Car Modding, Motorsport, Formula 1

means putting the engine back to factory specifications. This generally involves new piston rings, bearings and gaskets. When done by a competent engine builder the engine will perform as new.

A top overhaul only covers the replacement of components inside the cylinder head without removing the engine from the vehicle, such as valve and rocker arm replacement. A full overhaul however covers the whole engine component replacement which requires the engine to be removed from the vehicle, such as replacing the connecting rods and crankshaft bearings. By comparison, a full overhaul service costs more than a top overhaul service.

The choice of modification depends greatly on the degree of performance enhancement desired, budget, and the characteristics of the engine to be modified. Intake, exhaust, and chip upgrades are usually amongst the first modifications made as they are the cheapest, make reasonably general improvements, whereas a different camshaft, for instance, requires trading off smoothness at low engine speeds for improvements at high engine speeds.

Furthermore, tuners may also use analytical tools to help evaluate and predict the effect of modifications on the performance of the vehicle.