exhaust question
10-22-2008, 09:53 PM
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exhaust question
with a stage 2 and aem cold air intake
my math puts that at about the same air displacement as a 4.0 liter
what size exhaust would have enough flow?
wat about headers? and a downpipe, wat can i leave stock
my math puts that at about the same air displacement as a 4.0 liter
what size exhaust would have enough flow?
wat about headers? and a downpipe, wat can i leave stock
10-22-2008, 09:55 PM
#2
2.5" cat back diameter would be best for over all power range.
Mangaflow would be a good choice....
http://www.turbotechracing.com/produ...idproduct=2699
Mangaflow would be a good choice....
http://www.turbotechracing.com/produ...idproduct=2699
10-22-2008, 09:59 PM
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2.5" cat back diameter would be best for over all power range.
Mangaflow would be a good choice....
http://www.turbotechracing.com/produ...idproduct=2699
Mangaflow would be a good choice....
http://www.turbotechracing.com/produ...idproduct=2699
that was quick
Thanks
10-22-2008, 10:30 PM
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Ummmm... the order of importance for replacing the stock exhaust to increase flow is: Downpipe/Header/Catback. The stock downpipe is the single most restrictive piece in the exhaust and will net you the most total gains by replacing it.
Also, if your calculating your 'Air Displacement' from the fact that you are hitting ~15psi, then your totally off in left field bro. You have a positive displacement supercharger. Your psi comes about from the total air moved by the supercharger per rpm divided by the total flow of the engine per rpm.
With the Stage 2 pulley, your flowing a touch over 2l per engine rpm from the supercharger (not actually, but we'll ignore all the varies efficiencies for ease of explanation). Your engine can flow 1l per rpm without doing anything to improve it. There are some minor varibles in there (running out of cam at higher rpms, head flow limits, intake manifold flow limits, exhaust flow limits, etc), but overall that is what you got.
Quick math now. SC flow / Engine flow, (result * 14.5)-14.5 is what your boost gauge would read.
Sooooo... on average you would get 14.5psi. Real world, it will start lower then that and raise higher on the LSJ since the LSJ will be bumping all those flow limits at higher rpms. So figure 13.75~15.25 will showup throughout WOT.
Now, lets say that we increase the SC flow to 2.15l (stick a 2.9" pulley on it) and increase the engine flow to a touch over 1.1l. Math comes out to 13.75psi. Range would be 13~14.5 through WOT.
Second one flows more air and has more power, while having less boost. My car could be the second example, though my psi actually reads lower then that (12.5~14.25 through WOT).
Also, if your calculating your 'Air Displacement' from the fact that you are hitting ~15psi, then your totally off in left field bro. You have a positive displacement supercharger. Your psi comes about from the total air moved by the supercharger per rpm divided by the total flow of the engine per rpm.
With the Stage 2 pulley, your flowing a touch over 2l per engine rpm from the supercharger (not actually, but we'll ignore all the varies efficiencies for ease of explanation). Your engine can flow 1l per rpm without doing anything to improve it. There are some minor varibles in there (running out of cam at higher rpms, head flow limits, intake manifold flow limits, exhaust flow limits, etc), but overall that is what you got.
Quick math now. SC flow / Engine flow, (result * 14.5)-14.5 is what your boost gauge would read.
Sooooo... on average you would get 14.5psi. Real world, it will start lower then that and raise higher on the LSJ since the LSJ will be bumping all those flow limits at higher rpms. So figure 13.75~15.25 will showup throughout WOT.
Now, lets say that we increase the SC flow to 2.15l (stick a 2.9" pulley on it) and increase the engine flow to a touch over 1.1l. Math comes out to 13.75psi. Range would be 13~14.5 through WOT.
Second one flows more air and has more power, while having less boost. My car could be the second example, though my psi actually reads lower then that (12.5~14.25 through WOT).
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