Full dual vs Y and X setups

[SCV8]

Is the location of the new X within an inch of where the Y used to be?
Have had issues with altering the effective lengths of runners myself, usually easiest to try and keep it the same unless you have infinite fuel tuning capabilities.
If you've noticed, the S&S headers do this, both for fitment to several years/models, and presumably, for tuning reasons.

 

[JBrady]

Is the location of the new X within an inch of where the Y used to be?
Have had issues with altering the effective lengths of runners myself, usually easiest to try and keep it the same unless you have infinite fuel tuning capabilities.
If you've noticed, the S&S headers do this, both for fitment to several years/models, and presumably, for tuning reasons.

While the ability to optimize fuel delivery will help whatever system you choose it is not the primary concern with exhaust design. Keep in mind the MAF will compensate for the change in mass flow.

I agree that it is a good idea to place the merge in the same basic location as the factory but when you change pipe diameter you have altered the tuning of the pipes anyway. The factory places the first Y as close as reasonable to catalysts with the main obstruction being clearing the transmission.

When designing the S&S Headers I specified stock catalyst location as to allow their use with the stock system in stock location. I also wanted merge collectors and we got 2 of the 3 on each side as merge collectors (they are a tri-y design).

 

[SCV8]

Remember the MAF is only a sensor, and that the ECU does make for only a limited amount of compensation within a certain rpm range, that along with the fact that the ECU is in closed loop during wot/high rpms, makes for a great reason to just maintain oem lengths when all you have is a stock ECU.

 

[doey]

I put up a video of my car and what it sounds like. It has 2.5" pipes running into a 2.5" Y pipe, up to 3" cat which exits into a 3" pipe and out via a Lukey muffler.
[hopefully the M112 SC should be on soon]
http://photobucket.com/albums/y214/DoeyIG/VS%20Commodore/

It's a 1.5 mb file not 20 Right click then save target as
http://lextreme.com/members/Vs%201uz%201.5%20mb/Commodore%201uz-fe%201.5%20mb.avi

It's in drive because the camcorder kept sliding off the dash :veryhappy The engine is bit boggy because the injectors have been upsized for the SC. It hooks up just before it changes into top gear. Apart from those changes everything else is stock.

 

[JBrady]

Remember the MAF is only a sensor, and that the ECU does make for only a limited amount of compensation within a certain rpm range, that along with the fact that the ECU is in closed loop during wot/high rpms, makes for a great reason to just maintain oem lengths when all you have is a stock ECU.

Of course the ability of the MAF to adjust varies from vehicle to vehicle both by manufacturer and by year BUT the MAF is always part of the ECU imput. Open loop mode refers to the oxygen sensors which are in most applications narrow range and therefore ineffective at full throttle ratios.

In fact in some applications, noteably the LS1 engine, some people simply spray nitrous through the MAF and allow the ECU to add fuel up to the limits of the system.

With the Lexus application and headers the stock system has more than enough capacity for exhaust upgrade flow changes.

With cold air induction systems a change to the ECU is only usually needed if the MAF tube flow area (pipe size) is changed relative to the MAF element. This is what happens with the SRT intake, a larger pipe is fitted with the stock element and without reprogramming the signal the ECU will not provide sufficient fuel.

 

[JBrady]

I put up a video of my car and what it sounds like. It has 2.5" pipes running into a 2.5" Y pipe, up to 3" cat which exits into a 3" pipe and out via a Lukey muffler.
[hopefully the M112 SC should be on soon]
http://photobucket.com/albums/y214/DoeyIG/VS%20Commodore/

It's a 1.5 mb file not 20 Right click then save target as
http://lextreme.com/members/Vs%201uz%201.5%20mb/Commodore%201uz-fe%201.5%20mb.avi

It's in drive because the camcorder kept sliding off the dash :veryhappy

Doey,
Excellent work. Car sounds very nice. I look forward to the supercharged vidoes!

Now, question, you say dual 2.5" pipes into a single 2.5" Y pipe? Do you mean the pipe leading into the catalyst is a single 2.5"? Do you have the stock exhaust manifolds?

 

[doey]

No sorry! They're modified stock manifolds. The systems not tuned length. [I'll post some picks later if I can get a camera in there.] I took a closer look at what was done rather than what was said. [interesting ] The left hand pipe swings over to the right, around the trasmission, then connects to a custom made side-by-side inlet, single 3" outlet which connects directly to the catalytic converter. [different] It's a bit ugly but seems to work.

You need too hear it standing on footpath/sidewalk as comes past at speed. "Sweet!" I need somebody to stand on the side of a freeway holding a camera, any takers? :veryhappy

[Nothing to stupid]

 

[doey]

Here's what the exhaust sounds like in top gear. The 3" pipe sounds a bit hollow to me. If every thing goes right I should have the blower on in few weeks.

500k right click save as
http://lextreme.com/members/Vs%201uz%201.5%20mb/dore1uzz.avi

 

[jibby]

Doey, first of all I would really like to say that is super nice what you did with your exhaust system. It is really a complete setup... I am looking to change out my Y pipes tomarrow at a local high performance muffler shop from the stock ones. I am hearing the Y pipes will make a noticeable difference....I am going with 2 1/2" Y's on both sides of the magna-flow cat. conv.and a similar stretched Y design like Jbrady's. I am wondering how much louder it will get? Any thoughts on this upgrade fellas...? Headers are next to follow..Anything I should be made aware of before I do this mod?

 

[Pro]

here's one for you all. bit off topic but still Y pipe related.

two pipes feeding a single split entry turbo.

do you bridge the two seperate pipes with a single pipe just before the turbo, then run your wastegate off that, or do you just let the two pipes merge at the split entry and the merging is done post turbine?

 

[Lextreme II]

I just convert my stock exhuast to two 2.25" with two mufflers. I deleted center resonator, secondary resonators and replace stock mufflers from 2" to 2.25". The noise is slightly increase but not as bad as i would expected. I think the turbo is a great muffler itself. After I deleted the Y pipe, I do noticed i lost slight lower end.

Looks something like this:

 

[jibby]

:wtf: Pro240 - I have no idea, not a turbo guy?

Wow nice David, it was my understanding that you need to keep the X in place? How did you get around that with out causing problems? You are turbo'd though I almostforgot....I also lost noticeable low end torque when I changed out only the stock cat...believe it or not. I expect more of the same with the new Y's in place. Bye, Bye lowend:sorry: .....hello top end I guess:redface: ...

Side note: David you wanna race? A few of the guys are meeting up from this forum to give it a go this Sunday, and I am down... You will probably take me with that Turbo of yours if you decide to show....

 

[doey]

Doey, first of all I would really like to say that is super nice what you did with your exhaust system. It is really a complete setup... I am looking to change out my Y pipes tomarrow at a local high performance muffler shop from the stock ones. I am hearing the Y pipes will make a noticeable difference....I am going with 2 1/2" Y's on both sides of the magna-flow cat. conv.and a similar stretched Y design like Jbrady's. I am wondering how much louder it will get? Any thoughts on this upgrade fellas...? Headers are next to follow..Anything I should be made aware of before I do this mod?

Here's a thought! [I think it's a thought] It looks like you want a twin system. You could, [ I'm thinking again] put an X pipe before the tunnel, then run twin pipes down the tunnel exiting into another x-pipe and out the back. You'd have to put a cat on each pipe before the first x-pipe. unless you can get two scrawny ones in the tunnel.

 

[jibby]

Doey - I will chose to Supercharge and not Turbo in the future that is already predetermined for me regardless, and maybe not with this SC400 we will have to see.. Interesting on your thinking...

Maybe if JBrady is listening in maybe he can mention what he thinks of your exhaust idea... I am running nos now and just looking to get the best flow with the S@S headers that will be going in as soon as I get the chance to install...which could be anyday now...

 

[Pro]

dont run the X pipe in the hot area of the zorst - run it where the gas cools a bit otherwise the expanding gasses merge and create undue turbulence.

in other words, merge them about mid car -> diff.

 

[doey]

dont run the X pipe in the hot area of the zorst - run it where the gas cools a bit otherwise the expanding gasses merge and create undue turbulence.

in other words, merge them about mid car -> diff.

My understanding of the X-pipe is that as the gases cross, they reduce that tumbling effect and also create a venturi effect. Which in turn speeds up the flow. What your saying tho might explain why "people" suggest stepping the pipe diameter up a notch, and then choking it back down at some point to create a second venturi. If you’re only using the cats a second x-pipe can be a good spot to do this. If you only want a single pipe out the back, "they" of course run it into a y-pipe.

here's an example I googled



I hope I haven't been talking to much bulls**t.

 

[jibby]

Two into one then back to two and then back again to one.... Only one exhaust pipe outlet....I don't know about this one, has it been tried out yet with results?

 

[jibby]

Well the exhaust pro's and I looked over the exhaust system today completely and pretty much decided there is nothing more I can really do except remove the high flow cat and do the X. Any thoughts on how I can improve this exhaust flow without deleting the cat? Headers are going in shortly.

Believe it or not this little setup flows decent. The two pipes coming from the headers flow directly in to the two port openings of the magna high flow converter creating it's own high flowing Y then back out to the larger piping. The Y coming out to the larger pipes on the outer half seem to flow decent as well. This is the best I could come up with at a conventional muffler shop....

Running straight thru mufflers as well.

 

[doey]

Two into one then back to two and then back again to one.... Only one exhaust pipe outlet....I don't know about this one, has it been tried out yet with results?

That's two, x-pipe, two, mufflers,[3" pipe the rest the rest of the way from muffler] y-pipe, one.

Don't know why, after travelling so far with two pipes you'd bring it back to one pipe. The I.R.S maybe or one notch in you bumper bar.

It's good to see your exhaust shop gave an honest opinion in order to save you money. My original thought was designed to change the central pipe into a two pipes which, I thought might be less congested. When you think about it, the step up to the larger pipes you have at the back would clear it out well. Since your now flush with the money you've saved, it must be your turn too buy the drinks.

 

[jibby]

Thanks doey, yeah I'm good with this exhaust guy, we go way back and he is a friend of mine. He did suggest maybe going larger with the very center single pipe, but I would need to alter the converter to do that...We will see....