Long tube headers with 3" collectors, What size pipe from the collector to the y pipe would be sufficient ? 355 450hp spinning to 6700rpm

 

you don't have the mufflex y-pipe? that y-pipe is 3" but is flattened out in some areas to clear some items under the car.

 

The y pipe is for hooker headers, I have headman ball and sockets plus I can make a y pipe cheaper than what they offer

 

I've got the Mufflex Y-pipe, but if you're just looking for a picture to build on of your own, this might help you. I have Hooker LT's, 3" couplers into a single 4" Mufflex Exhaust (Magnaflow) muffler. I had to notch the Transmission Cross member for the clearance.

Hope that helps....





Front to back





crossmember notch 1

 

What I'm trying to find out is X size pipe supports X amount of volume and hp. On top of that there is scavenging. Both 2.5 and 3 pipe has there pro and con and I'm trying to decide which I need

 

Oh I thought you were just asking for what size pipe. I saw that in your first post you mentioned your Engine size/HP and RPM but I didn't relate them to your ultimate goal of finding out volumetric requirements to support said HP & RPMs.

We might need to know other information such as Carb Size (if carb) or TB size if FI. Intake port size, Head Port/Valve sizes & cam details. Obviously all of that needs to be matched up. As an example, it would be pretty silly to have a 600cfm Carb (or Stock TPI) and monstrous cam that isn't matched and think two 3" pipes into a single 4" exhaust is what's needed. Or a Holley Dominator 1000cfm Carb, Huge Cam, 195 cc heads requires a 2-1/2" I'm not saying that's your set up, but knowing that information would probably be helpful in determining what's needed....

My set up for comparison is 850 carb, .603/.618 lift cam .247/.253 duration, 210 CC AFR Heads with 2.08/1.60 valves. I originally had 2-1/2" couplers off my SLP shorty heads into a single 3" exhaust and ran 13.1 @ 104 tops. I changed ONLY the exhaust, tuned the carb a bit and ran 11.99 @ 117 the following year with my current set up (two 3" into a single 4")

If I'm understanding you correctly, that's what you're looking for? Good luck with finding your answer.

 

For your power levels the Mufflex Y is plenty for your combo. Yes there are different scavenger effects, but for your combo just go with the Mufflex Y into the 4".

 

Reading comprehension, you don't have much of it

 

LMFAO

 

Thanks for the pics, I have a UMI crossmember so routing will be a little different but not by much

 

Manners, you don't have much of it. We are just trying to help. If it's not what you are looking for then no need to resort to childish replies.

 

Start reading threads instead of regurgitating things you've read online, 2nd and 3rd post already covered it if you actually read a thread

 

Bought the majority of stuff I need to cut up and weld in for the y, 2.5 to 4" is too big of a jump and the 3" will flow a lot smoother. Just have to make my way around the crossmemeber