just thought this was interesting RE:exhausts - Alfa Romeo Forum
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Idea just thought this was interesting RE:exhausts

As most of you have alot more engineering knowledge than me you probably already know this but I thought it was very interesting so here goes

When I went to my local exhaust manufacturers for a custom pipe i told him i was looking for something a little more free flowing than the standard pipe but i didnt want a massive noisy chav thing.He then explained the basic principles of exhaust design to see what exactly i wanted.

A big bore exhaust creates more bhp by allowing the exhaust pressure out faster but only at very high revs does this become a benefit. On the other hand he can make a smaller diameter pipe 3" piping after the manifold to the rear and this creates a higher speed flow of gases which in turn creates a small vaccum in the other manifold pipes and when the other cylinders are opening the exhaust valves the gases escape very quickly as the exhaust is literally sucking them out.

basically this means at low revs a smaller pipe works better and releases power a little easier and at high revs a bigger pipe is better as it allows more flow. I took this as meaning very little difference but some small difference and i chose the smaller pipe with straight through silencers and the difference was noticeable as soon as the exhaust was warm. My car never ever spins the wheels taking off and it has a surge of torque at about 4,100rpm, now it spins unless you take off very very gently at low revs and the surge isnt as noticeable (according to the expert the torque is still there its just spread out more across the rev range).

I knew a bigger pipe wasnt always better but now i know why

hope i havent bored the **** aff yis

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Re: just thought this was interesting RE:exhausts

Glad your happy with your new exhaust Decky

Now get out there and spread the word to all those Chav Saxo and Rice Wagon driving types !!
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