a bunch of guys are trying to tell me that dual 2.25s will out flow a sinle 3", but I remember reading the area facts in one of my car magazines.

anybody with some proof is greatly helpful.

 

The area of the pipes breaks down as follows:
Dual 2.25": 7.952 square inches
Single 3" : 7.068 square inches

Big difference? Probably not.

 

That's not the flow area, because pipes are sized by OD.

If you assume 1/16" wall, the difference is about .5 sq in. Less than 10%.

More significant is whether your engine needs it. The factory saw improvement going to dual 2.25" cats over a single 3", but their pipes aren't mandrel bent.

A good aftermarket 3" mandrel bent system will work better than a dual factory 2.25" system.

 

Very good point. However, I think he is comparing a mandrel dual 2.25" system vs mandrel 3" system.

It still winds up at mandrel 2.25: about 7 square inches and the single mandrel 3" at about 6.5 square inches.

I dont think going from single 3" to dual 2.25" would see any gains though.

 

I think we're in violent agreement.

 

Agreed .

 

Does the turbulance caused by the y-pipe have any negative effects on flow? Just curious, would help the arguement on dual over single.. if they had the same (roughly) inner area, but if the single had turbulance problems..........

 

If nothing else, I have never heard a single exhaust that I have liked better than an equivelent dual exhaust as far as sound quality goes. You can argue this into the ground, but I have owned both and have friends with both- a good dual exhaust has a badass sound to it.

 

yes it does! the sound and the cost were the two big reason for me going with duals. and i like seeing the muffs poke down underneath the car. cost me less than $300 for headers back.

 

True duals with a crossover will flow better, make more power, and sound a lot better than a single 3".

But you have to take into consideration logistical problems with doing it. I've seen some fairly "clean" setups using hooker long tubes, but thats pretty much it.

What I may do eventually is run the long tubes, dual cats, then some dual mufflers. Should keep the flow up, and obnoxious noise down.

-- Joe

 

if this is true then why does everyone say the hedman headers and y-pipe are no good cause the 2.25in y-pipe, if they are putting it into a 3in system then thats ever more restrictive correct??

 

The hedman y pipe is a pile of crap period. Even if it wasnt 2.25", it is poorly designed. It looks like a factory piece, not an aftermarket performance product. I wouldnt even say it Y's, one pipe pretty much runs into the other at a 90* angle . That and its too small .

 

What y-pipe were you looking at? It has a y-collector. The ID of the y-collector is over 3.50". Probelm it's welded to a 2.50" pipe for stock thirdgens.

You cut that off, and weld 3" to it and your done.

I think your just being silly.

-- Joe

 

So much for the violent agreement.

 

I dont think I received the same y pipe you are describing from Hedman. Mine didnt even Y, the passenger side pipe just butted perpindicular to the driver's side pipe after the oil pan. NOT a performance piece.

 

Sounds like you are talking about the MAC Y-pipe, Heres a picture off the website. Super overpriced...