Before I was just running test pipes and a y pipe I it felt like i really picked up some power. Now I added a 3" exhaust and it feels like I lost power and its super loud. Is it possible that I dont have enough back pressure and lost torque/hp or might it just be that Im not used to it or the loudness?

 

y did u go with 3"? If ur N/A that is the reason u are losing power.

 

word

 

Why the hell do you need back pressure. What the hell does back pressure and the exhaust stroke of an engine have to do with more power? All of the valves are closed for the compression stroke so what gives?

 

^^^
Won't get into the lenghly explaination of internal combustion engineering between NA and FI applications here.
But trust us...
On NA, you don't want to go larger than 2.5" exhaust pipe. You have to retain a certain amount of backpressure for horse power.
The flip side is on FI applications. You want very little or no backpressure, so that's when you increase your exhaust pipe diameter over 2.5", like 3" as you did.

Sounds like you have two choices.
One is return the exhaust for a correct one on your existing NA set-up or...
Go FI with a SC or Turbo since you have the correct exhaust for those set-ups.

G/L

 

Thanks for the help. I understand the mechanics of a four stroke engine pretty well just dont see how a compression stroke or an exhaust stroke could be aided by backpressure. I guess im gonna have to get that procharger sooner than later.

 

Exhaust velocity. Exhaust velocity. Back pressure does not create power.

 

On a lighter note, you've got the exhaust for it, now you just need to get the turbo(s).

 

When a exhaust is too big, it definitely can cause a loss in low end power mostly TQ. The car will pick up steam in the upper end of the power band. But without backpressure the car will loose TQ with too large of a exhaust system.

It's best way to have a exhaust is to only make one .5 to 1 inch bigger than stock. Usually a 2.5" exhaust is perfect for a car like ours.

 

+1. 240ft/sec exhaust velocity is the target. Heres why.
http://www.team-integra.net/sections...sp?ArticleID=2

Also, 1 sq./in of pipe x-section for every 60 crank HP is a good rule of thumb.
http://www.team-integra.net/sections...p?ArticleID=16


All internal combustion engines, turbines included, have pressure pulses and wave reflections that have to be calculated for to obtain optimal efficiency. Bolting in bigger pieces of pipe rarely produces anything worthwhile.

 

Again, it has nothing to with "back pressure". The term is exhaust velocity. The goal of any well tuned exhaust is to keep the exhaust velocity high over the largest amount of rpm. Good exhaust velocty scavenges the exhaust gases straight out of the combustion chamber. When the exhaust piping is too large, the exhaust gases start to tumble over one another and build turbulance in the pipe which kills the scavaging effect. The scavenge effect is a high-pressure pulse with a trailing low-pressure area behind. Poor exhaust velocity and scavenging leads to a soft and weak low to midrange power. As the rpms increase, so does the exhaust flow and volume. In an almost-turbo like surge, the power goes from flat to strong. Too bad though because top end power is hardly utilized in any sort of race. It's all about mid to upper midrange since that is where engine's spend the most time accelerating.

Now with turbo cars, bigger really is better. The motor developes it's own atmosphere and moves a ton a air therefore exhaust tuning isn't remotely as crucial.

 

Holy crap! That's a great link.

 

Wow thanks bro, an explanation that makes sense.

 

Just reminded me of my GSX, when I dropped the down pipe and let the turbo spill straight down. Drove around the block...That baby spooled like a mad dog, holy boost spike pulled back in the drive way and bolted that baby back up.


Big exhausts can be great for FI but not for most NA apps