when do you detect the need of a bigger aftermarket plenum and on what application

[The Real Roadrunner]

also if you know so much about what plenum/inlet manifold volumes are required for what power levels care to share some info...?

Im happy to but currently i have waaaaay to much work on to write an essay on the subject.

here is some things to consider to start with

regardless of wether its na or fi 1.5-2X the capacity seems to work reasonably well. but as stated before this is a total volume from the back of the valve to the back of the TB.

generaly speaking the larger the chamber volume the better the distibution to each cylinder will be but this doesn't hold true at all times, and it can cause other unwanted effects.

avoid sharp turns as this creates disruption of airflow which is unwanted.

a belled end flows more than a sharp edge or cut off pipe.

a tapered plenum will help even out ditribution but its not the be all and end all.

having the TB facing in the right orientation (to the runners) and a nice divergent section off the back of it will yeild best results.

Leave short runners for race engines that buzz at 9000+rpm as they dont work well at low revs, 12+inches is the aim if you can fit them (not always possible) and this is from the back of the valve not the head face.

Volume isn't required for power, but having a large and evenly distributed amount of air is, and an inlet manifold should be designed to do this properly, but remember that space constraints will also limit what can and cant be done.



If you have well asked questions im happy to answer them but if i feel like im talking to someone who assumes they already know the answers then i don't bother replying (as there is generally no point)

Cheers
Linden

[jonathan yee]

wicked. thanks. answered all my questions, hope it's answered the OP's

i'll send you pics of my plenum manifold when it's near complete and you can tell me where to shove it if it's a POS