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post #1 of 15 (permalink) Old 07-05-2012, 09:45 PM Thread Starter
 
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LT headers and spintech X-pipe

Ok I have been piecing my exhaust together. I got Dynotech long tubes with 04 catted mid pipes. 02 sensor extenders. I bought the spintech 04 X pipe. I had flanges made and I have a friend who owns a muffler shop. He is going to bend my tail pipes and weld the flanges on to bolt up to my kooks after burner mufflers. The last piece of the puzzle will be the tune. I have my Diablo SLP tuner. Im hoping with this exhaust having less bends in it than the stock 05 exhaust, Im really hoping for good results. I dont have anyone in my area that Dyno tunes. I just have a dyno in my area and thay had some one that rented the shop 1 day a week but that guy has moved on. With that being said I just want to be clear. I am using the 04 mid pipe set up with the 05-06 tail pipes.--I will keep you guys posted. Waiting for the spintech to come in--------danfigg
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post #2 of 15 (permalink) Old 07-06-2012, 11:23 AM
 
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Please take and post pics.

Current: MGW-p, H-pipe, SS OTRCAI, Lovell rear springs, Eliminator shocks and Pioneer AVH-P3300BT, JBA LTs+catless mids, Drilled/Slotted rotors, Kooks Afterburners, catch can & Tune Next: ??? Wish list: Intake & TB, modest cam, UDP, gears
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post #3 of 15 (permalink) Old 07-06-2012, 12:58 PM Thread Starter
 
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Of course I will... Just waiting for the X pipe in the mail im sure it will take a week----danfigg
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post #4 of 15 (permalink) Old 07-06-2012, 03:10 PM
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I'm i the process of sorting out what I need to do to improve my exhaust system. One thing I found out early looking into it was that the internet is full of bad information on exhausts. Some of it is because some concepts don't translate directly into what's going on with an engine. Things like a smaller pipe obviously doesn't flow as well as a larger one under a static flow condition gets turned on its head when the resonance of a pulsing, cooling gas icomes into play. The hard thing to wrap our brains around is that pressures in a system aren't static like a garden hose but come in "pulses" more like a speaker.

First there's the gas pulse that travels down the pipe from the exhaust valve. There are sound pulses too that are traveling at a higher speed than the physical gas. That sound has an effect too. A good exhaust takes the effects of gas and sound pulses and utilizes them to help pack the combustion chamber with more air than would flow in just due to static pressure "flow".

Also if you measured the temperature of the gases at say the collector and them measure them at the tailpipe you'd see that it's dropped on the way. They put O2 sensors near the manifold because they have to be heated and the gases have cooled too much back farther so the sensors won't work. Gases that have cooled have shrunk. What was needed for a given flow at the start of the pipe is less at the end of it because more of the gas is packed into a smaller volume. It's another reason why stuff like bends and crimps at the end of the system aren't as much of a concern.

Headers use the pulses and reflections. Besides the diameter and length of the primaries affecting what RPM range it will work in the collector merges together the primaries and uses the waves and reflections to help upstream. Mid pipes are a lengthening of the collector so the diameter and overall length can aid or hinder overall "flow" and bigger isn't necessarily better. The X-pipe and muffler placement work in concert with everything before it.

IMHO the placement of some parts as well, the size and length (not too big and not too small) will do more than a few bends and crimps in the pipe. Even the cam timing events affect the design and flow.

I should find some of the technical links I've been perusing. The system I'm designing now is going to use a smaller diameter mid pipe, place the X-pipe as close to the headers as possible and change mufflers. Besides scavenging the X gives the two banks alternating pulses an opportunity to somewhat equalize pressures between them. A pulse from one bank that had one pipe ahead of the X now has two pipes. Because most of the actions that do the work are waves and reflections once they are dampened out by the X/mufflers if the pipes after the mufflers flow well enough the system of the engine does not "see" anything beyond the X-pipe/mufflers.

Cliff notes: The X may help altho I haven't seen any that are in the best location. They are supposed to be within 24" of the header to do the most good. I don't think you'll see much if any gain.

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post #5 of 15 (permalink) Old 07-06-2012, 06:59 PM Thread Starter
 
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Svede Im glad you chimed in. I went with the X because for some reason it was cheaper than the H. I went with the spintech because they actually bolt up the the stock mids. I brought it to the guy who is gonna bend my tails and the first thing he asked was if I was gonna keep the kooks after burners and that he needed the flanges. I was like got the flanges. His next question was "well when are we gonna do this". Im still waiting for confirmation on the X from maryland speed and it will be a go. Not much thought into this other than trying to make a straight of an exhaust as possible. Im thinking old school and I hope this helps with new school technology. ----danfigg
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post #6 of 15 (permalink) Old 07-07-2012, 02:58 PM
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It might help a bit with torque down low. The reason I think all the manufacturers put the X so far back was simply for fitment compatibility with the stock exhaust. Here is a good article on exhaust science. It underlines that the "common knowledge" about exhausts is often misguided and against what at first seems like a simple process

Auto Exhaust Science

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post #7 of 15 (permalink) Old 07-07-2012, 05:24 PM Thread Starter
 
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according to what i have read, the H/ X should be as far forward after the headers/exhaust as possible. It looks like I will be about 24 inches past the header. I have also read that an exhaust is tuned by how long the collector is. Some car have had peak power with just an 18 inch collector while other needed shorter or longer collectors. In our case it looks like we will get what we get. I dont have the use of a dyno and tech guys to tune it all in. Im just looking for as smooth as exhaust flow path as possible and it looked like the 04 mids into the 05 tails would be as smooth as I could get. X pipe has been shipped as per Maryland Speed.---------danfigg
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post #8 of 15 (permalink) Old 07-07-2012, 06:58 PM
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The X I'm taking off is about 36" from the collectors. I'm getting a Pypes X kit which has the pipes coming out of it too so I can get it ip as close as I can behind the tranny mount. The length of the collector is more effectively tuned on an open system. The use of a terminator is interesting



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post #9 of 15 (permalink) Old 07-08-2012, 10:20 AM Thread Starter
 
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sounds like you've been staring at the Jegs catalog like I've been. I sw there X and like the way they come out im assuming the narrow one that your referring to. The reason I went with the spintech X is because it has the flanges that mate up.-----We will find out soon enough----danfigg
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post #10 of 15 (permalink) Old 07-08-2012, 01:23 PM
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Ya the narrow one at JEGS and Summit . I think Summit had better prices. I think I can push the X up nearly a foot. Where ever I want a connection I just have 3 bolt header flanges welded on. Easier finding gaskets too.

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