high rpm power mod

[TomsSVX]

Bob, what would your ideal Plenum volume be?? I have been debating whether or not to make a custom one

Tom

[RallyBob]

Originally Posted by TomsSVX

Bob, what would your ideal Plenum volume be?? I have been debating whether or not to make a custom one

Tom

I never got to establish which worked best (on Jack's car) because I didn't modify his intake, an employee who works at XXTuning did the actual work. I was too busy with my own stuff and setting up my shop to work on it. I really *should* CC the plenum before he re-installs it on his car. My original intent was to make it modular, with a bolt-on top 'cover' and spacers, so I could test various plenum volumes on the dyno.

Anyway, my thoughts on the plenum volume for a naturally aspirated engine are 85% to 100% (2.8 to 3.3 litres) of the engine's displacement as a general guideline. I think it's less important on a forced induction engine unless you are really twisting the rpms.

[TomsSVX]

Not talking about my S/C svx I am thinking of doing it for my EG33 Legacy SUS

I see what you are saying though, food for thought, Thanks Bob

Tom

[oab_au]

Originally Posted by RallyBob

It looks externally rather large, but in fact is pretty darn small inside. Most of the space is taken up via the IRIS crossover and by the thick cross-sectional aluminum casting. The true plenum volume is less than 1/3rd the size it needs to be for a true performance engine, IMO.

It does look small, but when you consider that when the throttles are open, the plenum volume includes the two 65mm throttle bodies and the black box in front of them.
The unit you built for Jacks with the filter, would have increased the volume a fair bit.

Harvey.