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Thought I'd already commented on it, but I wouldn't even consider running original (LET to suit the valve alignments) pistons except in the rare instance where the pistons were in excellent condition and there was no noticeable bore wear (under a thou).
A few reasons for this are the piston is less stable in the bore, compromising sealing of the rings; the ring gap increases by a little over 3 times the bore wear, compromising sealing; the bore wears in an oval shape, with more on the major thrust side, which may compromise ring conforming to the bore.
With second hand pistons, especially of unknown history, they may be worn a little undersize (especially if there has been scuffing) which will increase bore clearance; the side of the piston groove may be worn or damaged, which compromises ring seal and may increase the chance of blow-by and piston failure and, less common, they may have hairline cracks which can result in terminal engine failure.
For a lower power engine, where combustion pressures and rpm are low, you may be OK but higher output engines have much higher pressures and loads so it is more important that a little extra is paid to ensure reliability.
 

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Hi everyone, I'm new to this site, and I'm just after a bit of info! I'm Vauxhall mad (or just mad I'll let you guys be the judge) I have a Corsa VXR, a MK4 Astra GSi (492bhp) and I also own a MK2 Astra GTE 16v

It's the GTE that I need a bit of info. It's fitted with a 20XE engine. But unfortunately the block is knackard. Now my plans are to turbo it. I want big power so not just to turn it into a C20LET. I have done lots of research however all the info I have found from forums is sort of 7-8+ years old and I know things move on. I'll cut to the chase, if I was to buy a bare X20XEV block, would I be able to mate this with the 20XE head? This is the info I need to have a go at this:

1. New crank, XE/LET/XEV the same?
2. Forged C20LET Pistons and steel rods?
3. Drill and tap holes in block for turbo oil feeds and returns?
4. Cambelt? What would work?
5. Z20LET oil pump?
6. Obviously uprated head to accommodate turbo build.
7. Aftermarket ECU kits? Omex/megasquirt? What are people's recommendations?

If anyone has any other info advice please feel free to share :)

Caine.
It’s a bit late commenting on this post, my car runs a Holden-built version of the XEV and I’ve been reliably informed that a SAAB B207r Head will fit into an XEV block.
 
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