1.6lTD long-runner intake manifold

[Master ACiD]

i think theres a scoop, just that its mostly out of the picture. see the black thing on the hood in the second picture? i think thats the firewall end of the scoop?

thats really nice, btw.

[fspGTD]

It sure does looks like the screaming yellow zonker.  That is an eye-catching intercooler for sure, you don't see top mounts on VWs too often, reminds me of the current Subaru intercooler setups.  Kind of funny though how the Subaru guys like to ditch them and go front-mount.  I think top mounts have problems with heat soak from the engine underneath when the car is sitting still.  You'd need to run a cooling fan or always keep the car moving to keep airflow moving downwards through it and not convecting hot air up from the engine.  Pretty neat install on the 16v intake manifold they way they did it, except it looks like it could use some baffling between the hood and intercooler to get more airflow from through the intercooler core and less escaping around its edges.

Here's a pic of the scoop I found for Andrew:

[RabbitGTDguy]

Well, it makes a little more sense now.  The design is definitely evolving a bit as it's being built. :oops: The blow off valve flange is now welded onto the plenum, the the air inlet flange is just about done.

When I first tried welding the BOV flange to the plenum, I tried my usual procedure of just going at the massive aluminum piece with a very large tip with very hot flame setting.  Well, this caused problems with the lightweight blow off valve flange coming up to melting temps much quicker than the relatively massive intake manifold piece which conducted heat away from the weld area.  Despite doing my best to direct the temperature of the flame to the manifold, the heat control was very poor, and I melted away some areas of the BOV flange - some where the v-band clamp touches, and one melt through was so bad even part of the critical o-ring sealing surface fell away!  :shock:  By the time that happened, I knew what I was doing just wasn't working, and so I stopped before the damage became irreversable.  I then came up with a new strategy: I would try pre-heating the manifold to 400 degrees F in an oven, then see if the larger piece would melt easier.  I used a smaller flame and less heat.  The pre-heating method worked so well, I manage to pull off a perfect 360 degree weld that perfectly fused and sealed the inside diameter of the blow valve to the plenum!    The molten puddle was much easier to control.  I'll have to remember to pre-heat more often when welding dissimilar metal thicknesses.  I also successfully built up a weld bead to replace the areas that had fallen away.  I'll have to shape them carefully with a file to restore the original surfaces.

The air inlet flange is coming along nicely.  With a hole saw, I made about a 2" hole in the face of the air inlet flange.  I'll enlarge that to at least the ID of the 2.25" boost tube to allow me to move one step up from 2" boost tube size if I wanted, and the larger hole will also give me better access to inspect and clean out the inside of the plenum.  To accomodate the larger hole size, I am leaning towards using a 4-bolt (trapezoidally shaped) sealing flange instead of a 3-bolt / triangular shape.  The material where I'll need to drill and tap one of the bolts is a little thin walled and I might only get about 1/4" of threaded meat though - worst case scenario is to add more threaded area, I'll need to cut the section away and replace it with a thick aluminum chunk in its place.

I am trying to figure out what to do with the boost tubing.  Here's what the old configuration of the engine bay and boost tubing looks like:


The intercooler outlet diameter is 2.25", and the old configuration of boost tubing has the air go through a crappy nonreinforced rubber 90 degree hose (would really like to get rid of this) before transitioning down to a 2" tubing size.  Even though I found the intercooler and boost tubes weren't highly restrictive after installing them as measured by my boost gauge, I'm thinking a little airflow optimization here might be worth my while.  Not sure yet if I'll stick with 2" OD boost tubing to the intake manifold, or step it up to 2.25" OD.

Jake... meant to do this days ago. But do you have a picture of how you did your radiator fan setup and puller for the intercooler? I'm thinking of ditching the stock fan configuration and in this pic I can almost make out the radiator...but not quite.


Man...Zonker's car is crazy. I remember seeing that a long while back! have a mk2 16v manifold just sitting here if anyone wants to play someday...

Joe

[fspGTD]

Joe - check out this thread on the old forum:
Fan on a FMIC, anyone?

[fspGTD]

I have basically finished the air inlet flange now.  It turned out really nice.  It's a roughly symmetrical trapezoidal shape and the bolt hole I was worried about possibly not having deep enough threads I think is going to be fine after all.  I also already cut out a flange to bolt onto it out of 1/4" aluminum plate which eventually will get the boost tube coupler brazed to it.  I carefully hand filed both mounting surfaces to try and make them flat, and boy was I pleasantly surprised when I initially test fitted those surfaces together... how tightly they mated together and how smoothly they rubbed against each other you would think they were made with a milling machine.    I think with a little silicone it is going to seal very well.

The BOV mounting flange has also been SAVED!    The surfaces where the o-ring and v-band clamp touch are filed down and restored very closely to their original contour.  An initial test fit of the BOV mounted to it looks good, but I may want to pressure test it before I run it.

I also got some new supplies and tools for this project.  All of my old plumber's rubber couplers and bends will be getting replaced with straight silicone transitions and couplers and 2" aluminum mandrel bent tubing.  I also am getting some new supplies to polish what I can easily reach of intake manifold runners: some cross-buffs and also some 80 and 120 grit flapper paper (emery cloth strips placed through a slot in a rod.)

Edit: here is a picture of the 8" long flapper stick polishing tool I made out of a 1/4" steel rod:

The stiffness of the sandpaper as well as the centrifugal force forces the paper out to make contact and conform very well with the walls of the runner...  Perfect for runner polishing!

[935racer]

Sounds great Jake  Can't wait to hear the reults of all your labour.

[fspGTD]

The intake ports are coming along...

just port matched:

after 60 grit flapper paper in an 8" rod:

[DVST8R]

Looking good! Now stop teasing and show us the whole thing.

[fspGTD]

I can show you how the plenum is looking:

I'm pretty pleased with how that boost tube inlet flange is turning out.  I may weld and file on it a little more, but it's just about done.  You can also see I sawed open a big hole in the plenum so I can reach my polishing tools into the cyl 1 and 2 runners.  I'll later make a plug and weld that hole shut.  (The BOV opening provides a convenient hole to reach runners number 3 and 4 for polishing. )

You'll have to wait to see the whole thing completed though, because I just work on it a piece at a time, and I still have a lot of work left.  To say this project is a challenging fabrication project is an understatement.  There are times when I feel I took a step backwards!

I've been having some problems working on this manifold because of how closely VW cast the EGR plumbing to the runners.  I cut and filed off all the EGR plumbing, but the way it was cast it just comes too close to the ports in a couple spots.

Here you can see the transition of the plenum to runner #3.  It's just barely in the light, but if you look in the upper left corner of the runner, you might be bale to see where the is a "bulge" sticking into the runner.  It is cast that way on purpose so the EGR passage didn't poke through into the runner!  It's very thin right there.

There was another spot where the close-routed EGR passage caused problems, on runner to cylinder number 2 it came very close in one spot.  There were casting/oxide voids here making the metal very weak.  Long story summarized, in trying to fix it I cut a corner in prepping the surface for welding it, and I just made it worse, making a molten blob of metal droop down into the runner.  In trying to clean that up I accidentally broke through all the way in one spot with a small crack, so now I've got to weld it to repair it again. :roll:

[DVST8R]

Your doing a fine job, keep it up, people don't realize how much of a learning curve there is and what kind of time it takes to build somthing custom, I will say this, it gets easier everytime you do it.

However after watching this buildup I have decided that for myself, I will never modify a VW intake to fit, I will just go straight custom with all new Al. if for no other reason then it takes so much less effort to weld.

[fspGTD]

I really haven't had much problem fusing to the cast aluminum VW manifold material with my latest welding techniques, I really only get bitten when I try and cut a corner.  Which is usually when I've just successfully completed a weld, and the piece is already all heated up and I've still got the welding equipment in hand, torch blazing, and I get a spur of the moment idea "this metal is welding so nicely, why don't I just weld this one other spot I've been meaning to get to..." without having properly surface prepped it (which would need to occur much earlier in the process.)  That is where the surface oxides can give me trouble with getting proper fusion.  I am also obviously really steep on the learning curve here with this whole oxy-actyelene aluminum welding thing... :wink:

Anyway I'm happy I'm using this manifold opposed to scratch fabricating, I think it would have been tremendously more work to do that, not to mention the material cost would have been a lot more for the mandrel-bent tubing so wouldn't have worked for my budget very well.  This A1 gasser manifold has the right shape and it seems appropriate features (plenum volume, etc).  A feature that would be really hard to duplicate with a scratch-fabricated manifold is the very nice and gradual taper in the runners, which seems to occur throughout their entire length.  To duplicate such a taper in a straight section of a scratch fab'ed manifold, you'd need to spend a lot of time custom forming sheet or turning off lots of material on a lathe to end up with the tapered shape, and I don't know how it would be possible to make it bend while tapering at the same time like the stock cast manifold runners do.

My new boost tubing materials have arrived!  (A couple silicone transitions and aluminum 90 degree mandrel bends.)  Merry early christmas to myself!  Won't be making any more progress with this though probably until later in the holiday season... got a busy holiday schedule planned.  It's not like I'm in a real hurry to get it done anyway though, with the weather being as miserable (rainy, overcast, wet, etc) as it is, I probably wouldn't have a good opportunity to test it anyway.  This is not a short term, "instant gratification" project.  But at least if it ends up successful, I hope to be happy enough with what I've made that I will have no need to consider any future iterations.  That's why I'm going to the effort of doign it right... IE: making it look good, polishing the runners so they flow well, doing very careful work not just slamming it together as quickly as possible, etc.

Seattle winters are very rainy and the days are also pretty short.  Sucks for a welding project, where I need daylight to help see what I'm doing, and when I need to do my welding outside for ventilation.  And I am doing all this just for fun anyway, so I just do a bit here and there.

[Justin]

Hey guys I love this post by fspGTD

anyway I know that it might not be a real long runner intake manifold but has anyone tried a TDI intake manifold? I got one this week since it will bolt right up and thats what i will be usiing for a turbo intake

later
Justin

[vwmike]

It's got the big 1.9 style ports so it won't match up very well unless you port the head (if it can be ported that far).

[RabbitJockey]

i always thought that runner length didn't make much difference on boosted cars

[Baxter]

Found a picture of a 1Y manifold.



Same port shape as AAZ/TDI (D-shaped)