Why doesn't anyone drive with open headers?

[N8dawg]

With many M3 exhaust systems leaning towards the ridiculously expensive, got me to thinkin, how come I don't see (hear) any M3s with open headers?

[Serious]

Originally Posted by N8dawg

With many M3 exhaust systems leaning towards the ridiculously expensive, got me to thinkin, how come I don't see (hear) any M3s with open headers?

because you would go deaf.

[shamoo]

It's actually not healthy for the motor to do that. You need a certain amount of backpressure

[Dengel]

this ^^^^

[1sikbmr]

NA cars need backpressure... with that said headers really do not do anything for this car... If you ask me it would probably lose torque

[Definitive]

With my valves open I'm running no muffler. Quite loud enough. I gain 3 hp with them open. I have a feeling with no cats or open headers you would lose hp.

D

[montreal red]

because cops would give you a fat ticket for running open headers ... hell i got pulled over and got a warning for my last exhaust... i dont think you can drive more than a week without getting pulled over with no mufflers or cats at all.

[Definitive]

Some how I do it with no mufflers, but Im sure Ill get it one day.

D

[piloto]

Originally Posted by shamoo

It's actually not healthy for the motor to do that. You need a certain amount of backpressure

This is not entirely true. No backpressure is best for top performance. However, the engine's fuel mapping would have to be adjusted to take advantage of it. In the case of the S65, short of remapping it, no back pressure isn't going to be advantageous. What do matter are the lengths of the header primaries. Using the Helmholtz principle, you can create a scavenging effect by taking advantage of a pulse wave from a shut valve to one that's open, essentially helping "suck" the exhaust out of the combustion chamber.

[Serious]

Originally Posted by piloto

This is not entirely true. No backpressure is best for top performance. However, the engine's fuel mapping would have to be adjusted to take advantage of it. In the case of the S65, short of remapping it, no back pressure isn't going to be advantageous. What do matter are the lengths of the header primaries. Using the Helmholtz principle, you can create a scavenging effect by taking advantage of a pulse wave from a shut valve to one that's open, essentially helping "suck" the exhaust out of the combustion chamber.

Was wondering how long it would be before someone came up with a correct response in terms of necessary back pressure.

[tlr]

Originally Posted by Definitive

Some how I do it with no mufflers, but Im sure Ill get it one day.

D

I also haven't gotten a ticket yet, but it's only been a few weeks with my cutouts. Knock on wood.

M3's exhaust without the muffler is so nasty, I love it.

[pbonsalb]

You would not be asking this question if you have ever driven a car with open headers. It is too loud to be fun for long and the first police officer to hear you would pull you over. .

[Georgeair]

Because it's not a '71 Ford truck. Relegated to off-road duty.

[N8dawg]

Originally Posted by pbonsalb

You would not be asking this question if you have ever driven a car with open headers. It is too loud to be fun for long and the first police officer to hear you would pull you over. .

I'm pretty sure Florida does not have any vehicle noise laws as far as engine noise goes.

[frenchM3dreamer]

regardless of the law, open headers is fun for about 3 min max, if you can keep it at high RPMs where it really screams and sounds like pure sex... but as someone said, you'll go deaf before you get pulled over, both of which are guaranteed to happen... i couldnt stand cruising with open headers for more than 5-10 min...
i had my car on a dyno with open headers. While i did gain 5hp (2% in my case), Dyno Man had to go get his ear plugs before he did the second run...

[elh0102]

Everyone likes to fool around with exhaust systems, but the M3 doesn’t leave a lot of performance on the table, unless you are tuning for strictly high rpm track use. Otherwise, almost anything you do will cost some low-end power efficiency, and the car is already lacking there. If you just want sound, play around with different mufflers.

[Nautik]

Get some exhaust dumps and have both I installed an exhaust dump kit on my Camaro and the guys here are right, it is fun for about 2-3 minutes with a wide open exhaust. You won't be able to hear anything and neither will anyone around you.

[///My5UV]

Originally Posted by pbonsalb

You would not be asking this question if you have ever driven a car with open headers. It is too loud to be fun for long and the first police officer to hear you would pull you over. .

This. I remember driving my old mustang to the exhaust shop after we got the motor in and put in the headers before realizing we needed to weld up a new exhaust fitting

[FStop7]

You'll also end up with a car full of fumes or even carbon monoxide poisoning. You need at least to do some kind of side exit exhaust or turndowns at the back. Just open headers will make you sick, literally.

[persian54]

Originally Posted by Definitive

Some how I do it with no mufflers, but Im sure Ill get it one day.

D

Why?

just push your button.. rev, and he'll be like "hmm it sound different, maybe i was imagining things! "

lol

[ploo]

Originally Posted by N8dawg

I'm pretty sure Florida does not have any vehicle noise laws as far as engine noise goes.

If I'm not mistaken, Florida doesn't even have any state inspections.

So jealous.

[N8dawg]

Originally Posted by ploo

If I'm not mistaken, Florida doesn't even have any state inspections.

So jealous.

Correct, it's a nice state.