about changing the plenum

**renxun** · 27-06-2007, 02:15 AM

im running a 1jz big single and i was wondering what are the advantage could i gain if i were to change to bigger size plenum? and is there a must to install the over size throtle if i use the oversized plenum? what are the gain could i expect to get from there..?

**ae95** · 27-06-2007, 04:23 AM

depends on how much hp your are making

**renxun** · 27-06-2007, 10:15 AM

currently just slightly above 400whp

**Adrian** · 27-06-2007, 01:21 PM

A bigger Plenum means you will loose some bottom end. But a bigger throttle body will help.
However you will increase your VE (Volumetric Efficiency) meaning you will get some more HP, providing its not to big of course.

**chris davey** · 27-06-2007, 01:33 PM

On the old site, there was a really good tech doc about how much air a given engine would consume at what boost level. Then work out the area of the current TB to determine if it is a restriction or not.

As I said, BIG power has been made on stock plenum and TB. There is probably some gains to be had still though.