2014-2020 Formula One 1.6l V6 turbo engine formula

[tuj]

As far as heat and idling, at least several years ago with the V8's, AFAIK, they were running selective cylinder ignition and injection cut when under long idle conditions. This effectively made the engines 4-cylinder machines temporarily. This is the only way I can think of to get around the variable cam ban to significantly alter the engine's properties of cooling.

[godlameroso]

https://youtu.be/A6bqiVbbvec?t=49m3s

Found this interesting it's a lecture on modeling combustion this part is about the chemical process in combustion. The way fuel chemically reacts during the combustion process.

Just in case:
Species being molecules involved in the chemical combustion proces.

[Tommy Cookers]

.........I cant see any reason for F1 to use "forced" EGR when detonation is such a threat to the engine.

well fwiw I (still after 4 years) suspect that some 'internal EGR' ie underscavenge is developed at high rpm
because it is the least bad way of running the PU at rpm substantially over the 10500 where the fuel rate cap starts
and all these research and production lean-running engines seem to use at least 0.5 bar backpressure

underscavenge is available at any rpm if the exhaust backpressure is suitably raised by management of the MGU-H load
we know the engines are running at as lean an AFR as possible (ie as combustion efficiency allows) at 10500 or slightly more rpm
ie maintaining boost above this rpm zone increases AFR and so degrades combustion efficiency
(though there's a minor gain in turbine recovery due to combustion post-cylinder)
we can keep constant massflow and this AFR by lowering boost and exhaust pressure but this reduces turbine recovery

but (in this rpm zone) maintaining the boost and raising the exhaust backpressure is the win-win policy
(well insofar as there is running time at rpm substantially over 10500 - this is maybe less than it was in earlier seasons ?)
win-win because the recovery is increased and so at least compensates for the loss in crankshaft power with raised backpressure
at least compensates as pressure energy post EVO is better conserved by higher exhaust pressure reducing velocity and supersonic (pressure) losses
since increased generating load tends to lower turbo rpm this may somewhat reduce boost and help contain in-cylinder temperature

anyway, such 'creative' designed-in underscavenge seems to be rather inescapable

[Brian Coat]

If, at higher RPM, we have same AFR as lean limit @10,500 plus more internal EGR, as I think you are suggested, don't we have more total dilution and higher probability of abnormal combustion?

Edit: abnornal combustion ilo misfire

[godlameroso]

If you look at the youtube link I posted, the lecturer actually goes into it and shows that air dilution is actually a viable lean burn strategy.



And that unburned gasses help combustion in that they retain heat and help the fresh fuel charge to vaporize in the chamber prior to ignition.

[Tommy Cookers]

If, at higher RPM, we have same AFR as lean limit @10,500 plus more internal EGR, as I think you are suggested, don't we have more total dilution and higher misfire probability?

conceptually ......
we have the same oxygen:fuel ratio (as that at lean-limit AFR) but higher inert gas:fuel ratio ie yes we have more 'total dilution'
but the temperature will be higher late in the combustion process and this should assist combustion to completion
(remember, suitable temperature management of charge air would also allow leaner running)

ok as I say there will likely be some fall of boost, even some fall of AFR (with raising backpressure at rpm where fuel rate flattening is implemented)
but less falling and more recovery than would be without raising backpressure
otherwise what else do people believe is done ?

heat dilution by our raised AFR lowers mean in-cylinder and exhaust temperature and so reduces energy lost to coolant and to atmosphere
adding further inert gas mass by backpressure underscavenge as above has similar (or greater ?) benefits
btw one 1940s NACA source noted that backpressure to an extent producing underscavenge did not affect the exhaust valves and benefited efficiency

[Brian Coat]

TC Re: Para 1 of your last post

This is not the effect I would expect to see when raising the internal EGR% on an engine already running at lean limited full load.

Any combustion-enhancing temperature effects will not compensate for the fact that the charge will be over-diluted, will they?

[PlatinumZealot]

All i know about turbo engines is that backpressure is bad at high rpms because it leads to knocking.
I have a hunch that there is no un burnt fuel in this efficiency formula. Haven't seen any black smoke out the tailpipes like in the eighties.

my basic mind is thinking you want to get the heat out of the cylinder out to the turbo. Not like street cars where we need egr (even interna) for emmisions and as a bandaid to help combustion. I jus't can't see it with these high AFR'..

Even in street car tuning.. When you retard the exhaust cam to open later u need reaaaly good headears or u will lose power. (too much gas left back in the chamber)..

Just can't see it.

[godlameroso]

All i know about turbo engines is that backpressure is bad at high rpms because it leads to knocking.
I have a hunch that there is no un burnt fuel in this efficiency formula. Haven't seen any black smoke out the tailpipes like in the eighties.

my basic mind is thinking you want to get the heat out of the cylinder out to the turbo. Not like street cars where we need egr (even interna) for emmisions and as a bandaid to help combustion. I jus't can't see it with these high AFR'..

Even in street car tuning.. When you retard the exhaust cam to open later u need reaaaly good headears or u will lose power. (too much gas left back in the chamber)..

Just can't see it.

The difference between these engines and street engines is the level of control. Exactly all street engines have zero MGU-H's attached to their turbos. A little squirt of motor mode here, a little wastegate action there, and suddenly what backpressure? With the MGU-H you can create conditions for only the amount of backpressure you need. Depending on the need, along with the MGU-K you'll increase the backpressure, for either harvesting, or for efficiency's sake, at some other points in the rev range you can reduce the backpressure, for better response or top speed or anywhere in between.

I think they use some fancy A.I. program to work out when to do all this to exploit it over a lap.

[gruntguru]

I don't see much benefit in EGR and I agree with PZ that detonation due to residual exhaust is likely to be the dominant effect. Detonation limits CR and PR which are primary drivers of TE (Power).

That is not to say that EAP cannot be higher than MAP. Wave tuning (especially with variable intake) can ensure a positive differential during overlap which is the ultimate determinant of passive EGR.

[mrluke]

All i know about turbo engines is that backpressure is bad at high rpms because it leads to knocking.
I have a hunch that there is no un burnt fuel in this efficiency formula. Haven't seen any black smoke out the tailpipes like in the eighties.

my basic mind is thinking you want to get the heat out of the cylinder out to the turbo. Not like street cars where we need egr (even interna) for emmisions and as a bandaid to help combustion. I jus't can't see it with these high AFR'..

Even in street car tuning.. When you retard the exhaust cam to open later u need reaaaly good headears or u will lose power. (too much gas left back in the chamber)..

Just can't see it.

You always have back pressure in a turbo engine. The turbo is pretty restrictive.

There is a trade off between energy recovered by the turbo and the impact of back pressure on the cylinder combustion. You will get to a point where back pressure is too high and is becoming detrimental but you wont ever have a point of zero back pressure.

As with all things it is a compromise and a balance.

[roon]

An addition I noticed to the formula for 2017:

5.3.6 No cylinder of the engine may have a geometric compression ratio higher than 18.0.

Presumably there is a concern about development moving toward ever higher peak cylinder pressures.

Upon reading this I noticed that the FIA defines engine displacement as the swept volume—the motion of the piston within the six equally-sized pistons, with a spec bore. Stroke & bore are thus specified: 53 mm x 80 mm.

By this definition, the combustion chamber is not volume regulated. Conceivably one could create a variable displacement device within their combustion chamber. Perhaps a plunger of some sort can be integrated into the combustion chamber, or within the pre-chamber of a TJI unit. I've illustrated the latter, below. Could such a function help facilitate different combustion modes? Dieseling? Or provide a detonation/knocking relief function. Upon knock detection, compression ratio could be reduced. Thoughts?

[roon]

Another thing I was curious about, since crankshafts came up in the Honda thread. These rules were added for 2017:

5.3.4 The crankshaft main bearing journal diameter (measured on the crankshaft) must not be less
than 43.95 mm.
5.3.5 The crankshaft crank pin bearing journal diameter (measured on the crankshaft) must not be less than 37.95mm.

Was this about limiting costs associated with developing thinner cranks? Or might something else have inspired this?

[godlameroso]

They "TPTB" didn't want a spending arms race to make lighter con rods, thinner journals, or making the crank too light. This is why I suggested a very simple but challenging way to shorten the crank is to use fewer main bearing journals on the crank. Each one you omit shortens the block by at least 43.95mm.

Meanwhile the money involved in getting something like that to work laughs in their face at their attempts to control spending.

[roon]

But again, block length is bore limited. Removing main bearings wouldn't necessarily alter bore spacing. I think the simplest solution for a (slightly) shorter block & crank remains coplanar cylinders with fork-and-blade conrods.