3" downpipe

Give Jason a call at RJC Racing. Grab the 3" with the biggie puck. Jasons products are top notch.
 
Terry Houston was one of first designers to make a dp with perfect fit no longer in business. All 3"dp's made today are of same design. Do you want internal or external is the question. Search the vendors for best type and price and search boards for best fit. I bought one from SE Turbo years ago perfect fit . They are no longer on website and not so good business stories.
 
The Houston pipes have such a good rep that even used...they demand the same money as new pipes. I have a mint condition 3.5 inch Houston pipe for my new engine and it is a beautiful piece of work.
I just recently sold my 3 inch RJC. If your gonna buy a new pipe, that's a good one to get. The GN1 internal is nice too. Not a fan of the external.
 
The 3" integral wastegate down pipe that is sold by RJC and G Body Parts is far superior to the old TH pipe, and any in production at this time! :)

First, this pipe is ALL stainless steel construction, the flange, the puck shaft and bushing included.

The outlet pipe radius has been increased and redesigned for better exhaust flow.

Mounting holes, always an issue on TH and other pipes, are now elongated for in-car adjustment of variables like different headers, turbo housings, motor mounts and other gremlins.

I have worked closely with both of these companies in pro-type and field testing of their DP's to provide feedback for product improvement so they can deliver the best of its kind! :D
 
Thank you all for your help.
I will continue to use an integrated wastegate.
I was looking at the 3” from fullthrottlespeed but $285 seems to good to be true. I cant tell if it has an integrated elbow/puck and the desrciption doesn't mention it. I dont think anyone at fullthrottle will answer the phone today either.
 
87GNcospg said:
Thank you all for your help.
I will continue to use an integrated wastegate.
I was looking at the 3” from fullthrottlespeed but $285 seems to good to be true. I cant tell if it has an integrated elbow/puck and the desrciption doesn't mention it. I dont think anyone at fullthrottle will answer the phone today either.
Click to expand...


Their description states [key words - no wastegate]:

"This is a GN1Performance "3 INCH FLAT FLANGE DOWN PIPE WITH NO WASTEGATE" for a 1986 or 1987 Buick Grand National"
 
I promise that description wasn't there an hour ago. Haha
Thanks for the realization that I may or may not be illiterate
 
My original Houston 3" SS pipe, which I bought from Terry personally, has been on 3 different cars of varying mileage with 4 different turbos and fit perfectly every time. I tried a couple of different modern knockoffs of this style pipe a few years ago that did not fit (hit the frame) while my original THDP pipe had plenty of clearance. From what I could tell, the real THDP had another slight bend near the frame which made it kick out more, giving plenty of clearance. Elongated mounting holes might have helped the others, but I'm still surprised no one has managed to completely copy that original design.
 
WE2Regal said:
My original Houston 3" SS pipe, which I bought from Terry personally, has been on 3 different cars of varying mileage with 4 different turbos and fit perfectly every time. I tried a couple of different modern knockoffs of this style pipe a few years ago that did not fit (hit the frame) while my original THDP pipe had plenty of clearance. From what I could tell, the real THDP had another slight bend near the frame which made it kick out more, giving plenty of clearance. Elongated mounting holes might have helped the others, but I'm still surprised no one has managed to completely copy that original design.
Click to expand...
I have an original Terry Houston DP on my car and it fits perfect, doesn't even come close to hitting anything. My brother bought a RJC and it doesn't fit worth a crap. We had to elongate the holes just to get it to bolt on. We then had to heat it and tweak on it to get it away from the frame.
 
I have the gn1 3" dp on my car. It fits pretty good in the car, no issues being too close other than the wheel well but it clears my headers I have on the car. I had to massage the bolt holes just a bit to make it pull up nice an tight like I wanted. I also have the external gate on it which I would not recommend for a street car as boost levels are pretty high because of the spring. I couldn't get it down past 25 lbs I had to hook boost reference to bottom port an vacuum to top and for some reason it brought boost down. Just my input on this, thought it might help.
 
Hotrodbuick said:
I have the gn1 3" dp on my car. It fits pretty good in the car, no issues being too close other than the wheel well but it clears my headers I have on the car. I had to massage the bolt holes just a bit to make it pull up nice an tight like I wanted. I also have the external gate on it which I would not recommend for a street car as boost levels are pretty high because of the spring. I couldn't get it down past 25 lbs I had to hook boost reference to bottom port an vacuum to top and for some reason it brought boost down. Just my input on this, thought it might help.
Click to expand...

If you want to control your boost better...cut your pipe apart and make the hole the correct size. Everyone who has had this pipe has had the same issue. Either high boost or bad creep. The small pipe from the flange to the ex gate is fine, it's the longer one that is not correct. Take your gate off and grind the weld off where the longer pipe connects to the 3 inch pipe. You'll find the hole is very small or nearly plugged. I've seen pics of 3 other pipes and then I cut my pipe apart and it was exactly the same. Once you grind it off, bolt your gate back on. Bolt the unattached pipe back to the gate and mark where the pipe makes contact with a sharpie. Remove it and open the hole up as big as you can. Now bolt it all back together and tig it back together. You'll have total control over your boost. It really is a kick ass pipe after doing this. I installed my pipe on my buddies car and it works great. ( I have a 3.5 pipe now.) I was almost to the point of trying a new $400 Tial gate until I saw the pics of how small the hole was. If you have a Dremel...it only takes about an hour and a half to fix and weld back together. Hope this helps you.
 
coach said:
If you want to control your boost better...cut your pipe apart and make the hole the correct size. Everyone who has had this pipe has had the same issue. Either high boost or bad creep. The small pipe from the flange to the ex gate is fine, it's the longer one that is not correct. Take your gate off and grind the weld off where the longer pipe connects to the 3 inch pipe. You'll find the hole is very small or nearly plugged. I've seen pics of 3 other pipes and then I cut my pipe apart and it was exactly the same. Once you grind it off, bolt your gate back on. Bolt the unattached pipe back to the gate and mark where the pipe makes contact with a sharpie. Remove it and open the hole up as big as you can. Now bolt it all back together and tig it back together. You'll have total control over your boost. It really is a kick ass pipe after doing this. I installed my pipe on my buddies car and it works great. ( I have a 3.5 pipe now.) I was almost to the point of trying a new $400 Tial gate until I saw the pics of how small the hole was. If you have a Dremel...it only takes about an hour and a half to fix and weld back together. Hope this helps you.
Click to expand...
Had to do this to 2 different gn1 pipes as well. I was pulling my hair out trying to figure out how to control my boost on the first pipe. These pipes are great if you can find one that fits well.
 
Hotrodbuick said:
I have the gn1 3" dp on my car. It fits pretty good in the car, no issues being too close other than the wheel well but it clears my headers I have on the car. I had to massage the bolt holes just a bit to make it pull up nice an tight like I wanted. I also have the external gate on it which I would not recommend for a street car as boost levels are pretty high because of the spring. I couldn't get it down past 25 lbs I had to hook boost reference to bottom port an vacuum to top and for some reason it brought boost down. Just my input on this, thought it might help.
Click to expand...

please explain how you have vacuum working on the top of the gate .............
 
Hotrodbuick said:
I have the gn1 3" dp on my car. It fits pretty good in the car, no issues being too close other than the wheel well but it clears my headers I have on the car. I had to massage the bolt holes just a bit to make it pull up nice an tight like I wanted. I also have the external gate on it which I would not recommend for a street car as boost levels are pretty high because of the spring. I couldn't get it down past 25 lbs I had to hook boost reference to bottom port an vacuum to top and for some reason it brought boost down. Just my input on this, thought it might help.
Click to expand...

Why didn't u just put a smaller spring in the gate?
 
kidglok said:
Why didn't u just put a smaller spring in the gate?
Click to expand...

Smaller spring wouldn't do much if the hole is too small. He has high boost issue with his and I had extreme creep. From 23 to 29 or more from start to end of run. Once you open the hole to correct size...pipe works like a dream.
 
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