SA To FB exhaust conversion question.
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Senior Newbie Member
Joined: Jun 2017
Posts: 1,051
Likes: 89
From: Downey California
I think on the stock exhaust you have there are 4 gaskets.
1) Large manifold to engine gasket (same gasket works on iron manifold or aftermarket steel header).
3) 2-bolt football shaped gaskets for joining pipe sections together.
Before you start buying gaskets and paying shipping, find the leak. It could be as simple as tightening a bolt.
1) Large manifold to engine gasket (same gasket works on iron manifold or aftermarket steel header).
3) 2-bolt football shaped gaskets for joining pipe sections together.
Before you start buying gaskets and paying shipping, find the leak. It could be as simple as tightening a bolt.
Last edited by Frogman; Mar 30, 2021 at 05:15 PM.
84SE-EGI helpy-helperton
Joined: Oct 2002
Posts: 3,584
Likes: 542
From: Phoenix, AZ
I don't know how much I can help further, but here goes;
1) the SA mufflers flow better than FB - it has to do with the more restrictive SA-specific Thermal Reactor, And could be why it's louder (*but also has a bit more power, due to a freer flowing exhaust).
B) Your exhaust manifold is an FB and missing the #1 and #2 pre-Catalysts. These are smaller and not fed fresh air, but also not necessary.
iii) Your main (*and only) cat is aftermarket and welded into place. This is normally sent fresh air from the Air Pump and EGR valve, but the port on the side of yours has been welded shut or plugged. If there's still an Air Pump and EGR valve in place,... where is THAT air going? Could be the source of your excess noise.
Four) Everything else is cobbled together and $200 worth of effort. You get what you pay for in this regard. I wouldn't expect any of the stock hangers or gaskets to fit, because the junctions look to be welded with whatever was available.
Funf) Your mechanic gets points for reusing the factory heat shields to try and cover it all up. Most are rusted through or in a ditch by the side of the road because ground clearance...
Regardless, your custom exhaust system needs a thorough inspection to determine the source of the leak. I'm betting it's a missing gasket where the flanges have just been bolted together with nothing between them. I'll also bet it backfires a lot,
1) the SA mufflers flow better than FB - it has to do with the more restrictive SA-specific Thermal Reactor, And could be why it's louder (*but also has a bit more power, due to a freer flowing exhaust).
B) Your exhaust manifold is an FB and missing the #1 and #2 pre-Catalysts. These are smaller and not fed fresh air, but also not necessary.
iii) Your main (*and only) cat is aftermarket and welded into place. This is normally sent fresh air from the Air Pump and EGR valve, but the port on the side of yours has been welded shut or plugged. If there's still an Air Pump and EGR valve in place,... where is THAT air going? Could be the source of your excess noise.
Four) Everything else is cobbled together and $200 worth of effort. You get what you pay for in this regard. I wouldn't expect any of the stock hangers or gaskets to fit, because the junctions look to be welded with whatever was available.
Funf) Your mechanic gets points for reusing the factory heat shields to try and cover it all up. Most are rusted through or in a ditch by the side of the road because ground clearance...
Regardless, your custom exhaust system needs a thorough inspection to determine the source of the leak. I'm betting it's a missing gasket where the flanges have just been bolted together with nothing between them. I'll also bet it backfires a lot,
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