Time to build a new intake manifold.. - page 2 - General - VWDiesel.net The IDI, TDI, and mTDI source.

• #15 by R.O.R-2.0 on 16 Jun, 2012 07:51
• So, i finished it up at about 11pm last night..
  
  GOD DAMN IT TAKES A LOT OF HOURS TO BUILD ONE OF THESE!! i can totally see why custom manifolds, like Nubworks, are SOO expensive. its because of all the labor/design included in the build..
  
  theres no instruction kits for this kinda thing, no DIY, no nothing like that..
  
  anyways, without further avail..
  
  
  
  
  
  the slit is NOT parallel, like some people have made.. i wanted the slot tapered, because that is the main function of a dual plenum manifold, is for it to EVENLY distribute boost.
  
  
  
  
  
  anyways, im not too pleased with the weld quality (dad wasnt here to help me set the welder, and im not practiced in aluminum welding like i am steel.. but thank god, there are grinders to take care of ugly welds.. just wish more people thought like that. you can not make an ugly weld any more ugly, so grind it down.
  
  another thing, the intake note, with nothing hooked to the manifold, rather than the ROAR it used to have, now it sounds MUCH MORE TAME as compared to before..
  
  cant wait to get my linkage setup rigged up, so i can actually build enough boost to see gains from this intake..
• #16 by theman53 on 16 Jun, 2012 08:00
• Talk to AKI 76 if you can. I think his mani he made me didn't have near that much taper. I was thinking maybe 1/2 to 3/8...it really isn't noticable unless you are measuring.
  
  I am not dogging, I am just trying to help. Whatever you do I am almost 100% sure it will be better than the VW design. Since you are not doing individual runners it should be less important than if you were.
• #17 by R.O.R-2.0 on 16 Jun, 2012 08:06
• Quote from: theman53 on 16 Jun, 2012 08:00

  Talk to AKI 76 if you can. I think his mani he made me didn't have near that much taper. I was thinking maybe 1/2 to 3/8...it really isn't noticable unless you are measuring.
  
  I am not dogging, I am just trying to help. Whatever you do I am almost 100% sure it will be better than the VW design. Since you are not doing individual runners it should be less important than if you were.
  

  
  thats what im thinking.. i did ZERO math on the slot. just drew some lines on there that looked good. if it works, it works..
  
  and there is NO WAY IN HELL that i went backwards from what was on there before.. i guarantee that it flows 100% better than stock..
  
  so far, ive had a pancake TD manifold, and a gasser manifold.. i dont see how this one i just built could be ANY WORSE than what ive had on there..
  
  the next manifold will be individual runners.. im gonna actually plan ahead for it tho, buy plenum material, and velocity stacks to weld on the ends of my runners..
  
  i just gotta find another stock TD manifold to cut up now. or else rebuild my AAZ head, and drop that on there.. should just do that, with all the turbo ive got, i should just go for a hybrid..
  
  
• #18 by theman53 on 16 Jun, 2012 08:17
• Proud of you sir. That cast aluminum is some rough welding. I wouldn't touch it when I blocked my overboost hole. I gave it to my guy and let him cuss it. So much crap in the casting to get a great looking weld, yours look pretty good.
  
  I don't know when you are making your next one, but my machinist has that flow/tumble machine that will show you what needs done to make it perfect.
• #19 by R.O.R-2.0 on 16 Jun, 2012 08:49
• Quote from: theman53 on 16 Jun, 2012 08:17

  Proud of you sir. That cast aluminum is some rough welding. I wouldn't touch it when I blocked my overboost hole. I gave it to my guy and let him cuss it. So much crap in the casting to get a great looking weld, yours look pretty good.
  
  I don't know when you are making your next one, but my machinist has that flow/tumble machine that will show you what needs done to make it perfect.
  

  
  i have no access to such a machine..
  
  prolly gonna be a joint effort between Josh and I, on the next manifold.. he has connections to EVERYONE/EVERYTHING in Portland..
  
  that overboost protection valve was a *** to block off.. instead of welding a circle over the spot it used to be, i cut it clear off..
  
  for those of you wondering:
  
  CAST ALUMINUM IS A ROYAL *** TO WELD!!! if i were to do it again, i would bake it at 4-500* for a few hours first, to try and neutralize some of the crud in the metal..
  
  anyways, im fairly happy with how it turned out..
  
  ANYONE GOT ANY SPARE TD MANIFOLDS LAYING AROUND?!?!
  
  i need to start stocking up on them now 
• #20 by libbydiesel on 16 Jun, 2012 08:54
• I think that slot is backwards and will actually create a severely imbalanced flow.  With a straight slot you will end up with the greatest flow near the boost source and the least flow farthest away because air will have been used up in the easier/closer path.  To attempt to balance that out, either the outer plenum is a tapered cone with a straight slot or a straight cylinder with a tapered slot that gets larger as it goes in farther.  You've done the reverse which will result in almost ALL of the air flowing to #1 and almost none to #4.
• #21 by R.O.R-2.0 on 16 Jun, 2012 09:43
• Quote from: libbydiesel on 16 Jun, 2012 08:54

  I think that slot is backwards and will actually create a severely imbalanced flow.  With a straight slot you will end up with the greatest flow near the boost source and the least flow farthest away because air will have been used up in the easier/closer path.  To attempt to balance that out, either the outer plenum is a tapered cone with a straight slot or a straight cylinder with a tapered slot that gets larger as it goes in farther.  You've done the reverse which will result in almost ALL of the air flowing to #1 and almost none to #4.
  

  
  how? the air is going FORWARDS.. with a parallel slot, the air travels forwards. and port #4 is where its going first..
  
  how come EVERY OTHER DUAL PLENUM intake ive ever seen, had the slit cut JUST LIKE MINE? they must all be backwards too..
  
  the way i look at it, is the air is coming in the inlet, and being forced towards #4 end of the intake.. the greatest pressure is going to be over the #4 intake runner. and the LEAST pressure will be at the #1 end, because the boost is being BLOWN PAST that end of the manifold..
  
  everywhere i read online, said that the slot starts LARGER, and taperes to SMALLER.. or else has a tapered plenum, and a straight slit.
  
  there are pics online of manifolds, from PROFESSIONAL companies, with the slot layout JUST LIKE MINE.. the slit starts out bigger, and by the end of the manifold (opposite the inlet) is where the slit is SMALLEST..
  
  maybe your looking at my pics wrong, or you havent had enough coffee this morning..
  
  i just dont see how EVERYONE who made them with a tapered slot, made them backwards.. i did ALOT of looking online. most manifolds use a tapered plenum with a straight slit. i was not equipped to build such a piece..
  
  so, the plenums are BIGGEST at the inlet, and SMALLEST at the far end. just like the slit in my manifold..
  
  HOW DID I BUILD IT BACKWARDS?!
• #22 by libbydiesel on 16 Jun, 2012 11:22
• You may be right.  In looking at dual plenum designs my focus has almost entirely been on the tapered cone style.  I would do a little rudimentary testing with leaf blower or compressed air as mentioned previously in this thread just to be sure. 
• #23 by R.O.R-2.0 on 16 Jun, 2012 13:38
• Quote from: libbydiesel on 16 Jun, 2012 11:22

  You may be right.  In looking at dual plenum designs my focus has almost entirely been on the tapered cone style.  I would do a little rudimentary testing with leaf blower or compressed air as mentioned previously in this thread just to be sure. 
  

  
  ill test it.. dont worry.. i just dont have time right now. im leaving for the weekend..
  
  even if its not PERFECT, it cant be any worse than what comes stock..
• #24 by AudiVWguy on 16 Jun, 2012 16:58
• Quote from: libbydiesel on 16 Jun, 2012 08:54

  I think that slot is backwards and will actually create a severely imbalanced flow.  With a straight slot you will end up with the greatest flow near the boost source and the least flow farthest away because air will have been used up in the easier/closer path.  To attempt to balance that out, either the outer plenum is a tapered cone with a straight slot or a straight cylinder with a tapered slot that gets larger as it goes in farther.  You've done the reverse which will result in almost ALL of the air flowing to #1 and almost none to #4.
  

  
  How the big boys do it.
  
  http://www.bufkinengineering.com/intake%20manifolds.htm
• #25 by libbydiesel on 16 Jun, 2012 18:10
• Yup I've seen that site.  I think i linked it on this forum a few years back.  Those are all tapered cone manifolds.
• #26 by clbanman on 18 Jun, 2012 09:31
• The way I understand it you do the wider slot closest to the air inlet because the air doesn't want to turn.   So by restricting the far end which is where the airflow wants to go, you force it into the near side of the tapered slot.   If you used the leaf blower previously mentioned or even a large shop-vac and some "smoke", you should ideally see similar amounts of air coming out of each port at the head flange.    I wonder if you could put some large balloons over the outlets and visually see if they expand/fill at approximately the same rate?
• #27 by R.O.R-2.0 on 18 Jun, 2012 10:48
• Quote from: clbanman on 18 Jun, 2012 09:31

  The way I understand it you do the wider slot closest to the air inlet because the air doesn't want to turn.   So by restricting the far end which is where the airflow wants to go, you force it into the near side of the tapered slot.   If you used the leaf blower previously mentioned or even a large shop-vac and some "smoke", you should ideally see similar amounts of air coming out of each port at the head flange.    I wonder if you could put some large balloons over the outlets and visually see if they expand/fill at approximately the same rate?
  

  
  with BOOST (restriction basically) it will even out the flow even more. both plenums will be charged equally before the port even needs air. i dont see it being an issue. im GOING to try the leaf blower/shop vac before i put it on, but im almost positive ive gotten it pretty close to what i was going for..
  
  i read that whole Audi rally car pic album, studied every pic closely, and then did some more studying.. every design ive seen, was a tapered cone, going from big at the inlet, to small at the end. and saw quite a few manifolds with straight upper plenums, but LOTS of those ones had straight divider slots..
  
  Aki-76 even told me i built it right, so im going to take his word on it 
• #28 by R.O.R-2.0 on 18 Jun, 2012 18:10
• well, the car runs cooler EGTs, and less boost going down the road.
  
  turbo spools quicker as well.
  
  im going to say that the manifold was a success..
• #29 by AudiVWguy on 18 Jun, 2012 21:11
• That's great, glad it worked out. What would you say the before and afters were for EGT's and cruzin boost?