jp4 or just jp4 head?

1. readie Established Member Joined: Oct 2008 leeds Posts: 2430 05' Clio 182

   #1 19th January 2011, 21:46

   is is worth swapping the S engine for the JP4?
   
   i have been looking at jp4 heads but i have been told something silly like: you need the block aswell as they use high comp pistons? and if you use a jp4 head will loose compression?
   
   what are the right comments on this? options?
2. Mochachino Saxperience Hardcore! Joined: Nov 2007 Guantanamo Bay Posts: 28700 oyster card

   #2 19th January 2011, 21:48

   Why do you want a JP4 if its for lower miles and just a standard replacment then may aswell do the whole engine with all the neccesary parts to enable it to work.
   
   If you are going for power then id stick to a full J4 engine, rebuild with larger valves if you like etc.
   
   If you really want a JP4 head then jus get the head but you cant go as wild as easily as on the J4 engine.
   
   Basically!
3. user_9396 Established Member Joined: Apr 2006 torquay (England) Posts: 1993 supercharged vts. 1.1 saxo. accord type r

   #3 19th January 2011, 22:05

   the jp4 valves are bigger but u will need the j4 springs followers collets etc to keep the strength, also the j4 vernier pulleys.
   the j4 has a stronger bottom end aswell so i would keep that.
4. readie Established Member Joined: Oct 2008 leeds Posts: 2430 05' Clio 182

   #4 20th January 2011, 19:37

   Well I'm converting my r engine going to be camming and mapping the engine and was thinking about power gains of the jp4 over all
5. boabVTR Frequent Poster Joined: Jan 2009 isle of bute Posts: 585 project saxo vts, escort gti,

   #5 20th January 2011, 22:07

   ive got alot of the parts you might be after mate. j4 valve springs etc.
6. readie Established Member Joined: Oct 2008 leeds Posts: 2430 05' Clio 182

   #6 21st January 2011, 10:38

   I have everything I would need for a j4 convert but I was wondering if it's worth using a jp4 head for the valves or a full jp4 engine for hi comp pistons
7. axsaxoman Saxperience Forum Bum Joined: Jan 2003 Scotland Posts: 3380

   #7 21st January 2011, 16:22

   jp4 engine does not hahave fully floaitng rods ,thats the other main dif ,but if going mega power +revs you will want forged rods as well
   forged rods + pistons from £750+ vat