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Best Y-pipe

FIND said:
there isnt much you can do to improve the design of it.
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Not sure this is much of a surprise, but we disagree there. The piping is too small, and all aspects of the merge are garbage from a performance standpoint. In fact, I would say the opposite of what you did... there isn't much you can do that WOULDN'T improve it's performance.
 
SicSE said:
Not sure this is much of a surprise, but we disagree there. The piping is too small, and all aspects of the merge are garbage from a performance standpoint. In fact, I would say the opposite of what you did... there isn't much you can do that WOULDN'T improve it's performance.
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The merge is garbage, but when you optimize the pipe, then you are eliminating the problem area.

I say that because 2.25 pipe is NOT to small. It is only marginally to small. 2.5 inch pipe is marginally to big. Given the volume of exhaust the duratec 2.5 breaths normally, it appears to me that 2.5 inch diameter pipe is to large and you start losing some of the scavenging effect. Granted, 2.25 is slightly smaller than optimal, and noone has ever tried it, however I am willing to bet that a mandrel bent 2.25 inch system with high flow components (muffler, resonator, cat) would net the same horsepower improvement as the 2.5 inch pipe does, however the improvement would be at lower RPMs. I think the optimal configuration for these cars would be dual 1.75 inch mandrel bent pipe all the way back through high flow components.

If I get another contour. I will put in the dyno time to prove this concept

However, all of what I said goes out the window when you go to a 3 liter or FI. 2.5" should be almost perfect on a 3 liter, perhaps still a hair to big.
 
FIND said:
when you optimize the pipe, then you are eliminating the problem area.
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Only partially. Optimizing does nothing to smooth the angle at which the Y converges, which is very abrupt.

FIND said:
I say that because 2.25 pipe is NOT to small. It is only marginally to small. 2.5 inch pipe is marginally to big. Given the volume of exhaust the duratec 2.5 breaths normally, it appears to me that 2.5 inch diameter pipe is to large and you start losing some of the scavenging effect. Granted, 2.25 is slightly smaller than optimal, and noone has ever tried it, however I am willing to bet that a mandrel bent 2.25 inch system with high flow components (muffler, resonator, cat) would net the same horsepower improvement as the 2.5 inch pipe does, however the improvement would be at lower RPMs. I think the optimal configuration for these cars would be dual 1.75 inch mandrel bent pipe all the way back through high flow components.
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Marginally too small, is still too small... sounds like you're splitting hairs just to tell me I'm wrong. Regardless, strictly by the numbers, you're right, the basic math agrees with you in terms of straight CFM's. But CFM's are only part of the whole equation. I showed a loss of power, (and very slight torque loss IIRC), from bolting my straight-through exhaust up to my Y-pipe. If CFM's were the ONLY issue, adding same-size piping to the end of an exhaust pipe would not yield any power loss. Thermal expansion/contraction and pumping losses from a given length of piping play a part in real world power production, and they are usually not accounted for when people do the math for performance modifications.
 
As far as the angle the pipes come together, I haven't seen any aftermarket pipe that does it much better. I think that is a moot point.

As far as a question of my math. No I include everything in my calculation. Gotta remember, I am a serious math nerd. I do math and physics for fun in my free time.

Marginally to big is still to big conversely, I am not splitting hairs, and I have no particular interest in telling you that you are wrong. Believe me, I am not just telling you that I believe you are wrong just because I want to, I dont really have any particular grudge against you. Depending on the amount something is oversized, the amount of turbulence in the border area can slow exhaust velocities even more than a slight restriction does. I take into account the effects of heat, friction, turbulence, scavenging, and other flow dynamics when I state my opinion that a well designed 2.25" system would perform the same or marginally better than a similar 2.5" system. Especially when used in conjunction with appropriate tuned headers. Though I believe that a true dual 1.75" pair would be the best solution.

Either way, I still plan on proving my calculations at some point. If I dont ever get around to finding a T-Green SVT that I can buy at a time that I can afford it, I will build a system to fit a standard V6 and work with someone who has an unmolested SVT to work out the exhaust question.

Other people are apparently going to take up the y-pipe debate. Only problem I can see with testing the Y-pipe would be inequalities in exhaust systems. That is to say, a person would need 2 exhaust systems to properly conduct the testing, one would have to be 2.25" and the other 2.5", and they would have to be equal in design aspects, the only difference between the two would have to be in the absolute volume they can flow given their sizes.

Now of course, understand that I am saying all this based upon the best power combination I can imagine for a naturally aspirated duratec under normal spirited driving conditions.

Though, we are veering off topic.... probably should stop here, move to PMs or start a new thread.
 
biminiLX said:
I'll keep my SHO Shop/BAT Y-pipe.
If you can find the post, DemonSVT made recommendations in timing for a tune for the best flowing Y-pipe (SHO/BAT). I had them saved somewhere for future reference, I'll try and check.
-J
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I remember that post as well...it was for that reason why I bought the BAT y-pipe...
 
FIND said:
now isnt the trubendz pipe pretty much the bat pipe?
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Yes and No...
bat..has 2" primary tubes from the manifolds/headers to the cat. When the 2 pipes meet...they go into a 2 in 1 out maganflow cat...to a 2.5" tubing size.
trubendz has 2.25 primary tubes from the headers/manifolds down to a smaller y-pipe....while entering a tube size of 2.5"

Trubendz
cougar_ypipe_cat_pic.gif


bat pipe:
http://97.74.103.94/files/cexhst.pdf




Now for tubing size aside for now.

The bat pipe will help with reduction of rasp/noise because the cat material is closer to the manifolds. But the problem then lies with the cat interupting the exhaust pulses at this point when both banks finally meet. Then we have the flex pipe which is further down...the line...having to have the magnaflow cat welds up front absorbing much of the stress...which causes the cat to bend a bit more. This is the very flaw that causes the magnaflow cat to break down internally leaving every sho-shop/bat-pipe with no cat. And is the very reason MSDS won't warranty their headers if you use a bat pipe! Only a msds y-pipe or stock y-pipe.

Now the trubendz...has it right..for the most part....minus crappy welds...and a poor y-connector. :shrug:
 
I see. Then, what trubendz needs to do, aside from the better welds, would be to go down to 2" primaries, and smooth their transition, and we would have a design that is superior to most of the other ones out there right?
 
Harrry said:
Then we have the flex pipe which is further down...the line...having to have the magnaflow cat welds up front absorbing much of the stress...which causes the cat to bend a bit more. This is the very flaw that causes the magnaflow cat to break down internally leaving every sho-shop/bat-pipe with no cat. And is the very reason MSDS won't warranty their headers if you use a bat pipe! Only a msds y-pipe or stock y-pipe.
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thanks for the explanation...I went through two cats when I had the BAT pipe...I knew other folks had similar problems, but never knew why...
 
Harrry said:
The bat pipe will help with reduction of rasp/noise because the cat material is closer to the manifolds. But the problem then lies with the cat interupting the exhaust pulses at this point when both banks finally meet. Then we have the flex pipe which is further down...the line...having to have the magnaflow cat welds up front absorbing much of the stress...which causes the cat to bend a bit more. This is the very flaw that causes the magnaflow cat to break down internally leaving every sho-shop/bat-pipe with no cat. And is the very reason MSDS won't warranty their headers if you use a bat pipe! Only a msds y-pipe or stock y-pipe.

Now the trubendz...has it right..for the most part....minus crappy welds...and a poor y-connector. :shrug:
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I used to have an SPmotorsports catted y-pipe (pretty much a BAT y-pipe) and the cat material was gone when I checked it out 3 years later, but could have been gone long before. Also the flange that connected to the rear exhaust manifold cracked and caused an exhaust leak.
 
DonKingKong said:
I used to have an SPmotorsports catted y-pipe (pretty much a BAT y-pipe) and the cat material was gone when I checked it out 3 years later, but could have been gone long before. Also the flange that connected to the rear exhaust manifold cracked and caused an exhaust leak.
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TUFTOUR said:
thanks for the explanation...I went through two cats when I had the BAT pipe...I knew other folks had similar problems, but never knew why...
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Guys i went through 2 cats...also! Drove me nutts..i thought it was magnaflows cat material that was bad....but after speaking to them about these concerns. I found that stressing the cat in anyway will break the material. Right when he said that...it hit me like a light bulb.:nonono:
Because the way the cat material is setup. He said there is 2 log styles. It's not just 1 big piece. So it's 2 log styles that are separated...so it leaves the middle of the cat housing...empty.
 
Wow, this is more than I could have asked for!

Awesome.

Im worried now that if I get this BAT pipe the cat won't last long... Do they warrenty their stuff? Could I get a replacement if the CAT were to fail?
 
FIND said:
I see. Then, what trubendz needs to do, aside from the better welds, would be to go down to 2" primaries, and smooth their transition, and we would have a design that is superior to most of the other ones out there right?
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Yes...but not to jump the gun...we have a y-pipe in the works...that will be the best IMHO overall.

It will be similar to the trubendz...but with a u-bend up front(a bit more pipe length then stock)...better y-pipe connection. and 2" tubes.:cool: It will come with and without a cat.
 
SVT said:
Wow, this is more than I could have asked for!

Awesome.

Im worried now that if I get this BAT pipe the cat won't last long... Do they warrenty their stuff? Could I get a replacement if the CAT were to fail?
Click to expand...

No,Yes

http://www.fulllineexhaust.com/catalogs/MagnaFlow_Catalog/catalog/universal/940.htm
94000a.jpg

94007


I have all this jazz written up in a full write up. Because i'm redoing the exhaust section. I'm also working with other people to fill the rest of the gaps. Once it's done it will be posted. It covers every question possible (most). Especially stuff like the bat down pipe etc etc. :)
 
So they do not back up their product... Not cool :rolleyes:. Haa

When will the ypipe be available that you are working on? I don't need one until the spring semester, which is actually coming fast... haha
 
SVT said:
So they do not back up their product... Not cool :rolleyes:. Haa

When will the ypipe be available that you are working on? I don't need one until the spring semester, which is actually coming fast... haha
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Well keep your eye out in the next couple months that is all i can say.
 
Harrry said:
Well keep your eye out in the next couple months that is all i can say.
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I will def. keep my eye out! I am on this y-pipe thing like fly on .

I will let you know when im about to order, if the y-pipe that you are testing is ready.
 
Harrry said:
He said there is 2 log styles. It's not just 1 big piece. So it's 2 log styles that are separated...so it leaves the middle of the cat housing...empty.
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For those that don't know, this is what makes a CAT, a three-way CAT. The two "logs", or bricks, are made up of different material to reduce the different pollutants. The front brick, (reduction catalyst), reduces NOx, the rear brick, (oxidation catalyst), reduces HC & CO.

Interesting about the in-production Y-pipe Harrry... is that when preliminary pics will show up?
 
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