Very nice link, tnk u!henry wrote: ↑14 Nov 2018, 11:47Here’s a presentation by Mahle on a project they did for the US government.https://www.energy.gov/sites/prod/files ... 2015_o.pdf
It discusses low speed, 2500 rpm operation. It, I think, gives some insight, but not definitive answers, into some of the discussion points on TJI.
On injection it says the injection event into the pre-chamber is >60° BTDC.
On ignition it says the prechamber ignites and then there is a delay before the jets are formed and the main chamber ignites. So essentially we have 2 ignition events to discuss. The first graph shows these at 25° and 9° BTDC respectively. I’ll leave those more knowledgeable to comment on whether this is early or late in comparison with normal spark ignition.
Fuel suppliers bring fuel upgrades throughout the season.saviour stivala wrote: ↑14 Nov 2018, 10:54Different fuels formulation use between races I believe are not permitted by the rules nowadays.
road fuel being 1.5% worse on laptime might suggest that (presumably the 'worst' version) NA F1 fuel wasn't slow burningsaviour stivala wrote: ↑14 Nov 2018, 10:54.... In the NA 2.4L V8 era both fast burn and slow burn fuel was being formulated and used according to circuit specifics needs, .....mentioning a particular test comparison and it’s results between F1 formulated fuel and that formulated for normal road car use of which both are as per FIA fuel formulation... FERRARI F1 F60 with its tipo 056 2.4L NA V8 Driven by Alonso at Fiorano. 4 laps ran using FI fuel resulted in a best lap time of 1:03.950. 4 laps ran using Shell normal road pump fuel resulted in a best lap time 9/10ths slower but the road pump fuel produced a faster top speed.......
if interested in that fuel comparison test try trace and viste "how close is F1 fuel to road car fuel//F1 news//james allen on F1" also "shell v-power race fuel vs shell v-power road fuel" at that time the test was also futured no "BBC-Jake Hmphery shell v-power fuel test".Tommy Cookers wrote: ↑14 Nov 2018, 13:40road fuel being 1.5% worse on laptime might suggest that (presumably the 'worst' version) NA F1 fuel wasn't slow burningsaviour stivala wrote: ↑14 Nov 2018, 10:54.... In the NA 2.4L V8 era both fast burn and slow burn fuel was being formulated and used according to circuit specifics needs, .....mentioning a particular test comparison and it’s results between F1 formulated fuel and that formulated for normal road car use of which both are as per FIA fuel formulation... FERRARI F1 F60 with its tipo 056 2.4L NA V8 Driven by Alonso at Fiorano. 4 laps ran using FI fuel resulted in a best lap time of 1:03.950. 4 laps ran using Shell normal road pump fuel resulted in a best lap time 9/10ths slower but the road pump fuel produced a faster top speed.......
and the road fuel was an expensive version intended for sporty cars so might have been faster burning than the usual road fuel
despite the usual assumption that the higher the ON the slower the combustion
current F1 fuel has presumably the highest possible mass-specific heat content and ON regardless of other properties
Slower combustion is not really an option. How the TJI makes up for "completeness" by utilizing multiple jets travelling radially outwards like a star shape to emmulate a near homogenous combustion. It's a pretty neat trick.saviour stivala wrote: ↑13 Nov 2018, 13:40The resultant fast flame speed when TJI combustion system is used that reduces the need for much ignition advance is the result of the main combustion chamber contents being ignited by a fast flame that is the result of an already combusted small content by a spark plug inside a pre-chamber. But talking about such technical matters regarding high speed operation of a F1 engine the following should be born in mind. A faster combustion (time wise) is not necessary a stronger and more complete combustion than a slower combustion, again (time wise). The present 1.6L T V6 ICE spending most of its racing life at a max power speed of 10500RPM fires all 6 cylinders 5250 times in one minute. The previous 2.4L NA V8 spending most of its racing life at a max power speed of 17500RPM used to fire all 8 cylinders 8750 time in one minute, at that time teams were using both fast burn formulated fuel as well as slow burn, depending on circuit specifics. In both cases (both types of ICE) the ignition advance used is solely aimed to move the maximum combustion pressure point to 14 degrees ATDC power stroke.
Agree that the Mahle TJI produces a near homogenous main (2nd) combustion by utilizing multiple flame jets produced by the 1st combustion which is started in a pre-chamber by means of a spark plug.PlatinumZealot wrote: ↑16 Nov 2018, 17:16Slower combustion is not really an option. How the TJI makes up for "completeness" by utilizing multiple jets travelling radially outwards like a star shape to emmulate a near homogenous combustion. It's a pretty neat trick.saviour stivala wrote: ↑13 Nov 2018, 13:40The resultant fast flame speed when TJI combustion system is used that reduces the need for much ignition advance is the result of the main combustion chamber contents being ignited by a fast flame that is the result of an already combusted small content by a spark plug inside a pre-chamber. But talking about such technical matters regarding high speed operation of a F1 engine the following should be born in mind. A faster combustion (time wise) is not necessary a stronger and more complete combustion than a slower combustion, again (time wise). The present 1.6L T V6 ICE spending most of its racing life at a max power speed of 10500RPM fires all 6 cylinders 5250 times in one minute. The previous 2.4L NA V8 spending most of its racing life at a max power speed of 17500RPM used to fire all 8 cylinders 8750 time in one minute, at that time teams were using both fast burn formulated fuel as well as slow burn, depending on circuit specifics. In both cases (both types of ICE) the ignition advance used is solely aimed to move the maximum combustion pressure point to 14 degrees ATDC power stroke.
This is injection. When is the ignition?saviour stivala wrote: ↑14 Nov 2018, 12:52The Mahle project presentation done for US Government was actually the one that convinced me that their TJI combustion system was not compatible with the needs of an engine that spends most of its working life rotating at a maximum power speed of 10500 RPM. That is apart from my opinion that it is also not compatible with FIA direct injection rules. But on the other hand it had nothing to do with my believed technical opinion that:- fuel in this here DISI ICE is injected at least 60 degrees BTDC. That maximum combustion pressure (PPP-peak pressure position) is at optimum when reached at 14 degrees ATDC (and an note here, this PPP most benefic position point goes for most engines I know off and have been around.
A post explaining all about ‘PPP’ has been posted a while back but still have to pop-up.
The Mahle TJI two ignitions are shown to be at 25 degrees and 9 degrees BTDC, but as is the case with any ignition these numbers are floating in accordance with among others, engine speed and engine load so move the PPP point to as near as could be to 14 degrees ATDC. as toringo wrote: ↑17 Nov 2018, 06:16This is injection. When is the ignition?saviour stivala wrote: ↑14 Nov 2018, 12:52The Mahle project presentation done for US Government was actually the one that convinced me that their TJI combustion system was not compatible with the needs of an engine that spends most of its working life rotating at a maximum power speed of 10500 RPM. That is apart from my opinion that it is also not compatible with FIA direct injection rules. But on the other hand it had nothing to do with my believed technical opinion that:- fuel in this here DISI ICE is injected at least 60 degrees BTDC. That maximum combustion pressure (PPP-peak pressure position) is at optimum when reached at 14 degrees ATDC (and an note here, this PPP most benefic position point goes for most engines I know off and have been around.
A post explaining all about ‘PPP’ has been posted a while back but still have to pop-up.
Hi, Why is that?saviour stivala wrote: ↑17 Nov 2018, 18:59This DI-GDI injection system lost the freedom of when to inject fuel