compression ratio

bodger · Post by **bodger** » Thu Feb 07, 2008 8:51 pm

i'm looking at changing my pistons from 8.13 to 9.25 :1 ...is it just the pistons that are differant ?
and is there any marking on the pistons to tell which is which ?
thankyou

Post by **katanaman** » Thu Feb 07, 2008 8:58 pm

Other than the newer 4.6/4.0 heads having a smaller combustion chamber yes its just the pistons. Its easy to tell the pistons apart because of the dish which is visibly deeper on the low comp pistons.

bodger · Post by **bodger** » Fri Feb 08, 2008 4:38 pm

thankyou , would it be ok to stick pistons from another engine in mine ??????

i will put new rings on and lightly hone the bores first

and shall i use the rods that come with the pistons or use my existing ones , i will be putting news shells in while it's apart anyway for the sake of £18 quid

Post by **katanaman** » Sat Feb 09, 2008 1:17 am

Personally I wouldn't use second hand pistons from another engine but yes it could be done. If you really have to go this route then I would advise you match the pistons to bore as best as you can. Old pistons from another engine will never give you the the best clearances but if needs must. Rod wise use your own rods, it makes no odds when you change the shells.