V4 Sti Heads on to 1995 Uk Turbo Bottom End?
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Scooby Regular
Joined: Jan 2013
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From: Basingstoke
V4 Sti Heads on to 1995 Uk Turbo Bottom End?
Been looking at some V4 Sti Heads, I asked in a previous thread about the gains but really need to know what it will take to fit them.
The fella selling them has said that the inlet manifold is different, I know i'll need to work out Compression Ratio. But is anyone able to list what is actually required or what additional parts I will need.
Also and I guess more relevantly is it worth it? The engine will be out of the car and the heads are both coming off due to headgasket failure. I wanted both heads tested and skimmed but the price of these heads is only marginally different.
Appreciate any feedback, still new to all this and couldnt find anything on the search.
The fella selling them has said that the inlet manifold is different, I know i'll need to work out Compression Ratio. But is anyone able to list what is actually required or what additional parts I will need.
Also and I guess more relevantly is it worth it? The engine will be out of the car and the heads are both coming off due to headgasket failure. I wanted both heads tested and skimmed but the price of these heads is only marginally different.
Appreciate any feedback, still new to all this and couldnt find anything on the search.
Scooby Regular
Joined: Dec 2012
Posts: 282
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From: England
They are a straight swap over, nothing additional required. They will match your inlet just fine. You'll need to modify the way the coil packs fit in and thats it. (your '95 engine has coil packs but v4 sti uses ht leads) this is easily done.
Worth getting both the deck and head skimmed in the event of head gasket failure for a good chance of first time fix. Make sure your fit thicker head gaskets when doing this as you don't want higher static compression ratio, so use cometic headgaskets. I would highly recommend putting new crank bearings in whilst it's apart too as you don't want to pull it all apart again in a few months time when the big ends go.
They are better heads with stronger lighter valves, better cams (higher duration with slightly less lift) for higher revving, under bucket solid shims, again for higher revving.
The early wrx heads you already have are the worst heads they put on an ej20 turbo, they're okay for about 300 bhp but I wouldn't trust the exhaust valves to stay in 1 piece.
Worth getting both the deck and head skimmed in the event of head gasket failure for a good chance of first time fix. Make sure your fit thicker head gaskets when doing this as you don't want higher static compression ratio, so use cometic headgaskets. I would highly recommend putting new crank bearings in whilst it's apart too as you don't want to pull it all apart again in a few months time when the big ends go.
They are better heads with stronger lighter valves, better cams (higher duration with slightly less lift) for higher revving, under bucket solid shims, again for higher revving.
The early wrx heads you already have are the worst heads they put on an ej20 turbo, they're okay for about 300 bhp but I wouldn't trust the exhaust valves to stay in 1 piece.
If you are running the standard 'dog-bone' pistons in your '95 bottom end, then 1.6mm thick MLS gaskets will keep the static C.R to around 8.3:1 which is good - provided the STi V3~4 havent been skimmed to death.
Personally I'm not keen on the sealing properties around the fire ring of the Cometic gaskets and tend to use Subaru and Cosworth head gaskets.
Mick
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