Piston combustion chamber

[Deantracy17 1]

Guys,

 

I have noticed that the pistons in my 1.6 engine are flat topped.  When I went through Telf's comprehensive 8V rebuild thread, I noticed his were dished?  Any idea why they are different?  I assume the compression ration will be higher with flat topped pistons vs' dished, if the head is the same??

 

Thanks in advance?

 

Dean

[welshpug 1,661]

check the stroke, it may be an 88mm stroke 1905cc 405 SRI or iirc a late BX gti type engine with a larger chamber in the head, these did have flat topped pistons.

 

if it is still a 73mm stroke then someone has swapped the pistons from one of the aforementioned engines onto the XU5/7 rods (same part)  to indeed raise the compression ratio, I don't recall exactly offhand what the ratio would be specifically but it'll be in the mid 10's to 1 from memory, so will need a tweak to the ignition timing and will cope with mild cam upgrades.