Sunday, April 3, 2016

From Conception to Execution: The evolution and realization of a Retro Mod - Part II

Part I dealt with the genesis of the idea for a way to make the modern Challenger look more "retro".

Part II details the design and fabrication process.

PART II 

With the realization that a faux body kit side pipe was not only economically unfeasible, but also not nearly authentic enough (meaning, it had to function as intended), I went to work designing real side pipes.

I chose to design my own as opposed to buying something "off the rack" for a couple of reasons.  Foremost was the fact that of the choices out there, some were either way too small and expensive (designed for Corvettes or Shelby Cobras) or were cheap chrome knockoffs found on the back pages of parts magazines.

The other reason was, the Challenger is just plain big; from wheel well to wheel well, it measures 82 inches, of which the door itself is 51 inches.  There is nothing on the market proportioned correctly.



Having abandoned the idea of replicating the George Barris faux side pipe rocker kit (as detailed in Part I) I began researching side pipes as most people recognize them:


As illustrated above, the standard side pipe has a heat shield (absolutely necessary if you want to avoid 2nd degree burns on your calves).  Also as pictured above, 99.95% of all the side pipes you can buy are chrome over regular steel.  I've seen enough "chrome" in my time rapidly fail and nothing detracts from the appearance you're trying to achieve than flaking "chrome".

I decided my pipes would be black but it's almost impossible to find black side pipes. 

So, I realized I'd have to go bare metal and have them coated (more money); a ceramic coating capable of withstanding exhaust temperatures for two pipes would run me $600 +.

My early design was going to incorporate a heat shield containing the diamond plate pattern of my car's overall design which I conceived of when still pursing the Barris rocker style pipe:


Once again I was taught a lesson in not knowing what I didn't know.  The first was that it would be almost impossible (meaning if possible, quite expensive) to have a 3 inch radius formed into a plate 4 1/2 inches wide.

The second lesson was that, despite over a dozen phone calls, I couldn't find a shop that could (1) produce such a radius, and (2) produce any type of radius on a piece more than 25 inches long.  This meant that I'd have to have a two piece heat shield, which for aesthetics sake alone would destroy the image of what I was trying to achieve.

After about a month of trial and error, I was almost ready to give up when my subconscious put 2+2 together and came up with a brainstorm idea; why not combine the two concepts?   Meaning, why not make a functional full side pipe but with the finned design of the Barris body kit?

Again, not knowing what I didn't know about welding; Every shop I spoke with said the same thing:  for the length of pipe I wanted, they would not, could not, guarantee the fins running the length of the pipe would be straight.

At this point I took stock in where I was on this project:
* can't afford the extruded process
* even if I could, couldn't use aluminum anyways if it was going to be functional (can't weld aluminum to stainless steel practically)
* can't find a place to bend sheets of stainless steel into the shape I needed
* can't find a place to bend sheets of stainless steel in the lengths I needed  

And yet, I wasn't ready to give up.  I kept surfing the net, following links upon links...then one day, it happened; the brainstorm to end all brainstorms!

I found a site that offered a free CAD program that would take the design you created and fabricate it. Suddenly I was hit with this idea:  why not design guides to slip along the length of the pipe that would hold the fins in place for welding?

I went back over my copious notes on the shops I had spoken with, and posed the idea to them.  Most didn't believe I was serious, some hemmed and hawed then gave me a ridiculous price to try.

One shop however, while reluctant at first, seized upon my idea of templates for the fins.  I cannot recommend enough Hi-Flo Custom Exhaust in Manassas Virginia.  Scott, the owner, is a true "car guy" who respects American Muscle cars, and Warren Donohue, the artist with a TIG welder who convinced him to take on this project.

I designed the templates, ordered them, then waited nervously as Warren took home the templates, two 72 inch lengths of #304 stainless steel exhaust tubing and the #409 stainless steel plates I had ordered and spent the next three nights, after working full days at Hi Flo, to TIG weld the fins to the tubes.  We went with the full 72 inches because we knew we'd have to cut to size once we had a tube ready to test fit.










Buoyed by Warren's confidence that he could do a clean weld keeping the fins straight with my templates, I set about securing the final component of my design; cutouts.

I researched this topic endlessly, reading any post or thread that had folks commenting on the types of cutouts they used, liked, disliked, etc.  Ultimately I selected the Badlanzhpe.com brand.  None of the multitude of reviews I read on these mentioned any of the issues commonly found with its competitors; that and they came with a 5 year warranty, and the owner of Badlanzhpe was easily contacted by email and responded quickly.  

UPDATE:  Despite how good the Badlanzhpe cutouts were, they still suffered the same weaknesses as the other traditional cutouts (burned out motors, failed gaskets, weakened flaps rattling)...so I did more research and went with NoWeeds (www.noweeds.net) which are both true exhaust diverters and don't require welding to install.  I was amazed at the quality of both the design and the construction of the NoWeeds and recommend them very highly

After two long days spent at the Hi Flo shop while Warren worked on my project in between his regular job (thanks again Scott for being so patient), the tubes were done...but that was only the first phase.

Warren and I debated on the best location for the cutouts; originally we were going to place them just after the X pipe.  However, as with all "design/build" projects, what looked good in theory doesn't always work in reality.  We had no room to run the pipe from the cutouts to the side pipes without some extreme bends.  And this brought up an issue for which none of us would have an answer until the project was done...

...how would they sound?

We elected to insert the cutouts after the CATS.  This would allow us to make a straight shot to the rear of the side pipes, from there we would spear the cutout pipes into the side pipes about 10 inches from the end.



We cut a hole in the front end of the rocker panel to insert the "intake" end, giving an appearance of it running into the chassis to the headers.  For the exhaust tip, we decided on a short tube, angled down and out (as shown in final picture above).

And so, after almost 6 months of designing, planning, sweating and re-designing, I'm proud to present my George Barris inspired, fully functional, modern interpretation of Side Pipes on a Challenger!











Oh, and to answer the question as to how they sound....they sound like a BEAST!  So far, this is the only sound clip I have; I'll update it with a better one as soon as I can.














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