3.5" downpipe with internal wastegate?

[Reedogg]

Does anyone produce a 3.5" internal WG downpipe with clearance for A/C and aftermarket KB/ATR style headers? TA sells one but it will not clear headers.
Thanks

 

[Mike Licht]

I do not know of an internal that will fit ATR headers anymore, there is externals which control boost better IMO

 

[Nick Micale]

We have local GN's that run low-mid 9's with a 3" DP, so unless you have more HP than, that the RJC 3" pipe will fit ATR headers and should do the job for you!

 

[Mike Licht]

I have seen low mid 9 cars run 3" down pipes, I have also seen the same guys go faster with a 3.5" pipe.

 

[Reedogg]

Thanks guys. Compared to other turbo cars and relative to engine displacement our 3" downpipes are undersized. There is room for a bigger downpipe if the inner fender is trimmed. How about availability of a 3.5 external WG with header clearance? I suppose if it's not available I will be assembling the parts to build one.

 

[ttypewhite]

Mark at TR Custom Parts has them. We ran a 3" DP on my Dad's 109 with a 71 turbo, then changed to Mark's 3.5" DP and picked up 20 more rear wheel. The ol boy's car made over 708rwhp at 28psi.

Here's the link
http://www.buickgn.com/downpipes3.5inch.htm

If you have a 4 bolt T4 style turbo and you get this DP you are going to have to cut the plastic inner wheel well. Or cut some off the DP and weld it back up to give you a better clearing distance so it doesn't require any cutting of your fender. Here are some pics of the DP after we took it to a chassis shop to add the external wastegate and tubing for it.

 

[Eticket]

Mike, was that downpipe from Mark a direct bolt on to the gt42 turbo with 4 5/8 vband connection? What headers do you have atr or TA??

 

[Eticket]

I see that's your dad's car and not your setup.. probably doesn't have the same sized vbands eh?

 

[ttypewhite]

I see that's your dad's car and not your setup.. probably doesn't have the same sized vbands eh?

John, my Dad has a set of ATR headers on his car with a 4" RJC exhaust, not sure about the flange size to my GT42, I have the BA 5" downpipe.

 

[Reedogg]

Thanks Mike. I'll probably go with one of those. It seems these downpipes from TR Custom Parts and GN1 are produced by the same manufacturer.

 

[Eticket]

The GT42 has a 4 5/8" outer diameter of the v-band flange.

 

[Ed Valvo]

The 3.5" TA Performance downpipe with internal gate clears the TA headers.

 

[SCOOBY DOO]

We have local GN's that run low-mid 9's with a 3" DP, so unless you have more HP than, that the RJC 3" pipe will fit ATR headers and should do the job for you!

RJC's 3 inch DP does NOT clear ATR headers...been there done that.