True duals?

[trhlz1222]

i got msds headers in now. its a pretty much stock 2.5 other then headers wires intake. i have magnaflow mufflers on it #14832. wondering if i would see much difference in volume if i was to put a new y-pipe on with true duals also. performance mods for later down the road include a turbo and possible 3L. would the true duals sound better then wat i have now or will it be even more raspy on high rpms?

[BrApple]

well true duals would eliminate the y-pipe as you would be running to exhuast pipes, one for each bank of the engine to the back of the car ... I believe you would end up wanting to add a X-pipe to the setup also.

should be plenty of info on this on the old forums

[trhlz1222]

is there any difference in the gains between stazis true dual setup and the one like off changs car that has bends in it? also has anyone tried to run true duals under the side skirts and out of the jack point cover? kinda like old stingrays had and some of the more modded stangs have?

[hotdimmes]

not true duals, but a few did run side exhaust to the rear jackpoint cover. I know at the very least, I have pictures of hector's old zetec looking like that. I dont think it's very safe as the jack point cover isn't far enough behind the rear door. It would be pointing at your passenger's legs/shins still.

[trhlz1222]

how would it hurt the passengers legs? i mean i understand heat wise but that would only come into effect if people actually got into the back and second if they were standing in the rear. right? can i see pictures of it or dont you have them accessable? i want to try this on the svt but unsure if its safe for the car and how raspy it would become without the space for a muffler

[bagged]

steeda has done this as well
and i wouldnt run exhaust through the side skirts for fear of heat damage

[icysvt]

steeda has done this as well
and i wouldnt run exhaust through the side skirts for fear of heat damage
my thoughts exactly!

[hotdimmes]

my thoughts exactly!

Why? It's no more damage than the surrounding area of bumper around the normal exhaust isn't it?

[trhlz1222]

steeda has done this as well
and i wouldnt run exhaust through the side skirts for fear of heat damage


do you mean through the jack point or in general up the side of the car?

[Steeda...]

Stazi doesn't have true duals

I gained 12hp and 15ft/tq at the wheels with my true dual set up. Also no real need for a X pipe on this engine. It shouldn't make a difference either way technically

coming out the side skirt would look lame!!!

[trhlz1222]

Stazi doesn't have true duals

I gained 12hp and 15ft/tq at the wheels with my true dual set up. Also no real need for a X pipe on this engine. It shouldn't make a difference either way technically

coming out the side skirt would look lame!!!

the reason for the xpipe was to reduce raspy cause i already have alot on high rpms. and the exhuast out the sdie would look good with a angled tip flush to the jack point cover. cut a whole in the jack point and sand it so its rounded and have the tip sstick out about 1/8 of an inch

[Steeda...]

Raspy? A xpipe isn't going to solve that. Sounds like more thought should have gone into your system. Mine sounded like pure sex at High RPM's

2 18" resonators
2 Magnaflow mufflers

no x pipe
Sho-shop y pipe cut apart and mated to the rest of the exhuast

[trhlz1222]

where would you put a cat for the people that have to abide by emission laws?

[Steeda...]

staggered right after the rear header meets the exhuast. pretty much in the stock location

[HolyRollerzC3]

i can post pics of my setup, the bends arent perfect, but i like it...

i had a y-pipe from BAT that i removed the 2in/1out cat from and was left with jsut the pipes, and i have a magnaflow cat, flex, magnaflow resonator and then bends back to supertrapp on each one!

sounds good, and does the job!

[trhlz1222]

do you got any sound clips too?

[S2Knott]

what size are the pipes that you guys have with truduals? i could amagine anything bigger than 2 1/4 because dont both the pipes have to run paralell in the exhaust channel?

[HolyRollerzC3]

what size are the pipes that you guys have with truduals? i could amagine anything bigger than 2 1/4 because dont both the pipes have to run paralell in the exhaust channel?

i run 2" piping, anything bigger is overkill... i do have one sound bite somewhere, i'll ahve to locate it or take another one, but i have an exhasut leak somewhere, i think where the one side connects to the headers, so i'll tighten it up before i make a sound clip!

[trhlz1222]

would 2" be good if a 3L and turbo was put it?

[striker2]

would 2" be good if a 3L and turbo was put it?
you cant run true duals with a turbo :troutslap:

[trhlz1222]

wat exhuast do you recommend with a turbo?

[striker2]

3" minimum for a V6
2.5" minimum for a 4 (although 3" is still better)

[trhlz1222]

so if i plan on turboin it just get a regular cat back with 3"?

[striker2]

so if i plan on turboin it just get a regular cat back with 3"?
yup. best option

[S2Knott]

so explain to me you truduals setup is it 2" the whole way? how isnt that a restriction? does it open up after the rear y pipe or something?

[zorrex]

yup. best option

Or just get a supercharger...:laugh:

[BK4293]

so explain to me you truduals setup is it 2" the whole way?

What did you say Tina?

[zorrex]

What did you say Tina?

:laugh:

[HolyRollerzC3]

2 2" pipes alows more air then 1 3" pipe?! Where is the lack of logic?

[zorrex]

2 2" pipes alows more air then 1 3" pipe?! Where is the lack of logic?

Well, actually, they would be very close to the same...The cross-sectional area of the 2" pipe = 2 pipes * (1" radius)^2 * pi = 6.28 sq in

The cross-sectional area of a 3" pipe = 1 pipe * (1.5" radius)^2 * pi = 7.07 sq in.

So the ONE 3" pipe WILL allow more air to flow through it than TWO 2" pipes. And in addition, with 2 2" pipes, there will be more friction losses in the 2 2" pipes because there is more surface exposed to the flow of air through the pipe...

:shrug:

[BrApple]

don't forget about the amount of air flow, the single 3 inch pipe will receives all of the exhaust flow from both banks where as the tru-duals will only receive half of the total exhaust flow from the engine ...

[striker2]

don't forget about the amount of air flow, the single 3 inch pipe will receives all of the exhaust flow from both banks where as the tru-duals will only receive half of the total exhaust flow from the engine ...
and the smaller diameter pipes will help to keep the velocity of the gas up.

[BrApple]

and the smaller diameter pipes will help to keep the velocity of the gas up.


yup thats correct


now Ian since you are currently taking fluid dynamics calculate the thickness of the boundary layer in both situation, a 2" and 3" pipe and that will give you an idea of how much area the pipe really flows

[zorrex]

yup thats correct


now Ian since you are currently taking fluid dynamics calculate the thickness of the boundary layer in both situation, a 2" and 3" pipe and that will give you an idea of how much area the pipe really flows

I'm too lazy, lol. Will there even be a boundary layer? :confused:. I would think the relative roughness of a rusted (over time, it would become rusted) pipe would be too great and there wouldn't actually be a "boundary layer."

[BrApple]

I'm too lazy, lol. Will there even be a boundary layer? :confused:. I would think the relative roughness of a rusted (over time, it would become rusted) pipe would be too great and there wouldn't actually be a "boundary layer."


pretty sure there would be, that the definition of flow in a pipe, the roughness is what will cause the air to be turbulent and seperate from the sureface creating the boundary layer

think of a velocity profile from a pipe cross section, the greatest flow is in the center and it tappers off to the walls of the pipe where the velocity would be zero

[zorrex]

And Brian, I was comparing the TOTAL area of both setups, that way they can be compared using total flow. But if you are saying that there will be a boundary layer, then that only supports the use of a 3"...More of a total surface area between the 2 2" pipes meaning more non-flowing fluid along the boundary layer...

[BrApple]

And Brian, I was comparing the TOTAL area of both setups, that way they can be compared using total flow. But if you are saying that there will be a boundary layer, then that only supports the use of a 3"...More of a total surface area between the 2 2" pipes meaning more non-flowing fluid along the boundary layer...


ok, so by area we know the single 3" pipe can flow more, so lets now look at velocity.

the 3" pipe will have a lower velocity then the 2" pipe, and remember that the smaller pipe has less volume to flow

i can't remember but the boundary layer has to be dependent on the velocity, area, etc

but more then likely the this isn't going to have a big affect in this, but techanically you would need to account for it, as well as all losses from bends in the pipe

[zorrex]

pretty sure there would be, that the definition of flow in a pipe, the roughness is what will cause the air to be turbulent and seperate from the sureface creating the boundary layer

think of a velocity profile from a pipe cross section, the greatest flow is in the center and it tappers off to the walls of the pipe where the velocity would be zero

Hmm. You may be right, but I'm still on the fence on this issue. I will work out calculations in the near future. What would be a good estimate for the flow of exhaust from a Duratec at 1k rpm, 2k, etc? I quickly whipped out a lab report I've been working on recently, and the epsilon (roughness value) for new stainless steel is .000084 inches +-50%, and for rusted steel it is .084 inches +-50%. The rusted value is quite high, and I wouldn't expect it to be that high in engine applications. Let me know what you think and I will run through some calculations...

[BrApple]

Hmm. You may be right, but I'm still on the fence on this issue. I will work out calculations in the near future. What would be a good estimate for the flow of exhaust from a Duratec at 1k rpm, 2k, etc? I quickly whipped out a lab report I've been working on recently, and the epsilon (roughness value) for new stainless steel is .000084 inches +-50%, and for rusted steel it is .084 inches +-50%. The rusted value is quite high, and I wouldn't expect it to be that high in engine applications. Let me know what you think and I will run through some calculations...


good estimate of exhaust flow, not really sure, I know at idle a duratec MAF reads about .7 #/min on average, and I have seen miine get upwards of 11~14 #/min at high rpm.

as for the epsilon of the pipe I would say go in the middle of the two values as a good average, the inside definately shouldn't rust as much or like the outside of the exhaust

[98TredSVT]

Stazi doesn't have true duals

I gained 12hp and 15ft/tq at the wheels with my true dual set up. Also no real need for a X pipe on this engine. It shouldn't make a difference either way technically

coming out the side skirt would look lame!!!

Was this over stock exhaust or what setup? Did you already have headers on there? I already have headers and an optimized y pipe, with a borla resonator, what kind of gains could I expect with true duals?

[elraido]

Was this over stock exhaust or what setup? Did you already have headers on there? I already have headers and an optimized y pipe, with a borla resonator, what kind of gains could I expect with true duals?

That was a fairly stock set up if I remember. No headers for sure. So that would only add more...figure totals would be at least 20 more hp to the wheels with both of them. If I had the money at the time, I would have ordered me some. And they ran under the gas tank in case you were wondering.

[Klasse Act]

I didn't have headers, but gutted pre-cats (aka the "mystery mod") and my last dyno at SZ04' had me putting down a corrected 171 hp to the wheels. I had 2 1/4" piping (too big IMO), dual Magnaflow resonaters, dual Magnaflow race mufflers and the car was loud, too loud IMO looking back on it, but it did flow though:shrug:

[The Five-Oh!]

I didn't have headers, but gutted pre-cats (aka the "mystery mod") and my last dyno at SZ04' had me putting down a corrected 171 hp to the wheels. I had 2 1/4" piping (too big IMO), dual Magnaflow resonaters, dual Magnaflow race mufflers and the car was loud, too loud IMO looking back on it, but it did flow though:shrug:

that car was ridiculously loud. I remember SZ05 when the best sound i heard was when chad ran out of gas...then we filled it back up and listened to a cessna the rest of the drive to the track.

[mjsvt]

you need a v8 to feel the true duals, a small v6 aint worth the money

[Pudmunkie]

I didn't have headers, but gutted pre-cats (aka the "mystery mod") and my last dyno at SZ04' had me putting down a corrected 171 hp to the wheels. I had 2 1/4" piping (too big IMO), dual Magnaflow resonaters, dual Magnaflow race mufflers and the car was loud, too loud IMO looking back on it, but it did flow though:shrug:

It may flow, but it sounded like BALLS!

[Barge]

Don't forget to take wall thickness into account when you are doing your math. Most of the tubing is 16gauge so you can go with 1/16th of an inch for your calculations. So basically you have to take 1/16th off your radius.

So 2 2" pipes are ~5.52 in^2

a 3" ~ 6.49 in^2

Just so ya know.

[Trapps]

do you got any sound clips too?

Check the exhaust thread for clips.

True duals, custom mandrel bent pipes, Magnaflow 2 in/2 out res, supertrapps & mystery mod:

http://www.contour.org/carprofile/files/871/media/Mov00221.mpg

Archives for pics and specifics.

[WiredMotorSports]

You talkin side pipes like this?
http://i62.photobucket.com/albums/h90/william81/side.jpg

[WiredMotorSports]

Maybe square...
http://i62.photobucket.com/albums/h90/william81/side1.jpg

[imnotacop420]

I didn't have headers, but gutted pre-cats (aka the "mystery mod") and my last dyno at SZ04' had me putting down a corrected 171 hp to the wheels. I had 2 1/4" piping (too big IMO), dual Magnaflow resonaters, dual Magnaflow race mufflers and the car was loud, too loud IMO looking back on it, but it did flow though:shrug:

So why do you say that 2 1/4 was too big? I just started shopping for mufflers and resonators, I am looking to go true dual this spring when I finally install my headers. I was looking into 2 1/4" piping mainly because I can find a better selection of mufflers.

Thanks

[99Mystique ATX]

So why do you say that 2 1/4 was too big? I just started shopping for mufflers and resonators, I am looking to go true dual this spring when I finally install my headers. I was looking into 2 1/4" piping mainly because I can find a better selection of mufflers.

Thanks

Anything bigger than 2" on a 2.5L or a lightly modded 3L is overkill. The issue with running 2 1/4 is that you lose flow velocity. While you may gain a little up top, you will lose much more down low for sure.

On a side note, I just purchased HolyRollerzC3's old true dual exhaust and that will be installed on Tuesday so I should have some pics and possibly videos up the middle of next week...