John 37

Hi all. Hoping for some advice here. My 08 STI Hatch is basically standard as far as I can tell. It has Milltek 3" exhaust with 1 cat, K&N panel filter and been mapped. 340hp on rollers. Car has 95,000 miles on it. I want to keep it a long time. I do about 5000 miles/year. Kept my classic 10 years. Hopefully this will last at least as long.
Had the usual head gasket probs a few months ago so I pulled the engine and fitted RCM gaskets with 11mm extreme studs. I also replaced cam belt, idlers, clutch plate & flywheel bearing. Water use now zero but it uses oil, has slightly low compression, struggles with MOT emissions and exhausts are black. I should have read this forum in more detail before but now it looks like the engine may need pistons and full rebuild.
I'm not looking for big power. It's road use only but, unusually, I tow a caravan. That means long periods of bigger throttle than a solo car. Reliability is my aim plus a wider power band if possible. Maybe a slight increase in max revs? I want to keep tmic and remove aux air pump. I would like to stay with 2.5L rather than a complete change. If I build for 430hp I should have plenty in hand.
Here's what I'm thinking.
Have dowels fitted to top of cylinder block to support cylinders. Skim top, rebore +0.25mm & hone to match forged pistons. What pistons? Should I fit more dowels between crankcase halves. I've only seen one place advertising dowels, Moorspeed I think. Is this adequate? Closed deck is overkill. Conversion to closed deck by fitting plates is attractive but is it worth the extra cost?
Heads left alone but skimmed clean, new valve stem seals, fit new RCM gaskets. Present ones are 0.78mm. Is this OK or should I go to 1.0mm to allow for block & head skim (didn't skim last time as marks were minimal). Cams looked fine so leave as is.
Check existing crank, keep if OK with new bearings. Will my engine have rear thrust bearing? If not, should I go for one?
Have turbo rebuilt. Not sure who yet.
New oil pump. What size?
Should I keep oil strainers on cam oil feed?
Should I fit stronger conrods?
I'm tempted to fit baffled sump? Std oil cooler should be OK.
Keep present clutch, gearbox, etc.
Fit air/oil separator, probably Grimspeed type.
I intend to have the machining done but build the engine myself. Obviously new gaskets and seals fitted throughout.
I want to get the basics right while the engine's out. Things like engine mounts can be changed later if needed.
Sorry this us so long. All thoughts are welcome. Is there anything I've missed?
Thanks

the shreksta

iTrader: (20)

for what it costs the closed deck conversion is a no brainer in my opinion

LewisScoob

iTrader: (5)

Your crank will be rear thrust.

Personally for the power you're going for I dont think there's a huge need for CDB inserting. Sounds to me like you need to have a chat with Alyn at AS Performance. He can help you out with options on internals, machine work and decking if required.

stockcar

"Pinning" or inserting the block with dowels causes specific stress points and in general is not recomended, far better to simply undertake a CDB and in the scheme of things is very cost effcetive