Exhaust questions

[YaBoyKingsley]

Hi guys I have a 78 brat that I’m putting a ea81 into and I noticed a hose going from the carberator to the manifold I want to know what this kind of system is called and I have a set of headers being made without that how does that effect emissions I can’t get out of them and please leave me a good catalytic converter and muffler combo for sound

[Knucklehead Saloon]

Thats tye EGR system. Exhaust Gas Retriculation. When new they take clean air from the air cleaner and stick it into the exhaust header to help combust unburned hydrocarbons coming from the motor. Lowers emissions.

 

When the EGR is old and stuffed (like mine was) the damn thing works in reverse and sucks exhaust fume and shoves it into the air cleaner. Engine suffers big power loss.

 

System I just got made has 1-3/4" headers into a narrow angle 2" collector. From there a 2"cat, 2"pipe, 2" resonator, 2" open chamber muffler.

 

Any bigger than 2 or 2-1/4 and you drop exhaust gas speeds to low and lose power from reduced scavenging effect.

[YaBoyKingsley]

Thank you so much and does a resonator does that muffle the sound at all sorry I’m 18 and I bought a brat for a project so I don’t know much about the exhaust system

[bratman2]

Magnaflow, they make a SS header with cat already in it. Then add a SS Magnaflow straight thru oval muffler. Don't remember the part number but I will try and look it up for you. That is what i am running on my 87 now. Sounds relatively quiet in the cab and pretty good outside when someone pulls away with it.

[Gloyale]

Thats tye EGR system. Exhaust Gas Retriculation. When new they take clean air from the air cleaner and stick it into the exhaust header to help combust unburned hydrocarbons coming from the motor. Lowers emissions.

 

 

 

That's not EGR.  Or how the EGR works at all.  Exhaust Gas Recirculation.  Not fresh air to exhaust.

 

Recirculates some exhaust back into the intake manifold to be burned.  EGR goes from port on exhaust of #3 cyl back into the manifold.  Lowers cylinder temps but does nothing directly for emissions.  Lower temps do reduce Oxides of Nitrogen (NOx)

 

 

What you described (fresh air supplied to exhaust) would be the ASV (air Suction Valve) system.  

 

 

But I I believe what he's talking about here is the warm air hose that was supposed to give warm air to the air filter box until warmed up, then a flap in teh air filter would switch and allow "cold" air from behind/near the fender.  about 2" diameter goes from a fitting on the exhaust pipe near pass CV and goes to the underside of the air filter snout.

[DaveT]

+1 Gloyale

[Knucklehead Saloon]

Ahhhhh thanks for that gloyale ! I get it now.

 

To the OP.. a resonator changes the exhaust note frequency (basically busts up the sound waves a little). Its job is to reduce droning sound coming from the exhaust.

[YaBoyKingsley]

Thank you so much guys

[YaBoyKingsley]

 

Magnaflow, they make a SS header with cat already in it. Then add a SS Magnaflow straight thru oval muffler. Don't remember the part number but I will try and look it up for you. That is what i am running on my 87 now. Sounds relatively quiet in the cab and pretty good outside when someone pulls away with it.

Any chance you could leave a sound clip