Dual Downpipes (from a 1.8 Gti) in a 1.6 n/a Diesel Qestions

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duffer
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Dual Downpipes (from a 1.8 Gti) in a 1.6 n/a Diesel Qestions

Postby duffer » Tue Nov 09, 2010 11:11 am

I got a really cheap deal on a Techtonic Tuning stainless steel dual

downpipe (nran' noo, never installed) and a 1.8 4-2 exhaust manifold.

I'm sure a few of you have already done this, so...

1. How did you rig up supports (for the flex section)?

2. What size pipe did you use? (appears to be 2-1/4")

3. How did you attach the straight pipe to the downpipe? (Would a 6" flex section be of any use?)

4. What sort of muffler did you install? (for peace and quiet)

5. Have you noticed any significant improvement in performance?

Any advice/information would be greatly appreciated.

Thank you
Blue 1986 Golf N/A Bought it in '94. Never been on the road since.
Green 1991 Jetta TD. Bought it 6 months ago.
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VWCaddy
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Postby VWCaddy » Tue Nov 09, 2010 4:08 pm

Haven't installed mine yet, but have a similar set of parts. Plan on using 2" s/s exhaust pipe for the back end, a flex coupler like below:

Image

And likely will try a s/s round tube muffler and muffled tip.

I have the alum. coated steel downpipe and it measures out 2" OD, so that is the size pipe I plan to use (plus I have some left from when I ran a similar setup on my old '81). My downpipe also does not have the flex sections, just the doubled up tubing from the flange down a ways.
Last edited by VWCaddy on Wed Nov 10, 2010 1:23 pm, edited 2 times in total.
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duffer
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Postby duffer » Tue Nov 09, 2010 4:23 pm

I just got my stuff yesterday, so it's not installed yet either. Only paid $150 (Cdn) for the lot.

I think what you're planning is pretty much what I had in mind, except that measuring the downpipe where the two converge, it looks like 2-1/4".

It might be easier to just continue on with the straight 2-1/4" stainless pipe, to the back, with a flex joint to relieve stress on the d.p. flex joint.

Thank you for your input. I was just wondering if someone, with prior experience had found a better way.

Thanks, again.
Blue 1986 Golf N/A Bought it in '94. Never been on the road since.

Green 1991 Jetta TD. Bought it 6 months ago.

Hasn't been on the road since.

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Postby Fatmobile » Tue Nov 09, 2010 10:06 pm

That downpipe probably has the support brackets that go to the block?
'91 Golf gasser converted to turbo diesel.
'83 Rabbit gasser, converted to diesel, then converted to run on vegetable oil.
2, '84 GTI projects cars

duffer
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Postby duffer » Wed Nov 10, 2010 12:11 am

Fatmobile wrote:That downpipe probably has the support brackets that go to the block?


Actually, no.

This is a "Techtonics Tuning" aftermarket downpipe.

It doesn't come with the support brackets.

That was what I was wondering about...how to rig
some sort of brackets to support the flex joint at the
top of the pipes.

I thought, perhaps, if I made up a bracket, bolted it to
the back of the block and put a further flex joint between
the downpipe and the straight-back pipe (to muffler) that
that would allow some movement of the exhaust piping
without straining the upper flex joint which, I believe, is
the weak point on these dual pipes.

Fortunately Tech. Tuning sells a s/s replacement flex joint
for these pipes.

Unfortunately, it costs more than I paid for the whole pipes assembly.

Any thoughts?

Thank you for your response.
Blue 1986 Golf N/A Bought it in '94. Never been on the road since.

Green 1991 Jetta TD. Bought it 6 months ago.

Hasn't been on the road since.

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Postby Fatmobile » Wed Nov 10, 2010 2:37 am

Flex joit at top of pipes?
Do you have a pic or link to it?
TT doesn't compete with Jack so links to it can be posted here.
'91 Golf gasser converted to turbo diesel.

'83 Rabbit gasser, converted to diesel, then converted to run on vegetable oil.

2, '84 GTI projects cars

duffer
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Postby duffer » Wed Nov 10, 2010 9:52 am

Fatmobile wrote:Flex joit at top of pipes?
Do you have a pic or link to it?
TT doesn't compete with Jack so links to it can be posted here.



www.techtonicstuning.com/main/index.php ... 2_12_50_47

Hope that's right.
Blue 1986 Golf N/A Bought it in '94. Never been on the road since.

Green 1991 Jetta TD. Bought it 6 months ago.

Hasn't been on the road since.

rsxsr

Postby rsxsr » Wed Nov 10, 2010 3:07 pm

Can you weld? If so, you can weld a tab on the front of the down pipe and use the factory bracket from the early rabbit. Part number is 055 253 193. It bolts to the engine block above the r/s cv joint. The factory actually sandwiched it with another bracket from the transmission 055 253 187 B. This will triangulate the down pipe between the exhaust manifold and the engine block before it turns rearward. This will ensure that the torque twisting will happen only at the flex joint.

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Postby Fatmobile » Wed Nov 10, 2010 8:26 pm

I don't think you need a flex joint with that downpipe.
it has one built in.
'91 Golf gasser converted to turbo diesel.

'83 Rabbit gasser, converted to diesel, then converted to run on vegetable oil.

2, '84 GTI projects cars

duffer
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Postby duffer » Thu Nov 11, 2010 12:16 am

rsxsr..
Thank you for a pretty detailed response. I only have an arc welder I've used on mild steel. Not sure about welding stainless, but I have a neighbour who's a proficient welder. We can probably work something out.

Thanks, again.

fatmobile...
Yeah, I know it has an integral flex joint.

What concerns me is the fact that the upper flex joint is, reputedly the weak point on these downpipes.

So, I thought that if the pipes had a weld-on support bracket, bolted to the engine block, disabling, to some extent, the upper flex, thus limiting, somewhat, the movement of the downpipes, then, it would be necessary to include a further flex joint ( such as pictured above) in order to permit some movement of the long straight-back pipe.

However, perhaps I'm just overdoing it. Just wanted to make sure I do this properly.

Thank you for taking the time to respond. Much appreciated.
Blue 1986 Golf N/A Bought it in '94. Never been on the road since.

Green 1991 Jetta TD. Bought it 6 months ago.

Hasn't been on the road since.

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Postby Fatmobile » Thu Nov 11, 2010 7:01 pm

I can see how that would be the weak link.
However it looks like it jumps far from the block quickly,
The MK1 downpipe rides closer to the block so the stock brackets worked great.
I'm not sure how you'd bracket this to the block.
'91 Golf gasser converted to turbo diesel.

'83 Rabbit gasser, converted to diesel, then converted to run on vegetable oil.

2, '84 GTI projects cars


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