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Throttle body sizing, twins?
Posted: Thu Aug 24, 2006 11:38 pm
by spetz
At what size is the TB too big for a 6A12?
I am thinking of cutting the plenu, getting rid of the twin length butterflies, welding a new plenum on, with the match ported and shortened runners and using 48mm TB per side of the plenum
Thoughts?
Posted: Fri Aug 25, 2006 2:21 pm
by SG
affects drivability heaps if you have too many throttles afaik, duno the limit though, you could get 6 pack throttles but you wouldnt have a bottom end rev range
a guy i know has had 4 pack throttles and vowed never to go back because the car was undriveable below ~3k rpm. not sure what he meant by undrivable, maybe it would stall due to low vacuum or something while on load.
Posted: Fri Aug 25, 2006 6:21 pm
by spetz
hmmm...
Though 6 pack is a bit different to just two 48mm
Does anyone have a calculator type thing that can calculate the total open area of two 48mm?
ie it is equal to single XXmm opening?
Posted: Fri Aug 25, 2006 6:27 pm
by SG
96....
its only air going thru the measured part afaik
Posted: Fri Aug 25, 2006 6:34 pm
by Bennoz
Go postal! 1 per cylinder!
Posted: Fri Aug 25, 2006 6:46 pm
by spetz
SG wrote:96....
its only air going thru the measured part afaik
haha you know you don't just add them to get that figure?
There is a special formula!
Posted: Tue Aug 29, 2006 9:52 am
by Dras
little bit a math for yal
area of a circle = pi * r * r
for 48mm the area is 1809 mm squared
if you have 2 you get 3619 mm squared.
This is the same as a single 67.88mm throttle body.
Unless you can get this mod done real cheap I would think a 65 mm or 70 mm single throttle body to be a more economical mod.
Posted: Wed Aug 30, 2006 3:15 am
by spetz
The twin setup isn't just for the sake of tb size though
It means I also get a better flowing plenum made, faster air speed from 2 smaller throttle bodies, shortened runners and getting rid of the butterflies in the runners