Two into One Exhaust

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Two into One Exhaust

Postby laffycaffi » Wed Feb 10, 2021 6:50 am

I'm getting close to finally making a decision about this exhaust I want to build out.I just installed some long tube headers and I definitely want to go two into one.

But I wonder... if you join the two into a single pipe, and then into a single inlet for a 1 in, 1 out muffler, do you lose the benefits you see in regard to better airflow, than if you go into 2 inlets into the muffler?

I really like these Magnaflow mufflers but It one comes with a one in, one out configuration. Otherwise, I'll prob go with Flowmaster 40, which has two in, one out.
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Re: Two into One Exhaust

Postby ZOSO » Wed Feb 10, 2021 8:06 am

laffycaffi wrote:I'm getting close to finally making a decision about this exhaust I want to build out.I just installed some long tube headers and I definitely want to go two into one.

But I wonder... if you join the two into a single pipe, and then into a single inlet for a 1 in, 1 out muffler, do you lose the benefits you see in regard to better airflow, than if you go into 2 inlets into the muffler?

I really like these Magnaflow mufflers but It one comes with a one in, one out configuration. Otherwise, I'll prob go with Flowmaster 40, which has two in, one out.


Magnaflow makes a dual/single muffler. The magnaflows are reversible so it can be single in dual out or dual in single out.
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Re: Two into One Exhaust

Postby laffycaffi » Wed Feb 10, 2021 8:26 am

You've answered my question, then!
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Re: Two into One Exhaust

Postby Digger » Wed Feb 10, 2021 12:50 pm

Don't get too hug up on performances losses. Most aftermarket exhaust systems are oversized for the average engine's performance.

I ran 2-1 exhaust, 2.5" diameter all the way with a decent 351W. Never felt like it was missing anything over the 3" exhaust it had prior.

Remember Bronco's are really short too and piping restrictions are a function of length/diameter, so a smaller diameter pipe over a short run will have comparable restriction to a larger diameter over a long run. If you have long tube headers, the 2-1 collector will likey be behind the t-case, the single exhaust from the collector to exit will only be 4-5 ft.

https://blog.tdotperformance.ca/guides/exhaust-back-pressure-how-to-choose-the-correct-exhaust-pipe-diameter/amp/
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Re: Two into One Exhaust

Postby Justin » Wed Feb 10, 2021 9:25 pm

One other benefit to going smaller is packaging and noise. I'm running a 3" and have had a hard time quieting it down. It's OK now, but took some work. You can also get tighter bends in a 2.5" than a 3", so wiggling it around the rear axle is easier.
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Re: Two into One Exhaust

Postby laffycaffi » Thu Feb 11, 2021 6:24 am

Great tips - appreciate it.
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