8mm Overdrive Chart
Percentage of Crankshaft Speed
Blower Spocket Tooth Count 60 to 42
C
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S
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T
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C
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60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
54
-
-
-
-
-
-
0.0
1.9
3.8
5.9
8.0
10.2
12.5
14.9
17.4
20.0
22.7
25.6
28.6
55
-
-
-
-
-
0.0
1.9
3.8
5.8
7.8
10.0
12.2
14.6
17.0
19.6
22.2
25.0
27.9
31.0
56
-
-
-
-
0.0
1.8
3.7
5.7
7.7
9.8
12.0
14.3
16.7
19.1
21.7
24.4
27.3
30.2
33.3
57
-
-
-
0.0
1.8
3.6
5.6
7.5
9.6
11.8
14.0
16.3
18.8
21.3
23.9
26.7
29.5
32.6
35.7
58
-
-
0.0
1.8
3.6
5.5
7.4
9.4
11.5
13.7
16.0
18.4
20.8
23.4
26.1
28.9
31.8
34.9
38.1
59
-
0.0
1.7
3.5
5.4
7.3
9.3
11.3
13.5
15.7
18.0
20.4
22.9
25.5
28.3
31.1
34.1
37.2
40.5
60
0.0
1.7
3.4
5.3
7.1
9.1
11.1
13.2
15.4
17.6
20.0
22.4
25.0
27.7
30.4
33.3
36.4
39.5
42.9
61
1.7
3.4
5.2
7.0
8.9
10.9
13.0
15.1
17.3
19.6
22.0
24.5
27.1
29.8
32.6
35.6
38.6
41.9
45.2
62
3.3
5.1
6.9
8.8
10.7
12.7
14.8
17.0
19.2
21.6
24.0
26.5
29.2
31.9
34.8
37.8
40.9
44.2
47.6
63
5.0
6.8
8.6
10.5
12.5
14.5
16.7
18.9
21.2
23.5
26.0
28.6
31.3
34.0
37.0
40.0
43.2
46.5
50.0
64
6.7
8.5
10.3
12.3
14.3
16.4
18.5
20.8
23.1
25.5
28.0
30.6
33.3
36.2
39.1
42.2
45.5
48.8
52.4
65
8.3
10.2
12.1
14.0
16.1
18.2
20.4
22.6
25.0
27.5
30.0
32.7
35.4
38.3
41.3
44.4
47.7
51.2
54.8
66
10.0
11.9
13.8
15.8
17.9
20.0
22.2
24.5
26.9
29.4
32.0
34.7
37.5
40.4
43.5
46.7
50.0
53.5
57.1
67
11.7
13.6
15.5
17.5
19.6
21.8
24.1
26.4
28.8
31.4
34.0
36.7
39.6
42.6
45.7
48.9
52.3
55.8
59.5
68
13.3
15.3
17.2
19.3
21.4
23.6
25.9
28.3
30.8
33.3
36.0
38.8
41.7
44.7
47.8
51.1
54.5
58.1
61.9
69
15.0
16.9
19.0
21.1
23.2
25.5
27.8
30.2
32.7
35.3
38.0
40.8
43.8
46.8
50.0
53.3
56.8
60.5
64.3
70
16.7
18.6
20.7
22.8
25.0
27.3
29.6
32.1
34.6
37.3
40.0
42.9
45.8
48.9
52.2
55.6
59.1
62.8
66.7
71
18.3
20.3
22.4
24.6
26.8
29.1
31.5
34.0
36.5
39.2
42.0
44.9
47.9
51.1
54.3
57.8
61.4
65.1
69.0
72
20.0
22.0
24.1
26.3
28.6
30.9
33.3
35.8
38.5
41.2
44.0
46.9
50.0
53.2
56.5
60.0
63.6
67.4
71.4
73
21.7
23.7
25.9
28.1
30.4
32.7
35.2
37.7
40.4
43.1
46.0
49.0
52.1
55.3
58.7
62.2
65.9
69.8
73.8
74
23.3
25.4
27.6
29.8
32.1
34.5
37.0
39.6
42.3
45.1
48.0
51.0
54.2
57.4
60.9
64.4
68.2
72.1
76.2
75
25.0
27.1
29.3
31.6
33.9
36.4
38.9
41.5
44.2
47.1
50.0
53.1
56.3
59.6
63.0
66.7
70.5
74.4
78.6
76
26.7
28.8
31.0
33.3
35.7
38.2
40.7
43.4
46.2
49.0
52.0
55.1
58.3
61.7
65.2
68.9
72.7
76.7
81.0
77
28.3
30.5
32.8
35.1
37.5
40.0
42.6
45.3
48.1
51.0
54.0
57.1
60.4
63.8
67.4
71.1
75.0
79.1
83.3
78
30.0
32.2
34.5
36.8
39.3
41.8
44.4
47.2
50.0
52.9
56.0
59.2
62.5
66.0
69.6
73.3
77.3
81.4
85.7
79
31.7
33.9
36.2
38.6
41.1
43.6
46.3
49.1
51.9
54.9
58.0
61.2
64.6
68.1
71.7
75.6
79.5
83.7
88.1
80
33.3
35.6
37.9
40.4
42.9
45.5
48.1
50.9
53.8
56.9
60.0
63.3
66.7
70.2
73.9
77.8
81.8
86.0
90.5
81
35.0
37.3
39.7
42.1
44.6
47.3
50.0
52.8
55.8
58.8
62.0
65.3
68.8
72.3
76.1
80.0
84.1
88.4
92.9
82
36.7
39.0
41.4
43.9
46.4
49.1
51.9
54.7
57.7
60.8
64.0
67.3
70.8
74.5
78.3
82.2
86.4
90.7
95.2
83
38.3
40.7
43.1
45.6
48.2
50.9
53.7
56.6
59.6
62.7
66.0
69.4
72.9
76.6
80.4
84.4
88.6
93.0
97.6
84
40.0
42.4
44.8
47.4
50.0
52.7
55.6
58.5
61.5
64.7
68.0
71.4
75.0
78.7
82.6
86.7
90.9
95.3
100.0
85
41.7
44.1
46.6
49.1
51.8
54.5
57.4
60.4
63.5
66.7
70.0
73.5
77.1
80.9
84.8
88.9
93.2
97.7
102.4
86
43.3
45.8
48.3
50.9
53.6
56.4
59.3
62.3
65.4
68.6
72.0
75.5
79.2
83.0
87.0
91.1
95.5
100.0
104.8
Blower Sprocket Tooth Count 41 to 23
C
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k
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S
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c
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T
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C
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t
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
54
31.7
35.0
38.5
42.1
45.9
50.0
54.3
58.8
63.6
68.8
74.2
80.0
86.2
92.9
100.0
107.7
116.0
125.0
134.8
55
34.1
37.5
41.0
44.7
48.6
52.8
57.1
61.8
66.7
71.9
77.4
83.3
89.7
96.4
103.7
111.5
120.0
129.2
139.1
56
36.6
40.0
43.6
47.4
51.4
55.6
60.0
64.7
69.7
75.0
80.6
86.7
93.1
100.0
107.4
115.4
124.0
133.3
143.5
57
39.0
42.5
46.2
50.0
54.1
58.3
62.9
67.6
72.7
78.1
83.9
90.0
96.6
103.6
111.1
119.2
128.0
137.5
147.8
58
41.5
45.0
48.7
52.6
56.8
61.1
65.7
70.6
75.8
81.3
87.1
93.3
100.0
107.1
114.8
123.1
132.0
141.7
152.2
59
43.9
47.5
51.3
55.3
59.5
63.9
68.6
73.5
78.8
84.4
90.3
96.7
103.4
110.7
118.5
126.9
136.0
145.8
156.5
60
46.3
50.0
53.8
57.9
62.2
66.7
71.4
76.5
81.8
87.5
93.5
100.0
106.9
114.3
122.2
130.8
140.0
150.0
160.9
61
48.8
52.5
56.4
60.5
64.9
69.4
74.3
79.4
84.8
90.6
96.8
103.3
110.3
117.9
125.9
134.6
144.0
154.2
165.2
62
51.2
55.0
59.0
63.2
67.6
72.2
77.1
82.4
87.9
93.8
100.0
106.7
113.8
121.4
129.6
138.5
148.0
158.3
169.6
63
53.7
57.5
61.5
65.8
70.3
75.0
80.0
85.3
90.9
96.9
103.2
110.0
117.2
125.0
133.3
142.3
152.0
162.5
173.9
64
56.1
60.0
64.1
68.4
73.0
77.8
82.9
88.2
93.9
100.0
106.5
113.3
120.7
128.6
137.0
146.2
156.0
166.7
178.3
65
58.5
62.5
66.7
71.1
75.7
80.6
85.7
91.2
97.0
103.1
109.7
116.7
124.1
132.1
140.7
150.0
160.0
170.8
182.6
66
61.0
65.0
69.2
73.7
78.4
83.3
88.6
94.1
100.0
106.3
112.9
120.0
127.6
135.7
144.4
153.8
164.0
175.0
187.0
67
63.4
67.5
71.8
76.3
81.1
86.1
91.4
97.1
103.0
109.4
116.1
123.3
131.0
139.3
148.1
157.7
168.0
179.2
191.3
68
65.9
70.0
74.4
78.9
83.8
88.9
94.3
100.0
106.1
112.5
119.4
126.7
134.5
142.9
151.9
161.5
172.0
183.3
195.7
69
68.3
72.5
76.9
81.6
86.5
91.7
97.1
102.9
109.1
115.6
122.6
130.0
137.9
146.4
155.6
165.4
176.0
187.5
200.0
70
70.7
75.0
79.5
84.2
89.2
94.4
100.0
105.9
112.1
118.8
125.8
133.3
141.4
150.0
159.3
169.2
180.0
191.7
204.3
71
73.2
77.5
82.1
86.8
91.9
97.2
102.9
108.8
115.2
121.9
129.0
136.7
144.8
153.6
163.0
173.1
184.0
195.8
208.7
72
75.6
80.0
84.6
89.5
94.6
100.0
105.7
111.8
118.2
125.0
132.3
140.0
148.3
157.1
166.7
176.9
188.0
200.0
213.0
73
78.0
82.5
87.2
92.1
97.3
102.8
108.6
114.7
121.2
128.1
135.5
143.3
151.7
160.7
170.4
180.8
192.0
204.2
217.4
74
80.5
85.0
89.7
94.7
100.0
105.6
111.4
117.6
124.2
131.3
138.7
146.7
155.2
164.3
174.1
184.6
196.0
208.3
221.7
75
82.9
87.5
92.3
97.4
102.7
108.3
114.3
120.6
127.3
134.4
141.9
150.0
158.6
167.9
177.8
188.5
200.0
212.5
226.1
76
85.4
90.0
94.9
100.0
105.4
111.1
117.1
123.5
130.3
137.5
145.2
153.3
162.1
171.4
181.5
192.3
204.0
216.7
230.4
77
87.8
92.5
97.4
102.6
108.1
113.9
120.0
126.5
133.3
140.6
148.4
156.7
165.5
175.0
185.2
196.2
208.0
220.8
234.8
78
90.2
95.0
100.0
105.3
110.8
116.7
122.9
129.4
136.4
143.8
151.6
160.0
169.0
178.6
188.9
200.0
212.0
225.0
239.1
79
92.7
97.5
102.6
107.9
113.5
119.4
125.7
132.4
139.4
146.9