Does a different exhaust do ANYTHING for the actual performance

Yeah but Only Farr cans

>>16790241
The header/manifold is important on all cars, and the whole thing is important on turbo cars (bigger and shorter is better), but just a catback or muffler or tip won't change anything but the sound.

depends on what you mean by "different"
on its own, not that much, but it is a supporting part that allows other parts of the engine to work more efficiently or at a higher capacity. A larger exhaust literally means you can support more exhaust flow without creating too much backflow. Now, backflow is a nuanced thing but generally a turbo car wants none while an n/a car can handle and in fact benefit from a little bit. I digress - more shitting means more eating, which means more digesting which means more power in the ultimate super retard terms.

>>16790241
oh hey! thats my car!

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Yes. Exhaust tips? No

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>>16790241
Fart can = power

>>16790270
>Now, backflow is a nuanced thing but generally a turbo car wants none while an n/a car can handle and in fact benefit from a little bit.
This is bullshit, stop listening to engineering explained m8

>>16790331
It's not bullshit senpai

>>16790317

if there is backpressure it will reduce over BHP

>>16790331
if you have a lambda sensor it can mess with it - but in general it doesn't make a huge difference. My point is the difference is there, and there are certain things that rely on backpressure to function
fuckface

>>16790353
It is fucking bullshit you fucking idiot. A fucking benefit attributed to stupid fucking back pressure by idiots such as your stupid self is caused by a super fucking complex thing a retard like yourself would never understand called pressure waves. A low pressure wave (stop me if I'm going too fucking fast for you) at the exhaust port at the right time can extract exhaust gas more efficiently. Length and diameter both contribute to this

>>16790368
Such as

>>16790382
For peak HP numbers, sure, no back pressure is the best for NA engines

But some back pressure will have benefit in the form of low-midrange torque

Shit well I've been schooled. Thanks for dispelling that for me....
Sorry I called you fuckface

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goiz goiz goiz does backpressure affect a 2-stroke more than a 4-stroke just cuzza how they werk? i feel like havin the intakek and the exhauts open @ sametime woul'd mean backpresure affecks the FA ratiao

>>16790241
If it's TURBO the fatter and more free flowing exhaust the better

>>16790431
NYET! THE EXHAUST MUST MERELY BE TUNED FOR OPTIMUM PULSE TIMING AT A LOWER RPM

>>16790431
BACK PRESSURE IS BAD YOU STUPID FUCKING CUNT

>>16790445
Yes

>>16790553
>>16790562
This advice is obviously for 4 strokes

Ok, so back pressure is caused by restrictions its just a fact of a 4 stroke i.c.e. less is better for high reving peak power... more cause the power band to shift, ideally you want a certain amount. Thats for NA cars. Turbo cars create enough pressure at the manifold and after the turbine they just want to evacuate the gasses.

The pressure waves mentioned are affected by the back pressure the cycle of these waves is created by the valve train timing, effected by the restrictions and denisty of the exhaust gasses. A good manifold and exhaust match your cam profile and optimum timing to help create over effiecient scavenging. Thus bringing more are and fuel into the cylinder.

Shall we discuss long tube,short tube headers twin scroll manifolds, and intake runner configuration next?

>>16790431
Who the fuck wants low-midrange torque? If you are getting an exhaust done you want high end power for driving spiritedly through twisty roads

>>16790445
2 strokes require negative back pressure to function properly. That's why they have huge funky shaped exhausts.

>>16790270
Assuming by "backflow" you mean "positive pressure in the exhaust behind the header," that's incorrect. Less is always going to be better for performance. NA 4 strokes tend to be very tolerant of backpressure though, and in increasing the size (and therefore maximum flow rate), you'll very quickly find yourself at a point where you're increasing the noise but not the power. And if you go much too big and exceed the engine's ability to pump out exhaust, you get a situation where exhaust air has to push its way past turbulent bubbles of stagnant air, which actually increases backpressure. Turbocharged engines don't rely on laminar flow of exhaust gasses, because there's already a turbine wheel in the way that throws that possibly right out the window.

>>16790765
Long time ago I had a 4 cylinder Civic, and the exhaust broke completely, right before the catalytic converter. Should have meant less back pressure, but the car was noticeably slower. How does that work?

>>16790241

So let me red pill you on something regarding exhausts as there seems to be a lot of misinformation flowing around here.

For maximum performance, the best exhaust configuration is simply open headers. There is literally zero resistance the motor has to deal with and the fumes are exhausted as quickly as possible.

With that said, this comes with a few problems, mainly that it doesn't deal with heat properly. So to solve this, you straight pipe it.

Now comes another problem. It's loud as fuck. It doesn't comply with emissions. It makes the generic consumer driving experience unpleasant.

Etc... and so on

The best exhaust in theory would offer the highest flow while also offering the highest degree of muffling. The unfortunate reality is that the latter is usually accomplished by reducing flow. But, manufacturers typically find a way to make it work.

Back pressure is complete bullshit nonsense and has nothing to do with raw performance. It exists to maximize efficiency which is something only retards care about

>>16790820
O2 sensor was getting whiffs of fresh air and dumping in more fuel. If it was carbureted, I don't know.

>>16790846
>For maximum performance, the best exhaust configuration is simply open headers.
I think everyone understands that. The problem seems to happen with some people's reasoning for why an open header performs better than an open port with a megaphone tip/velocity stack. They think it's because the header adds backpressure, when in reality it's creating a vacuum at certain points.

>>16790355
Some back pressure is needed for a gasoline engine.

>>16790918
That's wrong, read the fucking thread
>inb4 muh bate

>>16790865
Fuel injected. Maybe it was the O2 sensor, but it was a fair distance from the break.

>>16790387
back pressure is mainly good for lubricating muffler bearings

>>16790820
Your civic should have an in cat, or post cat o2 sensor itwas throwing your computerout, also your engine wasnt tuned to run open headers your cams probably had a profile to match your exhaust system and power band.. open headers are best when dumping air as you bounce off the top end..

>>16791046
Sorry I should've been more specific; it was an 1988 1.5L civic and I'm pretty sure the only o2 sensor was in the exhaust header.

So is the takeaway that untuned cars need back pressure, and will lose power if not tuned for it?

>>16791508
Not untuned cars, even tuned cars might need a exhaust. Its about your cam profile and power band on a car like that.

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>>16790241
Exhausts are a compromise between emissions and noise regulations. Also generally positioned so gasses do not flow directly or be sucked into the passenger compartment.

Decent headers and hi flow cat help the exhaust exit with the least resistance, without these you may as well be pissing in the wind. Catback is just for sound.

Also no such thing as "you need backpressure"

>>16791000
Unless we're talking more than half the length of the car, that'll be your problem. It could also be some sort of limp mode from the postcat O2 sensor readings, but that seems unlikely.

>>16791537
>>16790889

What I don't understand about back pressure is that you need actual exhaust fumes that wouldn't otherwise be able to be ejected fast enough in order for back pressure to even serve a purpose. You understand what I am saying?

>>16790647
>I found the nocarz 15 yearold.

>>16790647
you want the low to midrange torque to daily drive you to your JOB from which you get your paycheck which enables you to utilize top end power in the canyons you fucking busrider

>>16790918
why do people spread memes when they know nothing
you can literally dump the exhaust straight out to atmosphere after the headers and the car doesn't just fucking die spontaneously

>>16792351
How often do you WOT on your way to work? Never? Great, there's proof that you don't need more low and midrange power. You'd just do the exact same thing you do now, except you'd use less throttle to do it.

>>16792351
Why the fuck are you getting a custom exhaust on a daily? Are you too poor to own 2 cars?

>>16790640
You have literally 0 business discussing anything to do with an exhaust system

>>16791508
NO BACK PRESSURE IS EVER USEFUL, YOU SIMPLY DO NOT UNDERSTAND FLUID DYNAMICS.

>>16790382
Wow you really showed that stupid fucking retard using intellectual intellectuality that he's a stupid retard and you're an intellectual intellectual

>>16793646
This level of knowledge is so basic that I have to spice it up a little to even contemplate typing it out. But then I'm a professional and this is my life, and you're just some lost dickhead from /b/ thinking about school tomorrow.

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>>16790241
someone teach me how to triforce

>>16793648
You're autistic

>>16793676
I'm well aware mate but I'm also right

>>16790267

/thread

>>16790241
Larger diameter, straighter pipes are better for power.

The stock Lexus ISF exhaust has restrictors in its design so they could get better emissions. A full exhaust replacement adds ~40rwhp.