Pic related.(prob not the first to think of this) I was just thinking... A good exhaust system helps the engine "breathe" better, thus, "better performance". However, do you think that a good exhaust system could be pointless for any performance gain unless you upgrade your air intake as well? Lemme explain: better exhaust obviously means that the exhaust stroke pushes out all the smoke and fumes and fuel easier and faster. Stock air intake will obviously still be able to mix in a little more air than normal, but, I feel like maybe upgrading your intake too is the best way to go. Possibly the only way to get any worth-while performance gain.? Thoughts.? Agree, disagree?
Completely depends on the car. 95% of the time exhaust upgrade systems are for sound.
If not a turbo, I would expect any cat back system to have near zero performance benefits assuming the car is not the cheapest of ecoboboxes.
While stock exhausts are usually restricted to reduce noise, stock intakes are usually not restricted for the same reason, and mpg's. Also, 99% of stock CAI systems are better than what you can zip tie together in your garage (besides the fact that CAI doesn't do shit most of the time)
>>14729415
Also, this. Headers are usually the only exhaust part that adds power, the rest is just noise.
Air intakes that usually just sit in the bay negate their increased flow by having increased temperature. Actual racecar setups have intakes that protude outside the shell, usually through a headlamp.
A quality exhaust system will reduce backpressure, thus allowing increased air intake. As well, the heat dissipation will improve. Thus, you have a more efficient burn, and, as such would have it, more power.
I lost 25% fuel efficiency when the last 2 feet of my exhaust rusted off
So it has something to say.
Sounded rad though, if a bit obnoxious
>>14729425
OP here.. I never really thought that much about the stock intake. Also, one other question I guess because I have lots of things to throw out. Could the air to fuel ratio be negatively affected and become detrimental to engine performance if there is way too little restiction and way too much air? Computers calulate air/fuel so no matter what unless it's extreme the computera in the car should be able to sort it out sooner or later. I'm pretty sure the answer is a yes to that one, but I'm in the mood to have long detailed conversations about car stuff so I'm asking even though I'm pretty confident.
>>14729452
Yes that will happen. Air/fuel ratio is all calculated by computers in the car. If the engine is getting more air, it's gonna mix in more fuel to get the perfect combo for the best combustion.
I wanna just how much more power and better performance you can actually get just from exhaust and air intake modifications/upgrades
>>14729477
If you are turbocharged, a wider bore intake will actually improve performance because of the volume of air flow. Otherwise, HP gain is negligable with just your standard cone CAI.
They do sound nice, though. That is really why most people get them on their NA cars. If you want power, the $300 could go towards some cams or a differential or something like that.
>>14729477
Almost nothing unless you do a full header back catless exhaust and a cai that goes outside the engine bay. And a tune for it.
>>14729504
>>14729514
These things I'm aware of. I was just curious as to whether or not I could get a number and graphs and figures lol
>>14729531
Would need to know what car. Some intakes are as good as they are going to get. In a turbo car, it depends. If the turbo is perfectly matched to the system you can't pick up mutch. However if the turbo is capable of pushing more àir than its currently doing, a free flowing exhaust and ECU upgrade, should the ECU be controlling boost, will give you more power.
>>14729397
Air, fuel and ignition need to be upgraded to match an exhaust improvement. Usually a modified ECU can take care of this. However, intake design and fuel supply can quickly become a limit.
Basically, upgrading you engine is
>remove the weakest link
>upgrade it
>adjust AFR
>adjust ignition
And then doing it all over until you reach your desired power level.
>>14729425
The rest of the exhaust can eventually become a limiting factor though. A well designed exhaust system can especially increase torque in the lower RPM range.
90% of them don't do jack shit though.
>>14729452
That's what happens if you don't readjust your ECU (or carbs and ignition) to exhaust mods.
>>14729459
If the intake is extremely restrictive, it'll allow less air to pass through, and an ECU will adjust for that to get a correct AFR.
If the intake suddenly becomes extremly well-flowing, and you injectors/carb can't keep up, you'll get a very high AFR, your engine will run lean, and you'll melt engine internals. However, just a new intake isn't going to cause that.
>>14729397
No
A car at 7K RPM will move the same amount of air, stock or modified exhaust.
A restrictive exhaust causes backpressure which applies pressure to the rising cylinder on its exhaust stroke, which reduces the power output of the cylinder on its expansion stroke.
A less restrictive exhaust allows the engine to perform its exhaust cycle with less effort and thus less lost power.
As for whats a better intake vs exhaust, it would depend on your make/model of car. And even then it would only be what you could gather from google.
>>14729425
that would depend on the car, bmw's are notorious for having very restrictive exhausts.
Some stock vehicles come with very nice stock exhaust manifolds too. (Silvertop and blacktop 4AGE engines have a tubular manifold stock, much better than a cast POS that comes on earlier engines)
Could anyone recommend a decent exhaust kit for a bone stock Impreza 2.2L?
