building my 97 impreza into a 2.5 race machine
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Scooby Senior
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yes it's getting there kev and have more things on the way
plus im hoping that CDF RACING can get some fuel rails up and made so i can see what they are like 
also a big part of parts have came from ADVANCED AUTO PERFORMANCE PARTS which is located in bristol and are in association with roger clark motorsport and have been very helpfull and supply almost any parts/ tunning parts you can think of and are willing to go that extra mile to help and seem to know alot about imprezas and fords eg cosworth
plus they have machine shop ect..
soon as i can get five mins will get some more done
plus im hoping that CDF RACING can get some fuel rails up and made so i can see what they are like 
also a big part of parts have came from ADVANCED AUTO PERFORMANCE PARTS which is located in bristol and are in association with roger clark motorsport and have been very helpfull and supply almost any parts/ tunning parts you can think of and are willing to go that extra mile to help and seem to know alot about imprezas and fords eg cosworth
plus they have machine shop ect..soon as i can get five mins will get some more done
Last edited by The Stitcher; Jan 16, 2009 at 12:16 PM.
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Scooby Senior
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From: south wales rhondda
as for going farward a few more bits have came
arp head studs, new valve stem oil seals, and camshaft seals plus set of cometic head gaskets
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[/IMG]before sending my heads to be checked i have started porting heads
first scribed where exhaust gasket sits to open it up
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[/IMG]then took some picks in stages but this still aint finished as i run out of sanding flaps and grinding stones so will get some in the morning then it will be ready to polish after little mere work
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[/IMG]also done some work on the inlet side but still need to do a bit more to finish but as said run out of sanding drums
will not be polishing the inlet side it was more of just remove casting marks and dimples plus there is a ruff part just to the rear of the seat which i smoothed , i also started to thin or knife edge the devider in the middle but as said need to spend a little more time on the finish soon as i get new bits
pic of the ruff inlet
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[/IMG]pic smoothed
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[/IMG]pick of both exhaust and inlet smoothed
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[/IMG]inlet port smoothed and semi knife edged
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[/IMG]it has taken a good few hours just to get to this point with one so to get them all done and finished will take a long time plus its not as easy as it looks to do but the pics are not of them finished and will get pics of them when all done
Unfortunately the gasket on the exhaust post should not be used as a reference for porting except to centre the hole. The size of the exit is already the correct size, a good match for the inlet of tubular headers, and needs little or no enlarging.
You can get away with it if you have heavily ported cast headers, but tubular headers will cause a problem as the tube is typically 38mm bore.
You can get away with it if you have heavily ported cast headers, but tubular headers will cause a problem as the tube is typically 38mm bore.
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Scooby Senior
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Unfortunately the gasket on the exhaust post should not be used as a reference for porting except to centre the hole. The size of the exit is already the correct size, a good match for the inlet of tubular headers, and needs little or no enlarging.
You can get away with it if you have heavily ported cast headers, but tubular headers will cause a problem as the tube is typically 38mm bore.
You can get away with it if you have heavily ported cast headers, but tubular headers will cause a problem as the tube is typically 38mm bore.
just out off curiousity if i was too buy gt spec headers wouldnt i of been able to open the flanges slightly by coneing them to match the ports if they were slightly smallier??
Last edited by The Stitcher; Jan 16, 2009 at 10:58 PM.
You would be able to open up the flanged area a little, but IMHO you have made a slight error. On the whole thought I don't think it will adversely affect it a great deal. Standard sized exhaust ports seem fine with considerable amounts of power.
You do NOT want to make headers that have primary tubes the same size as the gasket hole.
You do NOT want to make headers that have primary tubes the same size as the gasket hole.
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Scooby Senior
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You would be able to open up the flanged area a little, but IMHO you have made a slight error. On the whole thought I don't think it will adversely affect it a great deal. Standard sized exhaust ports seem fine with considerable amounts of power.
You do NOT want to make headers that have primary tubes the same size as the gasket hole.
You do NOT want to make headers that have primary tubes the same size as the gasket hole.
Last edited by The Stitcher; Jan 17, 2009 at 12:15 AM.
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Scooby Senior
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don't know if anyone can advise me but was just thinking
i have 1.6 cometic gaskets but would i need a different size if the heads needed a skim or would they be ok to use if only a certain amount came off if they needed skimming ( heads have never been skimmed before )
i have 1.6 cometic gaskets but would i need a different size if the heads needed a skim or would they be ok to use if only a certain amount came off if they needed skimming ( heads have never been skimmed before )
Last edited by The Stitcher; Jan 17, 2009 at 09:56 PM.
Depends on pistons and head combo. If you bottom end is together, get the pistons to TDC and measure the deck height, ie the distance the piston is below the top of the block or above it. Check all 4 pistons as they do vary.
On EJ257 pistons you often find they are below the deck by around 0.4mm, in which case 1.6mm gasket is on the thick side from a squish point of view. However depending on the piston dish and head volume you're CR will be in the low 8s.
A nominal skim on the heads will still leave them with about 46cc volume, so you need to add the gasket volume the deck height volume (which will be a negative number if it's above the block) and the piston dish volume (should be on the box the pistons came in). From there you can work out your CR.
For deck height of 0.4mm, 1.6 mm gasket and 22cc piston dish
CR= (CCV+CV)/CCV
Cylinder volume is 614.275 cc
Piston dish eg 22cc
Deck volume is 3.11cc
Gasket volume is 12.81cc
Head volume 46cc
Total CCV is 83.92
CR = (614.28+83.92)/83.92 = 8.319
So the above example shows that you should be in the ball park, and the thicker gasket will certainly result in a closer to stock cam timing. But would give a squish of 2mm which is next to pointless. So you may find that a thinner gasket would not adversley affect likelyhood of det despite increased CR, but I would be wary of trying a 9:1 CR if you want to run a big turbo and aim for 500hp on pump fuel.
On EJ257 pistons you often find they are below the deck by around 0.4mm, in which case 1.6mm gasket is on the thick side from a squish point of view. However depending on the piston dish and head volume you're CR will be in the low 8s.
A nominal skim on the heads will still leave them with about 46cc volume, so you need to add the gasket volume the deck height volume (which will be a negative number if it's above the block) and the piston dish volume (should be on the box the pistons came in). From there you can work out your CR.
For deck height of 0.4mm, 1.6 mm gasket and 22cc piston dish
CR= (CCV+CV)/CCV
Cylinder volume is 614.275 cc
Piston dish eg 22cc
Deck volume is 3.11cc
Gasket volume is 12.81cc
Head volume 46cc
Total CCV is 83.92
CR = (614.28+83.92)/83.92 = 8.319
So the above example shows that you should be in the ball park, and the thicker gasket will certainly result in a closer to stock cam timing. But would give a squish of 2mm which is next to pointless. So you may find that a thinner gasket would not adversley affect likelyhood of det despite increased CR, but I would be wary of trying a 9:1 CR if you want to run a big turbo and aim for 500hp on pump fuel.
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Scooby Senior
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cheers pavlo
as for the heads one is done now and the other is almost there just a few more hours more on it
after they are done will be building heads back up but first a bit of a garage clear up
then will be starting to fit my 6 speed gear box with only 20,000 on it
it's a uk box and came with rear diff but no linkage or shaft but i have ordered these and should be here any day now
so thats the next job after heads are done
as for the heads one is done now and the other is almost there just a few more hours more on it
after they are done will be building heads back up but first a bit of a garage clear up
then will be starting to fit my 6 speed gear box with only 20,000 on it
it's a uk box and came with rear diff but no linkage or shaft but i have ordered these and should be here any day now
so thats the next job after heads are done
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Scooby Senior
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cheers guys
haven't done much in the last week but managed to get the heads skimmed and got them today
also managed to start cleaning the valves and will be lapping them in the next day or so then will be building them back and then it's on to fitting them to the block
anyone know what spec the under bucket shims should be between?? and cam clearence? any help would be great as i can't seem to fined any specs for the sti under bucket and can only fined wrx top shim specs
haven't done much in the last week but managed to get the heads skimmed and got them today
also managed to start cleaning the valves and will be lapping them in the next day or so then will be building them back and then it's on to fitting them to the block anyone know what spec the under bucket shims should be between?? and cam clearence? any help would be great as i can't seem to fined any specs for the sti under bucket and can only fined wrx top shim specs
right guys done some bits Wednesday managed to clean heads and lap valves in one of them and also started to cleen up the cam wheels
before and after of cam wheel will get a photo of all 4 when finished
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some of heads but camera is not the best and dose not do them justice as its only a 4 meg pixel
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and today managed to get the other head lapped and then put together and managed to get one fitted on the short block with the arp rod bolts and cometic gasket
only thing is i forgot to take pics of the build as i forgot all about the camera in the excitement of fitting them today
fitted the rod bolts and cleaned everything then followed manual on fitting them
sorry never got pics guy but will get some of them on the block asap and will try not to forget i again
before and after of cam wheel will get a photo of all 4 when finished
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[/IMG]some of heads but camera is not the best and dose not do them justice as its only a 4 meg pixel
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[/IMG]and today managed to get the other head lapped and then put together and managed to get one fitted on the short block with the arp rod bolts and cometic gasket
only thing is i forgot to take pics of the build as i forgot all about the camera in the excitement of fitting them today
fitted the rod bolts and cleaned everything then followed manual on fitting them
sorry never got pics guy but will get some of them on the block asap and will try not to forget i again
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Scooby Senior
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cheers fella
heads are on and all clearences with shims are correct and spot on
and cams are now on too
next job is to clean the rest of the cam wheels up 
i was going to paint the rocker chest covers blue but after i cleaned them up i thought i like them as they are
i will get some pics of the engine with heads on asap but will just show the gaskets which cost a small fortune as i did not want to get non original gaskets as i have used al original from start
and quick pic of the chest covers clean and can't wait till my new sump with baffel plate arrives
as its almost been a week but i blame the weather
will get pics when it arrives
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heads are on and all clearences with shims are correct and spot on
and cams are now on too
next job is to clean the rest of the cam wheels up 
i was going to paint the rocker chest covers blue but after i cleaned them up i thought i like them as they are
i will get some pics of the engine with heads on asap but will just show the gaskets which cost a small fortune as i did not want to get non original gaskets as i have used al original from start
and quick pic of the chest covers clean and can't wait till my new sump with baffel plate arrives
as its almost been a week but i blame the weather
will get pics when it arrives [IMG]
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Thread Starter
Scooby Senior
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From: south wales rhondda
finished off cam wheels and pic of them on engine
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looked at the idle pulleys and the toothed one and bottom one has play in them so have ordered new so hopefully will be here in a day or so and phoned about my new sump with baffle plate and should be here hopefully tomorrow
when idlers arrive i will put my old belt on as it's an original subaru belt and only changed it a month or so before it went pop
thinking of putting middle belt cover on and leaving the sides off
anyone know if this would be ok or other option would be to cut holes in the outer covers to see pulleys
just want it to look abit different
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[/IMG]looked at the idle pulleys and the toothed one and bottom one has play in them so have ordered new so hopefully will be here in a day or so and phoned about my new sump with baffle plate and should be here hopefully tomorrow
when idlers arrive i will put my old belt on as it's an original subaru belt and only changed it a month or so before it went pop
thinking of putting middle belt cover on and leaving the sides off
anyone know if this would be ok or other option would be to cut holes in the outer covers to see pulleys
just want it to look abit different


