The only time you want any kind backpressure in a rotary is for the stock 6-port actuators on N/A 13B's betweem 1984-1988. Which where opened by the "boost" of the exhaust backpressure.

A less than ideal setup, which Mazda later converted to a solenoid to open and close the Aux port sleeves.

 

Wow, that's a funky device ya got there.

:::Heads back to 2nd Gen Tech:::

 

Auxilliary ports on the 6-port engines are supposed to begin opening at 2.5 psi. That's not much for back pressure. I use a 1/8" copper tube, plumbing parts from Ace Hardware, on the header of my 2nd gen to open the aux ports. When they open up, it feels like the secondaries of a 4 barrel carb opened up.

 

OK, so what I am hearing here is the best exhaust system would be an RB header, upside down and cut off about 2 or 3 inches above the hood. Thats about as short as you can get it. I am also thinking that maybe the wind going over the car will help suck some of that nasty exhaust out as well.

How do we keep the windshield clean from all that carbon coming out of our new demo derby exhaust??? Also what would the real world HP increase be with something like this. I have an extra header and an extra hood so I am down for an experiment if someone is willing to contribute some dyno time money.

 

It's not back pressure that's good exhaust comes out in pulses you want the whole pulse into the exhaust before the next one comes that's where collector tuning comes from and as mentioned ten times before it's velocity you want. The higher the velocity the faster it's moveing through the exhaust. Stop reading internet garbage and talk so people that have been building engines for decades. Or pick up a book on physics or take a physics class and you'll feel better about it...

 

Alright, lets clarify some things. I may not be any kind of car expert, and particularly not an exhaust expert, but I do know a little bit about physics. I'm no physicist or anything either, but it's one of those things that's always interested me and I've learned a bit about it. (Kinda like RX-7s now, only I'm just starting )

1. There will always be backpressure. You are shoving gas from the exhaust against gas in the outside air. There's gonna be pressure even if the engine is spewing exhaust straight out into the atmosphere, with no headers, mufflers, cats, or anything else to deal with. Even if the exhaust were shooting straight into a complete vacuum there is still the inertia of the gas itself that is causing a tiny bit of pressure.

2. The goal of any good exhaust system is to minimize any extra restrictions that would increase the backpressure restricting exhaust flow. The basic and obvious way to have a low restriction exhaust is a header and a straight pipe. For quieter setups I personally don't know what's best, but I do know there is a lot of tuning of pipe length and shape, as well as placement and size of mufflers and cats and such.

3. This thread is about a cool little gadget that -says- it will both quiet the exhaust (which apparently it does pretty well) and increases flow, which I haven't heard anybody who has installed one correctly say it doesn't. So, if you haven't flow tested it yourself, don't have one, and don't really know whether it will or won't work, then don't say it won't work. Say why you don't think it will work and let the guy who has one get himself to a dyno to test it with and without the insert.

 

i have a WS exhaust on my accord that i kinda like. i wouldnt put one on the 7, but it looks decent on the accord haha

 

well in response to post #31 just to clarify things

1.backpressure gives torque no?

2. minimizing backpressure is better if u had a forced induction... hehe couldnt help myself (no im not gay although i live in the bay area)

3. not to be smart but this thread is about why tranquil is more of a ricer but the topic kinda changed after that silencer/exhaust flow thing appeared. btw on my bonez cat (see pic in a recent thread titled cats for smog) theres a silencer which replaces the monolithic (first) cat and then goes to the main (and only) cat. the silencer inside looks similar to the object discussed here with the bumps inside and how it is shaped to increase air flow while silencing the exhaust note except its not adjustable like the one you can insert here.

 

As I understand it, yes, sortof, but not really the way people think it does. I think it's something like more exhaust gas is crammed into the intake, which heats up the intake air/gas mix and allows a little more efficient combustion, and also burns a little of the leftover gas in the exhaust too, which gives a little low rpm boost. I believe it's especially effective if you are running lean, but I could be wrong. Yaw did a big writeup on that too on his website. I couldn't explain it to you, but it made sense when I read it, hehe.

You're right, I was still off topic. :P Tranquil you're such a ricer!

 

Back Pressure Doesnot Give Tq!!! Velocity Does and collector legnth and pulse legnth tunning does!! i'm done here be wrong and slow if you want too. Also so you know lover'd core mufflers generate more backpressure than any exhaust, but do little for noise. Infact in a class I had we figured that it was easier for an exhaust to push over a 1/2 steel plate through a 2" exhaust than it is to push through a 2" louvered core muffler. Thank you physics and math...

 

If the OP is a ricer due to the muffler, I guess I am too. My car was equiped with a muffler similar to the one shown in his pics, along with stainless 2.25 pipe when I bought it.
That 4" outlet/tip on my muffler looks wild poking out under the bumper. It looks even wilder when I back off the throttle above 4K and the fireballs start flying out......... (VERY effective anti-tailgating tool) LOL