Engine Tuning and Overhauling

This is the adjustment of the internal combustion engine, or modification to its control unit, otherwise known as its ECU (Engine Control Unit).

At GT4U, we finetune your vehicle engine through systemic adjustments to yield optimal performance, and increase the vehicles engine's power output, economy and durability. These may be mutually exclusive goals, and we might detune an engine with respect to output (work) in exchange for better economy or longer engine life by lessening the stress on engine components.

It has a long history, almost as long as the development of the automobile in general, originating with the development of early performance cars, and later, with the post- hot-rod movement. Tuning can describe a wide variety of adjustments and modifications, from the routine adjustment of the carburettor and ignition system to significant engine overhauls. At the other end of the scale, performance tuning of an engine might involve our mechanics revisiting some of the design decisions taken at quite an early stage in the development of the engine.

We set the idle speed, fuel/air mixture, carburettor balance, spark plug and distributor point gaps, and ignition timing were regular maintenance items for all older engines and the final but essential steps in setting up a performance engine.


A tune-up usually refers to the routine servicing of the engine to meet the manufacturer's specifications. Tune-ups are needed periodically as according to the manufacturer's recommendations to ensure that a vehicle runs as expected. Modern vehicles now typically require only a small number of tune-ups (relative to older automobiles) over the course of an approximate 250,000-kilometre (160,000 mi) or a 10-year lifespan, this can be attributed to improvements in the production process with imperfections and errors reduced by computer automation and also significant improvement in the quality of consumables such as fully synthetic engine oil now being available.

We could provide tune-ups that may include the following:

  • Adjustment of the carburettor idle speed and the air-fuel mixture
  • Inspection and possible replacement of ignition system components like spark plugs, contact breaker points, distributor cap and distributor rotor
  • Replacement of the air filter and other filters
  • Inspection of emission controls
  • In early days, mechanics finishing the tune-up of a performance car such as a Ferrari would take it around a track several times to burn out any built-up carbon; this is known as an Italian tune-up.

    Engine Overhaul

    An overhauled engine is an engine which has been removed, disassembled (torn down), cleaned, inspected, repaired as necessary and tested using factory service manual approved procedures. The procedure generally involves honing, new piston rings, bearings, gaskets, oil seals. When done by a competent engine builder the engine will perform as new. The engine may be overhauled to 'new limits' or 'service limits', or a combination of the two using used parts, new original equipment manufacturer (OEM) parts, or new aftermarket parts. The engine's previous operating history is maintained and it is returned with zero hours since major overhaul.

    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. It may or may not include a valve job. A major overhaul however covers the whole engine assembly, which requires the engine to be removed from the vehicle and transferred to an engine stand. An overhauled engine refers to a major overhaul. By comparison, a major overhaul costs more than a top overhaul.