Mocking up an exhaust system - done

rjplenter

rjplenter

True Classic
After seeing systems on this forum using the Camaro muffler I decided to see if I can put together an exhaust for our Barn Find.

A muffler, a flexible joint and a collection of tubes...



Maintaining equal length of the secondary pipes...








Mocking up the rest of the pipes and trying to decide where the flexible joint will go.



Before any tack welds are placed I'll have to dry fit it in the car to make sure it fits in the tight space.

My father-in-law is a master welder so he will be doing the final welds.

Cheers,

Rob
 
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Super

Great initiative Rob,
I'm sure you can do it.

Keep us informed and don't forget pictures :wink2:

Rob by the way your new signature picture is Great:love:
 
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Very nice start.

When you determine it's mid-range enhancing, duplicatable at a decent price, and quiet as the stock exhaust, I'll be the first to drop a deposit!
 
I made it fit like this:

X19exhaust.jpg


Using a race cat, connected to the Allison Header
 
May have to wait for a cold day...

Yves, merci mon ami! And yes, there will be more photos. The dilemma now is, I want to take out the inlet manifold and drop the standard system to try the fitment, but I'm really enjoying driving it again after being off the road for nearly 3 months.

Tom, I doubt it will be as quiet as a standard system and I seriously doubt I have the time or the resources to turn this into a production item. So far all the parts have been available online and I'd be happy to post a detailed list if it works out.

Hussein, I have read your exhaust posts many times and I'm familiar with your drawing. We don't need a cat here, but I think incorporating a flexible section is important. Do you have any other photos of how you hung the muffler?



I can kinda see what you did...

Cheers,

Rob
 
I have no flex section. If you won't have a cat, no reason not to add a flex just off the header/exhaust connection. Just make sure it's the rigid liner style, the others collapse inwards & cause a restriction.

IMG_7716.jpg


IMG_7720.jpg


Hangers are rubber block style with a steel mounting strap with multiple holes. Bolted to where the original hangers attached to the inner panel
 
Rob... I was gonna say the same thing as Hussein...

But shut my mouth 'cause I don't know just how big or heavy that Camaro muffler is.

Using a smaller muffler as Hussein did... I believe the tubing will support it nicely without a flex coupling especially if the muffler is suspended as well. It just might work well here also with the Camaro muffler as you have several hefty fittings with this "Tri-Y" configuration.

Lastly... I do support the use of this muffler if one really wants a dual exhaust look but who are we fooling? I lean towards a good sounding (without drone...) single muffler with an ever-increasing size (maybe 2" inlet and/or a 2 1/2" outlet) with a fat round pipe exiting where the factory pipe was. Function first... Just something to think about.
 
Black-Tooth said:
Lastly... I do support the use of this muffler if one really wants a dual exhaust look but who are we fooling?
Click to expand...

Not trying to fool anyone. I like the bumperless look. I like the look of a '74 grille on a '75. I like the cleaner look when various seams and the rear side lights are deleted. I like the look of the Euro (and Aussie) style front side lights.

I also like the look of a pristine X as it came out of the factory...
 
Good design

Rob,
I recall some time back we were attempting to come up with a good design for a header and exhaust by calculating the various sizes, lengths, configurations, etc. (I think it was you involved in that project). And it seems we found that the old 'Tri-Y" Anza header came extremely close to what the formulas dictated. I believe that is what you are using for the major portion of your header? If so, then your system should work very well. Your secondaries look to be a good layout for that header as well. I do not know anything about the muffler you are using (in terms of its design with this system), but I understand wanting the twin outlet look.
I think you on the right track to building a really well designed exhaust, good job. Please keep us posted.

EDIT: Opps, I just saw your earlier post about the header...my assumptions were correct about it. And I totally agree with Steve C's suggestions for improvements to the header's design. Before you actually weld yours up, perhaps consider finding someone to make a copy that incorporates those improvements. Hopefuly it could then be made for others as desired. Thanks for continuing to persue this, seems to have died out awhile back.
 
Sooo, I couldn't wait to try it...





It looks okay from this angle, but the point at which the original pipes terminate is too short to clear the chassis. So I have to rethink the design.

I've made a couple of calls but yet to find someone who wants to work with me to make improved copies.

Thanks for the extra photos Hussein, a lot clearer.

Cheers,

Rob
 
Reply

Hi Rob. I have 2 sets of the same Ansa header you are using, so I am quite intrigued by your progress.

My day job for the last 25 years involves design and manufacturing of exhaust systems, and processing warranty claims to see why they failed. I've learned a few things.

Firstly I can tell you that you definately need a flex in the system. The engine is mounted on big rubber mounts and moves quite a bit. Something has to allow for that. And for sure you need a sturdy brace at the end of the header. Connecting the end of the header to the engine block or tranny. Otherwise the weight and vibration of the header is taken - with a lever effect - at the front header flange. Trust me, without a brace, it WILL - after time - crack.

Once you have the header well connected to the block, then you must realise that the weight of the rest of the exhaust system is supported by the body (with rubber hanger or springs). But because the header moves with the engine and the muffler is connected to the body, there then MUST be a flexible joint between the two. Fiat used a flexible joint with springs between the two. On the early cars this flex joint was between the manifold and front pipe. On the later cars it was between the cat and the muffer. Alternately, on the '74 US cars, and the euro cars (which had a lighter exhaust system with no cat), the entire exhaust system was bolted rigidly to the engine/trans. And NOT connected to the body at all. You must one or the other.

So in your case, the proper appproach would be:

Where your header ends finally to a single pipe (just after the last collecter), weld on a flange. (This will also make installation and later removal and service easier) ]. Make a sturdy brace that connects this flange to the engine block or trans.

Between this flange and the muffler, use your flex pipe. You can then support the muffer to the body with the stock springs or rubber hangers.

Then your proposed system should work great. Efficient design, low restriction, short pipe lengths. Should make great power !!

BUT.....although it sounds great in theory....there is a chance you MAY - I repeat MAY - end up with excessive booming or droning at certain RPMs. About 90% of cars use a muffler AND a resonator (they eliminate different noise frequencies). The only way to add a resonator would be to make your header exit to the right , go over and add a 180 degree bend to add one ( a resonator) across the car before another 180 degree bend into the muffler. This would add a bunch of pipe length and another bend to the system. And would completely change your header design.

Or stay with your initial configuration and you may have to try some mufflers of different construction to get an acceptable sound. Probably your best approach. After all, Fiat did manage it (on the euro cars) without a resonator so it SHOULD be possible....

Good luck. Cheers, Doug
 
How does a rigid support for the header to the engine/trans really help? With that in place, there is no allowance for the expansion of the header tubes under heavy load - I've seen headers glow. Plenty of videos where they become cherry red, too. I can see having a support on a cast iron manifold - however even those (Volvo uses them) are usually a spring steel that allows for expansion.
 
A supportive connection can be compliant in certain directions and not in others, to your Volvo point designing the structure to allow for this means you don't need to use spring steel.

Better support of a tubular header is generally more necessary than with a cast iron one which has sufficient strength to support its own weight and the weight of the down pipe.

Most factory systems provide some flexible connection between the various parts for very good reason. I have noted a huge difference in longevity of my car's exhaust systems in my modern cars versus the cars of my past. My current Golf at 13+ years has had one minor component fail (the compression joint between the catalytic converter and the rest of the exhaust system. Clearly the changes in materials have been part of this but I am certain the means by which the various parts are constrained has been a big part of it.
 
Doug (rx1900)

Considering that you own a couple of the Anza headers and work for an exhaust company, would it be possible for you to find someone that could 're-make' them with the modifications proposed by 'SteveC'?
 
Reply

Dr. Jeff : Yup

Hussein: Okay, you want a Volvo parallel ? Volvo 240 and 740 models had a 2 into 1 long front pipe bolted to the exhaust manifold. Near the back end of the front pipe was a bracket that was bolted to a brace to the tranny. Often these pipes would come back for a warranty claim cracked and broken at the front flange. In EVERY single case we could see (from rusty thread holes) that the installer had not hooked up the brace. The purpose of the brace was to support the pipe and to dampen and quell the vibration. NEVER once did we see a pipe fail where the brace was hooked up. Sounds like you work for a Volvo dealer. If you dont believe me, ask some of the old time Volvo mechanics what happens if you leave the brace off.

We also saw the same situation on many other cars. Please note the original Fiat design on your X1/9. They too put a brace connecting the flange between the converter and the muffler to the tranny. They wouldn't have gone to all that expense for no good reason.

And trust me, installing a header just makes matters worse. Thin tubing - especially stainless - is much more prone to cracking.

And the only manifolds I have ever seen glowing red hot is on a high boost turbo under race conditions.....
 
Reading above posts with great interest.

Unfortunately, the muffler companies are great at giving sizes and materials, but I've never seen any info that would let me tune out a "drone" before I bought their product.

Likewise aftermarket companies do not seem to offer resonators that are matched to particular brands of exhaust. And resonators seem to be as expensive as mufflers (if not more).

It seems they want people to just buy something and throw it on there.

Definately agree on using a flex-pipe.

Not sure how to engineer a engine brace on a tube header, but I guess it could be done with some fiddling and welding. Never seen anyone brace their tubular headers but it sounds wise

Side question, has anyone utilized a same-side muffler in a custom exhaust ? http://www.magnaflow.com/02product/shopexd.asp?zone=main&id=11490 I was seriously considering this approach for my restoration because it's so easy to incorporate into my 4:1 header design.

Does the dual exhaust sound better than single?
 
100% agree with Doug on this one... you either mount the entire exhaust system so it moves with the motor, or you mount the system with the muffler hung from the body, and some sort of flex coupling between the muffler and the front pipe.

The 2.25inch systems I do are sprung with the motor and braced just like the euro systems (gearbox mount and lower engine mount) ...

the other way I do it is to make a twin out front pipe / OE twin outlet manifold that bolts/gasket together, and I use the original single out manifold mounted ball/socket/springs and long studs and attach that to the OE stainless muffler at it's inlet flange (our systems here - up to 1981 - in Australia are like your US spec cat systems but without the cat convertor) ... the ball ended stub fits nicely into a 2.25inch pipe that I use as the tertiary section (collector) ... again I like a generous pipe size and volume here as I think it counts as an 'expansion box' and adds volume/length to the system...

even with the stock stainless muffler it makes a very noticable increase in performance... so much so that even female customers who had the mod done (simply to get rid of the squeaky/leaky front ball/socket connection) could feel that something had changed... "what have you done, it goes sooo much better' was the comment I got the next time they bought the car in for a service...and they had no idea or desire to have the performance enhanced, but no one complained!!

I just don't get why people would spend hundreds of $$ for extractors when for 90% of engines the stock twin out manifold system will perform more than adequately... Rob is going for a stroker 1600 so in his case I can see the point, but nearly $1000 for a commonly used vendor sold exhaust system could be spent much more wisely...

SteveC
 
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