Matching head to a manifold

1. Ste Saxperience Post Whore Joined: Mar 2007 Yorkshire Posts: 5415 Saxo

   #1 9th August 2007, 14:56

   Do all aftermarket manifolds line up with you're head outlets?
   
   Also if you get youre head ported, do you port the manifold where it joins the head... as i cant see any way you'd be able to do the rest!
2. Ryanp Super Moderator Joined: Feb 2004 Tonbridge United Kingdom (England) Posts: 38236 Vtr, 172, throttle bodied track slut

   #2 9th August 2007, 14:57

   not all are the same
   
   eg vtr/vts.
   
   porting a manifold/head together can give very good results.
   
   usually the manifold is allready larger bore than the head so it doesnt need anything other than a slight skimming of the face sometimes
3. Dibz Infrequent Poster Joined: Jun 2006 Posts: 240 106 GTi

   #3 9th August 2007, 19:29

   Ive been thinking of getting my manifold ported ready for when i get my head ported but have been thinking wether its needed due to them having bigger ports than head like said. The problem is not knowing how much the head will be ported and so not able to match head to manifold accurately...?
4. Ryanp Super Moderator Joined: Feb 2004 Tonbridge United Kingdom (England) Posts: 38236 Vtr, 172, throttle bodied track slut

   #4 9th August 2007, 19:29

   you should have the ports on the head matched to the manifold at the same time. so take em to the person doing the headwork if you want this done
5. Dibz Infrequent Poster Joined: Jun 2006 Posts: 240 106 GTi

   #5 9th August 2007, 19:38

   yer true, just mine will be already on in prep for cams and then will prob buy a new cylinder head with the work done from Q.E.P for example. suppose thats not the best way but cant really afford to have my car off the road whilst the work is done
6. Ryanp Super Moderator Joined: Feb 2004 Tonbridge United Kingdom (England) Posts: 38236 Vtr, 172, throttle bodied track slut

   #6 9th August 2007, 19:40

   qep are good at headwork. fantastic infact. they would be able to help with the exhaust ports matching the manifold if you felt it was needed, they would say if it was a waste of time though,
7. Dibz Infrequent Poster Joined: Jun 2006 Posts: 240 106 GTi

   #7 9th August 2007, 19:43

   You rekon head work with cams alone is wasted? i like the idea of getting it done and getting the most from what i have but it is a alot of money...
8. Ryanp Super Moderator Joined: Feb 2004 Tonbridge United Kingdom (England) Posts: 38236 Vtr, 172, throttle bodied track slut

   #8 9th August 2007, 19:45

   personally it depends on how far you are going.
   
   headwork is good to do at this stage if you intend on fitting TBs and stand alone,
   
   what i was referring to being waste of time was the port matching, qep would comment on how much benifit tyhey felt you would get.
9. Dibz Infrequent Poster Joined: Jun 2006 Posts: 240 106 GTi

   #9 10th August 2007, 00:07

   Im not going to bother with TB's, cams will be as far as i will go. Im guessing headwork isnt worth the money if im keeping the standard inlet?
10. user_15989 Saxperience Forum Bum Joined: May 2007 Posts: 4857

    #10 10th August 2007, 08:31

    You do not really want your manifold to match up with your head. You want them to be inline but you want the exhaust to be bigger bore. There should be a step there to act as a gas lock. At least that is one way of looking at it and its the way Peugeot Sport, Citroen Sport, GMC, Longman and what was TMS when they were still about did it. That is one theory on it anyway.
11. Ste Saxperience Post Whore Joined: Mar 2007 Yorkshire Posts: 5415 Saxo

    #11 10th August 2007, 09:51

    Quote:

    Originally Posted by AXracing You do not really want your manifold to match up with your head. You want them to be inline but you want the exhaust to be bigger bore. There should be a step there to act as a gas lock. At least that is one way of looking at it and its the way Peugeot Sport, Citroen Sport, GMC, Longman and what was TMS when they were still about did it. That is one theory on it anyway.

    What does it do?
12. user_15989 Saxperience Forum Bum Joined: May 2007 Posts: 4857

    #12 10th August 2007, 23:23

    Its stops air moving the wrong way. If you look at a river especially if there is a bend just before or just after where your looking you will see that different parts of the river flows at different speeds. If you look closely you will see that in some places the water actually spins round and can even flow the wrong way. Same thing happens with engine gas. The step so close to the valve actually stops the exhaust gas flowing the wrong way and backing up towards the engine. Sort of hard to explain but think you may get what I am trying to say.
13. bullit Saxperience Hardcore! Joined: Dec 2005 e-hollywood Posts: 17160 toyata hilux

    #13 10th August 2007, 23:29

    interesting stuff
14. Dibz Infrequent Poster Joined: Jun 2006 Posts: 240 106 GTi

    #14 11th August 2007, 00:10

    Quote:

    usually the manifold is allready larger bore than the head

    Probably why they do that then..
15. smearsvtr Established Member Joined: May 2007 My House in Burton on trent near derby Posts: 1025 Saxo 1.1 96 Saxo VTR 2000

    #15 11th August 2007, 01:45

    well surely if u do this u could be losing backpressure which could cause it 2 lose power?
16. user_15989 Saxperience Forum Bum Joined: May 2007 Posts: 4857

    #16 11th August 2007, 20:55

    That is the point of the step, Its stops the gasses going things you don’t want them to on a free flowing exhaust system.