Manifolds

1. Manifolds

2. Intake Manifolds • Construction • Cast iron • Cast aluminum • Plastic • Composite • Plastic @ aluminum

3. Intake Manifolds • Plenum • Runners • Long – build low RPM torque • Short – maximum high RPM power

4. Intake Manifolds • Exhaust crossover • Coolant passages • Thermostat housing • Vacuum ports • EGR passages

5. EGR Valve • Exhaust gas recirculation • Used to reduce Nox (oxides of nitrogen) • The EGR system mixes spent exhaust gasses with the fresh A/F mixture. • The inert exhaust gas displaces some of the A/F mixture (5–10 %), thus reducing combustion temperature. • High temperatures are the main cause of Nox.

7. Carburetors and TBI • The carb/TBI unit delivers an air/fuel charge • Most of the fuel in this charge will evaporate by the time it reaches the combustion chamber (up to 60%)

8. Carburetors and TBI • The remaining fuel droplets will be carried to the combustion chamber at high velocities (300 ft/sec). • Swirling aids in the atomization of fuel • Guide vanes • Abrupt bends • Rough inner walls • What about golf balls?

9. Carburetors and TBI • At low velocities (under 50 ft/sec) the fuel droplets will separate from the charge and form on the runners of the manifold. • This is known as separation • A/F mixtures must be richer at idle to compensate for this

10. Carburetors and TBI • Manifold runner cross-sections must be large enough to flow sufficient charge at high RPM but … • small enough to maintain a sufficient velocity for fuel droplet suspension. • This is one reason why racing engines have a high idle.

11. Carburetors and TBI V-? Design • On a dual-plane or 180 degree manifold one half of the carb. or TBI unit feeds half of the cylinders. • Runners may be tuned • On a single-plane or 360 degree manifold all cylinders are fed from one open plenum. • The intake runners are therefore split into two separate passages at different heights.

12. Open @ Closed Manifolds • Open – the bottom of the manifold is separated from the lifter valley. • Benefit – the bottom of the manifold does not contact the hot oil. • Cooler temp = denser charge

13. Open @ Closed Manifolds • Closed – the bottom of the manifold is the top of the lifter valley. • Benefit – the bottom of the manifold contacts the hot oil. • Better atomization of fuel at cold temps. • Coking may occur on a closed type manifold if a heat shield is not used. • Thermo-barrier paints are also used.

14. Air-gap Manifold

15. Port Injection Manifolds • The fuel injector is located approximately 3” from the intake valve. Therefore: • Runners are for air flow only • Swirling is not as necessary • Plastic manifolds

16. Exhaust Manifolds • Generally cast iron • May be annealed (heat-treated) • May be tubular steel • Will generally house an o2 sensor • Cracks • Leaks

17. Headers • Runners • Collectors

18. Headers • Reduce restriction for better high RPM power • Tuned headers – designed to combine individual pulses into one large pulse. • The pressure behind this pulse is lower than atmospheric pressure. • Thus – a pulsing vacuum is present called: Scavenging

19. Headers • Low to medium RPM power and torque • Long runners (34-38”) • Long collectors (12-15”) • High RPM power and torque • Increased diameter runners • Shorter runners and collectors Benefits are measurable above 3500 RPM

20. Headers • Ceramic coating • Properly working headers should make a rapping sound between 3500 to 5000 RPM.

21. Oil Pumps

22. Oil Pumps • All recent automotive oiling systems are of a full-pressure design. • Typically driven by the • Camshaft • Distributor shaft (one-half engine speed) • Crankshaft (full engine speed)

23. Oil Pumps • All production oil pumps are positive displacement pumps. • All oil that enters must exit • May be gear or rotor type. • Pumps are sized so that approximately 10psi of pressure is available at idle. • Pressure increases by approx. 10psi per 1000 rpm

24. Gear-Type Oil Pump

25. Rotor-Type Oil Pump

26. Oil Pumps • The oil pump is the only component of an oiling system that receives unfiltered oil. • On all oiling systems oil exiting the pump will feed directly into the oil filter. • The screen on the pickup is the only method of debris stoppage.

27. Oil Pumps • Oil pump pick-up screens utilize metal covers to prevent cavitation (aeration). • Cavitation is caused by • Oil being exited out of the pump faster than it can push it. • Air being sucked into the pump via a sudden stop.

28. Oil Pressure Regulation • All full-pressure oiling systems utilize a pressure relief valve • Generally spring regulated • The higher the spring tension the greater the oil pressure • Excessive oil is bled back into the inlet side of the pump.

29. Oil Pressure Regulation • 3 to 6 gallons of oil per minute are required to properly lubricate an engine. • Excessive oil pressure does not lubricate an engine better and requires more horse-power to maintain.

30. Oil Pressure • Effected by: • Oil viscosity • Engine/oil temperature • Engine integrity • Excessive bearing clearances. • Oil pump integrity • Excessive gear/cover/housing clearances.