How do they define 'ambient' temp?
Is it based on the track tower weather station data,
the air measured at engine level above the track,
or air at/in the engine ram intake?
That could be a problem, where 2 hours before a race may be hot but by race time a cool front has passed through and the air temperature dropped by a long way....
it would mean fia wants best effort. they want air not to be cooled too much(some ice or nitrogen) or mostly. they will have data for all teams so will be able to compare.
I think this was discussed at some point in the past ~30000 posts, but I'll put it out there again:
Would there be any possible benefits to running only 4 cylinders? Would it even be legal?
I m thinking along the lines that a 4 cyl engine is often more efficient than a 6 cyl engine, so maybe a 4 cyl engine with 1.067 L effective capacity might have some merit to it, but this is sooooo far from my zone of comfort!
In particular I am thinking of benefits from having 2 "fake cylinders", which do not need the same space, structural integrity and cooling as the others, or maybe of running only 4 of the 6 cylinders at any time, but cycling so that each cylinder only fires in 2 of each 3 opportunities, with the third one left mostly for cooling/venting purposes.
This might even interact with some rumors of engines purposely revving much higher than 12000 rpm (or trying to).
Last edited by hollus on 07 May 2017, 00:31, edited 1 time in total.
TJI prechamber scavenging sometimes they aren't sufficiently scavenged due to various reasons, turbulent flows during cylinder scavenging etc.
The MGU-k can assist torque until it is scavenged fully, with all jet ignition engines being hybrids except during development of the concept.
The intake turbulent flow is likely important to effective scavenging of prechamber. The pressure at the jet ports in the prechamber to draw out or flow through the prechamber to effect scavenging.
The main and prechamber need to be separate and communicate through the jet ports with enough isolation so the prechamber functions correctly maybe they use a mini rotary valve in the F1 Implementation, after all both Mercedes and Mahle Jet ignitions inventor had direct involvement with it. So a single injector can work for both main and prechamber.
I think this was discussed at some point in the past ~30000 posts, but I'll put it out there again:
Would there be any possible benefits to running only 4 cylinders? Would it even be legal?
I m thinking along the lines that a 4 cyl engine is often more efficient than a 6 cyl engine, so maybe a 4 cyl engine with 1.067 L effective capacity might have some merit to it, but this is sooooo far from my zone of comfort!
In particular I am thinking of benefits from having 2 "fake cylinders", which do not need the same space, structural integrity and cooling as the others, or maybe of running only 4 of the 6 cylinders at any time, but cycling so that each cylinder only fires in 2 of each 3 opportunities, with the third one left mostly for cooling/venting purposes.
This might even interact with some rumors of engines purposely revving much higher than 12000 rpm (or trying to).
I think you'll find that the chaotic consequences of running ganged cylinder groupings in staggered firing sequences,
has proven far more problematic in practise for some (Honda) than was predicted by results from single-cyl test units..
..despite 'simulation modelling' suggesting that its systems - ought to also function well, en bloc..
"Well, we knocked the bastard off!"
Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).
I think this was discussed at some point in the past ~30000 posts, but I'll put it out there again:
Would there be any possible benefits to running only 4 cylinders? Would it even be legal?
I m thinking along the lines that a 4 cyl engine is often more efficient than a 6 cyl engine, so maybe a 4 cyl engine with 1.067 L effective capacity might have some merit to it, but this is sooooo far from my zone of comfort!
In particular I am thinking of benefits from having 2 "fake cylinders", which do not need the same space, structural integrity and cooling as the others, or maybe of running only 4 of the 6 cylinders at any time, but cycling so that each cylinder only fires in 2 of each 3 opportunities, with the third one left mostly for cooling/venting purposes.
This might even interact with some rumors of engines purposely revving much higher than 12000 rpm (or trying to).
Let's look at it another way. What if the formula was 100 kg/hr max fuel flow etc but no stipulation of engine displacement - only the displacement per cylinder. Would 6 cylinders (ie 1.6 litres) be the magic number? I doubt it. In fact your 4 cyl, 1.067 L is probably a lot closer to the money. Less friction, less combustion surface area (heat loss). Whether it could be done (fully implemented I mean, with only 4 pistons moving) without infringing the rules I doubt very much.
As far as cycling cylinders, they almost certainly do that already - for part load operation. Which begs the question - why not do it at full load if it increased efficiency? The friction benefit would not be there but any combustion benefit?? would.
Thanks, GG.
So what about having a fully functional V6 to satisfy the rules but never injecting any fuel into two of the cylinders? Could be the central ones, or the outside ones is the cylinders are offset somehow.
Hmm, what about never injecting in 3 of the cylinders? The engine would end up being similar to that in my VW Up
Thanks, GG.
So what about having a fully functional V6 to satisfy the rules but never injecting any fuel into two of the cylinders? Could be the central ones, or the outside ones is the cylinders are offset somehow.
Hmm, what about never injecting in 3 of the cylinders? The engine would end up being similar to that in my VW Up
Wouldn't you then be wasting quite a lot of energy lugging those pistons and valves around as well as compressing the volume that will never produce any useful work?
Yes. Less so if the exhaust outlets can legally be closed. The idea (likely wrong) is that the efficiency gains in the fired cylinders could be larger that the parasitic losses from the "inert" cylynders.
Possible saves in weight and size from cylynders that do not support combustion are hopefully obvious.
Yes. Less so if the exhaust outlets can legally be closed. The idea (likely wrong) is that the efficiency gains in the fired cylinders could be larger that the parasitic losses from the "inert" cylynders.
Possible saves in weight and size from cylynders that do not support combustion are hopefully obvious.
There would be very minimal weight saving from pistons at least as they have a specified minimum weight, also the bore and stroke are specified by regulation too so cylinder size will be about the same for active and inactive ones. I think weight saving would be minimal.
I think the cylinder has to be valved and the valves have to function the same for all cylinders, so there would be compression and exhaust regardless of firing or not. That latter part I am not too sure on though. Maybe they could just have these dead weights floating up and down with no resistance but for friction.
[...]As far as cycling cylinders, they almost certainly do that already - for part load operation. Which begs the question - why not do it at full load if it increased efficiency? The friction benefit would not be there but any combustion benefit?? would.
And if they would cycle it, the impact on durability could be mitigated...since the single cylinder load per combustion event would go up 50% (from 16.67 kg/h x cyl to 25 kg/h x cyl)
5.1.11 An insert within a PU component is a minimal, non-dismountable part whose function is solely
to locally support a function of this component. The total volume of inserts within the
component cannot be more than 10% of the total volume of the component.
Is this an indirect way of saying the pre-chamber can only comprise 10% of the combustion chamber volume?
For reference this is in the latest 2018 technical regulations.
Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).
The second patent you posted suffers from the same needs posted in the Honda engine thread. Particularly in the unwanted EGR in the pre-chamber. Perhaps that is a big challenge with 1 injector and 1 spark plug. And if you are suffering excessive EGR in the pre-chamber from a poor design then one would be forced to run rich in order to compensate for the combustion instability this would cause.
Maybe the upgrades to the intake and fuel systems were made to combat this excessive pre-chamber EGR. Makes sense if the big engine change Honda is planning revolves around a new head and pistons.
The second patent you posted suffers from the same needs posted in the Honda engine thread. Particularly in the unwanted EGR in the pre-chamber. Perhaps that is a big challenge with 1 injector and 1 spark plug. And if you are suffering excessive EGR in the pre-chamber from a poor design then one would be forced to run rich in order to compensate for the combustion instability this would cause.
Maybe the upgrades to the intake and fuel systems were made to combat this excessive pre-chamber EGR. Makes sense if the big engine change Honda is planning revolves around a new head and pistons.
I actually think that they want the EGR and that that could be one of the upsides to running a pre-chamber.
This is true a certain amount of EGR is good because it retains some heat and allows gas to vaporize improving combustion, at the same time, too much leads to fuel dilution which makes combustion unstable. Finding the Goldilocks amount of EGR can't be easy, considering you are not placing an injector in the prechamber makes it even more difficult. So you either have to improve the CC design and supporting hardware or you're forced to run band aid fixes.
Then you have to consider the possibility that new information learned during your band aid fixes can improve your design in the coming upgrade. It's definitely a tricky situation, you never know when newly aquired knowledge can give back life to an old concept that was perceived as a dead end, or turn the concept you're working on into one.
