Page 9 - Basic Engine Pada Alat Berat febri

Silinder 1 Power Exhaust Intake Compression

Silinder 2 Compression Power Exhaust Intake

Silinder 3 Exhaust Intake Compression Power

Silinder 4 Intake Compression Power Exhaust

3. Valve timing
Adalah saat membuka dan menutup valve intake dan valve exhaust. Misalkan F.O
= 1-2-4-3

Valve intake opens = 15° BTD C (Before top dead center).
Valve intake closes = 40° A B D C (After bottom dead center).
Valve exhaust opens = 50° B B D C (Before bottom dead center).
Valve exhaust closes = 20° A T D C (After top dead center)

Gambar 4. Sudut Putaran Poros Engkol

Dari data tersebut, dapat diketahui panjang langkah:

Intake stroke = 15 + 180 + 40 = 235.
Compression stroke = 180 - 40 = 140.

Power stroke = 180 - 50 = 130.
Exhaust stroke = 50 + 180 + 20 = 250.

Total stroke = 235 + 140 + 130 + 250 = 755.
Jadi over lapping = 755 – 720 = 35.