I have RB header, 2.5" SS system with a muffler right at the end.

My system is straight till it gets right at the rear wheels and then turns up and then connects to the muffler.

I saw a bypass pipe, which had a cap over one end and allows exhaust to flow through unless you uncap this bypass and then it just dumps it out, before the muffler.

My questions are.. Will the dump make any more power?

The dump will be right before the system starts to make its first turn by the rear wheels, so I will have some piping before the dump, maybe 6 feet before.

Should it be this far back, or closer to the collector of the header?

This is drag racing only...

Thanks..

 

Normally I see these bypass pipes used right after the header, but Ive never seen one on a rotary before. If you have a s4, youll need some way of actuaing your 5th$6th ports, since they use exhaust backpressure to open. Truthfully if you already have a decent high-flow exhaust, it probably woudnt be worth it.

 

No ports to worry about here.

I assume my muffler and the bends in the piping could be improved with this bypass.

 

Just a really loud 7

 

You do know that a rotary engine is like the loudest engine ever.

anyway, having no muffler should free up a few more hp, thats just another restriction in the exhaust.

this place down the street from me makes a bypass that you can open from a button inside your car.

 

I have one that is operated with a cabin mounted cable, but its a leaky ****** and most likey sounds crappy, because it won't seal up...


This why I am looking at these ones you unbolt.. they appear to seal up good..

 

You might want to be careful where you dump your exhaust as you will get flames out of it. Especially drag racing.

Hella freekin loud!!!

Edit: Oh yeah, you may want to make the length from the collector to the dump a harmonic of the exhaust pulse frequency. Look around for tuning exhaust/intake lengths on the net. I have found a few sites that have equations, but you will need someone around here to give you an estimated exhaust gas temp figure to use them. Sorry don't have any links handy....maybe later.

Might as well put some science behind the length.

 

You have no idea how loud an open pipe is going to be...

Before you do this, just disconnect your current exhaust and go run around the block once.. I bet you change your mind very very fast

 

i was racing at blackhawk farms raceway one day, when this yellow FB pulled over and some guys ran to the car, jacked it up, and pulled off the exhaust cuz it got damaged somehow and was dragging on the ground.
I was thinking this thing is going to be super loud! when it started, i was covering my ears but i was surprized how quite it was at idle. But when he hit the gas, thats when the fun started. Needless to say, we could tell exactly where he was on the track at any given moment without looking...

 

O, BTW, on the RX-8 i think mazda figured out a way to quiet the exhaust down on the rotary engine. The reason why ours is so loud is because the exhaust comes off the engine at supersonic speed and what we hear is a sonic boom. Youll notice that the new RX-8 engine has a side port exhaust. They found a way to slow it down so it wouldnt be so loud...

 

Years ago to be street legal, I cut the exhaust pipe (piston engine) and welded a 4 bolt flange to each piece. When I ran at the drags, I would drop the rear portion down, and bolt in a 30" pipe with a flange that let the exhaust exit under the doors on both sides.
If yon can visualize- exhaust pipe bolted to extension pipe, rear upper flange bolt connected to lower bolt. That way all stays firm, with no movement.

 

Here are a few links for exhaust length tuning:

http://www.engr.colostate.edu/~allan...ge7/page7.html

http://<br /> <a href="http://home....html</a><br />

http://www.eng.ed.ac.uk/~jchick/Y5/t.../pt7.htm<br />

The last one is for intakes, but the principle is the same.

 

I've had the kind with the bolt-on cover on a different car. It's a lot of fun at the track. Your car is gonna be VERY loud with it open, but go for it! You can always close it off. There are some other brands that make electrically actuated cut-offs-- I think "blast-offs" is one, these do not leak like the cheap JC Whitney cut-outs. The Flowtech RaceReadies are the cheapest way to go without having a crappy result.

PJ