The V8 Owners Forum -

Please take into account that the true CR can be less than quoted by the factory. Doing the math based on actual measurements I had to skim the block with 4,6 pistons to get even close to factory figure of 9,35. Pistons were down in the bore about .040" at TDC. After skimming they are now about .015 down the bore, I use 28 cc heads and thin gaskets. CR is around 10.3 with my components.

Like Stevie said, measure what you have and do the math. One thing though, does every block have enough room to clear a 4,6 crank ?

or use 4.0 pistons and that will bring the compression up. Same pistons but a smaller dish in them.

yeah but surely if i decided to use 4.0 pistons, i would have to use the 4.0 rods as well, as the 4.0-litre engine uses a rod 155.2 mm in length, and the 4.6-litre is 149.7 mm..

Nope,the longer rods in to 4.0 are there because the crank has a shorter thow.With 4.0 rods and 4.6 crank the pistons would be sticking out the top of the bores!!!Regards doug

Ah i see. Thanks for the info so far guys - i appreciate it.