2014-2020 Formula One 1.6l V6 turbo engine formula

[Abarth]

Thinking about it, they could even fire opposite cylinders at the same angle and having in fact an engine with 240 deg firing intervals, which would lead to the lower pitched sound......

[matt21]

4. The crankshaft mercedes is showing seems to have 4 journals but is in fact 6 throw, IF this video is correct. Opposite cylinders should be spaced 30 deg to achieve even firing intervals, in the video it seems to be 90 deg, which would lead to both opposite pistons reach TDC at the same crank angle. That would also lead to even intervals. Interesting! Maybe this would give some advantages in free mass forces and moments...?

If you number cylinders like this (1 = 1st cylinder left bank)
1 4
2 5
3 6
and assume a firing order 1-5-3-6-2-4 you get intervals of 120 degree.

For your solution you have to fire 1&4-3&6-2&5 which would give a big-bang engine.

The screamer gives more outright power but the big-bang is in general easier on the tires.
In MotoGP this was done to give the driver better control during drifts as you have dulls in power delivery.

But IMO they can change the firing order (screamer/big-bang) during the race or is there anything in the rules forbidding this?

[Abarth]

[...]
But IMO they can change the firing order (screamer/big-bang) during the race or is there anything in the rules forbidding this?

This will not be possible as you have to change the camshaft angle 180deg of one cylinder bank, which is not allowed.

Interesting information about the reason for the "big bang" solution in motorcycles though, thanks.

[matt21]

I had something wrong in my firing-order. It should be 1-6-3-5-2-4 for the screamer. then you can have a big bang, if you have following crankshaft.

[CBeck113]

If the video is true, then they have 3 pairs of cylinders at 90°, each pair 180° apart from each other...even if they were running a 3-cylinder firing order (or big bang or whatever), that still wouldn't be balanced at all, unless they were running the big bang on 1&4 and 3&6, while 2 and 5 fire singluarly. But what would that bring?

[matt21]

If the video is true, then they have 3 pairs of cylinders at 90°, each pair 180° apart from each other...even if they were running a 3-cylinder firing order (or big bang or whatever), that still wouldn't be balanced at all, unless they were running the big bang on 1&4 and 3&6, while 2 and 5 fire singluarly. But what would that bring?

The pairs 1/4, 3/6 and 2/5 are 240° from each other , in that order. Please refer to the diagram above.
this would give a perfect 3 cylinder firing order.

[Abarth]

Holm already pointed this out...Regulation:

5.1.10 The crankshaft may only have three connecting rod bearing journals.

As far as I can imagine, it's not possible what we were talking about....

[321apex]

Each bank of cylinders will see firings (of their neighbors) at 240 deg intervals, with a shared pin crank, regardless of the bank angle. For that purpose then, it is key to consider each bank as if it was a separate engine.

With inlet plenum being large, the engineers may choose to cause a tuning effect between any 3 trumpets of each bank by designing their placement as an adjacent set. I am not saying that they will, but that they may do so. Same will happen to the other bank's trumpets.
On the exhaust side, each cylinder bank header will see 240deg pulses and for it's tuning aspects this will be even, which is good.

So overall, the engine can be designed to maximize volumetric efficiency without negative effects of less than optimum bank angle for shared pin crank.

The caveat lies with the torsionals of the engine, specifically the crank having to absorb these uneven firings of 90/150/90/150. I am not worried about the durability of the crank, but the effect of uneven "shocks" being passed on thru to all other rotating components, especially cam drive and ancillaries. Torsional damping of sorts will definitely have to be adopted to make the cam drive live as well as to minimize internal friction. Since the V6 will have 40-50% higher BMEP, the pulses will be that much stronger compared to 90 deg even firing V8.

Racing engines by their nature can not use rubber/mass damping devices that waste energy such as street engines. Instead for years there have been spring type devices used to attenuate torsional vibrations. Early on, Cosworth adopted a solution called the "quill", which they've used for years. Other racing engine companies used similar principle in their solutions. You may read about it here on p.4 , and see it in graphic form on page 15:
http://www.google.pl/url?sa=t&rct=j&q=& ... 8935,d.ZG4

In closing, I will share a thought that perhaps Renault underestimated the torsional effects at the interface of crankshaft and MGU-K where at least initially during Jerez test they were having durability problems.

[Tommy Cookers]

the bmep will be at least 100% higher than eg 2013 F1

AFAIK ......
the torsional moments from reciprocation inertial loads are higher than those from firing (in NA engines at peak power rpm)
granted the 2014 engines have much higher torsional moments from firing than we have known since 1988
the cam drive has a whole mess of loads of its own anyway

there will always be a crankshaft (torsional) damper
the crankshaft system will be designed for high stiffness to produce a high enough torsional natural frequency ....
such that the damping required (to keep stresses down) is fairly light, not enough to produce excessive heat and/or other risk
all race engines cranks have natural frequencies safely higher than needed for peak rpm
though F1 has used ring flutter (radial) natural frequencies within the normal rpm range (ask Mr Brundle or Peugeot)

in the above respects 2014 should be a walk in the park
let's remember that Honda won with a more uneven-firing 80 deg engine at very high bmep
and Ferrari won with 65 deg NA engines up to 2.8 litres

[321apex]

the torsional moments from reciprocation inertial loads are higher than those from firing (in NA engines at peak power rpm)

If the above were to be true, then an engine would not produce any net power.

[Tommy Cookers]

the time-averaged sum of the inertial moments is zero
the time averaged sum of the gas moments is very non-zero
that's how the piston engine works

and the crankshaft will break from excessive torsional stress if the rpm is high enough
(ie when tested externally driven with no engine firing)

[langwadt]

the time-averaged sum of the inertial moments is zero
the time averaged sum of the gas moments is very non-zero
that's how the piston engine works

and the crankshaft will break from excessive torsional stress if the rpm is high enough
(ie when tested externally driven with no engine firing)

http://youtu.be/Myfp2sUducE?t=3m33s

[321apex]

....

You seem to be trapped in the 1st order, while I was referring to the harmonic torsional vibration which is primarily generated by the firing pulses and may exist from 1st all the way to 10th order of reasonably significant magnitude.

[Tommy Cookers]

there are of course harmonics of several orders in the inertial torques (due to complex geometry and mass distribution)
they are of course calculable
the effects of harmonics from whichever source never seem to be a problem to the crankshaft in real-world cases
ie when the design and damping have made the primary response safe the harmonic responses always seem to be safe

and remember that the (primary) inertia torque frequency is at twice the (primary) firing torque frequency (in a 4 stroke)
so will be much closer to the system's natural frequency and thereby dominate the system damping needs (over the firing torques)

the Yamaha footage usefully posted by langewadt shows that inertia torque is the biggest factor (in an NA SI engine)
of course it might not be in eg a heavily boosted and slow-running marine CI engine

in 2014 near-simultaneous firing would lower the firing (primary) frequency (though increasing the 'forced response' firing stress)
(compared to the near-even firing that we expect of the 90 deg 3 crankpin rules)
it might be worth considering eg if we expected this to benefit the turbine

some thought true simultaneous firing was the answer to 'big bang' Yamaha mystery when it appeared about 10 years ago
if firing torques were dominant in NA race crankshaft design it would have allowed a crank with less bearing friction (less bearings?)
Yam knew inertia torques were dominant, so went cross-plane, giving a slimmer diameter and so less bearing friction etc
handy in a fuel-limited class

[ppj13]

Er, if we believe the video of the mercedes engine, it will not be a big bang, but a "huge bang" firing order.

It's 5, 1 & 3 & 4 & 6, 2.

Like: bang, BANG, bang...................bang, BANG, bang.....................

in terms of explosions every 120 deg: 1, 4, 1, 0, 0, 0. (regular split pin 90deg V6 (renault) models being 1, 1, 1, 1, 1, 1).

Kind of making a mono-cyl but with a pre and post work stroke to make the life of the drivetrain slightly easier.

In the front and rear piston pairs, right bank is "advanced" 90deg, but in the middle pair the right bank is "retarded" 90º.

It seems insane to me. But I have to say the exhaust of that engine does sound insane.

It could be a joke of the PR department. It could be interesting to make the math about balancing this thing.

It all depends if you believe the thing that big bangs improve traction (without much costs if both intake and exhaust manifolds are free, aka no restrictors).

Edit: it's even more huge banger than I state, as pre and post work strokes are separated 90deg, not 120. All pins are at -90, 0 and 90.