combustion (later/faster/more complete)?
Honda were one of the originators of heated fuel in F1 with the RA168e. I would be surprised if they are behind other teams on this.ncassi22 wrote:So do I understand this correctly? For next years engine they'll be using the fuel heater and trick-injectors
to inject fluid at a super critical state (more homogeneous), and then use TJI for combustion (later/faster/more complete)?
It just seems that is what the Honda guys have to do it to be competitive. They apparently can't make max of power at the same rpm, maybe because their compromised compressor can't quite match max boost pressures.nokivasara wrote:I tried to find an answer to this but didn't so maybe you guys can help me out:
Why does the Honda rev higher than the others, I thought the sweet spot was around 10500-11000 RPM or thereabouts, but on the on-board footage of the McLaren they rev much higher. More than 12k Rpm.
Why is that?
That is not the reason. They can not yet reach the elevated compression rate of mercedes. This means they have not the same quantity of air injected per cycle. In order to condact the right amount of air flow to the turbo generator the only solution is to compensate by incrementinc the rpm. Very simple. The problem is that at higher rpm the efficiency drops a little because of more energy wasted by friction and engine heat exchange. Next year they will inprove tji combustion or other tricks with the aim to increase compression ratio. This way not only peak pressure is higher but more important you increment air flow to exhausts hence tueboPierce89 wrote:It just seems that is what the Honda guys have to do it to be competitive. They apparently can't make max of power at the same rpm, maybe because their compromised compressor can't quite match max boost pressures.nokivasara wrote:I tried to find an answer to this but didn't so maybe you guys can help me out:
Why does the Honda rev higher than the others, I thought the sweet spot was around 10500-11000 RPM or thereabouts, but on the on-board footage of the McLaren they rev much higher. More than 12k Rpm.
Why is that?
Thanks, I know a thing or 2 about tuning diesel engines but haven't really paid any attention on the development on the SI engines. Internet is a wonderful source for information but there's so much of it that sometimes it's hard to find anything useful...Pany wrote:That is not the reason. They can not yet reach the elevated compression rate of mercedes. This means they have not the same quantity of air injected per cycle. In order to condact the right amount of air flow to the turbo generator the only solution is to compensate by incrementinc the rpm. Very simple. The problem is that at higher rpm the efficiency drops a little because of more energy wasted by friction and engine heat exchange. Next year they will inprove tji combustion or other tricks with the aim to increase compression ratio. This way not only peak pressure is higher but more important you increment air flow to exhausts hence tueboPierce89 wrote:It just seems that is what the Honda guys have to do it to be competitive. They apparently can't make max of power at the same rpm, maybe because their compromised compressor can't quite match max boost pressures.nokivasara wrote:I tried to find an answer to this but didn't so maybe you guys can help me out:
Why does the Honda rev higher than the others, I thought the sweet spot was around 10500-11000 RPM or thereabouts, but on the on-board footage of the McLaren they rev much higher. More than 12k Rpm.
Why is that?
You aren't going far enough back in the day. Before fuel cooling there was fuel heating. The specific example GG mentioned can be found here:BrunoH wrote:http://www.f1technical.net/forum/viewto ... ?f=4&t=445
back in the day they were doing the opposite in F1.. they were cooling the fuel for extra performance... hence the ban...
gruntguru wrote:Honda were one of the originators of heated fuel in F1 with the RA168e. I would be surprised if they are behind other teams on this.ncassi22 wrote:So do I understand this correctly? For next years engine they'll be using the fuel heater and trick-injectors
to inject fluid at a super critical state (more homogeneous), and then use TJI for combustion (later/faster/more complete)?
Temperature back then was 80*C IIRC - that is a long way from super critical. I would be worried about spontaneous ignition if you injected super critical fuel.
Ah yes thankyou for the response. I was mulling this over. I read a few articles (some focusing on gasoline as well as two stroke diesels) and it seems those are the two ways in which utilizing this phenomena can be leveraged for improved efficiency - 1 - creating a super critical environment into which fuel is injected and 2 - injecting the fuel in a super critical state to improve the homogenatiy of the mixture itself (reducing pre-ignition and allowing for later firing.)godlameroso wrote:gruntguru wrote:Honda were one of the originators of heated fuel in F1 with the RA168e. I would be surprised if they are behind other teams on this.ncassi22 wrote:So do I understand this correctly? For next years engine they'll be using the fuel heater and trick-injectors
to inject fluid at a super critical state (more homogeneous), and then use TJI for combustion (later/faster/more complete)?
Temperature back then was 80*C IIRC - that is a long way from super critical. I would be worried about spontaneous ignition if you injected super critical fuel.
The pressure and temperature needed for gasoline is ~260 C and anywhere between 60-40 bar depending on fuel chemistry and a host of other factors. Both conditions can be easily reached in the combustion chamber, and fuel supply system. There are plenty of sources of heat to get the required temperature, for example the MGU-H itself runs quite hot. I suppose the devil is in the details and perhaps full on supercritical spraying isn't what's required but rather pre-conditioning the fuel so that when conditions inside the combustion chamber are correct, the desired state manifests itself.
Now there are a number of different ways to do this, not just heating and pressure, but in the fuel chemistry, and exploiting it via other means like partial electrolysis of the fuel prior to delivery to break down a certain percentage of long chain molecules. Or to promote oxygenation. There's no one magic bullet but rather the trick is in creating the eco-system that allows the fastest leanest burn with the highest exhaust density.
*Edit:
Perhaps all the other conditions exist so that the high boost pressures are the final catalyst that drives the fuel to such a state.