Humbug
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 posted on 2/11/07 at 10:13 AM |
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Silencer positioning
I am thinking of changing my cattd stainless silencer for something like an R1 carbon can.
Currently the silencer is in the "normal" position, i.e. alongside the cockpit, but it struck me that a smaller can would probably fit
along the angled side of the engine bay - advantage would obviously be that passengers are less likely to be burned on entry/exit  . Also, a bit less
pipework will weigh less...
Assuming that the can doesn't stick out beyond the outside edge of the wheels, is there any reason why this might not be a good idea? The only
thing I could think of is that the exhaust will exit in front of the cockpit so fumes could blast the occupants, but I am pretty sure I have seen pics
of a BEC (Toniq?) with the whole can inside the engine bay and just the end pipe poking through the side. Also, I would have thought that the fumes
are more likely to blow backwards, rather than up.
Thoughts anyone?
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twybrow
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| posted on 2/11/07 at 10:21 AM |
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I would be concerned with the length of the pipes if you move the silencer closer to the engine. Exhaust gas scavenging can play a major part in
performance, so too short a length could impact that. Best bet, find a book on exhast design (or the forula for primary legnth) and work out the
optimum length for your application.
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Hammerhead
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| posted on 2/11/07 at 10:21 AM |
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amazing!!
I was thinking the exact same thing this morning for my 1.8 K series.
I'm as interested as you in peoples thoughts on the subject.
A lotus elise has short pipes due to the mid engined layout. I could measure them on my elise and let you know as a guide to minimum length.
[Edited on 2/11/07 by Hammerhead]
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Humbug
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| posted on 2/11/07 at 10:54 AM |
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quote:
Originally posted by Hammerhead
amazing!!
I was thinking the exact same thing this morning for my 1.8 K series.
I'm as interested as you in peoples thoughts on the subject.
A lotus elise has short pipes due to the mid engined layout. I could measure them on my elise and let you know as a guide to minimum length.
[Edited on 2/11/07 by Hammerhead]
That would be great - thanks (my K is only a 1.4, but still useful info) - I guess the rough length from the output end of the precat to the inlet of
the can would be what I am after
Cheers
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mistergrumpy
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| posted on 2/11/07 at 11:02 AM |
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Calvins car also had the exhaust all under the engine with just a rolled lip protruding. I think he's withdrawn all his pictures though.
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graememk
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| posted on 2/11/07 at 11:10 AM |
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calvinx's car also had buggered body work near the exit as well.
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mistergrumpy
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| posted on 2/11/07 at 11:20 AM |
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Yea I bet it would play hell with the gel goat and all them carbon deposits would't be great
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bimbleuk
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| posted on 2/11/07 at 11:41 AM |
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RE: The Elise exhaust
Upgraded manifolds usually lengthen the primaries right under the engine.
The exhaust goes through a CAT, turns 180deg, through the silencer, then 180 and another 90 to get out the back. So in total its probably longer than
a typical 7 system.
I tried an exhaust with a silencer where the CAT normally is which just exited downwards after. Only problem with it was the noise so I went back to
the factory layout in the end.
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Hammerhead
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| posted on 2/11/07 at 11:46 AM |
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340r rear
You are right probably is longer than a seven as headers are closer to the front of the car and the bends create more length (see 340r pic).
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Humbug
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| posted on 2/11/07 at 12:00 PM |
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cheers
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907
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| posted on 2/11/07 at 04:09 PM |
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Hi All
A couple of points....
If a packed can were to be used it would get hotter and possibly burn the packing quicker.
Shorter runs tend to give a higher note.
I'm a lover of the deep throaty growl myself.
Atb
Paul G
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RazMan
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| posted on 2/11/07 at 04:18 PM |
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Apart from the scavenging aspect you will probably find that shorter headers will make the exhaust note louder and more 'waspy'.
I recently extended my tail pipe (courtesy of 907) by 500mm to a central exit and the sound got much deeper as a result.
A bit like a musical instrument really - the longer the tube, the deeper the sound.
LOL - talk of the devil Paul
[Edited on 2-11-07 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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MikeRJ
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| posted on 2/11/07 at 04:31 PM |
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quote:
Originally posted by Hammerhead
A lotus elise has short pipes due to the mid engined layout.
And they aren't very effective because of it. My brothers just fitted a Piper 4-2-1 on his Elise, and the primaries are hugely longer than the
Rover manifold. He reckons the difference in performance is significant, and it's not even been remapped yet (running an Emerald ECU).
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907
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| posted on 2/11/07 at 04:34 PM |
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quote:
Originally posted by RazMan
LOL - talk of the devil Paul
Hi Raz
Hey! Less of this "Devil" business.
You must be getting me mixed up with my Mother in Law 
It was her birthday this week. Well, it was Halloween.
Paul G
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