performance exhuast..not so?
Discussion
i run a supercharged golf g60 , its had a jetex stainless system on it for ages , 2.5 " bore and rather loud
id been feeling a bit of a chav with it being soo loud and a good deal came up on a genuine vw complete system (2.25"bore)
swapped it on and its near silent compared to this other one , what suprised me more is it feels way more rapid in the mid range and just as good everywhere else, id feared it might dull the performance a little
anyone else found the same , im thinking vw's design peeps probably do know more than a couple of lads in a shed with a few universal silencers and a welder lol
id been feeling a bit of a chav with it being soo loud and a good deal came up on a genuine vw complete system (2.25"bore)
swapped it on and its near silent compared to this other one , what suprised me more is it feels way more rapid in the mid range and just as good everywhere else, id feared it might dull the performance a little
anyone else found the same , im thinking vw's design peeps probably do know more than a couple of lads in a shed with a few universal silencers and a welder lol
The back box fell off my Dturbo and it ended up needing a new midsection too. Definitely seemed keener to rev with the new bits on. Exhaust dynamics are a pretty complex thing
Strangely I couldn't hear any difference in tone or volume running without the muffler - same old spanners in a tumble dryer soundtrack!
Strangely I couldn't hear any difference in tone or volume running without the muffler - same old spanners in a tumble dryer soundtrack!
Edited by collateral on Friday 11th June 19:20
small DOHC engines usually need the back pressure to circulate the exhaust gasses properly. You gain at the top end but lose out at the middle and bottom with a free flowing exhaust.
Cam in block engines or turbo engines generally want as little back pressure as possible as free up power throughout the rev range
Cam in block engines or turbo engines generally want as little back pressure as possible as free up power throughout the rev range
Gather round for a little bit of exhaust knowledge...
Backpressure is never good for any exhaust system, despite what the staff writers of Max Power say.
An ideal high power exhaust is open headers out of the side of the bonnet, but as people don't just want high power all the time, and the noise, they do a lot of pipe tuning.
In the midrange, the manifold design is planned to collect the individual pulses of exhaust gas from each cylinder and release them into the rest of the system with perfect timing.
In between these pulses is an area of low pressure, and this low pressure is also timed to bounce upto an exhaust valve as it opens.
This low pressure helps suck out the gasses and increases the volumetric efficiency, which is the amount of fuel/air mix it can get in.
The finely designed system does have to cover a few other tasks, namely quiet and cheap, so there is a little conflict between them.
A decently designed exhaust addition will play off these against the power, a badly designed fart can can kill the fine tuning but just make it sound louder, and therefore well fast mister.
If people actually notice the loss, they'll put it down to the loss of backpressure, but it's down to the well planned exhaust tuning.
Backpressure is never good for any exhaust system, despite what the staff writers of Max Power say.
An ideal high power exhaust is open headers out of the side of the bonnet, but as people don't just want high power all the time, and the noise, they do a lot of pipe tuning.
In the midrange, the manifold design is planned to collect the individual pulses of exhaust gas from each cylinder and release them into the rest of the system with perfect timing.
In between these pulses is an area of low pressure, and this low pressure is also timed to bounce upto an exhaust valve as it opens.
This low pressure helps suck out the gasses and increases the volumetric efficiency, which is the amount of fuel/air mix it can get in.
The finely designed system does have to cover a few other tasks, namely quiet and cheap, so there is a little conflict between them.
A decently designed exhaust addition will play off these against the power, a badly designed fart can can kill the fine tuning but just make it sound louder, and therefore well fast mister.
If people actually notice the loss, they'll put it down to the loss of backpressure, but it's down to the well planned exhaust tuning.
A few years ago when I had a Fiat Coupe 20v Turbo, I had exactly the same experience.
I fitted an aftermarket exhaust (can't remember which one but it was a well known brand) but after a short while the car started to smoke a lot at idle. Nothing could be found wrong with it, the valve stem & piston seals were all OK so it was suggested that the exhaust and lack of back pressure could be at fault. I honestly don't know if that really was the case but I got a genuine Fiat exhaust back on it and it stopped the smoking and felt noticeably, very noticeably, faster.
I fitted an aftermarket exhaust (can't remember which one but it was a well known brand) but after a short while the car started to smoke a lot at idle. Nothing could be found wrong with it, the valve stem & piston seals were all OK so it was suggested that the exhaust and lack of back pressure could be at fault. I honestly don't know if that really was the case but I got a genuine Fiat exhaust back on it and it stopped the smoking and felt noticeably, very noticeably, faster.
Gassing Station | General Gassing [Archive] | Top of Page | What's New | My Stuff