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October 9th 2006
Firing Order on a Formula 1 V10
Pierre-Jean Tardy
Brief presentation of our 2005 World Brief presentation of our 2005 World Champion F1 Engine Champion F1 Engine
V10
3 liters displacement
Naturally aspirated
4 valves per cylinder
Variable trumpets
Max Speed : 19250 RPM
Max power : ~900 hp
Weight : ~107 kg
Engine PerformanceEngine PerformanceA good engine has to help get good lap times : peak power is not sufficient, therefore we created a lap time performance index.
Lap Time - Effect of power curve shape
707274767880828486889092949698
100102104
14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500
Engine speed (rpm)
Engi
ne P
ower
(%)
Engine # 1
Lap Time - Effect of power curve shape
707274767880828486889092949698
100102104
14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500
Engine speed (rpm)
Engi
ne P
ower
(%)
Engine # 1
Engine # 3
Lap Time - Effect of power curve shape
707274767880828486889092949698
100102104
14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500
Engine speed (rpm)
Engi
ne P
ower
(%)
Engine # 1
Engine # 2
Engine # 3
Same peak power, but 0.45’’ gap on Barcelona track
Same lap time, but gap of 27 hp
Role of firing orderRole of firing orderParameters of firing sequence :
•Crankshaft design ( sequence between each cylinder on 1 bank)
•Ve angle ( sequence between 2 cylinders on 1 Ve)
•Camshaft design ( choice between firing or scavenging TDC)
The firing order impacts :• Reliability (dynamics)
• Performance, because of :•“Free” acoustic couplings between intake ports
•Acoustic coupling between ports and plenum
Therefore, it is important to understand:•Eigen modes of the plenum
•Excitability of these modes
•Influence of these couplings on volumetric efficiency
SimulationSimulationFunctional specification:
• Being able to characterize firing order and plenum design on a whole performance curve within 1 day
• Reactive design : ability to guide new evolution designs from the analysis of 3D acoustic phenomenon
Simulation tools :• Since 2000, we have been designing and evolving a specific software “GT-Mesh”able to translate a plenum CAD into a GT-Power model. It can also help the post-treatment with 3D visualizations and animations from the gp files.
• GT-mesh allows the building of specific meshes to be used on 3D linear acoustic softwares (Plenum Eigen modes and frequency responses) or Star-CD
• Fine analysis work with Star-CD / GT-Power coupled simulations
• Plenum design DOE and optimization using morphing tools
GTGT--MeshMesh
Basic firing ordersBasic firing ordersThere are 24 « basic » firing orders divided into 2 symmetric groups of 12 Firing Orders:
Firing order 1 2 3 4 5 6 7 8 9 101 1 7 2 9 4 10 5 8 3 62 1 7 2 8 3 10 5 9 4 63 1 7 2 10 5 9 4 8 3 64 1 7 2 8 3 9 4 10 5 65 1 7 2 10 5 8 3 9 4 66 1 8 3 7 2 10 5 9 4 67 1 7 2 9 4 8 3 10 5 68 1 8 3 7 2 9 4 10 5 69 1 8 3 10 5 7 2 9 4 610 1 8 3 9 4 7 2 10 5 611 1 9 4 7 2 8 3 10 5 612 1 9 4 8 3 7 2 10 5 613 1 8 3 10 5 9 4 7 2 614 1 9 4 10 5 8 3 7 2 615 1 8 3 9 4 10 5 7 2 616 1 10 5 9 4 8 3 7 2 617 1 9 4 8 3 10 5 7 2 618 1 9 4 10 5 7 2 8 3 619 1 10 5 8 3 9 4 7 2 620 1 10 5 9 4 7 2 8 3 621 1 9 4 7 2 10 5 8 3 622 1 10 5 7 2 9 4 8 3 623 1 10 5 8 3 7 2 9 4 624 1 10 5 7 2 8 3 9 4 6
Firing Sequence
Simulated Power CurvesSimulated Power CurvesFiring order
80%
85%
90%
95%
100%
19500185001750016500155001450013500Engine Speed (rpm)
FO1FO2FO3FO4FO5FO6FO7FO8FO9FO10FO11FO12
Simulated performance indexSimulated performance indexAs expected from high speed power figures, lap time performance index shows 3 groups of firing orders.
RS25 GT-Mesh / GT-Power Simulation : performance offset with base plenum
0
0.1
0.2
0.3
0.4
0.5
0.6
18000 18250 18500 18750 19000 19250
max engine speed (rpm)
Lap
time
perf
orm
ance
inde
x ga
in (%
)
delta between FO4 and FO1
In the first group N°4 gives the best results: compared with RS24 firing order (N°1), the performance gain increases with max speed.
0A1 0A2 0A3 OA4 OA5 OA6 OA70A8
0A9OA10
OA11OA12
V
103.4103.3 103.3
103.9
101.7
101.4 101.6101.5
100.8
100.5 100.6
100.2
98.0
99.0
100.0
101.0
102.0
103.0
104.0
Perf
orm
ance
inde
x G
Tpow
er
Firing Order
V10 - RS25 : max speed = 19000 rpm
Volumetric efficiency Volumetric efficiency cylcyl. to . to cylcyl. FO4 vs. F01. FO4 vs. F01
80%
85%
90%
95%
100%
19500185001750016500155001450013500
Engine Speed (rpm)
FO1FO4
AnalysisAnalysisCorrelation between performance at high revs and number of consecutive firing neighbors on 1 bank (free acoustic couplings).
For example, FO9 (1-3-5-2-4) is the worst whereas the ideal one is FO4 (1-2-3-4-5).
High revs power = f(firing order)
0
1
2
3
4
5
6
7
8
1 2 3 4 5 6 7 8 9 10 11 12Firing order number
Pow
er c
ateg
ory
0
1
2
3
4
Nr o
f suc
cess
ive
firin
g ne
ighb
ours
19000 rpm power category
number of successive firingneighbours on a bank
Analysis Analysis Nevertheless, the correlation is not perfect: free acoustic couplings between ports do not explain all!
For example, firing order N°12 (1-4-3-2-5) and N°1 (1-2-4-5-3) have very different performance whereas they both have 2 consecutive firing neighbors.
This is due to other acoustic couplings between ports and plenum.
AnalysisAnalysisCoupled Star-CD / GT-Power simulation allows to confirm that a port can help the volumetric efficiency of his neighbor when the later fires next
ConclusionConclusion
The simulations were confirmed on the dyno, with a good power and performance index improvement.
Therefore, despite increased external vibrations, Firing Order N°4 was adopted on the RS25, which was a little step (among many others) towards the world championship…
Thank you for your attention
Pierre-Jean Tardy