The <$100 Lower IC pipe (pancake pipe) upgrade

nathan_b said:

Interesting fine:

the intake hose off a (t3 ircc) 1.6td fits on the turbo outlet and makes a perfect offset 90 degree turn. I used that when i did my 1.8t pipe on my 99.5 6 months ago. works perfect.

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The hose fits the VNT-15 outlet and has the proper angle to meet the 1.8t pancake? Can I get a little more info on this?

www.siliconeintakes.com, get a 45 & a 90 in 2" and a 3" long section of 2"od thin wall exhaust tubing if you have a VNT17, get some good smooth bore clamps, pein the exhaust tubing from the inside on each end in 4 places to keep the hoses from blowing off, you will need to shorten the 45 by about 1/2 ". Done for less than $50.

Very nice improvement in spool up and smoothness with the larger turbo.

I am going to try this on my other stock turboed TDI and see if it is an improvement.

Would those pieces work with a vnt-15 also? I'm looking for a 1.8t pancake pipe now. Thanks!

I can buy a complete 1.8t lower intercooler pipe with pancake used for 50 dollars. Is this a direct bolt in? What parts are useable and what needs to be replaced? Thanks

Outlet on a vnt15 is 1 1/4"

So I can buy the used 1.8t complete lower intercooler pipe and then maybe salvage the parts that connect to the intercooler since they are probably the same intercoolers then just buy a few pieces from your link there to connect the 1.8t pancake pipe to my vnt15? Should I just order the pieces you listed? I also have found an aluminum pancake pipe off a pd130 I wonder which pancake pipe would be easier to fit on my golf? Which would you recommend Memphis? Thank you.

So I should order a 45 and 90 2" pieces and 3" inch piece of 1 1/4 od exhaust tubing along with 4 smooth bore clamps and ill be able to connect the 1.8t pancake pipe to my turbo? Are those pieces for connecting to the intercooler and turbo? If I'm purchasing the 1.8t complete lower intercooler piping what will I need? I should be able to use some of the gti pieces right rather than buying all new? Thanks

I'm going to order the 2" hump coupler with 2 2" t bolt clamps to hook up to my stock vnt15 output hose. My question is will this clear my diesel geek side skirts? I have the full aluminum skid plate and side skirts? Thanks! I think it will?

Stock hose from intercooler to pancake, 2" 45 on other end of pancake, some sort of 2" to 1 1/4 adapter, 1 1/4 90 on turbo outlet.
It will be very simple to figure out once you get it apart and start looking.

The conclusion of this thread was just a 2" hump coupler with 2 2" hose clamps is all that's needed to attach pancake to factory vnt15 outlet pipe. My question is will it work with diesel geek side skirts? Thanks!

I figure why replace factory turbo outlet pipe if its working fine? The restriction is the factory tdi pancake pipe not the turbo outlet? Right.

The factory output pipe has the built in 1 1/4 to 2" adapter on it that's why all you need is the 2" hump coupler to attach the pancake pipe to it? Right?

Is it just me or does the 2 inch hump hose only work for late ALH powered TDIs? I have noticed that those having problems just using the hump hose have early ALH MK4s. Just my observation but this isn't as easy as it seems at first glance.
I have a early build 2000 Golf (07/99; it has the same outlet pipe and PP as the 99.5). The 2 inch hump hose does not let the 1.8t PP bolt right up when using the outlet pipe from an 03 Golf (the stock outlet pipe on my car is not suitable for his upgrade: it does not have the metal connector at the PP end and is smaller in diameter than the later ALH outlet pipe as well). I'm going to have to follow 1heavyfoot and cut the outlet pipe, remove some length, turn it, and rejoin it using a coupler to get it to fit correctly without kinking. I have most of what I need to do it, just haven't done it yet. I've had bigger fish to fry (head gasket, timing belt, turbo rebuild, etc.). I will try to post pictures of the mods I'm talking about when I do this later.

52172 said:

I'm going to order the 2" hump coupler with 2 2" t bolt clamps to hook up to my stock vnt15 output hose. My question is will this clear my diesel geek side skirts? I have the full aluminum skid plate and side skirts? Thanks! I think it will?

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arne487 posted about this. Quoted below.

arne487 said:

I have one in an ALH with Dieselgeek's FMJ and Panzer plate. A little tight, but it fits.

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52172 said:

The conclusion of this thread was just a 2" hump coupler with 2 2" hose clamps is all that's needed to attach pancake to factory vnt15 outlet pipe.

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Not necessarily. Some have posted that this did not work on their ALHs and they had to to more than just the hump hose to make it fit.

52172 said:

I figure why replace factory turbo outlet pipe if its working fine? The restriction is the factory tdi pancake pipe not the turbo outlet? Right.

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Read the research that Richptl did and reported in this thread.

52172 said:

The factory output pipe has the built in 1 1/4 to 2" adapter on it that's why all you need is the 2" hump coupler to attach the pancake pipe to it? Right?

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For the later ALHs, yes. For the early ALHs, no; there are more parts needed.

SuperAdellic said:

arne487 posted about this. Quoted below.
Not necessarily. Some have posted that this did not work on their ALHs and they had to to more than just the hump hose to make it fit.
Read the research that Richptl did and reported in this thread.
For the later ALHs, yes. For the early ALHs, no; there are more parts needed.

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Thanks for answering all my questions, I appreciate it! My golf is an 01, so the 2" hump coupler and two clamps is all I need? I ordered the pp yesterday off ebay for 20 shipped. I'm gonna order all the upper intake pipes also to do a complete intercooler piping upgrade and get an ebay smic for 140 dollars. I'm gonna run 2" aluminum pipe for the upper. I really appreciate the forums and everyone being so helpful! It's great.

Yes I did some pressure drop testing on my PD100 and the turbo outlet diffuser is a very important component as the velocity coming off the turbo is extremely high, so you want to have an efficient recovery of velocity pressure into static pressure. A poorly configured expansion at the turbo outlet will create more pressure loss than the rest of the entire piping system! This was no surprise to me because I am in the HVAC business and if people do the same thing on high pressure fan outlets, where the velocity is also very high relative to typical ductwork velocities, the same thing happens.

Also I have about 25,000 miles on my car since my own upgrade. Again I have a BEW engine. The VNT-17 for my car is "clocked" with the outlet pointing towards the fenderwell, I have a Kerma adapter plugged in, a THS213 hose, 1.8 T pancake pipe, Godspeed SMIC, and ALH upper pipe. I am putting in some PD150 injectors soon because my car now has loads of air and I need some more fuel. I can easily hold 25 psig boost pressure.

So on my 2001 alh golf I should do more than the 2" hump coupler to attach the pp to the turbo outlet? What parts are needed for an 01? Thanks

52172 said:

So on my 2001 alh golf I should do more than the 2" hump coupler to attach the pp to the turbo outlet? What parts are needed for an 01? Thanks

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His car is a BEW engine, the succesor to the ALH, which you have. Two different turbo outlet pipes. You shouldn't need more than the hump hose and two clamps. IMO, you should start with the clamps and the hose, put it together, and see how you like it. If you feel the need to change it, then do so and report your changes, impressions of the new setup, and, if possible, some VAGCom measurements of the new setup.

Thanks. Ill start with just the 3 pieces.

Richptl said:

Yes I did some pressure drop testing on my PD100 and the turbo outlet diffuser is a very important component as the velocity coming off the turbo is extremely high, so you want to have an efficient recovery of velocity pressure into static pressure. A poorly configured expansion at the turbo outlet will create more pressure loss than the rest of the entire piping system! This was no surprise to me because I am in the HVAC business and if people do the same thing on high pressure fan outlets, where the velocity is also very high relative to typical ductwork velocities, the same thing happens.

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I'm interested in how abrupt transitions in the flow path would cause the airflow to slow down and pressure to drop. Is this due to vortices forming just after the transition? Would a smooth transition piece look something like a funnel with the air going in the small end and out the big end?
When you did the pressure drop testing, you were testing with vacuum, but turbocharged engines work on pressure. How does in/HG vacuum translate to psi lost (pressure drop) due to the transitions throughout the system? Is there a ratio that can be used to determine the pressure drop in psi that your measurements represent? I'm trying to get a feel for the pumping losses in a stock system versus the upgraded components being sold. Thanks in advance.

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Ordered the 3 pieces last night along with 2" 45 deg aluminum pipe and couplers to replace upper intercooler piping all for 96 bucks shipped. Much better than paying Id or kerma 250 dollars just to redo the plumbing!!!!! Now I'm ordering an ebay smic like the euro jet for 138 shipped. It's a no brainer to me.

SuperAdellic said:

I'm interested in how abrupt transitions in the flow path would cause the airflow to slow down and pressure to drop. Is this due to vortices forming just after the transition? Would a smooth transition piece look something like a funnel with the air going in the small end and out the big end?
When you did the pressure drop testing, you were testing with vacuum, but turbocharged engines work on pressure. How does in/HG vacuum translate to psi lost (pressure drop) due to the transitions throughout the system? Is there a ratio that can be used to determine the pressure drop in psi that your measurements represent? I'm trying to get a feel for the pumping losses in a stock system versus the upgraded components being sold. Thanks in advance.

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This is basic fluid mechanics starting with the Bernoulli equation. SMACNA publishes fitting pressure loss equations for low velocity incompressible flow such as for ductwork. For a car the flow is compressible and velocities are much higher, but still subsonic. One thing that you are eluding to that might be counter-intuitive is that an abrupt expansion results in more energy loss than an abrupt contraction. So when expanding from a small size to a larger size, always avoid sharp angles. Ideally expand at about 15 to 20 degrees. Faster expansion results in high turbulence and poor pressure recovery.

My pressure tests were for comparison purposes. The conversion is 28" wc is one psi. But I didn't have a calibrated mass flow. Still I think the pressure drops I saw would be on the order of magnitude of what you would find as applied on a vehicle.

In a nutshell, avoid like the plague sudden transitions from a small size to a much larger size, ie at the turbo outlet. Elbows are not as penalizing as size changes.

So the worst thing anyone could do would be to buy a cheap galvanized exhaust reducer and use it to transition from 1 1/4" turbo outlet size to a 2" or 2 1/2" size. That would be a killer fitting.

If you are clever enough to fabricate a different piping system for your car, you can make a simple home-made flow test apparatus using a vacuum cleaner and clear plastic tubing filled with water as a manometer. Pull through the stock setup - normal flow direction. The repeat a test with what you plan to use for your improved setup.

My 01 turbo outlet is just going from the 1 1/4 to 2" and continuing on all the way to my egr valve all 2" with minimal bends. Should work just fine with the 28 lbs of boost ill be throwing at the system. The smic has 2.5" inlet outlet, but that should help fill the higher than stock factory intercooler, along with the 28 lbs boost.

Richptl said:

This is basic fluid mechanics starting with the Bernoulli equation. SMACNA publishes fitting pressure loss equations for low velocity incompressible flow such as for ductwork. For a car the flow is compressible and velocities are much higher, but still subsonic. One thing that you are eluding to that might be counter-intuitive is that an abrupt expansion results in more energy loss than an abrupt contraction. So when expanding from a small size to a larger size, always avoid sharp angles. Ideally expand at about 15 to 20 degrees. Faster expansion results in high turbulence and poor pressure recovery.

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When I read your explanations posted earlier in this thread, I pictured in my head the waterflow experiment in the Mythbusters episode about tailgate up vs. tailgate down. It showed a bubble of rolling air would form just behind the cab due to the abrupt transition off of the roof into the bed. That's why I asked about vortices forming right after abrupt transitions. Is that representative of what is happening after an abrupt transition in our intake tract?
All of the manufacturers of turbo piping that I have perused lately seem to use much steeper angles than 15-20 degrees, 45 degrees at least is my rough guess.

Installed this today on my alh. There is no noticeable increase in power but it did completely eliminate the sound of my turbo. I have a straight pipe exhausted and the turbo was very loud, now I can't hear it all. I figured it would have made it louder. Is this normal?