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[humbucker]

capacity   Bore      stroke
2.5_____81.6___79.6
2.6_____83.2___79.6
3.0_____86_____85
3.2_____87.5___88

am i to assume from this crude chart that x30xe pistons will not fit y32se?

[Andy B]

capacity   Bore      stroke
2.5_____81.6___79.6
2.6_____83.2___79.6
3.0_____86_____85
3.2_____87.5___88

am i to assume from this crude chart that x30xe pistons will not fit y32se?

From your dimensions, it seems they'll go into the bores, but will be a bit on the baggy side!!! 

[Kevin Wood]

From your dimensions, it seems they'll go into the bores, but will be a bit on the baggy side!!! 

Yep, you'll get a little piston slap, I'm afraid. 

Kevin

[humbucker]

ok, thought so  next question...

if replacing x30xe pistons with new items, due to engine rebuild, and going for standard items, is there any do or don't rules, i.e. only go for genuine items, dont go for aftermarket brand X or whatever?

and out of interest, what is the average cost for a set of 6 new pistons?

[Kevin Wood]

I'd say it depends why you are changing them.

If you've got a damaged one and the engine is otherwise in reasonable nick, use a second hand one.

If you are doing a serious overhaul I'd question whether it's worth the money over and above sourcing a reasonable 2nd hand engine.

Nevertheless, if you are putting a complete set of pistons in an engine it probably makes sense to go for an oversize set and get it rebored and properly honed so you are back to an "as new" level of wear rather than put new pistons in old bores, even if the level of wear is not too bad.

Last time I bought new pistons (for a ford Zetec) they were about 50-60 quid a pop IIRC. Multiply by 6 and they make the cost of a rebore less significant.

"Genuine" from a dealer they would be sill money, if available, I'm sure, but they are probably made by Mahle or AE or one of the big names anyway and a decent engine workshop would be able to source them (and bore the block to the correct clearance as well - that way you have a single source if anything goes wrong!).

Kevin

[2woody]

I'd suggest that a rebore with new pistons is going to cost you about the same as an early Elite with MOT

[humbucker]

the pistons i can get at a very good price, i just wondered whether i can drop them straight in to replace existing items (i'm thinking of replacing piston rings anyway so kill two birds with one stone) or whether this will cause problems?

[Kevin Wood]

the pistons i can get at a very good price, i just wondered whether i can drop them straight in to replace existing items (i'm thinking of replacing piston rings anyway so kill two birds with one stone) or whether this will cause problems?

I can't see a benefit to changing them at all if the old ones are OK and the engine doesn't need a rebore. They aren't really a "wear" item. In addition, the original pistons may well have been selected during engine manufacture to give a more precise fit in the bore than you will achieve by fitting new pistons without a rebore.

If the engine had good compression and wasn't burning oil I would leave the whole bottom end alone, TBH, aside from perhaps checking the condition of the bearings.

That said, I don't know the full reasons for your rebuilding the engine in the first place so perhaps I'm missing something?

Kevin

[humbucker]

thanks kevin. it was more an 'out of interest' question as im rebuilding a 3.0 for an engine conversion and as i'll probably be whipping heads off etc figured i might have a go at replacing the pistons if the rings look like they need some attention