88lxi-shortram
10-14-2013, 08:57 AM
i was surfing through prelude power earlier and found this write up on how tb spacers arent worth buying but instead modifying the plenum is the key to increase volume. my question is has anyone ever done this?5539
quoted from the page:
adding volume to the plenum will usually produce gains in power.
but the location of where the volume is added is what gives it that bump in power, caused by less turbulence mainly. adding plenum volume at the TB mounting location really doesnt do anything at all.
the best way to add plenum volume and actually see a gain in power is to cut the webbing out of the plenum, then round off or knife-edge the edges of the ports in the top of the butterfly plate. then have a custom spacer made to go between the butterfly plate and the plenum to raise the plenum up a bit, making sure the spacer does not have webbing either of course; only the surrounding border.i hadn't fully finished yet when that pic was taken, but you get the idea. then make a spacer that is the same exact shape as the mating surface of whats left on the plenum.
the benefit of this is that the runners will now be able to gather air from a broader angle due to the plenum surface above the inlets being further from the actual inlets. remember, air has momentum, and it doesnt like taking sharp turns when there isnt something to physically guide it through those turns. so by raising the plenum further from the runner inlets, you are allowing the runners to gather air from a larger chamber, and in a more direct line of motion instead of being forced to suck from the side and making the air curve more than it wants to
quoted from the page:
adding volume to the plenum will usually produce gains in power.
but the location of where the volume is added is what gives it that bump in power, caused by less turbulence mainly. adding plenum volume at the TB mounting location really doesnt do anything at all.
the best way to add plenum volume and actually see a gain in power is to cut the webbing out of the plenum, then round off or knife-edge the edges of the ports in the top of the butterfly plate. then have a custom spacer made to go between the butterfly plate and the plenum to raise the plenum up a bit, making sure the spacer does not have webbing either of course; only the surrounding border.i hadn't fully finished yet when that pic was taken, but you get the idea. then make a spacer that is the same exact shape as the mating surface of whats left on the plenum.
the benefit of this is that the runners will now be able to gather air from a broader angle due to the plenum surface above the inlets being further from the actual inlets. remember, air has momentum, and it doesnt like taking sharp turns when there isnt something to physically guide it through those turns. so by raising the plenum further from the runner inlets, you are allowing the runners to gather air from a larger chamber, and in a more direct line of motion instead of being forced to suck from the side and making the air curve more than it wants to