Effect of Silencer on engine's performance?

[ibnekhalid]

few days back i had the pipe of silencer broken due to rust. My mechanic has advised me to get the rear "dholki" changed because its life is over. he says that it effects the performance of engine e.g. Pick, Gas consumption........
can any body guide is he right? if yes than HOW it happens?

[bubble]

mechanic is rite coz if you wont fix it, ur car will drink alot of petrol/cng and pick obviously would be lower than its original so change it... and the sound will be changed aswell

[ibnekhalid]

thanks for response, i am interested to know how does it happen?

[ujbhatti]

Hi Khalid,
It happens because more force is required to get the smoke out from the cylinders if your exhaust passage is blocked.
Normally if you have a clean exhaust passage, when the exhaust valve opens the piston easily pushes out the smoke caused after petrol/gas is combusted. If however you have blockage then the piston will use more force in pushing out the exhaust gases and hence you will loose power from your engine going to the wheels as some of it will be used up to force the exhaust out.
Think of blowing air out from a straw. What happens when you block some part of the straw?? You have to blow out the air harder from your mouth to get it through the straw. I hope this calrifies your question.

[Shakills]

^^ ujbhatti is right.
exhaust noise is not related to its performance but it is cause if you more noise mean you have less silencing or clogged exhaust system and car feel very free and more powered due to this easy out flow of gases.

I have expereinced this by removing bikes muffler from silcener, bike runs extra faster. same goes for cars, if i install a new exhaust, it always give extra comfort for the car engine.

[insaan]

if the exhaust gas is free to exit the cylinder, the result would be better performance and WORSE fuel economy because the cylinder will be able to accept more quantity of fresh air in a cycle hence more fuel consumption.
if the exhaust gas experiences some resistance to its flow, then some of it remains within the cylinder forcing-in a lower quantity of fresh air per cycle which results in lower fuel consumption and lower performance.

[ibnekhalid]

@insaan watever u have said that is opposing others opinion. can u elaborate further? thanks