ItsNiceToBurnRice

I know I have a Bonez high flow cat, I just wanna cut my mufflers off and weld some straight pipes on for the time being, I dont have 800 bucks to put a whole system on now, plus Im tryin to work out some kinks in the motor. So I just wanna hear some exhaust screamin', will my back pressure be ok so that my ports open? Cause if they wont, then its obviously not worth it. Thanks everyone!

tesla042

...You could always tie them open if you want high end..

-Tesla

FC3AZ

I like this idea, I might do it myself to get a new sound, and save me MAJOR cash. So, how bout it? Back pressure ok? or no? Thanks....

t_mak@mail.plymouth.edu

Your car will be slower with no mufflers

RX-7 GT

how?

t_mak@mail.plymouth.edu

no back pressure

The Ace

Just go here http://www.rotaryengineillustrated.com and all will be explained. NA engines need the backpressure for low end power, while turbos dont need ANY backpressure at all

FC3AZ

Well, I do have the complete stock exhaust system( from the header back). The previous owner replaced the 2 or 3 stock cats with one new cat. That still wont provide enough back pressure?

FC3AZ

come on now, TTT

hypntyz7

The rotary engine does not need or want backpressure to make the most power. However, the intake system was designed upon backpressure. IF you take away the backpressure you have to change your intake(by wiring open the 6 ports) to match. IF you want your intake to remain stock(6 ports) than your exhaust has to remain stock. A NA rotary would be at its strongest with the 6 ports wired open and a totally open exhaust.

Ryde _Or_Die

I think the very best performance would be by having no back pressure...but having use of your 6 ports. Open them with your air pump. I will find out how well this works.

FC3AZ

Ok, this is what I am askin..........How do high flow muffler designs keep the 6 ports open, if you say with no back pressure they should stay closed? Correct me if I am wrong......High flow mufflers are the same as no mufflers??? I am a tad confused....please help!!!!!!!!

The Ace

In a NA, you need a minimum amount of backpressure to open the 5th and 6th intake port (dont know exactly how much, heard something about 2psi ??). Because your stock exhaust provides much more than that, you can replace with a catback, that can still provide that little bit of backpressure, but not any more! Just the absolute minimum needed for the 6ports. So you still have the funcionality of the 6ports, and you have the highest flowing exhaust possible


PS: Thats why custom exhausts are a possible danger. The designer/maker must calculate this minimum amount of backpressure, and take it into account...

FC3AZ

Ok, so let me get all this in perspective.......sorry for annoying some of you.

Stock header, 1 cat, no muffs = no 6 ports

Stock header, stock cats, no muffs = no 6 ports

Stock header, 1 cat, aftermarket muffs = yes 6 ports

Stock header, stock cats, aftermarket muffs = yes 6 ports

??????????? Am I 100% correct????????

Ryde _Or_Die

Do we even have a stock header? Thought it was just a stock downpipe.

FC3AZ

Sorry, got the term wrong...... downpipe/header/manifold/piece o' chit, whatever that thing is under the heat shield.