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Series 5 Turbo II Exhaust to downpipe flange

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Old Apr 1, 2023 | 06:03 PM
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Series 5 Turbo II Exhaust to downpipe flange

Hey all - I’ve searched high and low for a part that I just can’t seem to find. It’s a flange that attaches the downpipe to the turbo and I have an exhaust leak there. I’ve found plenty of different kinds but they don’t really match the shape of mine. I’ve attached some pictures for more clarity. I’d appreciate any help.



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Old Apr 1, 2023 | 06:35 PM
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welcome to the board.

is this the flange you're looking for?

https://www.racingbeat.com/RX7-1986-...ges/16180.html
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Old Apr 1, 2023 | 07:02 PM
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Originally Posted by diabolical1
welcome to the board.

is this the flange you're looking for?

https://www.racingbeat.com/RX7-1986-...ges/16180.html
Thanks! Unfortunately no, it’s a plate that goes underneath here:




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Old Apr 2, 2023 | 10:50 AM
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are you talking about the gasket?

https://www.racingbeat.com/RX7-1986-...ets/16319.html
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Old Apr 2, 2023 | 11:38 AM
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The turbo backing plate.

This piece was never available separately from the turbo.

I have made a stainless backing plate so I could weld an external wastegate to it.

the stock cast iron chunk is going to be the most warp resistant material.

If it really did get warped somehow, it could be surface ground.

I have made/used multi layer metal gaskets between the turbo and backing plate.

Make sure its not an under tensioned WG flapper that is tinking with exhaust pulses or the WG flapper pivot leaking when cold.

If the car is on a lift a cold start with water vapor leaking will show you whete the leak is.

Make your exhaust louder do you dont notice tiny exhaust leaks?

Last edited by BLUE TII; Apr 2, 2023 at 11:40 AM.
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Old Apr 2, 2023 | 11:43 AM
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The fit between turbo and backing plate does look suspicious.

Should remove and check both plate and turbo for flatness.
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Old Apr 2, 2023 | 12:17 PM
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Originally Posted by BLUE TII
The turbo backing plate.

This piece was never available separately from the turbo.

I have made a stainless backing plate so I could weld an external wastegate to it.

the stock cast iron chunk is going to be the most warp resistant material.

If it really did get warped somehow, it could be surface ground.

I have made/used multi layer metal gaskets between the turbo and backing plate.

Make sure its not an under tensioned WG flapper that is tinking with exhaust pulses or the WG flapper pivot leaking when cold.

If the car is on a lift a cold start with water vapor leaking will show you whete the leak is.

Make your exhaust louder do you dont notice tiny exhaust leaks?
Thank you! Good to know I’m not going insane trying to find an unavailable part. I’m going to take it off and measure it so I can cut a new gasket for that spot. I’m getting some fumes in the cabin so ideally this will solve it. I’ve replaced the rest of the exhaust with the RB rev2 and accompanying components so this will be the last step. The last problem will be getting those studs out without snapping the heads off…
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Old Apr 2, 2023 | 01:11 PM
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RB Rev TII downpipe flange likes to leak too from my experience.

Get downpipe flange ground flat snd make sure the downpipe pipe/bends arent keeping the flange from sitting flat.
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Old Apr 2, 2023 | 01:13 PM
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Put a plug in the spare tire well hole in the hatch. Thats usually how exhaust gets in the cabin on FC.
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Old Apr 2, 2023 | 02:08 PM
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Originally Posted by BLUE TII
Put a plug in the spare tire well hole in the hatch. Thats usually how exhaust gets in the cabin on FC.
Just lifted up the carpet and found the hole. Thanks for the tip! Can’t wait to be able to drive this thing again. I’ve inhaled so much gasoline my hearts started to go dorito shaped.
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