2 files changed, 14 insertions, 0 deletions
diff --git a/engine.c b/engine.c
index a7fbf11..1817180 100644
--- a/engine.c
+++ b/engine.c
@@ -3,7 +3,20 @@
 #include "unit.h"
 #include "engine.h"
 
+
+/* A four-stroke piston engine takes two revolutions per cycle. */
+#define REV_PER_CYCLE 2.0
+
+
 void
 init_engine(Engine *e) {
 	memset(e, 0, sizeof(*e));
 }
+
+VolumeFlowRate
+volume_flow_rate(const Engine *e) {
+	double n = as_rpm(e->rpm);
+	double d = as_cubic_metre(e->displacement);
+	double ve = e->ve;
+	return cubic_metre_per_min(n * d * ve / REV_PER_CYCLE);
+}
diff --git a/engine.h b/engine.h
index 3ec3dcf..eaa7dc6 100644
--- a/engine.h
+++ b/engine.h
@@ -6,3 +6,4 @@ typedef struct {
 } Engine;
 
 void init_engine(Engine *e);
+VolumeFlowRate volume_flow_rate(const Engine *e);