by David Gentleman » Thu Jul 07, 2005 6:53 pm
Heres the catch. If you have a 2.5 Z7U engine, the pistons actually have high thick crowns for strength (so they are basically high compression pistons)..the lowered compression actually comes from Renault shortening the stroke on the GTA turbo by 10mm...
.,.which means, if you stick in the 2.8 crank, it will be running something like 10.5:1 compression, so you have to change/modify the pistons too.
What you can do, is in theory (ive been checking what Venturi done in the past), is fit the Z7X low comp laguna bottom end to the V6 Turbo heads. The GTA heads have a larger dome in the head than the A610, so matched up to that bottom end brings the compression down to 7.3:1
Still lots of work though...