Exhaust modification question.

[Tom]

Some of you know i have an "interesting" exhaust on my 182.

If i remove both backboxes and replace with pipe (so its unsilenced) will performance suffer?

Currently the exhaust is manifold -------- < Backboxes
What im thinking of doing is Manifold ------------< or manifold------small silencer---<

Any Thoughts?

 

[fmp_]

the first box in the system is most important, so any after that are just for silencing.

will be pretty crazy loud with no boxes!! lol

 

[Tom]

As i thought, noise isnt really an issue.

I just need to figure out the placement of that first box, i might but the cat back on and run unsilenced.

 

[Hollister]

As i thought, noise isnt really an issue.

Untill you:

a) get stopped by the police if it is a road car

or

b) are unable to take it on track if it isnt a road car

 

[Tom]

For arguements sake why dont we assume i didnt ask the "how loud will it be" question

 

[ben_p]

whos biulding this for you Tom

 

[Tom]

Remsport/TBR

 

[ben_p]

LOL

 

[MillerLight]

you'll get a ASBO!

 

[Tom]

Anyway, am i right in thinking that the initial box should be situated about 40-50cm from the manifold outlet? then from there i shall run 60mm to the rear.

Tempted to not run two outlets to minimise the boom generated from the y-piece.

 

[MarkM]

Anyway, am i right in thinking that the initial box should be situated about 40-50cm from the manifold outlet? then from there i shall run 60mm to the rear.

Tempted to not run two outlets to minimise the boom generated from the y-piece.

Is space (you can fit a bigger silencer under the boot) the only reason why exhausts are silenced close to the the outlet of the system? I have never seen an exhaust with a silencer in the middle and nothing at the back.

Heres a bit of science about it

http://www.lortim.demon.co.uk/vsih/exhaust.htm

Its about bikes but there is some pulse theory in it.

 

[Tom]

Ive no idea, hence the question.

If it was up to me it would be straight through, but im not sure thats best for power.

 

[MarkM]

Ive no idea, hence the question.

If it was up to me it would be straight through, but im not sure thats best for power.

Silencers are a restriction in the exhaust system and increase back pressure so no silencers are better.

What pipe bore are you going to use?

 

[TeZ]

isnt 3" to 3.5 best.

 

[ben_p]

3"!!!!!!!!!!!!!!!!!! 2.5" normally.

3.5" is veron bore

 

[Tom]

Ive no idea, hence the question.

If it was up to me it would be straight through, but im not sure thats best for power.

Silencers are a restriction in the exhaust system and increase back pressure so no silencers are better.

What pipe bore are you going to use?

60mm, i thought back pressure could be ones friend?

Tez shut up.

 

[MarkM]

isnt 3" to 3.5 best.

Too big.

Its pretty complex I think. A bigger bore would give a more peaky, higher bhp but smaller would give better torque.

I think a couple of designs and a bit of dyno time would be useful.

If you arent going to remap it then you want something that works well in the rpm that the standard system makes power in I would have thought.

 

[MarkM]

60mm, i thought back pressure could be ones friend?

This is rpm dependant aswell more backpressure gives better power at low rpm and less gives better power at high rpm.

I suppose a reduction in bore size is a better way of increasing back pressure if you need to.

 

[Tom]

The current exhaust gave me small gains on a local RR i use. (about 6bhp ish at peak smidge more than that lower down.) not bad for £1.47

I will have a play with some pipe setups and post the results.

Shame it sounds so f**king terrible.