JForand - Atlanta Build

[jforand]

I also have JE pistons but mine are meant to work with the wrx heads (P/N: 291059), which have a smaller combustion chamber. So JE increases piston volume to -25.50 cc to bring the compression ratio back down. Your JE pistons (291061) have a volume of -16.50 cc, so they're probably meant to go with sti heads. You also have the standard bore (99.50mm), which means your block has not been over-bored yet.

Do you have any pictures of the scraping? Replacing piston rings and verifying dimensions isn't too much of a pain with a bit of research. It's good insurance but does take time..

A shot from each cylinder. Two are a bit worse than the other two. All in all I would not say anything is bad. You can't feel anything with a finger nail.

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Shot of the piston top

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And then a couple of the head

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So as I understand it (not well, i assure you) the D25 heads have the more hemisherical chamber and are smaller in volume (roughly 51cc) from the preceding B25 heads. In other words, to keep the compression ratio in check you would want a deeper piston to count the shallower chamber. It would appear that I have a shallow combustion chamber and a shallow piston making for a higher compression ratio. How do I know this combo will work? It seems to not be jiving at this time. I am not aware of how the heads worked. I thought the B25 was a previous generation and and the D25 took over. You seem to be indicating that one came on the WRX and the other on the STI.

Yes, I am sitting at the standard bore of 3.918" I think which works out to be 99.517mm. I spent some time on JE's website trying to find a set of rings and wow was that difficult. If I am to buy from them I guess I will be calling them.

As I bet you can tell the head got knocked around a bit off the motor. There is a bit of a gash in a couple places, one that traverses a gasket seal and if you look closely the ground prong on the one spark plug is bent to the side of the electrode.