why the different plunums

[xxxscimitarxxx]

sure this is not a new question but ouldnt find an answer in search

why is there a difference....is one better than another

[LGAFF]

Stock one on the left has individual runnners, the one on the right has had the primary and secondary runners merged together or siamesed for greater flow. The siamesed runners are not a stock option, most were done by Jeal or other tuners.

[Locobob]

The full siamese plenum pictured on the right can support a higher volume of air than the stock plenum casting will allow. It is a fairly pricey mod and is best suited for use on highly modified engines - usually strokers.

[Kevin]

wait till ya throw in the dropped plenums

[blackjack]

dropped plenum ????
bj

[billybaloneey]

The full siamese plenum pictured on the right can support a higher volume of air than the stock plenum casting will allow. It is a fairly pricey mod and is best suited for use on highly modified engines - usually strokers.

No one ever responded to the question about, "What is a dropped plenum?" Can anyone describe the difference between a dropped and stock plenum? Anyone have a side by side picture of a dropped and stock plenum?

Also, are siamesed plenum's made from stock plenum's with aluminum/metal filler, or some type of fiberglass or bondo as a filler in the valley's between the runners? Are siamesed plenum's...besides the runners...typically ported also?

[Locobob]

No one ever responded to the question about, "What is a dropped plenum?" Can anyone describe the difference between a dropped and stock plenum? Anyone have a side by side picture of a dropped and stock plenum?

Also, are siamesed plenum's made from stock plenum's with aluminum/metal filler, or some type of fiberglass or bondo as a filler in the valley's between the runners? Are siamesed plenum's...besides the runners...typically ported also?

A dropped plenum has extra internal volume added to it by cutting out part of the bottom section and welding it back together with some added material. I don't have a pic handy but it kinda resembles a deep sump oil pan.

A fully siamesed plenum is made by cutting out the outside center sections of the two side by side runners then welding in some curved sheet aluminum in its place. Some have metal filler added to the outside to smooth out the appearance. Typically these types of plenums have some agressive porting involved as well.

Here are a few pics of a full siamese job in progress.

http://i418.photobucket.com/albums/pp270/locobob68/KevinPietro001.jpg

http://i418.photobucket.com/albums/pp270/locobob68/KevinPietro002.jpg

http://i418.photobucket.com/albums/pp270/locobob68/KevinPietro004.jpg

[xxxscimitarxxx]

I thought l had thrown in a post on the dropped plenum....but it seems to have vanished

see the DRM website and the pic of the LT5 with the huge injector ram pipes ..... pretty sure they are on a low 'dropped' plenum

[Kevin]

No one ever responded to the question about, "What is a dropped plenum?" Can anyone describe the difference between a dropped and stock plenum? Anyone have a side by side picture of a dropped and stock plenum?


dropped plenum does the same thing. the lower part of the plenum is cut and rewelded to make it a larger volume of air that can be moved through it.

[scholtmj]

Found these pictures online of the motor Corey Henderson built for Bonneville. Siamese ports and dropped plenum. Hope he doesn't mind me posting these!

http://i398.photobucket.com/albums/pp64/speedweek/P1010288.jpg

http://i398.photobucket.com/albums/pp64/speedweek/P1010293.jpg

http://i398.photobucket.com/albums/pp64/speedweek/P1010294.jpg

http://i398.photobucket.com/albums/pp64/speedweek/P1010295.jpg

[Polo-1]

FrankenPlenum

[xxxscimitarxxx]

re the DRM intake....not a dropped plenum as l said....

Now for that l would cut a hole in my hood :-D

[Jeffvette]

re the DRM intake....not a dropped plenum as l said....

Now for that l would cut a hole in my hood :-D

Used in the Lotus Elise GT race car. Flat plane crank as well.