1 Automotive Engines Part 4 (Cyl. Head)

2 Cylinder Head

3 A cylinder head is a casting generally made out of iron or aluminum Allows Fuel & Air in Allows Exhaust Out Holds the valves, valve springs and retainers and one or two camshafts (overhead cam engines only). May also allow for acc. mounting

4 Iron Heads Cheaper than Alu. Better Tq. Due to heat retention Better Sealing (same expansion rate as block) Heavier

5 Aluminum Heads More Expensive than iron Higher HP due to better heat transfer Can go at least 1 pt. higher CR Can be up to 40lbs. lighter

6 Cylinder Head Parts Ports – allows intake charge into combustion chamber, and exhaust out Port

7 Cylinder Head Parts Sealing Surface – mating surface to block Sealing Surface

8 Cylinder Head Parts Valve Guide – controls valve alignment

9 Cylinder Head Parts Combustion Chamber – where combustion occurs Many shapes and sizes

10 Combustion Chamber Styles Hemispherical or Pentroof - The "Hemi" – A hemispherical combustion chamber is one half of a sphere cast into the bottom of the cylinder head. – The valves are placed at the outside of the bore area and at a specific angle from the crankshaft centerline.

11 Hemispherical or Pentroof - The "Hemi"

12 Combustion Chamber Styles Wedge-Shaped Chambers – Inclined basin recessed into the deck of the head – Steep walls in such chamber design force the air/fuel flow path and deflect and force it to move in a downward spiral around the cylinder axis

13 Wedge-Shaped Chambers

14 Combustion Chamber Styles Bathtub or Heart-shaped – any chamber that's not a wedge or hemispherical – Heart Or Kidney Shaped

15 Bathtub or Heart-shaped

16 Port Design Cross Flow – Intake & Exhaust ports on opposite sides of head Reverse Flow – Intake & Exhaust ports on same side of head

17 Cross Flow Best flow Cool intake charge High HP Intake Exhaust

18 Reverse Flow Pre-heating of intake charge Exhaust under intake Poor Flow High torque Intake Exhaust

19 The End