Exhaust Questions...
07-29-2002, 07:21 PM
#21
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I didnt say you were dumb, it seems just the opposite, and that you have been misinformed.
Im suprised that they said stuff like that at fresh alloy.... what board on fresh alloy were you on?
Im suprised that they said stuff like that at fresh alloy.... what board on fresh alloy were you on?
07-29-2002, 07:37 PM
#25
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Originally posted by sinfestboy
IT IS BAD
go to a forum that is based purely on performance and aske there... here are a couple
streetracing.org
freshalloy.com
rx7club.com (It may be based on rotaries, but ig you go to the general automotive section, its stuff besides rotaries)
IT IS BAD
go to a forum that is based purely on performance and aske there... here are a couple
streetracing.org
freshalloy.com
rx7club.com (It may be based on rotaries, but ig you go to the general automotive section, its stuff besides rotaries)
07-29-2002, 07:46 PM
#27
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I am on aim...always
Regarding the back pressure for exhausts...
without going into too much detail for NA applications back pressure is nesseary for a few reasons:
It helps create torque, honda engines need as much as they can get. Having the exhaust gases still in the piston chamber at mid and low RPMS increases compression helping keep torque up.
Emissions regulatsions -I say this is bull**** but especially in california this is becoming more and more of an issue. Having exhaust gases still in the piston chamber burns cleaner...a big :fawk: to all you green freaks in office in cali...
As engine RPM increases there is less and less time for exhaust gases to be evacuated from the piston chamber. Fortuantly the intake and exhaust valves are also moving much faster, so while at low RPM back pressure is desired for torque, and a small amount of exhaust gas remains in the piston chamber upping the compression....At high rpms the exhaust is creating such a low pressure zone behind it that it can actually suck intake air all the way through the piston and out the exhaust valve before the exhaust valve closes. This obviously is not desirable so engine designers need to design a cam profile that allows for as much exhaust flow, while minimizing the amount of intake air thats wasted out the exhaust. The back pressure is still always necessary though, without back pressure pulling intake air into the piston chamber, the power is unnecessarly limited.
Regarding the back pressure for exhausts...
without going into too much detail for NA applications back pressure is nesseary for a few reasons:
It helps create torque, honda engines need as much as they can get. Having the exhaust gases still in the piston chamber at mid and low RPMS increases compression helping keep torque up.
Emissions regulatsions -I say this is bull**** but especially in california this is becoming more and more of an issue. Having exhaust gases still in the piston chamber burns cleaner...a big :fawk: to all you green freaks in office in cali...
As engine RPM increases there is less and less time for exhaust gases to be evacuated from the piston chamber. Fortuantly the intake and exhaust valves are also moving much faster, so while at low RPM back pressure is desired for torque, and a small amount of exhaust gas remains in the piston chamber upping the compression....At high rpms the exhaust is creating such a low pressure zone behind it that it can actually suck intake air all the way through the piston and out the exhaust valve before the exhaust valve closes. This obviously is not desirable so engine designers need to design a cam profile that allows for as much exhaust flow, while minimizing the amount of intake air thats wasted out the exhaust. The back pressure is still always necessary though, without back pressure pulling intake air into the piston chamber, the power is unnecessarly limited.
