[PukkaSilvia]

For greater power than 225bhp the following will have to be installed.


WALBRO 255 FUEL PUMP is a must 100%. If this is not done you will end up putting a hole in your pistons or at the least constantly blowing head gaskets..(I have done a right up on installing one of these in this how-to section)

The exhaust system has to be a custom free flow system of 2 3/4" bore-3" bore with a free flow rear silencer. These systems can not be bought off the shelf but there are custom exhaust companies around along with pipework being readily available from place like demon tweeks. The shape of the s12 exaust is not comlicated and you could make a system yourself if your handy with a welder.

Boost pressure will need to be in excess of 16psi. The standard turbo or a s13 t25 will not be enough. You have a few choices here. Most common upgrades are t28 turbos found on s14 200sx or bought off the shelf. A hybrid t28 with uprated internals i.e 360 degree bearings etc would give you better drivability as the s12 engine will be starting to suffer from lack of immediate response as spool up will take longer. The other option is a t3 turbo from a sierra cosworth. Do not buy an rs turbo t3 as these are different and smaller.
Again a hybrid unit would be nicer but again not essential. I had a std t3 on a std s12 engine and found it great fun at 15/16psi. Anything below this was boring and i would of preferred the standard turbo.

Fueling will need to be modified as the standard 270cc injectors will be flat out already at 225bhp.
You have many options from piggyback ecu's to complete management setups. Complete aftermarket management is far better but cost a fortune.I get the feeling s12 owners dont normally spend this kind of money so for most of you piggy back ecus are the way to go at the moment unless someone works out a way of remapping the std ecu.Piggyback ecu's modify signals between your standard ecu and its sensors and ancilleries. Apexi Safc11 is a common choice.There are other ones out there so shop around.
Fit whatever bigger injectors fit. you can go for s13 injectors very cheaply and these will supply enough fuel for a modified standard internalled engine(270BHP Maximum). The next common size up is 444 injectors from a skyline. They can be distinguised by there mustard yellow colour. There also a common upgrade for s13 owners. Theu are always available on ebay.

Your car should be dynoed and setup correctly and checked for detonation at this stage.
-------------------------------------------------------------------------
In order to fit either turbo mentioned above fittings will need to be modified.
For a t28 you will also need the s14 t28 downpipe and a new oil line to the turbo (companies like hydroquip,pirtec,aeroquip make them)
The t3 will need a t3 flange welded to the bottom of the standard s12 manifold and a custom downpipe made using a downpipe flange from a cosworth breakers. (The flange looks very similar to a s12 exhaust flange but slightly bigger)