Relative values

Author

admin

Browse pages
Current page

1

Current page

2

Current page

3

Current page

4

Current page

5

Current page

6

Current page

7

Current page

8

Current page

9

Current page

10

Current page

11

Current page

12

Current page

13

Current page

14

Current page

15

Current page

16

Current page

17

Current page

18

Current page

19

Current page

20

Current page

21

Current page

22

Current page

23

Current page

24

Current page

25

Current page

26

Current page

27

Current page

28

Current page

29

Current page

30

Current page

31

Current page

32

Current page

33

Current page

34

Current page

35

Current page

36

Current page

37

Current page

38

Current page

39

Current page

40

Current page

41

Current page

42

Current page

43

Current page

44

Current page

45

Current page

46

Current page

47

Current page

48

Current page

49

Current page

50

Current page

51

Current page

52

Current page

53

Current page

54

Current page

55

Current page

56

Current page

57

Current page

58

Current page

59

Current page

60

Current page

61

Current page

62

Current page

63

Current page

64

Current page

65

Current page

66

Current page

67

Current page

68

Current page

69

Current page

70

Current page

71

Current page

72

Current page

73

Current page

74

Current page

75

Current page

76

Current page

77

Current page

78

Current page

79

Current page

80

Current page

81

Current page

82

Current page

83

Current page

84

Current page

85

Current page

86

Current page

87

Current page

88

Current page

89

Current page

90

Current page

91

Current page

92

Current page

93

Current page

94

Current page

95

Current page

96

Current page

97

Current page

98

Current page

99

Current page

100

Current page

101

Current page

102

Current page

103

Current page

104

Current page

105

Current page

106

Current page

107

Current page

108

Current page

109

Current page

110

Current page

111

Current page

112

Current page

113

Current page

114

Current page

115

Current page

116

Current page

117

Current page

118

Current page

119

Current page

120

Current page

121

Current page

122

Current page

123

Current page

124

Current page

125

Current page

126

Current page

127

Current page

128

Current page

129

Current page

130

Current page

131

Current page

132

Current page

133

Current page

134

Current page

135

Current page

136

Current page

137

Current page

138

Current page

139

Current page

140

Current page

141

Current page

142

Current page

143

Current page

144

Current page

145

Current page

146

Current page

147

Current page

148

Current page

149

Current page

150

Current page

151

Current page

152

Current page

153

Current page

154

Ro dive values

Two Cosworth e gines, 40 years and 350bhp apart: Mike Costin, one half of the design team, relates the DFV’s origins and how much technology has changed i are problem solvers, and that gives them a different perspective. While the world at large remembers the DFV as the most successful racing engine of all time, Mike Costin, co-founder of Cosworth, remembers things differently. The hype

is unimportant to him. What he recalls is the engineering process — problems encountered, solutions found.

And the DFV had its problems, the most severe of which nearly spoiled that fairy-tale debut win in Holland. Solving that timing gear mystery took Cosworth into new territory, and culminated in an invention still widely employed today.

Improved materials, enhanced design and manufacturing techniques, pneumatic valve closure — all contribute to making today’s Fl V8s very different from the 40-year-old DFV. On its first dyno test Keith Duckworth’s 3-litre achieved 408bhp at 9000rpm, rising to 480bhp (160bhp/litre) at 10,500rpm near the end of its pre-eminence. Today’s Fl engines, from just 2.4 litres, generate around 750bhp (313bhp/litre) revving to a governed 19,000rpm. But while the engineering challenges are even sterner now than in 1967, Costin isn’t a fan of what almost limitless budgets have done to the design process. He’s content to have worked during racing’s most enjoyable era, and to have had studied at “the University of Duckworth”. DYNO PROBLEMS

MC “We had two initial problems with the DFV. The first was piston cracking. On each side of the piston we had four small holes for gas and oil to pass through, and they were acting as stress-raisers. A small modification to the forging cured that.

“The second problem was crankcase breathing. We weren’t getting oil out of the heads quickly enough, so it accumulated there. Initially, we had to add ugly external piping to get over this. We’d tackled the problem successfully in the FVA/FVB F2 engine and all our FJ engines before that, and carried the same principles over to the DFV. But the V8 had a much higher throughput of oil. Instead of three gallons we were putting 6.5 gal/min just through the bearings. The old rule that you used scavenge pumps of twice the capacity of the pressure pump didn’t work. We initially overcame the problem by fitting a twin-vane auxiliary pump on the end of the existing scavenge pumps. This had a good volume capability for its size and the scavenge system just about worked, but only just. Eventually Keith designed a complete new scavenging system using lobe pumps, like a Roots blower, with a capacity of 55gal/min. These removed so much air that we had negative pressure internally to tell the oil where to go. At the top of the engine we put a small hole to allow air in to give a controlled pressure difference across each section of the engine which guided the oil in and out. We had no more breathing problems.” SOMETHING WORSE

“The really big problem with the DFV was a timing gear torsional issue caused by torque spikes. It didn’t come to light until we started racing the engine. It could never have been foreseen, because its magnitude was just not appreciated at the time. Keith called in a Rolls-Royce engineer as a consultant who took one look at the timing gears and said there was no problem with them or the bearings or the pins in respect of taking the horsepower. So it must be something to do with stab torque — very brief transient torque peaks.

“We’d never done research into this but we put a proximity transducer on a gear pin and looked at its output on an oscilloscope. This allowed us to measure how the pin bent in reaction to the torque it was transmitting. Testing quickly showed that the mean torque was very low, as we expected, equivalent to 8.8hp. But for around 1.5 degrees, every now and again — quite often, in fact — there was a stab torque that went right off our scale. We estimated it to be higher than the mean torque from the crankshaft itself.

“A key problem was finding a fix that would fit into the space, which couldn’t be increased because the engine was an integral part of the car’s structure, so Keith designed the famous quill hub, using 12 tiny quill shafts. It accommodated the enormous stab torque through its springiness and had friction faces for damping, so it didn’t introduce a resonance problem. That cured everything. As far as I know, every F1 engine to this day still uses Keith’s quill hub.” BEHIND THE WHEEL

“I did all the testing on the FVB four-cylinder [effectively half a DFV] in a Brabham chassis — and the first two days of DFV testing, although that’s not in the history books. The first day was on the runway at Hethel, the second at Snetterton. Graham Hill then took over, but can’t have done much testing before Zandvoort otherwise they’d have uncovered the timing gear problem and might never have gone there with the 49.

“We didn’t do much on the first day because the clutch friction discs failed. We took the car back into the workshop, saw Bob Dance who was looking after the Cortina team, and asked him to lend us one of its twin-plate friction assemblies. That was a Cosworth unit — in fact, I’d designed it myself — and it became the standard DFV fitment.

“At Snetterton the next day I did 20 or 30 laps until the bracket bent where the top rear radius arm attached to the monocoque. That was a problem they had for a while with the 49. I remember touching 175mph on the back straight.

“Although I didn’t have any problem with the torque delivery, some drivers complained about it. The engine’s pickup was a bit splashy because we’d designed the fuel injection cam on the dyno and richened the mixture up a bit where you changed down. As each engine came back for service, the fuel cam went on the jig to check it, but one of Jack Brabham’s cams was quite different. He’d modified it. When we put it against the graph, we found it was exactly up the line we’d originally developed without enrichment. So we reverted to that and it improved the engine slightly. We didn’t tell Jack…” A DIFFERENT ETHOS

“I would say a good half of what is designed and manufactured these days is scrapped because of the manner in which things are tackled. We would never manufacture anything until we were pretty certain it would work. Keith, Ben Rood and I would talk for hours about a design while it was still a concept. Now it’s normal to scrap a high proportion of parts made because they will not assemble with other parts. “Budgets are higher and time pressures are greater now but you never know which pushes which. Teams go to sponsors and say, ‘We’ve used up all that money, it’s not enough — we need some more’. I don’t think they put it quite that way. Mind you, I started out as a young cynic and have steadily grown to be an old cynic.” ID