i heard that getting the really big fart in a can exhaust actually kills hp because it allows back pressure on the engine and that the stock restricts, and that's why in drifting they use 2.5" and nothing bigger

 

A large diameter muffler ("fart in a can exhaust") will not "kill" HP because the muffler does not create any backpressure. It's like sawing off the last 2-3 feet of your exhaust pipe, IF anything it will decrease (very slightly) the amount of backpressure the engine "sees", increasing the amount of high-rpm horsepower. But, basically any muffler put on a stock diameter exhaust pipe system will do nothing for performance...
Torque is another matter altogether, and usually the less backpressure the less torque is available down low in the rpm range, so obviously it's not good to have a 4" Deisel truck size exhaust on a 1.6L NA Honda motor...
However, are you talking strictly about the muffler or the entire exhaust system from the cat back?

Yes, a larger pipe can be beneficial, ONLY if it is used throughout the exhaust system...

So, you "heard" wrong, make sure you correct the guy who told you that (my guess is someone who doesn't like civics lol)
As for drifting, I don't know about that (I do not follow it much), but I know for a fact that Forced Induction vehicles (alot of drifting nissans are turbo) will benefit greatly from a larger than 2.5 in exhaust pipe. just go ask any DSM owner, they'll tell you 3" all the way!!

 

well i heard it on a drifting show

 

and those guys are always right

 

isn't horsepower a by-product of torque you kind of contradicted yourself and I agree with the drifting show, unless your running a turbo or an excessive amount of combustion pressure on an N/A car than 3 inches is too much on hondas that are stock or just have a few mods. Why do you think it sounds like that because its not being pushed out of the engine smoothly and cant push the combustion all the way through that size diameter pipe for that long of a distance P.S. it's called BACKPRESSURE so if you want to be a stereotypical Honda and be called a rice burner because you make that nasty fart noise, then cool get the 3 inch exhaust, but if you want to sound like your actually making power and actually feel that power than I would go with no more than a 2n1/2 inch exhaust until you are pushing forced induction.

 

First, since you guys "heard" it on a drifting show, then it must be true, LOL... That's gotta be the funniest thing I've ever heard...
I mean no offense to you guys, but just watching some show on drifting is not going to explain the mechanics of the exhaust system...
Every car is different, so how could you possibly say that 2.5" is the BEST option for sport compacts?
Also, FYI, your theory about the 2.5" pipe is wrong... I'm not gonna rip on ya, but you need to understand the theory behind it... I have a 2.5" pipe AND I'm running boost

I'm telling you from experience, and from my education...

I know ALL about the technical aspects of fluid dynamics (fluid in this case is air) and the term backpressure, as I have an engineering degree...

LOL... No, Horsepower is NOT a "by-product" of torque (what does this mean anyway?)
HorsePOWER is a FUNCTION (mathematical equation) of torque. Consider the formula for HP, which was derived from calculus, and shows the relationship between TIME and FORCE. This is commonly called POWER (just as in electrical circuits, a light bulb for example, uses power, a force (emf or current) over a time increment)...
HP= (TQ*RPM)/5252 HP (force to move 1lb through 1 foot distance in time of 1 sec)
Most importantly, HP is dependent upon TIME AND FORCE (the only variables in the equation), not just force (which is what torque is, twisting force)... Ever wonder why you can "feel" torque but not Horsepower? Ever see a mustang owner wonder how in the hell you beat him in your 100 lbs of torque 1.6 liter? It's called efficiency

My advice is to pick up a book from the library it will give you TONS more knowledge than some TV show...

Finally, please don't just believe anything you hear on TV, cause chances are it's all about the advertising... They will "tell" you what is good, so you go buy it, get it?

 

yea, but they said that the backpressure from the exhaust cause a decrease in hp. the bigger the pipe is the less pressure inside of it, and the drop in pressure can cause outside air pressure to force air back inside the exhaust and put a strain on the engine

 

They are talking from their ass.

Turn off the TV and read some real information:

http://www.team-integra.net/sections...?ArticleID=355

http://www.team-integra.net/sections...p?ArticleID=47

http://www.team-integra.net/sections...p?ArticleID=48

http://www.team-integra.net/sections...sp?ArticleID=2


The information is heavy in areas compared to the garbage they show on TV, but it is correct information, not hear say.

 

well i found this in what you just showed us: "This is how aftermarket exhausts can cause a loss in low end power. Incorrectly sized exhaust pipes can disrupt the airflow, allowing exhaust gasses to be sucked back in during this valve overlap period."

"For most N/A applications this pipe size would be 2.25" in diameter. A common mistake sometimes talked about in "tuner" magazines is that you need some backpressure for the system to flow properly. This is a myth created by amateur testing methods."


"
This would be another one for the Magazine Mechanics. "This muffler will reduce backpressure and you'll see at least 15-20HP with this ultimate free flowing design!" By now I hope we can see what a big fat load of crap that is. In the stock exhaust system, the pulses have already been jammed together, and the backpressure has already affected the engine. So you change your muffler to a better flowing one, so what? The amount of backpressure in the exhaust system remains unchanged. You're just putting a fire hose at the end of a garden hose, the flow remains unchanged. So unless your exhaust has reduced backpressure enough so that the muffler becomes a restriction, then changing the muffler to a "free flowing" design will have no effect on real-world performance."

on this page: http://www.team-integra.net/sections...p?ArticleID=47

did you even read this stuff before you posted?!

 

As a matter of fact, I did...and I understand it. I think you are beating around the bush trying to find some shred of evidence to prove that a drifting show knows exhaust flow dynamics that hold true to every single application.

It is true on a stock car, but saying that they use 2.5" and nothing bigger is retarded. You are honestly going to tell me that a 3" for a turbocharged car is too big? Last time I checked, there are an ass load of turbo cars that drift.