what is the main function of the lower and upper intake manifolds?why are there 2?what function do they serve besides flowing air?

thanks

 

umm. what year is it and na or turbo??

 

1990 turbo rx7

 

it's just an intake as far as i know. i think only the NA's had the cool stuff. It is an uim and a lim so it is easyer to remove and put back on becouse of the 180 it makes out of the engine.

 

Someone got ahead and correct me if I am wrong. There are a few reason that you need the UIM and LIM. First the manifolds provide provide the place for the secondary fuel injectors. I also believe that the intake manifolds are designed in way almost like the exhaust manifold/headers. How the intake manifolds are designed are the length, width up them, not only attempt to keep the intake velocity of the air at the optimum level, but are also pulse tuned for the car and the engine that they are in. Sorry, this is very brief, but you question is very broad, I am sure someone here could get you a very excellent and technical description.

 

To cast those in one piece would have been a bitch too.

 

i thought only the NA's had the hole dynamic chamber, pulse wave system.

 

The S5 NA had the VDI system on them if thats what you are refering to.

 

the VDI is a more advanced form of what the S4 has but he has a TII intake that dose not have this system.

 

You still would need a tuned intake. There are still flow, velocity and pulse waves to deal with, its just more crucial on an NA.