JP4 head (engine rebuild)

1. moxy89 Saxperience Post Whore Joined: Feb 2008 Southampton Posts: 8188 Astra vxr with added boost

   #1 12th December 2009, 15:11

   Right i want my engine rebuilt in the summer.... and i am debating to rebuild my current engine with 61k on it or put a jp4 engine in it..
   
   although my car has a low miles and is serviced every 3kish... i am considering bodies and cams. prob piper 285 so i want my engine to be sound before i fit them...
   
   putting the jp4 engine is just a start swap ? what gains would i see just from putting a JP4 head onto my saxo bottom end cheers
2. Boyes Regular Poster Joined: Apr 2008 Sheffield Posts: 276 Peugeot 106 GTi, Clio 172

   #2 12th December 2009, 16:25

   Couldn't say a particular BHP gain but... They have considerably larger valves as shown here.
   
   Not my picture btw steffrallye's.
   
   So when going for more bhp could be handy having the larger valves.
3. Sparco_Tom Saxperience Addict Joined: Jan 2007 Aylesbury, Bucks Posts: 12836 Yeaaahh Fiesta

   #3 13th December 2009, 13:51

   jp4 heads have a better flow rate down to the valves being bigger. The quicker the mixture can run its cycle the better