3" turbo back 316 stainless steel exhaust, home made!

[lind4hl]

Jamo got it here!!

i use 3 mounts on my 3" also (avant) 1 @ rear box 1 where the middle box sat and 1 in the catalyst hangers (with rubber mounts to allow movement for the flexi)

[Error404]

looking good mate - out of interest what did you use to cut the pipe off square? 9" grinder?
(thinking of trimmming back my horribly oldskool DTM tail pipes! )

Can someone explain the mechanics of packpurging when welding exhausts? I know the reason for it, but not the actual method of doing it

[93URS4Avant]

Apologies for the delay - I have retained the original pipe but it is chopped off just before where the WG joins the pipe.

It seemed that as I was running only two pipes - I was informed that the lack of back pressure had affected my valve stem seals, resulting in oil leaking past the valve stems whereby it would collect within the exhaust system and burn, creating smoke, when the car was started, or when sat in traffic I'm not overly tecchie - and this si the explaition I recieved - it is plausible and it is either that or the turbo seals.
I am having the top half of the engine rebuilt as we speak which will include the valve stems being replaced along with everything else gasket-wise. hopefully this will prove one way or another.

[quattro]

Yes a mounted 9" grinder with a 1.9mm alu oxide cutting discs, dosent go all the way through but its the best way i have of doing it.

@ Jamo and lind4hl Ok i can see how only using 3 works, what mount do you use?

[lind4hl]

looking good mate - out of interest what did you use to cut the pipe off square? 9" grinder?

Can someone explain the mechanics of packpurging when welding exhausts? I know the reason for it, but not the actual method of doing it

What do you want to know really??

Backpurging is that you use a protective gas on the inside of the tube so you the weld "floats" out nice on the inside and dont leave any (dont know exact english word) "crap" on the inside that will slow up the flow/not as strong weld.

When you backpurge i use Argon, same as i use on the outside of the pipe, you just tape the top of the tube and sticks some small holes in it so the gas wont go out as fast, place an hose in the tube from the underside and seal the hole. the tube need to be placed upwards as the gas is rising automaticly, and then you start welding the joints from the underside and up, (otherwise the gas just will go out in the joint below)

anything else, just ask

[lind4hl]

quattro: for the rear i used SS pipe that fitted in the OE mounts (same diameter as oem)

and also on the middle, in the front i did some special stuff that is hard to say in english for me

[terrybullwon]

Alex there are some good videos on you tube, tin foil and bottle of gas works pretty well.

[quattro]

Any one else with stem seal problems and 3" exhaust?

[lind4hl]

Quattro, btw, you should have welded the cone on the turbo flange on the inside, the flange dont get as crooked then, but outside works also, but i would have put it up in a mill to get it straight again

[quattro]

You mean with heat when welding right?

I bolted it to a thick sheet and welded it in sections so not to get it too hot, bolts up ok but i wont really know untill i start her up.

[lind4hl]

Correct

otherwise, use something that is 100% straight, place it on the flange and try to get a feeler guage (right word?) between somewhere, then you will know if its crooked

[quattro]

Didnt think of that, ill try the feeler gauge in the morning!

[lind4hl]

Work-related secret

[quattro]

Feel free to let some more slide! lol

[Error404]

Cheers Alex and James, i'll ahve a look.
I plan to buy some TIG gear this year and get practicing so I can make my own system aswell when i get clsoer to getting my engine build underway