red6speedss

iTrader: (26)

Ok here is my plan. I am installing pacesetter headers. I going to come off the headers with 2.5 into an X-pipe. I am going to put both pipes over the passanger side. But will I be able to fit dual 2.5 without a BMR relocation bracket, or should i just go with 2.25 for the section over the axle to be shure. Once I get over the axle I will have two 4" round magnaflows on each side. not shure on tips yet. What do you think? Thanks, Brett

BrianC98Z28

iTrader: (11)

you can fit 2.5, but this sounds like a rigged setup, again this is my opinion and take it for what its worth, it seems everyone is on the true dual train and doesnt take the time to do them right. With the BMR relocation bracket you CAN run 3in OVER the axle all mandrel bent. I've personally seen it done and its the best dual system ive seen yet hands down. Seems like everyone whats to rig up a system and say they have duals. Stay with 2.5 if anything otherwise it'd be pointless. My opinion put in the time and effort needed 3in mandrel bent over the axle is the ONLY way to go.

Brian

10thAnivHawk

^^^I think 2.5 would be fine I'm thinking about doing something similar. unless you start making over 500rwhp I don't believe you will have to be worried about the flow capabilities of your system. And don't forget you want enough exhaust gas velocity so you don't suffer to much on your low end tq.

red6speedss

iTrader: (26)

factory is single 2 3/4 pipe. Even if you only went with dual 2.25 piped that is still eqivalent to a single 4.5 in pipe. For this reason as well as clearance issues I think I am going to go with 2.5 after the headers, and 2.25 over the axle, then back to 2.5 out the back. Being that dual 2.25 would flow the same as a 4.5 in single i don't think this would be restricitve unlss i was putting out over 500rwhp. What do yo think? I thought about just getting the BMR relocation bracket and running 2.5 all the way out, but i am woring about messing the suspension geometry up. So I believe I will go 2.25 for the section over the axle. thanks

mrr23

iTrader: (3)

dual 2.25 is equal to about a single 3". dual 2.5 is equal to about a single 3.5".

you can do a dual 2.5" over the passenger side and still use factory suspension pieces. bassani has done it already. click the pink banner to see pics of the system on that car.

red6speedss

iTrader: (26)

2.25+2.25=4.50 so how does dual 2.25=a single 3in pipe. Please explain this to me.

mrr23

iTrader: (3)

it's not a matter of simple addition. you need to find the area of a circle to determine how much flow it can handle.

kpowr82

iTrader: (9)

No it's not. First of all, it you don't have a well thought out, designed and tested setup, then you have no idea what that exhast is flowing. Improper x junction placement can cause all kinds of exhaust turbulence. Crush bends will magnify this even more.

Here's an example: Think of cross sectional area in terms of flow. The greater the cross sectional area, the more air you can cram in right? A piece of 4.5" inner diameter straight pipe will have a cross sectional area of 16 in^2. A piece of 2.25" inner diameter straight pipe will have a CSA of 4 in^2, multiply that by two since you have to pipes, and you only end with 8 in^2. That is roughly half the CSA of a single 4.5" pipe. It's actually MUCH more complicated than this, some things I don't understand yet.

Something else to think about, the 4.5 single pipe has almost 1.5 times more surface area. Assuming the exhaust gas has the SAME PRESSURE as the exhaust gas in the TWO 2.25" pipes, more exhaust gas velocity is lost due to friction in the 4.5 pipe. HOWEVER, gas pressure will not be the same if you are comparing two different exhausts on the same car. The 4.5 single pipe will create less pressure on the exhaust, thereby reducing the amount of friction in the ehxuast. The 2.25" pipes however are quite the bottleneck, meaning not only more frictional loss will occur, but also more gas turbulence, thus slowing the exhaust gas velocity down.

All in all, TWO 2.25" pipes have a cross sectional area and inner surface area that more closely resemble a single 3.25" pipe. Even then, factor in frictional loss and increased gas turbulence, and you probably have an exhaust system that flows as well as a 3" catback (assuming you're 2.25" exhaust is mandrel bent).

mrr23

iTrader: (3)

ok some math for you.

area of a circle is Pi x radius squared

pipe--- area
2.25" = 3.97 sq"
2.50" = 4.90 sq"
3.00" = 7.06 sq"
3.25" = 8.29 sq"
3.50" = 9.62 sq"

dual 2.25" = 7.94 sq"
dual 2.50" = 9.80 sq"

mrr23

iTrader: (3)

and this is what happened when i swapped from the borla 3" adjustable catback with small open plate to the bassani tru-dual 2.5" with x-pipe on the wife's car. both with stock tune and cam.

kpowr82

iTrader: (9)

And I'm guessing Bassani had a lot of time and money invested in that system. That's why it costs so much (not really THAT much, considering it replaces the y-pipe and the catback). The most important part of a true dual system is not just pipe diameter, but x placement.

BTW, I'd like to see mrr23's car with the mufflex 4" compared to the Bassani 2.5". I'd bet your numbers would be within 3 hp and 3 ft lbs.

red6speedss

iTrader: (26)

My grandfather owns an exhaust shop so we are going to make this setup. Will I be able to squeeze 2.5 over the axle without any rattles, or should I buy the BMR relocation bracket to get further clearance? Will the BMR reloactor keep my suspension in factory geometry? Thanks, Brett

mrr23

iTrader: (3)

time, money, stainless steel, x-pipe replacing y-pipe, etc...

send me a stock y-pipe and the mufflex and we'll see or have mufflex do it. i'm up for it. hell, i might can find my original y-pipe.

mrr23

iTrader: (3)

the relocator has nothing to do with the suspension geometry. if you can bend the pipes just like bassani did, then you won't have any rattles.

red6speedss

iTrader: (26)

I can bend the pipes but not mandred bent. Can I buy just the section ove the rear from bassani? How much was your kit? I like the kit, but why did they go through all the trouble of a dual setup and only use single muffler?

mrr23

iTrader: (3)

ground clearance. underbody clearance. noise level. the muffler is a dual in/out design. click the pink banner and you'll see pics of the inside of the muffler as well. also, once exhaust is back that far, it's cooler than when it first comes out of the motor. again, no need for alot of big pipe.

the entire system is
stainless steel 949.00
aluminized 779.00

through http://www.vincihighperformance.com i have the stainless steel on both cars.

red6speedss

iTrader: (26)

Would I be able to purchase just the section that goes over the axle?

mrr23

iTrader: (3)

you can call bassani and find out.

red6speedss

iTrader: (26)

Thanks

DaddySS

Not recommended. Remember you never want to go smaller as you move away from the exahaust source. The hot exhaust is expanding and if anything you want to give it room to expand and accelerate. 2.5s will fit fine, just take your time to get them set up correctly.