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How are exhausts designed?

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Ribenapigeon
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PostPosted: 22:29 - 19 May 2013    Post subject: How are exhausts designed? Reply with quote
If you were to make your own exhaust how would you go about designing it?
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Gazza M
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PostPosted: 22:59 - 19 May 2013    Post subject: Reply with quote
get a book! I have one for the formula student team I'm in that we're using, outlines the basic theory of getting the lengths and diameters of the headers right.

Basically it's tuning the lengths so that you get the pressure waves created by the valves opening reflecting back from the end of the pipe. This creates a negative pressure wave which goes back up the pipe, if you time it right it will get to the exhaust port when the valve opens back up which helps suck out the combustion products from the cylinder. You pick the rpm you want this to happen at, and plug in the numbers.

It's not gonna be perfect as everything is idealised as a straight pipe, so there are various corrections you can make for the bends etc.
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haroman666
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Joined: 17 Sep 2008
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PostPosted: 23:03 - 19 May 2013    Post subject: Reply with quote
Gazza M wrote:
formula student team


And which uni-team are you on? Lower down the table than Hertfordshire? Wink haha

I wasn't on my uni-team but I totally know people who are!!! Laughing

(EDIT) Is all in jest my man. Just realised how cocky that sounds Laughing No malice intended!!!
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Ribenapigeon
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PostPosted: 23:06 - 19 May 2013    Post subject: Reply with quote
I found this article https://www.zggtr.org/index.php?topic=960.0

Seems mind bogglingly complex
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Ribenapigeon
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PostPosted: 23:08 - 19 May 2013    Post subject: Reply with quote
Gazza M wrote:
get a book! I have one for the formula student team I'm in that we're using, outlines the basic theory of getting the lengths and diameters of the headers right.

Basically it's tuning the lengths so that you get the pressure waves created by the valves opening reflecting back from the end of the pipe. This creates a negative pressure wave which goes back up the pipe, if you time it right it will get to the exhaust port when the valve opens back up which helps suck out the combustion products from the cylinder. You pick the rpm you want this to happen at, and plug in the numbers.

It's not gonna be perfect as everything is idealised as a straight pipe, so there are various corrections you can make for the bends etc.


What's the title of the book, I may never actually build an exhaust but I like to know about this sort of stuff.
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Gazza M
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Joined: 19 Nov 2010
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PostPosted: 23:14 - 19 May 2013    Post subject: Reply with quote
haroman666 wrote:
Gazza M wrote:
formula student team


And which uni-team are you on? Lower down the table than Hertfordshire? Wink haha

I wasn't on my uni-team but I totally know people who are!!! Laughing

(EDIT) Is all in jest my man. Just realised how cocky that sounds Laughing No malice intended!!!


I'm at Cambridge, we're not that brilliant, it's completely extra-curricular and the department don't seem to like people doing vaguely practical stuff!

And Boozehawk, we have that basically to get the initial calcs done and then can put everything into a simulation program to optimise it all.

Book is called 'Performance Tuning in Theory and Practice: Four Stroke' by A. Graham Bell. Got it for £2.99 off ebay Laughing
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Gazza M
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PostPosted: 23:15 - 19 May 2013    Post subject: Reply with quote
https://www.ebay.co.uk/itm/Performance-Tuning-in-Theory-and-Practice-Four-Strokes-A-Foulis-book-By-A-G-/310611833322?pt=Non_Fiction&hash=item4851e871ea
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Ribenapigeon
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PostPosted: 23:16 - 19 May 2013    Post subject: Reply with quote
Cheers i'll look it up
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haroman666
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Joined: 17 Sep 2008
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PostPosted: 23:22 - 19 May 2013    Post subject: Reply with quote
Gazza M wrote:

I'm at Cambridge, we're not that brilliant, it's completely extra-curricular and the department don't seem to like people doing vaguely practical stuff!


I didn't realise Cambs had a team! My hometown is Cambridge so that's cool.

Like I said, wasn't on the team myself but I'm acutely aware that the FS cars at UH are the love-child of the masters students mainly. There's second and third years that design stuff for the cars but their input is slightly more guided than the masters students and if they don't like it then it doesn't get put on the car!

I'll stop de-railing the thread now Laughing
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Old Thread Alert!

The last post was made 13 years, 41 days ago. Instead of replying here, would creating a new thread be more useful?
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