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Titans need backpressure my A##

14683 Views 221 Replies 33 Participants Last post by  DRTYAZN, 
deerslayer
Here is a video from a member on CT. He was running 14.0X forever with 07+ exhaust with 2 spintec mufflers. Now he's running just straight pipe after the headers with 2 14" magnaflows and ran a 13.7. He has NO X pipe or Y pipe on his truck. We argue on here about the X or the Y being better and now we have a member running this....LOL

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deerslayer
14.32 @ 94.07.........corrected time is a 14.12 no cool down, doing that now. I gained .1 with headers over stock gutted manifolds. Ill need a -300 or better da to run 13's, all in all im happy with it:)
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O-FiveCC
Cool that thing down man
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DRTYAZN
Man, I need to unsubscribe from this thread now... the more DS updates, the more i want to say, F It and do my exhaust renovation project... but, I just spent huge $$$ today on preventive maintenance, complete RP fluid exchange (both diffs, tranny, and engine) and minor DIY mods... as well as ordered axle seal repair kit for both sides, and will be ordering new brake pads for both front and rear... I even had to dip into my exhaust renovation funds I had been saving... :( I guess I need to work a couple of 6 day weeks to boost my mod funds to stay on my set timeframe of future modding I had planned for...
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O-FiveCC
You did the right thing drtyazn. If I didn't have oil change (done), trans fluid change, rear end fluid change, tire change, and coolant change all planned, I'd be modding right now
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W
deerslayer said:
14.32 @ 94.07.........corrected time is a 14.12 no cool down, doing that now. I gained .1 with headers over stock gutted manifolds. Ill need a -300 or better da to run 13's, all in all im happy with it:)
Click to expand...
nice time.
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deerslayer
Best time was a 14.31 @ 94.1 mph, corrected it was a 14.09 @ 95.2 mph. I can tell you this, the straight pipe off the headers are not hurting performance in any way whatsoever! DA tonight was 1300 by the way. So I gained .1 with the headers over stock manifolds gutted. Stock manifolds gutted, I have to say are a pretty sweet deal for free. LOL Like I said, I'll need a -600 or better DA to run 13's but that's cool because my trucks race weight is 5200# and a lot of the guys running 13.8=13.9 weigh 4800-5100#.

Here are my future plans for spring and fall racing. I want to get some different tires, like street radials. I think the Nitto AT's are slowing me down due to resistance. That might be worth .1 by itself or more. I'd also like to do a little more weight reduction. Roll pan bumper will be worth another .08 or so. That should put me in the 13.9 range in a 0 DA.

Night ya'll I'm tired:) Hope the testing of the straight pipes helps some of the back pressure debates. Last weekend with the 2.25/3 Y pipe setup I ran a 14.41 in a 1600 DA.
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Gene 5.6
760 Titan said:
Backpressure is ABSOLUTELY necessary for an engine unless your valves are set up properly to run without it. It's not about how large the ports on the head are, it's about how well the head flows. Look at ANY honda head. the ports are tiny, but they flow stupid amounts of air through them due to the way its channeled through the head. Basically backpressure is needed to help maintain pressure in the combustion chamber. Unbolting your exhaust still wouldn't give you zero backpressure. You'd have to let it come straight out of the ports for that, and I promise you it will run like 10lbs of **** in a 5lb bag. Additionally, saying that "the intake, throttle body, intake manifold, heads and cams all dictate where the power will be made" isn't really accurate. You basically named all the parts of an engine, without the crank and pistons, which are the base of power production. They determine the displacement, strength, and compression ratio of the engine. Internal combustion effeciency and power production revolves around air. Exhaust will shift your power curve, and MIGHT get you as much as 15 ponies, but your real gains will come from finding ways for more air to get in, rather than out.
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The argument about an engine needing back pressure has already been answered so I'll skip that and dissect the remainder of your post.

I don't understand your statement "It's not about how large the ports on the head are, it's about how well the head flows." So a port that is smaller in size but more efficiently "shaped" can flow as much air as a larger port that is a little less efficient? You do realize that the size of the port is relative to it's efficiency, right? So a smaller port = less effective no matter how smooth it is. Try blowing into a straw and then a water hose. Tell me which is easier to push.

It's a simple equation: more air + more fuel = more power.
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Wow only .1 this really makes me want to just muffler swap and gut my primary cats and get a retune. I would save $800.00, that's too much to spend on .1! Take that 800.00 and save it for when a true trac group buy goes on for 08+ :)
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gweasel77
Killer time's DS!!! Nice work on the exhaust testing too!

I'd like to see you run it on a dyno just to see what the curves look like with that config.

I think a light rim/tire combo + some weight reduction would put you right @ 13.9x on the right day!
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O-FiveCC
Was your truck pulling any timing this time out as opposed to last time?
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deerslayer
O-FiveCC said:
Was your truck pulling any timing this time out as opposed to last time?
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Nope not this time, timing was good and it maxed at 34 degrees. Afr's were 12.3-12.9 during the runs. My truck pulls hard as hell to about 80 mph and then the weight kills me I guess. It still pulls o.k but not like if it was 4600-4800#'s. I'm expecting too much out of my truck I think. To run a 14.09 corrected time is pretty damn good for a 5200# beast. LOL What kind of tires would be good to run on the track that have little resistance? Something I can run on the street too. If I get some I'll probably save my nitto's for just winter driving. I bet my tires are hurting my times by .1-.15 not because of the weight just drag all the way down.
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deerslayer
08crewcab said:
Wow only .1 this really makes me want to just muffler swap and gut my primary cats and get a retune. I would save $800.00, that's too much to spend on .1! Take that 800.00 and save it for when a true trac group buy goes on for 08+ :)
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Yea if you gut those cats you will gain an easy/free .1-.15 all day!! Once you get trutrac if they ever come out with it for 08 and up, you might be the first 13 second non header titan. Not many 07+ Titans race and they will be the ones to hit 13's w/out headers because you guys run on average .1 to .2 faster in the 1/4 mile mod for mod and I hit 14.18 before headers so you could easily hit 13.95 or better with traction.
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ViperPowa
Good job Jason, you'll get 13's soon bro, I think you'll get there with a little more tweaking. 07 IM, DTT, 16inch rims and some MT ET Streets and 13's won't be a problem. Maybe you have found the limit of the 4wd efficiency, time to go 2wd with a LSD and sticky tires.

When was the last time you changed engine, trans, and diff oil?

Regardless those are good times and props for actually testing stuff out and giving back the results good or bad. Lots of guys your helping out in the process, definitly a good contribution to the board.
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deerslayer
ViperPowa said:
Good job Jason, you'll get 13's soon bro, I think you'll get there with a little
more tweaking. 07 IM, DTT, 16inch rims and some MT ET Streets and 13's won't be a problem. Maybe you have found the limit of the 4wd efficiency, time to go 2wd with a LSD and sticky tires.

When was the last time you changed engine, trans, and diff oil?

Regardless those are good times and props for actually testing stuff out and giving back the results good or bad. Lots of guys your helping out in the process, definitly a good contribution to the board.
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Yea thanks man!! I'm going to get some street radials hopefully, 07 IM, and a roll pan bumper. After the baby is born of course:) Wife is due in 2.5 weeks! oil is changed regular but I've never change tranny fluid. I'm on 51K right now, you think changing it would help? Diff front and rear were change at 40K.
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Citadel
Not trying to barge in here but I just switched to dual bullets this morning with no X-pipe. From what I understand on here there really isn't a loss other than towing torque if I leave it this way? Seems everyone on here running dual mufflers has some sort of merge or X-pipe.

Thanks
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ViperPowa
deerslayer said:
Yea thanks man!! I'm going to get some street radials hopefully, 07 IM, and a roll pan bumper. After the baby is born of course:) Wife is due in 2.5 weeks! oil is changed regular but I've never change tranny fluid. I'm on 51K right now, you think changing it would help? Diff front and rear were change at 40K.
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Congrats and god bless your family, hope all goes well with delivery and may the child be healthy. Are you ready for no sleep again for a little while ? lol

As long as your trans fluid isn't discolored or burnt smelling your fine, what's your change interval 60k? In my truck I change tranny and rear end oil every 15k miles but my truck only has 17k miles on it now so I only had to change once so far :D You don't want to know how often I change my oil lol.

What were your 1/8mile times and traps with this header and exhaust setup vs before it? I wonder if the 2.25's is killing your flow from the 1/8th mile up. You have any pics of the new exhaust setup? You shoulda listened when I told you to go 2.5 lol, jfwy.
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ViperPowa
Citadel said:
Not trying to barge in here but I just switched to dual bullets this morning with no X-pipe. From what I understand on here there really isn't a loss other than towing torque if I leave it this way? Seems everyone on here running dual mufflers has some sort of merge or X-pipe.

Thanks
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Gotta be a little more specific on your setup bud, do you have stock manifolds and midpipes? Where where did you modify from, how far back is your mufflers and dumps, what size piping are you running before the mufflers? Etc. All that will affect what your lowend loss vs midrange and top end gain will be.

The x pipe helps create another scavenging point downstream from your headers. The further downstream your exhaust pulse travels the cooler it gets and the more it's velocity will slow down. The x pipe helps keep your velocity up. If your going to do full dualls it's best to keep the piping as short as possible but dumping it directly under the cab does make for an annoying ride for many. So then you have to choose between that, making an x pipe merge point, staying with long separate tubing that's velocity will be slowing down by the time you dump it behind your cab (especially after running through mufflers), or making some electronic cutouts upstream so when open you can have all the power potential you need for racing and still have a bearable exhaust for long rides when closed.
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Citadel
ViperPowa said:
Gotta be a little more specific on your setup bud, do you have stock manifolds and midpipes? Where where did you modify from, how far back is your mufflers and dumps, what size piping are you running before the mufflers? Etc. All that will affect what your lowend loss vs midrange and top end gain will be.

The x pipe helps create another scavenging point downstream from your headers. The further downstream your exhaust pulse travels the cooler it gets and the more it's velocity will slow down. The x pipe helps keep your velocity up. If your going to do full dualls it's best to keep the piping as short as possible but dumping it directly under the cab does make for an annoying ride for many. So then you have to choose between that, making an x pipe merge point, staying with long separate tubing that's velocity will be slowing down by the time you dump it behind your cab (especially after running through mufflers), or making some electronic cutouts upstream so when open you can have all the power potential you need for racing and still have a bearable exhaust for long rides when closed.
Click to expand...

Sorry, not an exhaust guru. Hopefully this pic will help. The only modified component is the two bullets and piping.


Thanks
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DRTYAZN
... just a thought, but I know my heavy lifted 4X4 is quite a bit faster ever since I installed my glass fenders and bedsides... so if you fellas could find someone to make reasonably priced glass or ABS plastic stock style fenders and bedsides, along with a glass hood, those modded track Titans would surely knock off major time... ;)
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O-FiveCC
You could get you some BFGoodrich KDW's for tires, their good for the power level your at
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