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74ls1tr6
Calvin Grannis
Elk Grove,CA
(1150 posts)

Registered:
11/10/2007 10:05AM

Main British Car:
74 TR6 / 71 MGB GT TR6/Ls1 71 MGB GT/Ls1

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Exhaust question, X -pipe, H-pipe for dual exhaust??
Posted by: 74ls1tr6
Date: February 16, 2008 12:05PM

Does anyone have experience with dual exhaust? I'm using 2.5" SS exhaust from my headers on my LS1. I have done some research online. The H-pipe will equalize pressure for the V8 engine as the X-pipe will give you a hum or buzz sound.

Any knowledge or information would be great.

Thanks in advance,

Calvin


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

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Re: Exhaust question, X -pipe, H-pipe for dual exhaust??
Posted by: NixVegaGT
Date: February 16, 2008 02:50PM

Hey Calvin. I've been tumbling the same question in my head for the past few months. I haven't seen any info on the "buzz" effect. I can say I had an Xpipe in my Vega with the 215 before I pulled it. It didn't sound buzzy at all. It was a lot quieter than I expected.

The numbers point to the Xpipe having an advantage with a silenced system vs. an Hpipe. The Hpipe also does better when located in just the right place however. One method I've heard of is to put in the dual exhaust and paint the tubes right behind the collectors. The spot where the paint burns off quicker is where the Hpipe should be located. This is sometimes a bit inconvenient if the crosspipe is in a spot that is hard to locate it.

The consensus seems to be if you have the space to put in an Xpipe, do it. I will be doing that myself.

Hope that helps.


74ls1tr6
Calvin Grannis
Elk Grove,CA
(1150 posts)

Registered:
11/10/2007 10:05AM

Main British Car:
74 TR6 / 71 MGB GT TR6/Ls1 71 MGB GT/Ls1

authors avatar
Re: Exhaust question, X -pipe, H-pipe for dual exhaust??
Posted by: 74ls1tr6
Date: February 17, 2008 11:38AM

[www.gotduals.com]

Hi Nicolas,

Thanks for your response.

That makes sense painting the pipes to see where the hot spot is for an h-pipe.

I went down yesterday to Muffler Tech (website at top of page) who deals with alot of high performance cars. I talked with Chris, I told him what I was doing with the TR6 and he said, need to go with the x-pipe setup with an LS1, have done both h-pipe and x-pipe, then dyno tested, x-pipe came up with higher hp in the end results. X-pipe has a smoother flow than H-pipe.

To quiet down the droaning noise in the passanger seating area that free flow mufflers cause, Chris said, run mufflers in series, a set of Magna-flow mufflers after the headers, then x-pipe, another set of Magna-flow mufflers , then out to the tips. Magna-flow 2.5" inlet/outlet 4"x14"or 18" dia/length mufflers.

So If I have the space I will go with the series setup and x-pipe. If I run one set of Magna-flow mufflers I may have the friendly police looking at me being here in California :-).

I agree with using the x-pipe.

Calvin


Moderator
Curtis Jacobson
Portland Oregon
(4411 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

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Re: Exhaust question, X -pipe, H-pipe for dual exhaust??
Posted by: Moderator
Date: February 17, 2008 02:44PM

I don't know much about H-pipes, but one thing I've been told is that they work best if the volume of air in the crossover tube is maximized. I gather that no significant amount of air actually travels through that tube, instead it behaves like a reservoir to help buffer out pulse-effects further down the system.

Four Magna-flow 4"x14"or 18" mufflers? Sounds heavy and expensive too.

If you must have four mufflers, this article suggests using two different muffler technologies in series: [www.britishv8.org]
(For example, using a chambered muffler such as a FlowMaster in conjunction with an absorption muffler such as a Magna-Flow to get the desireable characteristics of both.)


74ls1tr6
Calvin Grannis
Elk Grove,CA
(1150 posts)

Registered:
11/10/2007 10:05AM

Main British Car:
74 TR6 / 71 MGB GT TR6/Ls1 71 MGB GT/Ls1

authors avatar
Re: Exhaust question, X -pipe, H-pipe for dual exhaust??
Posted by: 74ls1tr6
Date: February 19, 2008 08:53AM

Thank You Curtis,

I did read the article from Larry. A lot of good information in there. I scaned this article sometime ago before making the leap for the V8, was going to use my 68 TR250 3 weber setup until I found water in the engine, ( still have sitting on engine stand wondering if I can get the head off without damage) have tons of peformance parts for the 6 engine, sitting on all this to see if one of my twin sons want a TR6 or?

My end results with the exhaust, was to install a ss x pipe right under the T56 trans, (closer to down pipes from header without having sharp turns into x pipe) continue on up through frame, (where original exhaust was installed) exit out right before R200 differential, then curve outwards (for both pipes, very tight with 2.5 ss pipe) to clear differential into FlowMaster 40's ,and last point tail piece downwards a little.

I will try this first and see what happens. I'm sure it will sound pretty beasty but it will get rid of wanting a Cobra for so many years. Still the British wins over the Cobra :-)

Note: When I was down at Muffler Tech yesterday picking up parts to do the exhaust, Chris said a red TR6 came in for a flex pipe because he was breaking welds from the the power of his 350 Chevy engine. I'm going to contact this person and get him to do a "how it was done article" if I can. I saw him about 3 months ago coming out of the muffler shop and ran him down to stop him for questions. Now that was a big task chasing him in my Honda Element, took 2 miles to get next to him and wave him over,(dang) had the whole family in the car at the time,(imagine a toaster chasing a V8 TR6 :-) hilarious). A very unique setup he had. I did get a business card from him. He did say he looks on BV8.org....(Trying to get caught up with the MG section of "how it was done" and a long way to go).


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