Different Pistons??????

[BlackBetty]

After finally aquiring another engine and opening it i have found that the donor engine has very different pistons in comparison to the ones I have in the original engine. The differance is that in the original engine the pistons have a 50 etched on the head and they are partically completely flat, whilst the donor engines pistons have a 40 etched on them and they have a sunken bowl in the top very much like a combustion chamber. This is approximately 2.5mm to 3 mm deep. Both types are in perfect condition.

Now herein lies the question, Which would be the right one to use? and if so, then why?

Any Suggestions?

 

[BRE Fabrications LTD]

Seems you have everyone stumped.

Have you tried ih8mud yet? There are quite a few members on there with Venezuela spec cruisers that run the same 1fz, with coil packs instead of distributers, as you do.

Just a guess though, would the pistons without the recesses yield a higher compression, and more power, than the ones with recesses? Or can you only increase the compression ratio by doing work to the head?

Sorry I can't help regarding the pistons...