DCSBlack Knight

I installed a B&B Exhaust system including the racing pipe. Got what was promised about 18hp increace. One major side effect thought. Man was it loud. Coulf have cracked the nieghorhood windows. Also found out that do to local tack regulations, to take the car on the local international raceway on practice day the car was too loud.

Corrected the problem by installing a 36" gas pack muffler. Didi not effect the newly gained hp but sure got the noice under controll. Now not only does the car have the additional hp but the sound is tame enough to be street legal and legal for the track on practive day during the week. The Best of both worlds.

Outlaws eXtreme

I could swear somewhere in this forum that someone said Exhaust does little to nothing to the HP gain. Or at least that was for the Greddy exhaust....

What's the deal now? Is there a "real" significance?

DCSBlack Knight

I don't know about the claculations, but in the real world, the B&B syatem with the racing pipe made a lod of difference. In another case where the system was custom fabricated the increase was about 11hp. The only difference was the race pipe repacment for the cat was not part of the equation. Flow through exhaust is making a differnce for us. A big difference.

shaunv74

Read this article on Racing Beat's website. This seems like a fair test with solid scientific results...

http://www.racingbeat.com/FRmazda4.htm

DCSBlack Knight

Well matimatics is a good start, but nothing beats pratical feild application to verifiy the therory.

Mathimaticly a bee can't fly, but bees tend to defy the sience which syas they can't fly.

B&B system with race pipe, with added glass pack achived about 18 =- added hp.

The $1,200.00 for headers for only a 4hp =- gain does not seem cost effective.

Waiting for the new superchargers systems. That will with out doubt add the extra hp to provide the edge on the track.

shaunv74

How did you determine your gains...in the real world?

That was my point with the article. Racing Beat pulled an engine out of a car, put it on an engine dyno, Cut off the Cat and muffler and got 8 hp. They say the max they have seen testing their exhaust and any other is 2-3 hp with the cat still in place. They estimate a full race setup would yield 10hp max.

The bottom line is be careful what manufacturers (and people on this forum)claim without providing some kind of test data.

DCSBlack Knight

Put on a dyno.

mspeed11

for what its worth....i made my own exhaust for my 8 ( OK my brother did ). he used the factory muf, cutting it open to remove the silencers inside. then he welded a t in the inlet and straight pipes to both outlets. once that was done he rewrapped it with a thin peace of sheet metal so it could still use the factory hangers. as god as my witness it sounds awesome!!!!! none of the aftermarket exhaust systems that iv heard even come close to the sound of a straight piped one, it even pops like a f1 car between shifts (with a flame)
but you guys can pay 500 to 700 for 2 hp if you want, me, ill turn heads for pennies any day!
if you are interested and live in the Austin or Houston area, more can be made!!!!!

DCSBlack Knight

Try a B & B with race pipe. The end result will all but shatter the windows for 10 city blocks. Pop is an understatement. Had to install a 32 inch glass pack so that it would be street legal.

mspeed11

i would love to hear what the B&B race pipe would sound like on my car...hehehe straight pipes all the way....holly bomb shells batman

zoom44

would this be your brother the mazda tech? isn't gutting the factory muffler illegal?

rotarygod

Gutting the muffler isn't illegal as it doesn't affect emissions. If it were illegal, we wouldn't be allowed to cahge them. Gutting the cat is illegal.

zoom44

thanks rg

mtpot1

At 30 years old, a loud exhaust is not what I am looking for. I had fun with that about 12 years ago in my mustang. Anyway, I bolted on the Borla exhaust system. The data I saw suggested that it would provide comparable HP gains as the others, but without the noise. It is a little more "throaty" than the stock, but not loud at all. I am very happy with it. All the racket from my car is coming from under the hood as a result of the K&N intake.

the-jewish-rx8

rotary god im looking for an exhaust system. i dont care if it is quit or noisy im just looking for the one that will make the rx8 go the fastest can u give me an idea on what to get

shelleys_man_06

I'll fill in for RG, since he seems to have fallen off the face of the planet . To make power through the exhaust, a main point would be to minimalize the stock backpressure. Lower backpressue leads to more flow, IMO.

the-jewish-rx8

yeh i read his post but it would be nice if you could give a system that gives the most power

rotarygod

Wow, I spend a couple of days with my woman and suddenly the club is mad at me! She always says I'm here too much. I can't win either way.

I started this thread to help address what systems are the best and what to look for. Go back to page one. The exhaust system is only as good as it's weakest point. It only flows as good as it's worst flow point. A bigger exhaust isn't necessarily going to give you power. I am personally a fan of Racing Beat or Borla. I have my reasons but as with everything else that is an opinion. Others like the HKS, Greddy, etc...

Go back and read page one. Then make your choice.

feelthesweetbea

ok rotarygod, I got a question for you to answer.

Porsche and BMW have very advanced mufflers coming straight from the factory. One thing that Ive noticed is that their are butterfly valves that will open and close (before or after the muffler) depending on engine loading. Can you give us some insight on the benefits of having these valves in the exhaust stream?

The only thing I can think of off hand is that the valves change the length of the exhaust, thus acting like a tuned intake (Valves like in the intake of the rx-8). Is there more to it than that?

rotarygod

Ferrari also uses valves in the exhaust of some of their cars and the new Mercedes SLR does too. You've pretty much hit it. It isn't there to make the exhaust longer or shorter. They are there to retune the exhaust system for a broader powerband. It works. There is one Japanese company that makes a similar setup for the RX-8.

mikeb

what company RG

feelthesweetbea

i am curious about the company as well. be nice to know forsure that a company took the time to actually engineer a valve system. its gotta be worth something then

shelleys_man_06

Does anyone here think that future rotary engines will someday share the same exhaust technology as piston engines? For example, the Dodge SRT-4's exhaust system just consists of a resonator; there's not cat! How does one improve on cleaning up the rotary so we can enjoy the benefit of not having to rely on a catalytic converter?

shelleys_man_06

Are there any differences between an N/A exhaust and a forced induction exhaust?

DCSBlack Knight

Easy,

Get a B&B cat back with racing pipe. The results will be no cat, and a lot more power. Oh, fair warning. The stock tune is so rich on the RX8 once the cat is removed, the 8 will spit fire like you would not believe. Once the novelty of throwing a 15 foot fore ball wares off after revving the car into the 9k+, check out Canzoomer for a piggyback ecu to adjust the tuning of the car to max out the performance. You will love the result.