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TBI= Throttle Body Injection. OHV= Overhead Valves
TBI means the they've placed a fuel injection unit where the carburetor used to be. The injector sprays gas down the intake and it's sucked into the cylinder through the runners of the intake manifold. That method isn't used too much anymore because it's less efficient. The new injection is called PFI, for Port Fuel Injection. There's a fuel injector mounted behind the valve at each cylinder. That way, only air runs down the runners of the intake manifold, not air and gas. The problem with running both is that on a cold day, the gas would condense along the walls of the runners. That's why PFI is more efficient.
Overhead valves are less efficient than Overhead Cams. The overhead valve is operated by a rocker arm, push rod, and valve lifter. An overhead valve is also much larger. But two small valves actually let in more air than one large valve. That's why most newer efficient engines have 4 valves per cylinder. They're opened and closed by the camshaft, eliminating all those other moving parts.
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