Right then .. JP4 conversion

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

   #1 2nd October 2009, 20:30

   right my saxo has just hit 58k and wanting a rebuild next summer... Raunchz will be doing it instead of rebuilding mine he mentioned putting the C2 vts engine in... will have low low miles as the car will be driven hard on the track hence i want a rebuild....
   
   what will need changing and what sort of miles should i get the conversion atm my saxo engine runs fine 3 services in 7k so look after it....
2. TU-Tuning Saxperience Hardcore! Joined: May 2006 Bristol Posts: 16575 JP4urio, 306 DTurbo SportShed

   #2 2nd October 2009, 20:31

   Seems like a good idea, unless you plan on uprating the cams?
3. moxy89 Saxperience Post Whore Joined: Feb 2008 Southampton Posts: 8188 Astra vxr with added boost

   #3 2nd October 2009, 20:35

   well i have cams for the vts (saxo) can i not uprate the cams on a c2 also how hard are jenveys to get.... if it easier to get parts might get the saxo engine rebuilt 65k a good miliage to get it done
4. TU-Tuning Saxperience Hardcore! Joined: May 2006 Bristol Posts: 16575 JP4urio, 306 DTurbo SportShed

   #4 2nd October 2009, 20:38

   Not to the same level, the pistons in the JP4 bottom end are domed and dont have cutouts so you cant fit cams with as high lift as you can with J4 engines. Hence why people run J4/JP4 hybrids; bigger valves, better pistons. JP4 rods are weak too.
   
   
   Depending on your long term plans, with such a well looked after, reliable lowmileage J4 Id stick with that one to be honest.
   
   Not going against Ross' advise though, the guys a ledge
5. moxy89 Saxperience Post Whore Joined: Feb 2008 Southampton Posts: 8188 Astra vxr with added boost

   #5 2nd October 2009, 20:42

   he is a legde. he is always given a helping hand... he does everything to it service the lot i know his work it top... i just want a rebuild just to know the car will last i have no intention to sell it for some while.. espically the look on type R owner when you go past LOL
6. raunchz Saxperience Addict Joined: Jul 2005 Solihull / Bournemouth Posts: 14233 2015 Lapiz Blue Golf R

   #6 2nd October 2009, 20:53

   Yo children !
   
   I was only thinking about moxy's car being off the road whilst his engine is out being rebuilt, instead of just dropping a very low mileage jp4 lump in there.
   
   Ultimately it depends on the desired spec tbh. depending on whether hi comps are being used, then IMO cheaper to buy a low mileage jp4 lump, and use the head off of it (inc. cam covers) and build up a hybrid jp4head/j4 bottom end. Although, could just buy and rebuild a j4 engine, swap it for yours and then sell your old engine on.
   
   Is just £££ though, when you could spend it on a diff car if need be.
   
   I'm happy with my spec at the mo and wouldn't really want to spend a lot more ££££ on the engine itself (ie 734 cams and pistons etc. but tempted with some headwork with the aim of keeping it reliable but good bhp) I'm running a 90k bottom end, rebuilt head with bodies and cams. And touch wood it's been reliable so far (no less reliable than a standard j4 engine IMO).
7. moxy89 Saxperience Post Whore Joined: Feb 2008 Southampton Posts: 8188 Astra vxr with added boost

   #7 2nd October 2009, 21:03

   cause your a saxo whore and can service look after it yourself when mine goes wrong give you a call and just hope your local lol. think the rebuild will happen next summer with jenveys being fitted mate.... best start saving
8. raunchz Saxperience Addict Joined: Jul 2005 Solihull / Bournemouth Posts: 14233 2015 Lapiz Blue Golf R

   #8 2nd October 2009, 21:17

   Quote:

   Originally Posted by moxy89 cause your a saxo whore and can service look after it yourself when mine goes wrong give you a call and just hope your local lol. think the rebuild will happen next summer with jenveys being fitted mate.... best start saving

   IMHO I'd look to keep the engine relatively standard. So maybe get hold of a bare j4 engine, we'll rebuild it, then fit new followers, nice cams (BP285'2,ph3's etc) and then bang some JEnvey's on, Predator, lightweight flywheel and nice xsi gearbox and should be plenty fast enough and still be able to be reliable.
   
   The next jump up is to maybe get the standard piston cut-outs machined deeper/high comp pistons, then maybe look to go for some Newmans PH4's. Should be the ideal time if going for a slightly wilder spec as the engine will be apart/ripe for a slightly overbore (79mm I'd say) and then fit some hi comp pistons and ph4's.
   
   Head wise, from reading, would need uprated springs (no prob to fix as head will be apart anyway)
   
   Could be fun
9. user_4153 Frequent Poster Joined: Oct 2004 Cambs Posts: 630 Vts track car

   #9 2nd October 2009, 22:30

   58k and an engine rebuild? Dont be silly.
   
   I know of race cars being used on 100k+ and still going strong.
   
   Unless you have symptoms of potential problems, spend the money elsewhere.
10. user_16990 Frequent Poster Joined: Jul 2007 Posts: 810 2001 VTS

    #10 2nd October 2009, 22:50

    Anyone had/heard of any issues with valve clearence when using the JP4 head on a J4 bottom end? Standard or uprated cams btw.