standard manifold

[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?

[saxokid100]

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...........:y::y:

[liam-o]

might sound stupid, but why not have 4 branch to 4 exhaust? or 4-2

[spiderxjz82]

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.... :P

[liam-o]

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?

[spiderxjz82]

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.

[liam-o]

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?

[spiderxjz82]

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...