Beretta.net

Why is is bad to have dual exhaust? on the Beretta? I thought the fact that we have a better flow of spent gases will equate to more horsies.

I forget why exactly...but there are a couple reasons why its not a great idea.  First its not true dual unless you can get some headers made...its just a y pipe.  Second there is less backpressure, and these cars use that to their advantage.  Something like that, I don't think its been covered in over a year.

Yeah, its because of the back pressure. We dont have big enough engines, even with the V6's, to make enough power out of dual exhaust. They may SOUND sweet, but they suck...

Another main issue is that there is really nowhere to run the dual pipes. I'm talking from the engine compartment back.

the dual tip system is used on the Grand Am's and would work on th Beretta.   The Z04 body has a slight cutout in the bumper making it look weird with duals.

Wouldn't the flow be more "flowing"? Isn't less pack pressure = more HP (or more released HP?) What is back pressure anyway? The only time in which I can actually notice back pressure was when cars make that poping, sputtering sound.  My car used to have it, until I installed a new cat and new exhaust pipes along with a straight thru muffler (and recently switched to a HKS dragger type canister muffler   )

Well it gives you less low end tq, you can get more low end tq with a more restrictive setup, now if you make a true dual exhaust and use nice big mufflers you should be fine, or if you make that v6 pump out a bit more power you could also do that, when you have low backpressure at lower rpms when ur car isnt pumping out that much exhaust gas then u loose a bit of tourque, but when the rpms are higher and ur making the gas to flow through there you would benifit from it.(i think)

So how much back pressure to still retain the torque rating? I heard something about 5psi?

you can get too much of a good thing. you can free ti up where there is no back pressure and cause problems.
I know franz from fdp performance is running true dual on his cavy with no problems.
he modified headers for a 2.8 blazer to work.
any higher flow exhaust will cost you some torque.
I have 2.25 mandrel bent tubing on my alero V6 and things are great 2.5 custom bent seems to work great on berettas. two of my friends have this and it works out really nice. with this size the off the line power loss is minimal and the top end gain is totally worth it! the ideal system would restrict the exhaust off the line the open to full potential when rolling good.

Quote Well it gives you less low end tq, you can get more low end tq with a more restrictive setup, now if you make a true dual exhaust and use nice big mufflers you should be fine, or if you make that v6 pump out a bit more power you could also do that, when you have low backpressure at lower rpms when ur car isnt pumping out that much exhaust gas then u loose a bit of tourque, but when the rpms are higher and ur making the gas to flow through there you would benifit from it.(i think)

        pretty good job as far as digi's question as to what is back pressure...back pressure is the idea of the gases being restricted in your exhaust piping whiel moving away from your exhaust manifold......

if you hate physics, stop right here J/k

        when your car is runnin it burns gas right?!?! RIGHT, and when something burns, it gets really hot, right?!?!? RIGHT!!!

you guys are smart!!!

       anyway, when air is hot, the particles in the air are smaller and less dense, thus they able to move alot faster.....faster as opposed to what you may ask?
       faster then if you are runnin 3"+ inch exhaust.....this is because the longer it takes the gases to pass through the end of your pipes, means the longer those gases have to cool down....and it cools, it takes the engine longer to expel those gases from the pipes.....
     the two are in a kind of proportion to each other.....the reason you see everyone getting 2.25" is because that gives our engines the best balence between TQ and HP, TQ being the existing backpressure, and the HP being the ability to flow with ease......
    once you start tinkering with an exhaust, you play around with that proprotion.....you open your pipes up to say 2.5"(like myself), and i prob lost a few ft/lbs of TQ, yet i may have gained an inverse amount of HP...my 3.1 has 140hp and 185TQ.....so my engine right now probably puts out say 145hp and 180TQ.....follow??!?!?

could you tell im bored?!?!!?  

i know you are, and I appreciate the explanation.

hey i didn't ask what back pressure was
although one more bad thing aobut low back pressure is fuel consumption..

my bad......i had a long day!!! and yeah i hear ya on the fuel economy dropping, ive been notincg a few more runs to fill the tank up over the course of a motnh then i have previously....but that might also be because my seals are goin...{shrug} oh well......

I will be adding the dual cuz I will be cutting the collector pipe from my headers in 2 spots then weld the extension to the back. It is possible and yes you will loose back pressure but in my case I run NOS so I don't loose low end torque and I gain top end speed. So I guess it's a win win situation.

Nice try, Brad!!  
      But you aren't GOD, GOD is GOD!!

   (Had to say that!!)