Tips on reboring an engine.

All you need to know about "Reboring an engine"

To increase the power of an engine you can increase the cylinder capacity.  The best way to increase the cylinder capacity of an engine is by physically making each cylinder a larger diameter. 

Firstly sit down and do your research.  You need to check that you can get a gasket, piston with rings and other components to match your chosen bore capacity. You cannot undo the reborn and certainly do not want to have to redo it again.

There are two main types of engine firstly the cast iron block and secondly the aluminium block.  The cast iron blocks are good candidates for RE boring.  It is recommended that you get the block stress tested before proceeding especially if you are making substantial changes to the diameter.  Aluminium blocks may not be RE bored easily, but you may be able to get different size steel cylinder liners to achieve a similar effect.

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We boring and engine is a specialist job and not something that can be performed at home unless you have a very accurate drilling machine.  You cannot afford to drill off centre or you risk a piston going awol during some enthusiastic driving.

You'll also need to check that the head will fit on to your new cylinder capacity.  You need to check that the gasket still provides an airtight seal.  It is also a good idea that you get the head re machined to match the capacity you have selected, and this will help air flow into the engine.

Another option to increase the cylinder capacity of an engine is by using a stroker kit.  This changes the length of the crank and when combined with a lower profile piston you are able to increase the amount of capacity within the cylinder.

 Running in the engine after a rebore involves lots of low speed but high load driving. By this we mean plenty of hill work, towing and stop start driving.  You must keep the revs of the engine and down during this time.  It is also vital that you avoid oil additives which prevents the bedding in process from taking place effectively. If you have scored a crosshatch pattern into the cylinder wall this will help the piston and ring to bed in properly whilst the engine is under load.

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6 Responses to “Reboring an engine”

  1. Joe says:

    I have an 02 mustang GT. Was told by Fox lake racing that if I installed their stage 2 heads with appropriate cams, and P51 intake manifold I could gain about 90 rwhp. Others I’ve talked to say that 30 rwhp is realistic. What do you think a realistic gain would be for this modafication ?

  2. KAPAL SUNIL says:

    I want to convert my indian engine low cc engine into high cc. please help me I am a automotive technician. I want innovativeness in indian engines.

  3. Andrian says:

    I want to incrise my 2e engen a powerful power what can i do?

  4. kalu says:

    howcan reboring increase the power of an engineblock

  5. WASEEM AHMAD says:


  6. Antonio says:

    After reboring the motor do you have to get a custom tune on your ecu so it can recognize the different compression ratio and would there need to be a change in the air to fuel ratio because of the different comp ratio and also for your ecu to recognize the oversized pistons you put in?