IHADAV8.com - Turbo Buick Tech, and Nonsense

Tech Area => General Buick Tech => Topic started by: ~JM~ on June 16 2021, 03:48:57 PM

Title: 3" Down Pipes?
Post by: ~JM~ on June 16 2021, 03:48:57 PM

Who makes a 3" DP (internal waste-gate) that provides clearance between top of pipe & the bottom of the A/C heater box?

Title: Re: 3" Down Pipes?
Post by: Steve Wood on June 16 2021, 06:00:49 PM

I suspect this is the best made one   https://rjcracing.com/product/downpipes/  also the most expensive

Here is one from GN1 sold by Full throttle Speed   http://www.fullthrottlespeed.com/gn1-performance-stainless-3-downpipe-with-internal-wastegate.html

You can search for an used one on FB or turbobuick.com as well

Title: Re: 3" Down Pipes?
Post by: ~JM~ on June 16 2021, 06:57:28 PM

I'm familiar with RJC quality. I have a call in to them.

The DP I just installed has very little clearance between top of pipe & bottom of A/C box.

Thanks

Title: Re: 3" Down Pipes?
Post by: Steve Wood on June 16 2021, 07:40:06 PM

Be sure your driver's side engine mount is not collapsed

Title: Re: 3" Down Pipes?
Post by: ~JM~ on June 16 2021, 08:02:22 PM

Quote from: Steve Wood on June 16 2021, 07:40:06 PM

Be sure your driver's side engine mount is not collapsed

Just installed HR engine mounts.

Body mounts are still original, but don't look overly compressed.

Looks like the bend towards the horizontal plane takes place too early in the pipe run.

Title: Re: 3" Down Pipes?
Post by: Steve Wood on June 16 2021, 08:35:55 PM

using both of the HR mounts tends to lift the engine a bit on both sides and this will put the pipe closer to the pinch weld.  If you have a 1/4" of room or even 3/16's it should never touch assuming the front of the test pipe or cat is attached well.  The engine just does not move much even if the transmission  mount is not so good.

On the other hand, some of these DP's are made somewhat inconsistently and you probably have touched upon the problem

Title: Re: 3" Down Pipes?
Post by: ~JM~ on June 16 2021, 09:20:11 PM

Installed HR mounts in "low" position, new trans mount, rebuilt cat hanger (previous member of TB forum rebuilt), Pypes 2.5" dual exhaust with 3" test pipe.

Plenty of clearance near body pinch weld & everywhere else. A piece of notebook paper slides between top of pipe & the bottom of A/C box heat shield.

Believe the DP is from TA Performance but not 100% certain.

Title: Re: 3" Down Pipes?
Post by: Steve Wood on June 17 2021, 09:27:34 AM

I read the comments on the TA Performance site and it appears their headers are tailored for their headers.  The comments say they will work with the factory headers IF the heat shield is removed or modified so it would appear what you are seeing is normal for their headers.

I have the old TH downpipes on both cars.  They go under the box and are probably a 1/4" from the bottom of the box at their closest point.  Until you mentioned it, I had never specifically looked at it for clearance.
 

Title: Re: 3" Down Pipes?
Post by: kjhansen on June 21 2021, 06:23:43 PM

I ordered a 3" downpipe from RJC about 8 weeks ago.  It's still not made, much less delivered.

Title: Re: 3" Down Pipes?
Post by: ~JM~ on June 21 2021, 11:41:41 PM

Quote from: kjhansen on June 21 2021, 06:23:43 PM

I ordered a 3" downpipe from RJC about 8 weeks ago.  It's still not made, much less delivered.

Heard from Jason today. He has a back-log that he is shipping out this week & next.

In my limited experience it is unusual for him to be behind.

Title: Re: 3" Down Pipes?
Post by: phil_long on June 22 2021, 01:58:43 PM

It's very rare that RJC is behind. I guess that means business is good?