Plenum Chamber Size... - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

XESpakman · 06-20-2003, 03:36

Can anyone tell me what altering the size of the plenum chamber and length of my intake tubes will do? I have an XF BTW.
Thanks

qwikcorty · 06-20-2003, 22:34

i dunno about the plenum for NA cars, but turbo cars apparantly love lots of plenum volume. dont ask me why.
longer runners will give u added torque down lower and shorted runners will give u added power higher in the rpm range.
look at the ef-ba falcon 6 cyl inlet manifolds, they are pretty good, long runers down low-3800 and switches to short runners above 3800.
i think its 3800 anyways.

XESpakman · 06-23-2003, 01:22

cool. thanks
does anyone know what changing plenum chamber size does?

gm dstroya · 06-23-2003, 02:13

for n/a work go for a plenum thats 4.1 lt

general rule of thumb is for n/a you have equal plenum volume to the engine cappacity
for tboost situations you should run an extra 50 % capactiy in plenum so for the 4.1 you then have 6.1 or so litre's

for exteme boost applications you run a plenum thats 2 times the cappacity of the engine so thats 8.2 lts.

runner lengths.

the longer you have them the more tourqe you will have in the lower rpm range the shorter they are the more power you will devlop in the high rpm range.

i'd suggest a 8-10 inch (from the face where the manifold meets the head) long runner for a good balance of tourqe/power

cheers.joe.

madmelon · 06-23-2003, 02:42

what is the plenum chamber and where is it?

gm dstroya · 06-24-2003, 04:17

plenum chamber is the box that the throttle body attaches to and the pipes on the inlet manifold go in to

XESpakman · 06-25-2003, 02:39

Why should the plenum be the same size.
The stock plenum only looks 1.5 to 2 litres.