exh diameters? you asked , email.
there are computer models for that.
if you have a CAT, it dont matter much. as that missing kills EGR and that kills smog test passing, for high NOX and HC
but in a pure tuning situation, no cat.? you have no cat?
the engines VE can be tuned, with proper sizing of the exhaust. "volumetric Efficiency"
perfect VE is 100% (the engine pumps air at 100% efficiency) 400cc per slug of air. (each piston, 400x4 is 1.6L) just air, when burning fuel this volume is vastly larger.
at low RPMs the EV is already very high with 4 valves per jug.
but at higher speeds and loads (less stock EV) , the exhaust can be tuned 2 ways, diameter and length. it's like a trombone musical instrument.
in fact, some race motors. have say 90% EV at full track speed, so the TUNER, adjusts the exh. tube (2 way), for even greater than 100% VE , sounds impossible but the valve over lap can do that. the exhaust literally sucks (scavenging)
on the intake (a free turbo effect ) but only works at 150mph on a track and at one speed. (as tuned by tuner to do , just exact that,. full power in straight-a-ways.)
for the street a long pipe gives best low end torque. and does long intake (CAI messes that up) (kinda nice on the streets or off road)
and diameter, if you make it too big, you kill scavenging effect. (lost exhaust velocity)
how big is too big. I dont know.
that would take some very expensive dyno time or track time. some guys have this data but is secret and not applicable due to other big changes on motor, displacements/heads or turbo, etc.
1.-5/8 inches (41mm) is perfect, over that is over kill (or worse, lost scavenging) beyond that, is track times, or (dyno) or computer models at 1.6L and YOU pick MAX EV point in RPM.
http://www.exhaustvideos.com/faq/how-to-...eter/#easy
above is with free flowing mufflers.
there are computer models for that.
if you have a CAT, it dont matter much. as that missing kills EGR and that kills smog test passing, for high NOX and HC
but in a pure tuning situation, no cat.? you have no cat?
the engines VE can be tuned, with proper sizing of the exhaust. "volumetric Efficiency"
perfect VE is 100% (the engine pumps air at 100% efficiency) 400cc per slug of air. (each piston, 400x4 is 1.6L) just air, when burning fuel this volume is vastly larger.
at low RPMs the EV is already very high with 4 valves per jug.
but at higher speeds and loads (less stock EV) , the exhaust can be tuned 2 ways, diameter and length. it's like a trombone musical instrument.
in fact, some race motors. have say 90% EV at full track speed, so the TUNER, adjusts the exh. tube (2 way), for even greater than 100% VE , sounds impossible but the valve over lap can do that. the exhaust literally sucks (scavenging)
on the intake (a free turbo effect ) but only works at 150mph on a track and at one speed. (as tuned by tuner to do , just exact that,. full power in straight-a-ways.)
for the street a long pipe gives best low end torque. and does long intake (CAI messes that up) (kinda nice on the streets or off road)
and diameter, if you make it too big, you kill scavenging effect. (lost exhaust velocity)
how big is too big. I dont know.
that would take some very expensive dyno time or track time. some guys have this data but is secret and not applicable due to other big changes on motor, displacements/heads or turbo, etc.
1.-5/8 inches (41mm) is perfect, over that is over kill (or worse, lost scavenging) beyond that, is track times, or (dyno) or computer models at 1.6L and YOU pick MAX EV point in RPM.
http://www.exhaustvideos.com/faq/how-to-...eter/#easy
above is with free flowing mufflers.
http://www.fixkick.com