JP4 head, J4 Block.... Questions/Confirmation.

1. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

   #1 6th April 2010, 13:22

   Right guys,
   
   I'm wanting to fit a JP4 head to my J4 block....
   
   Now, I've stripped the head down and I'm wanting to put my J4 cams in. I realise I need to change the springs & spring retainers for my J4 items also.
   
   But I'm ok to leave the rest as JP4 items yarh? Spring seats, Collets and tappets.etc? Because I keep reading that you need to use the J4 tappets but after some research it seems they are the same in both heads so I can't see the point in using the older ones Can anyone confirm this?
   
   
   Also I use the standard 0.6mm JP4 gasket with this block yerh? What pulleys? J4 and a J4 belt?
   
   Muchas Gracias!
2. bluenotesmiley Established Member Joined: May 2008 Thanet, Kent Posts: 1529 White MkII VTS Black MkII VTS

   #2 6th April 2010, 13:37

   I got a belt kit the other day that I ordered for my VTS but it was for JP4 engines too. Went on like a normal J4 belt kit.

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3. raunchz Saxperience Addict Joined: Jul 2005 Solihull / Bournemouth Posts: 14233 2015 Lapiz Blue Golf R

   #3 6th April 2010, 13:48

   j4 pulleys
   
   I'm pretty sure jp4 collets, spring seats are fine to use.
   
   Not 100% about followers. Got some jp4 ones here, I'll have a quick look at them when I get a sec.
   
   j4 belt and idlers/tensioners

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4. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

   #4 6th April 2010, 13:50

   You hero
5. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

   #5 6th April 2010, 13:54

   oooo. What about headgasket?
   
   The bottom end will be running low comp pistons so JP4 gasket will be find yerh?
6. raunchz Saxperience Addict Joined: Jul 2005 Solihull / Bournemouth Posts: 14233 2015 Lapiz Blue Golf R

   #6 6th April 2010, 14:06

   You running a turbo? As might want to fit a slightly bigger hg (oem j4 is 1.5mm) to help you out if inlet temps rise?
   
   Im yet to understand the affect of squish area on combustion so can't comment about just fitting a hugely thich hg to lower compression further.
7. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

   #7 6th April 2010, 14:17

   Will be yes...
   
   I've read over on 106oc that the JP4 head lowers compression slightly anyway. So fitting a J4 gasket will lower it even more. So probably best bet would be to use the J4 so compression ratio is only lowered by the new bottom end.
8. Sophia_Bush Saxperience Post Whore Joined: Jan 2007 Shropshire Posts: 9994 Moonstone Blue 106 GTi

   #8 6th April 2010, 14:27

   use either a 1.6 or 1.8mm mls hg will give you more margain for safety compression wise when boost goes on

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9. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

   #9 6th April 2010, 21:01

   Been searching and reading all day. Still not got a definitive answer.
   
   Waiting on a couple of replies to emails which will hopefully get me somewhere.
   
   
   

   Quote:

   use either a 1.6 or 1.8mm mls hg will give you more margain for safety compression wise when boost goes on

   
   I initially thought this, But assuming I'm lowering compression with new pistons and if.... if the JP4 head lowers compression even more, then fitting a larger gasket is going to lower it another chunk. So I'm going to end up with an engine that doesn't run great when off boost and requires a lot of boost to make power.....
10. Andy_K Saxperience Post Whore Joined: Jan 2004 in the garage trying to fix the car Posts: 5882 Mondeo st tdci & Supercharged vts

    #10 6th April 2010, 21:07

    Finding answers regarding head gasket thickness isn't easy lol. Spoken to a couple of lads on 106oc with turbo'd gti's, and both stuck to the standard J4 hg (1.5mm), if this helps

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11. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

    #11 7th April 2010, 21:50

    Quote:

    Originally Posted by Andy_K Finding answers regarding head gasket thickness isn't easy lol. Spoken to a couple of lads on 106oc with turbo'd gti's, and both stuck to the standard J4 hg (1.5mm), if this helps

    Tell me about it. It's doing my nut in now.
    
    
    Were those guys using a jp4 head on a j4 lump then? As I've spoken to a few guys over there and getting all sorts of bloody answers. Seems to be the only way to find out is to calculate it myself.......
12. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

    #12 7th April 2010, 22:23

    Taken Gav's advice and going to run a 1.5mm gasket.
    
    
    
    Cheers Gentlemen
    
    
    That's all for the moment
13. Sophia_Bush Saxperience Post Whore Joined: Jan 2007 Shropshire Posts: 9994 Moonstone Blue 106 GTi

    #13 7th April 2010, 22:27

    well put it this way dude low comp pistons anyway, bigger cc JP4 head so compression there will go down a smidge aswell and the normal 1.5mm gasket will be fine. In all honesty unless compression dips into the 7s then off boost wise will be fine
14. user_10473 Saxperience Forum Bum Joined: Jun 2006 Swansea Posts: 4946 Bianca White Peugeot 106 S2 Rallye, Saxo VTS

    #14 7th April 2010, 22:29

    Quote:

    Originally Posted by Sophia_Bush well put it this way dude low comp pistons anyway, bigger cc JP4 head so compression there will go down a smidge aswell and the normal 1.5mm gasket will be fine. In all honesty unless compression dips into the 7s then off boost wise will be fine

    Then that's sorted it then!
    
    Cheers mate