TCCoA Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
116 Posts
Discussion Starter #1
Hey guys,

Just wondering. I have finished my PI Engine build with Ported Intake and Exhaust ports. I have matching shorty headers for it but I'm not sure what kind of exhaust to put on. I want to get it all done in one shot but I looked on SCP's website and they have two setups. They have a true dual setup and a Y pipe setup. I asked the exhaust shop what they were going to do and they said they were going to put two high flow magnaflow cats, remove the third one. Then they said they would make a Y pipe going to two magnaflow mufflers. The pipe diameter would be 2.25"

Shouldn't it be a true dual system instead. every P.I mustang i see has a true dual setup. The exhaust shop was talking about pressure on the low end or something like that. I didn't fully understand because i don't know about exhaust systems. I can only trust what hes saying. But from what i see everyone has a custom true dual exhaust setup here.

Should I stop him and say I want a true dual setup instead?

Thanks guys
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,363 Posts
The backpressure theory is complete B.S. A smaller pipe will give better scavenging at lower flows because gas velocity is high, but will restrict flow at higher RPM. A larger pipe will give better scavenging and flow at higher RPM but you'll lose some gas velocity at lower RPMs - reducing the scavenging effect down low and thus torque. This is why you tend to lose a bit of low end torque with a bigger pipe but gain power up top. It is NOT backpressure! Think of what happens with clogged cats. Lots of backpressure - absolutely no power (if the engine runs at all).

2.5" duals are an all around good choice if you are going PI and/or have any further plans down the road. For you since you've got a PI motor with some head work, definitely go duals.
 

·
Registered
Joined
·
116 Posts
Discussion Starter #5
Thanks for all the info
I am running fords shorty headers for a mustang with two magnaflow high flow cats. Deleted the 3rd cat. 2.5 inch pipes going to a 3 inch pipe and back out to 2.5 inch pipes again with magnaflow mufflers. I like how it came out. Ill post a video later on today.
 

·
Registered
Joined
·
23 Posts
I don't think you'll create enough power to take advantage of a true duel exhaust. Single 3 inch exhaust can handle over 500whp. But if you want it go for it. It's your car. If it were me. 2 1/2 inch pipes meet into a single 3 inch y back to a set of mufflers. Done. No cats. No resonator. Unless the law permits.
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,363 Posts

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,363 Posts
Here is another chart that is a little more technical...

 

·
Super Moderator
Joined
·
5,013 Posts
You got some rust back there, Shadow21. Maybe a bit of POR15? :diablo:

BTW - Down here we call that "severely rusted".

RwP
 

·
̇
Joined
·
3,701 Posts
Down Tubes

Shadow21 said:
Here is a picture of my setup

Looks pretty good.. ;)

That's a similiar set-up to mine..


The only thing I need to really change on my set-up is the Down Tubes..


I've been looking at these on SuperCoupePerformance



I don't want to spend $200 on a pair of Down Tubes though.. :facepalm:


Anyone got a link for a pair of these half price?.. :D






Rayo..
 

·
Registered
Joined
·
1,253 Posts
There are plenty of people that say true duals. My exhaust guy said it was better with a single 3" in a Tbird since there would be less bends. I have stock PI with a Magnaflow resonator with two in and a single 3" out Ys to 2 Magnaflow mufflers, I also have no cats. Lots of people say that car sounds mean.

Just sharing:)
 
1 - 18 of 18 Posts
Top