I ran my UK94 Impreza (briefly) at 26PSI boost at a Hillclimb. This was before I learnt a lot about fuelling and turbo's

I holed a piston. It ran fine, but felt more lethargic to be honest. Low revs it was down on power, but on boost it still went well. On startup it put out a blue cloud of oil smoke.

The car also suffered from starting problems as I guess the compression was knackered. However once it started it ran reasonably well. Infact well enough for me to complete the rest of the day hillclimbing ! However it did leave on a trailer

The bores were OK, and I had it rebuilt with Cosworth forged pistons. (Bloody expensive !)

Following the rebuild it was put on APEXI boost and fuel management at 1.3bar. Not as quick, but a lot safer.

An expensive lesson

 

sounds like my prob mate. mine has the apexi fuel and boost controllers, and once rebuilt, boost will be back up again

am going to use cosworth pistons, about 800 quid for the set.
also cam regrind and ported heads, with metal head gaskets.

cheers
ian

 

not much to report. lifted the engine out at tea time, me and the old man, with a log and some rope....**** it was heavy
will get a hoist for the refit due to the fannying around locating the lower studs [img]images/smilies/mad.gif[/img]

not had time to strip it down as ive been swapping top mounts on a mates gti-6 this eve.
will post piccies of what i find in the morning

 

ok, heres the crack so far.

removed the head, and chamber and piston is black and oily. no damage to the bore, and none to the valves or piston either, well not to the crown anyway.

so im thinking a ring now then ??

been told the pistons can be removed without splitting the block, where are the access holes, cant se any in the correct place?

cheers

p.s. few piccies in a moment, but nothing exciting

 

There are access holes. The damage to the piston may not be visible on the crown. Look around the edges, and you will proabably see signs of whre it has melted. You WILL see it when you remove the pistons.
Remove the flywheel, and you will see access panels on the rear of the block.
On the front, remove all the t/belt tensioner bracketry, and behind it there is a 14mm hex blanking plug, which is for pin access. Similar on drivers side, altho visible without removing anything.

 

how are the pins secured in the pistons then? are they circlip or press fit?

cheers