Downpipes - check your flanges!

[Bent6]

FWIW - I picked up an old ATR 3" DP with external gate provisions I had laying in my shop and measured it today. I was measuring the wastegate discharge tubes but stumbled across something interesting. While the downpipe tubing IS 3", the opening in the flange is only about 2.75"! There is plenty of material to port this flange out to match up with the actual pipe so I'll be taking a die grinder to it before I ever use it again. I wonder if other downpipes have this issue as you know most mfrs source the tubing and flanges from different places unless they hand fab their own and there aren't many doing that with all the Chinese crap out there. Something worth checking.

 

[bison]

FWIW - I picked up an old ATR 3" DP with external gate provisions I had laying in my shop and measured it today. I was measuring the wastegate discharge tubes but stumbled across something interesting. While the downpipe tubing IS 3", the opening in the flange is only about 2.75"! There is plenty of material to port this flange out to match up with the actual pipe so I'll be taking a die grinder to it before I ever use it again. I wonder if other downpipes have this issue as you know most mfrs source the tubing and flanges from different places unless they hand fab their own and there aren't many doing that with all the Chinese crap out there. Something worth checking.

This has to be checked on all dp's especially if you have a GTQ/HPQ. There is always some material to remove.

 

[3.8vsix]

I just checked my atr ext wastegate and it is 2.5 I am glad you pointed that out. Something I have not thought off.

 

[pacecarta]

heres before and atfer on my atr 3" external on a gtq wheel

 

[charlief1]

Never thought about it but good point. Thanks for the info

 

[Audie1]

Never thought about it but good point. Thanks for the info

+1

 

[novaderrik]

isn't the opening on the turbo housing itself only about 2.5"?
if so, then what's the benefit of hogging the flange out?

 

[pacecarta]

i didnt hog it for nothing the flange was overhanging the turbo exhaust,
if you look at the first pic the darker carbon ring around the hole shows where the turbo opening is with a gtq wheel

the wastegate was also a little small compared to the pipe that runs to the gate so i opened that up to the pipe and then made a template of the pipe and opened the turbo wastegate hole to match

 

[SPOOLFOOL2]

My THDP flange overhung about 1/16" in a few spots. A dremmel and five minutes fixed it.

Mike B.