Engine Building
Subaru Impreza WRX Engine Build
By
Apr 11, 2008, 22:14

Subaru Impreza WRX 2002 Engine Build and Upgrade

JE Pistons

 

This Impreza WRX came to us as a standard car (excluding exhaust) with a complaint of a knocking noise from the engine, so we were commisioned to carry out a engine strip to find the problem.  

 

ARP Fasteners

Upon full stripping, it was noted that the knocking was caused by big end shell failure resulting in excessive tolerances. Before the rebuild process, discussions were made and it was agreed that an upgrade to the engine should be done as more power was required.  

Cosworth

 

ACL Race Series Bearings

The upgrade is to include competition components from leading manufacturers who we have listed below.

• JE Pistons
• ACL
• Cosworth
• ARP

Before the components can be fitted extensive stripping, cleaning and measuring is to be done so we can workout what size components we need to supply and which components will need to be replaced due to excessive wear,

Piston Measurment

the parts to be machined will include cylinder bores that will be taken 0.50mm (+0.20") oversize, crankshaft will need to be polished on all journals, cylinder head is to be fitted with new valve guides (not k-line inserts which is a cheap alternative) the cylinder heads will also need to be machined on the head face to ensure a good finish for the gaskets, also the valves and valve seats will be recut to ensure good sealing ability. Before we send the block and cylinder heads for maching they are also cleaned and then glass bead blasted in our industrial guyson beed blast cabinet, this removes all the tarnish from the metals giving a new finish that is very pleasing to the eye.

We have spent many years looking for professional machine shops who can offer us the service and quality we require as standards do vary greatly from engineering company to another, the machine shops we use carry out engineering for some of the most powerfull engines in the world and have up to date equipment that can offer the precision we require, after all the quality of the machine and operators experiance will reflect on the quality of the build.

 

Subaru Impreza WRX 2002 Block

The image shown is one half of the impreza cylinder block, as you can see the item has been cleaned and the journal tunnels have also been polished to ensure a perfect shell fitment and contact to enable the heat from the shells to be passed through to the cylinder block.

Piston Ring Orientation

The image to the right is showing the piston ring orientation, when fitting the top and second piston rings it is very important that these be positioned correctly on the piston, they have a top side and also need to be positioned at the correct degree, failure to do this will result in poor engine performance and also excessive oil consumption, the lower oil control rings also need to be gapped and positioned. Piston rings also need to have the end gaps measured and adjusted to suit the application, again failure to do this will result in poor engine efficiancy and oil consumption issues.

Piston Ring End Gap Measurement

Pistons rings have various identifying marks, some have small dots and others have numbers/letters on them to distinguish the top side, there are many types of piston rings designed for various types of racing but we are not going to discuss them in any further detail in this article.

 

Bore Lubrication

Before fitting the pistons it is very important that the cylinder bores and piston have a sufficiant supply of oil coating to prevent any damage when fitting the pistons and on the initial startup, it will also help prevent any corrosion/sticking issues if the engine is going to be stored before fitment for any length of time.

Oil Sump Paint Stripping

When carrying out engine builing of this nature we will also renovate any parts that are looking a little worse for wear, here the oil sump showed signs of surafce corrosion so to prevent the corrosion from spreading and eventually eating through the skin causing a oil leak, we strip the paint and carryout a respray to give a new finish.

Please call back soon as we progress with the rebuild we will continue to add further information and images.

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