compression versus deck height
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compression versus deck height
What is the relation between say 10:1 cr pistons and .035 deck height and the same pistons with 0 deck height. What does the cr rise say for every .010 less deck height? In a 390
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Joined: Jan 2003
Posts: 8,600
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From: Iowa
The amount depends on the other factors of the compressed volume, like gasket volume and head CC's.
Doing some calculations:
68cc heads
10cc dish pistons
4.4" .041" gaskets
.035" deck clearance
4.080" bore, 3.784" stroke
=9.47:1 compression
68cc heads
10cc dish pistons
4.4" .041" gaskets
0 deck clearance
4.080" bore, 3.784" stroke
=10.19:1 compression
Difference = .72
76cc heads
10cc dish pistons
4.4" .041" gaskets
.035" deck clearance
4.080" bore, 3.784" stroke
=8.82:1 compression
76cc heads
10cc dish pistons
4.4" .041" gaskets
0" deck clearance
4.080" bore, 3.784" stroke
=9.43:1 compression
Difference = .061
So you see, it varies. A normally higher compression motor will gain more from that .035" than a lower compression motor.
Doing some calculations:
68cc heads
10cc dish pistons
4.4" .041" gaskets
.035" deck clearance
4.080" bore, 3.784" stroke
=9.47:1 compression
68cc heads
10cc dish pistons
4.4" .041" gaskets
0 deck clearance
4.080" bore, 3.784" stroke
=10.19:1 compression
Difference = .72
76cc heads
10cc dish pistons
4.4" .041" gaskets
.035" deck clearance
4.080" bore, 3.784" stroke
=8.82:1 compression
76cc heads
10cc dish pistons
4.4" .041" gaskets
0" deck clearance
4.080" bore, 3.784" stroke
=9.43:1 compression
Difference = .061
So you see, it varies. A normally higher compression motor will gain more from that .035" than a lower compression motor.
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