Hi,



i'm wondering, what purpose a plenum has and how it effects performance.

the FC manifold does have a plenum, the FD one doesn't.

there are larger plenums, smaller ones...

but why?



could anyone give basic hints about plenums in generall or point me to some useful sources?



thanks



Chris

You need this.....





http://www.amazon.com/exec/obidos/tg/detai...=glance&s=books





A plenum can be tuned to use the pressure pulses created by the intake ports. With the right size plenum and intake runner length, the pressure rises in the intake as the intake ports open to help push more air into the combustion chamber. (this is one super simplified take on it)

Yeah, tyson hit it. The air in the runner hits the plenum, and turns around and fires back at the port. You try to time it so that the returning pulse hits the port at opening.

judging by the reviews it must be a really nice book.

thanks for the hint, guys!



edit: it's pretty old though https://www.nopistons.com/forums/pub...DIR#>/wink.png but i guess it's nice to know the basics

[quote name='Old Splatterhand' date='Apr 29 2005, 09:25 AM']judging by the reviews it must be a really nice book.

thanks for the hint, guys!



edit: it's pretty old though https://www.nopistons.com/forums/pub...DIR#>/wink.png but i guess it's nice to know the basics


[/quote]





THat book is heavy reading for most people. Expect to read and reread if you not familiar with the basics.

the fd manifold does have a plenum, its just not very big.

[quote name='Old Splatterhand' date='Apr 29 2005, 07:14 AM']

i'm wondering, what purpose a plenum has and how it effects performance.

the FC manifold does have a plenum, the FD one doesn't.




[/quote]

Im guessing it has an effect on torque or low end power, cause the cosmo RE has a large one.

[quote name='kahren' date='Apr 29 2005, 12:42 PM']the fd manifold does have a plenum, its just not very big.


[/quote]



In the actual intake manifold there is basically no plentium.





[quote name='RONIN FC' date='Apr 30 2005, 08:39 AM']Im guessing it has an effect on torque or low end power, cause the cosmo RE has a large one.


[/quote]



I dont think big plentiums help so much in the torque department. Long skinny runners are the big helpers there.



im still learning so...

plenum is a plenum, small or large its there

[quote name='TYSON' date='Apr 29 2005, 08:40 AM']You need this.....

http://www.amazon.com/exec/obidos/tg/detai...=glance&s=books

A plenum can be tuned to use the pressure pulses created by the intake ports. With the right size plenum and intake runner length, the pressure rises in the intake as the intake ports open to help push more air into the combustion chamber. (this is one super simplified take on it)


[/quote]





Bah, that book had one picture of a plenum intake as something new and futuristic. Overall was not impressed.