Simulating an Entire Car Engine (yes, it makes noise) [video]

Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by sakopov on Saturday August 06, 2022 @12:26PM (#32369450)

I think it's the length of the headers that contributes to the sound (I'm sure in combination with other components). I know the boxer engine in Subaru WRX/Impreza STI models has unequal length headers which allowed exhaust fumes to exit in a staggered pattern producing the iconic Subaru rumble.

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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by Tempest1981 on Saturday August 06, 2022 @01:45PM (#32370088)

Is this "curly exhaust" idea a new thing?

"Why are the 2023 Acura Integra's Exhausts Are Shaped Like Curly Fries?"

https://www.integratalk.com/threads/why-are-the-2023-acura-i...

Excerpt:

By snaking the exhaust piping into that circular route, Honda is lengthening the exhaust pathway, lowering the resonance frequency without using a traditional muffler . Honda engineers tell us that the design as first installed in the Si also emphasizes the 300Hz to 600Hz frequencies "to deliver a more aggressive sound." Skipping the muffler, Honda also was able to achieve that sound with a 27-percent increase in exhaust flow.

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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by olivermarks on Saturday August 06, 2022 @02:16PM (#32370345)

It's very common for aftermarket exhaust headers to be a spaghetti of equal length curved tubes into a collector for better flow. Lots of videos on this discussing specific engine types and goals. I'm assuming Acura are taking this approach further down the exhaust system as well?

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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by ericbarrett on Saturday August 06, 2022 @03:36PM (#32370899)

I imagine fluid modelling with all the variables needed to meet manufacturing requirements (material, space constraints, across RPM ranges, etc.) and the speed to allow an engineer to iterate the design—keeping up with integration requirements—hasn't been practical until recently.

I bet this saves the money, too; a muffler is an extra component you need to source and/or build. Bending some extra pipe seems a lot cheaper.

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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by tekknik on Sunday August 07, 2022 @07:52AM (#32375768)

> I bet this saves the money, too; a muffler is an extra component you need to source and/or build. Bending some extra pipe seems a lot cheaper.

Now hold on, extra length on the exhaust manifold / headers are not going to reduce sound so much you don’t need a muffler. And the muffler is far from the most expensive part in the exhaust system, which would be the catalytic converter.

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Re:Simulating an Entire Car Engine (yes, it makes noise) [vi... by Gordonjcp on Saturday August 06, 2022 @02:50PM (#32370578)

The aircooled flat-four in the Citroën GSA had a grapefruit-sized resonance chamber on one exhaust manifold to match up the exhaust pulse timings between the left and right bank. It also revved to about 8000rpm, which was hilarious away from the traffic lights.

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