I got a pm from Andrew and I thought this would make a good read for those playing with subaru


Neill, can I pick your brain for some ideas. Wanting to up the HP in my Fasty once the 915 box goes in. Its pretty well stock 94 motor with TD05, standard injectors etc etc and a Microtech tune. Currently getting 242hp atw @15psi. Would like to squeeze 300hp. The only obvious thing I am going to do is put the splitter onto the dump pipe for better flow and port/polish the stock headers.

You know much more about these engines. Where would you be thinking of modding to get a safe tune to reach my desired figures.....................may be wishing but still dont want any internal changes, just looking at bolt on bits if possible.

What can these engines/turbo cope with?

Hi Andrew , the subaru EJ20 G of the vintage 1994 is very close to the V2 sti of that year . These items are the same on each motor TD05H & the injectors & manifold.

Power gains are to be had with

1) better cams V2 ( V3 I would go for )
2) 1.5mm metal STI head gaskets ( more boost ) $180.00 trade ( well worth the swap out )
3) forged pistions
4) change your fuel rails ( see the TT post I put in this section )
5) yellow top injectors ( daily driver )
6) pink top injectors ( racer )
7) mod your dump pipe ( cheap fix )

The motor you have should it be when you remove the heads a closed deck case , this is very good IMO the best to date . Guys now try to find these for sleving to 2.35 cc . I am building two of these now & when I get a window I do a post on it .


My mate Rob has a V3 STI ( GC8 RA STI ) the mods I just did were as follows
fuel pump
pink injectors
fuel rail mod
VF34 turbo ( it has a 3" zorst & a spilter )
pod air filter ( apexi ) ( I have seen these flow 450HP )
Power FC
18 PSI boost

it made 198 kw at all ( 4 wheels ) I told the guy on the lap top to keep it at that for a safe tune .

I would not polish the headers & I would keep the zorst pipe work no more than 2 & 1/2" with a good quality cat & use the RS liberty WTAIC ( I have a few WTAIC in my shed )

I hope this helps , seagull

PS Lukes motor will have the same mods as above in a few weeks I need to check his cams

sounds about right Neil..........we've got 260 hp at the wheels without a cam change.

Thanks Neill. Good reading. Yes the engine I have is the closed deck.