Dual exhaust

[85ranger2.8]

Our project ranger continues to evolve and now that the heads are off and just back from the machine shop, I am wondering if there would be any benefit to a 2.8 by running dual exhaust? It has been durasparked and all the smog stuff is gone. If I could find some inexpensive headers or a boneyard 86' aerostar anywhere (nowhere to be found in my area), I would maybe do it while everything is torn down. Has anyone tried that and if so, are the benefits worth it? Any suggestions would be appreciated since we need to decide pretty quickly. Thanks!

 

[RonD]

There are no benefits, performance wise , assuming single exhaust system is done correctly.
Benefits of single exhaust is cost, one muffler, one Cat converter, one pipe
Benefits of dual exhaust are sound and looks, you can also get a benefit in ground clearance since exhaust pipe doesn't need to cross-over to one side


Exhaust systems need to evacuate the exhaust without impeding the flow, so no back pressure, no 4 stroke engine runs better with back pressure, a myth.

Tuned exhausts use smaller pipes at the heads to create a velocity into a larger pipe(collector), as the smaller pipes exhaust velocity reaches the larger pipe there is a pressure drop, like a siphon action, this drop in pressure effects the other pipes on that same collector, this creates a lower pressure at the exhaust valves on that bank of the engine.
This lower pressure "pulls" exhaust out when exhaust valve opens, so less engine power is used to "push" exhaust out, this leaves more power in the crank and so rear wheels.
This is called a scavenging exhaust, it doesn't require anything but the math to figure out pipe sizes and lengths.
BUT.......this scavenged lower pressure is specific to an RPM range, so headers can be designed for low RPM range, mid-range and high-range, they get lowest pressure at lower, mid or higher range, can't have all 3, lol.
Factory exhausts are designed for mid-range, most headers are designed for low range but you need to check, racing headers are designed for high RPM range.

The Myth of back pressure comes from factory scavenging exhausts, people would install larger pipes on the heads, "free flow" system, this would lower the velocity so remove the scavenging effect of lower pressure.
When they went for a test drive they found they had less power, their conclusion was "this engine must need back pressure".
Results were correct, if you remove scavenging exhaust you will lose that extra power, but their conclusion was wrong.

 

[85ranger2.8]

I think we'll keep it as is

Wow, thanks Ron. You always have such great and detailed information and I appreciate your willingness to share it! Thanks again! (and again and again, lol)