1.6lTD long-runner intake manifold

[greggearhead]

The nasty tight bend at the end might hurt flow more than any gain - I flowed a lot of intake manifolds on the bench, and it was surprising what worked and what didn't.  Granted- this is just airflow and not inertia tuning.  

Also, the steel intake manifolds on air cooleds that had Dual Kadron carbs eons ago had sealing issues.  I am sure with a decent flange and good machining that wouldn't be an issure - just a heads up.

Haven't read this thread in a while, any 5-6 cyl VW/Audi/Volvo Diesel intakes that might work?

[fspGTD]

Dave - thanks for your help suggestions.  You have IM!

Greggearhead - I don't know of any other manifolds that employ long runners that would bolt on while clearing the high-mounted turbo.

The bend seems like a necessary evil of having the manifold clear the high-mounted turbo.  Although I think it might look like more of a bend than it really is, because the airflow enters the head at a downwards angle.  I measured the actual dimensions and bend radius of this bend a while ago... I need to find the notes.

Mr-Brick-Yard - How might the 1.9D (1Y) manifold be desirable?  Got any pictures of one?

If there is some compelling reason to use a manifold that has "D" shaped runners, it is feasible.  My racing class doesn't allow head porting, but it does allow gasket matching and the removal of material in the runners of the head up to 1" from the manifold bolting surface.  So the runner shape could transition from a "D" shape to round shape up to 1" into the head.

[fspGTD]

measurements of the 1.6lTD intake manifold lower bend:

The centerline bend radius is 1 5/8".  It makes a 68 degree total bend.  The angle of the runner as it enters the head is 22 degrees from horizontal.  The inside diameter of the gasket-matched intake port is 1 3/16".

[veeman]

>> (from page one by Blades) The Audi 5KTQ intake manifold.  It's got bigger runners and better airflow

I've seen a number of people use that style intake in the gasser world.  It's true that the manifold is indeed larger and has better runners and I had thought about using one on my 1.8 gasser race motor (FSP engine).

After doing some research and comparing the parts, I found that it would have required signifigant work to adapt this manifold correctly for use on the 8V head.  

Other than chopping off the fifth runner, the ports on the 5ktq manifold would actually enter the head at a higher point than the stock manifold and at a slightly better angle.  The Audi manifold, as a result, also does not extend fully to the bottom of the ports on the head.

From what I read, you'd have to remove quite a lot of material on the top of the ports on the head and possibly add some at the bottom.  At least one person had concerns about the thickness of the "meat" of the head above the ports at the rear of the head...not sure about a diesel head.  

Others have done it and reported good gains (supercharged gas engine) but that came with the disclaimer that it took quite a lot of time to finish.

In my class, that extensive head work is not permitted, so I'm going to go with a G60 manifold.  It seemed to be a good compromise of runner width, shape and throttle body position.  The A2 gasser digifant (last version of the 8V gasser) also seemed promising as well.  Longer runners than the A1/G60/Fox intakes...

[Baxter]

The 1Y inlet manifold is this.

As the 5cylinder one pictured back there only it's 4 cylinder.
It has D shaped ports.
It's inlet pipe is a plastic flange with 4 bolts and different size adapters could simply be bolted on, they would have to be made in the first place though

I have one under the bench, did you lot not get those? 1.9 N/A ?

[fspGTD]

Mr-brick-yard: thanks for the info, however it doesn't sound like it would clear the high-mounted turbo.  

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Here's the latest with this project.  I bought a big 1"x2" extruded chunk of aluminum and braized that to the lower 1.6lTD intake manifold runners that I chopped off from the plenum.



The aluminum braize is really interesting stuff... it's very strong (tensile strength over 40kpsi), and it is also noticeably harder than aluminum.  (You can definitely tell the difference when you hit it with a file.  It's much harder to chew through!)  It is very easy to apply with the oxy-acetylene torch, but because it's all runny liquid during application, you can't do as many things with it as you can with welding where you can build up material here and there, etc.  But the braize has its uses.

The next step is to remove a bunch of material from the chunk to lighten it up a bit and also drill the ports out.  I decided to braize the chunk first and machine it later so that I wouldn't have to worry about it being lined up perfectly during the braizing procedure.  The flat surface also worked well to hold a puddle of the liquid braize on top of.

[fspGTD]

I've made some progress on the custom 1.6lTD intake manifold project.  I drilled and tapped all the holes for mounting the upper manifold piece to the lower piece.  Using a drill press, I got the holes right on the money and perfectly parallel, so the bolts just dropped right in with no binding while assembling upper piece to lower piece.  I was pleased with the way the plenum and manifold runners ended up sitting in their final position atop the junk head.  I figure I'll probably have maybe a touch under 1" clearance between closest part of plenum and hood.  I might have to do some clearancing in a couple areas to make everything fit, for example near the #1 runner I found it gets close with the turbo's compressor housing.  It also might be a bit tight in one spot around the oil filler cap, but I'm not too worried about it.

With the upper and lower pieces bolted together, I scribed around the upper part where I wanted to remove the material from the 1"x2" aluminum slab.

Edit: here are the latest pics of the scribed surface.  


You can see I have just started eating some material away using the drill press.

My plan is to eat a line of the material around the scribe line away, one drill press plunge at a time, and then "connect the dots" with a hacksaw or coping saw.  Then I'll use hand files and die grinders to clean up the remaining rough edges.  I also set the gasket on top of the aluminum slab and scribed inside the port openings; I'll also remove material inside the ports using the drill press.

Hey, if the ideal tools (like milling machines) were always available for these sorts of project, they wouldn't build as much character now would they? :wink:

I'm just happy to have access to a drill press and not have to hacksaw and handdrill all the way around that thick aluminum piece! :lol:

[VWRacer]

Don't get me wrong, Jake, because I love playing with things...but did you ever try fitting a Mk1 GTI intake manifold?

[fspGTD]

Stan - The problem is that with the stock transverse-engine mounted 1.6lTD, with the high-mounted turbo, there is no room for any of the long runner intake manifolds to simply bolt up straight to the head.  This pic helps illustrate the space restrictions:


So the route I am taking is trying to make the long runner manifold fit by bolting it to a custom adapter that raises and rotates the long runner manifold.  This allows me to leave the turbo mounting location as it is.

PS - that A1 GTI manifold looks exactly the same manifold as what I'm going to use!    (Compare yours to the one in the pics from this post: http://www.vwdiesel.net/phpBB/viewtopic.php?t=614&start=27 )

[Master ACiD]

why not just flip the turbo and manifold upside down? seems like the exhaust manifold works rightside up or upside down, so it would be easier to flip the turbo and manifold and take youre car into a muffler shop to get a new exhaust out on, than it would be to spend weeks milling a intake manifold using a drill press?

better yet, just flip the turbo and manifold. put a 90 degree elbow on the turbo outlet and have that come up through a hole in the hood. it would look totally mad max.

[greggearhead]

I think that has been discussed already and he has decided to go this way for now.  All the additional work of flipping the turbo for an experiment might not be worth it.

I hope to mount my turbo lower so I can use a regular gasser manifold of some sort.

[fspGTD]

better yet, just flip the turbo and manifold. put a 90 degree elbow on the turbo outlet and have that come up through a hole in the hood. it would look totally mad max.

You know you guys can have some pretty wacky ideas, but I love 'em!  :wink:  Unfortunately in my racing class, cutting a hole in the hood is not allowed, and the exhaust must terminate aft of the driver.  Otherwise I might consider it!  (I guess there is also the little problem that under heavy acceleration, the column of soot in front of the windshield might obstruct a clear view of the course! :lol:)

I actually am enjoying this aluminum fabrication project, as it's challenging for me and I'm learning new things working with the material.  It is not my top priority, and so it might take a while, as I just work on it here and there.  But so far I'm comfortably within my budget: expenditure for the aluminum block was like $16 and I already had the other parts.  The time is good for doing the test fitting and manifold development while the head is already off the block.  

[Black Smokin' Diesel]

I was wondering, if you turned the exhaust manifold upside down (I know it's been discussed) but cut off the turbo flange and welded it the other way would it work?

The turbo would not be upside down and you'd have clearance for a long runner intake.

BTW nice work on your custom intake!

[vwmike]

better yet, just flip the turbo and manifold. put a 90 degree elbow on the turbo outlet and have that come up through a hole in the hood. it would look totally mad max.

You know you guys can have some pretty wacky ideas, but I love 'em!  :wink:  Unfortunately in my racing class, cutting a hole in the hood is not allowed, and the exhaust must terminate aft of the driver.  Otherwise I might consider it!

We were working on our own mad max Rabbit. It has expanded metal for a grill and a big deer catcher on the front. It's also lifted. Unfortunately it sounds like it spun a bearing and it it's probably too much work to fix just for a mad max mobile so we can run over stuff. K cars are $200 and work fine for running over stuff.....We were going to weld up a basket for the top and put the spare and some cans of diesel up there.  

[fspGTD]

I was wondering, if you turned the exhaust manifold upside down (I know it's been discussed) but cut off the turbo flange and welded it the other way would it work?

Cutting thick high-nickel cast iron/stainless of the turbo exhaust manifold and re-welding it while maintaining good airflow and strength could be very difficult.  But it could be feasible to fabricate a simple steel or stainless adapter to rotate the turbo by 180 degrees.  I can see some advantages potentially when combined with flipping over exhaust manifold, as it would leave the air filter location alone, and more of the air intake and boost tubes and air tubes could be adapted or re-used than if the exhaust manifold were flipped with turbo bolted to it as it originally is.

Although this is a good new idea, I'm going to continue down the custom intake manifold route.

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On my intake manifold design, I estimate the runner length of the manifold runners will be roughly 12" (9" runner of the A1 manifold, plus approx 3" additional the extension/adapter.)  Adding in the 4" intake runner length that's in the head makes a net runner length of 16".

Simulating this in a spreadsheet I made that calculates various things, the Chrsyler formula predicts torque will be boosted in the range of 4400-6450 RPM, and most significantly at 5250 RPM.

The organ pipe formula predicts 4 torque-boosting reflective values would be put into my working range: the 3rd RV (at 6200 RPM), 4th RV (at 4650 RPM), 5th RV (3700 RPM), and 6th RV (3100 RPM).

All of the RPMs calculated assume a constant 104 deg. F air intake temp.  Doing a sensitivity analysis of how much the boosted RPMs vary as a result of changing air intake temps (which result from changes in ambient air temps as well as imperfect intercooling under boost pressure), the boosted RPMs rose 200-300RPMs when increasing the manifold air temps from 86 degrees F to 140 degrees F.