standard manifold

1. liam-o Established Member Joined: Apr 2009 Posts: 1346

   #1 11th May 2009, 23:01

   looking at my vtr(90bhp version) (heat shield covering the manifold) it looks like a 4-1 but cant see for sure
   
   and why change the manifold, i can only assume its to let the gasses escape quicker, but whats the difference between the standard and a "performance" manifold?
2. user_10418 Saxperience Addict Joined: Jun 2006 Wirral Posts: 13584 Wickerd red VTS MK2, Two tone VTS MK2,vvc Metro..

   #2 11th May 2009, 23:03

   Quote:

   Originally Posted by liam-o looking at my vtr(90bhp version) (heat shield covering the manifold) it looks like a 4-1 but cant see for sure and why change the manifold, i can only assume its to let the gasses escape quicker, but whats the difference between the standard and a "performance" manifold?

   Performance mani"s flow much better...........
3. liam-o Established Member Joined: Apr 2009 Posts: 1346

   #3 11th May 2009, 23:14

   might sound stupid, but why not have 4 branch to 4 exhaust? or 4-2
4. spiderxjz82 Infrequent Poster Joined: May 2008 Northampton Posts: 193 VX220 S/C

   #4 11th May 2009, 23:15

   Doesn't sound stupid. There's a load of reasons why. Mainly due to back pressure. Don't think an engine would run too well letting all cylinders off seperately....
5. liam-o Established Member Joined: Apr 2009 Posts: 1346

   #5 11th May 2009, 23:21

   still not quite grasped back pressure, although i read a post saying the in forced induction engines (turbos ect) the idea is to eliminate back pressure
   
   still cant grasp how having pressure in the system is good,
   
   if theres pressure its because the system isnt letting the gasses out fast enough and the engines pushing more and more out causing the pressure
   
   but if theres none, this means the engine doesnt need to push?
   
   also, is the standard manifold a 4-1?
6. spiderxjz82 Infrequent Poster Joined: May 2008 Northampton Posts: 193 VX220 S/C

   #6 11th May 2009, 23:25

   The standard isn't so much a 4-1, well, it is, but they all merge very early. Very short piping before it branches into 1.
   
   Back pressure - reducing it, is generally good for fluid flow. But sometimes when you have a system such as a 4-2-1/4-1, it can change the characteristics of the flow, allowing freer movement at certain flow rates.

   1 user thanked this post: liam-o
7. liam-o Established Member Joined: Apr 2009 Posts: 1346

   #7 11th May 2009, 23:29

   okay, thanks, i guess ill have to read up more about back pressure to find out more
   
   last thing? the manifold has a heat shield? is this "shield" to stop you touching the manifold or to stop even hotter air getting into your engine bay or what?
8. spiderxjz82 Infrequent Poster Joined: May 2008 Northampton Posts: 193 VX220 S/C

   #8 11th May 2009, 23:33

   Stop warm air going upwards really, keeps heat down. Protects the bonnet area from heat spots. I'm sure in some way it might help performance as well...