Posts Tagged ‘diy exhaust’

Building the Patriot Sprint / Roadster Weld-up Header Kit With Sidepipe

Tuesday, March 11th, 2014

Building the Patriot Sprint / Roadster Weld-up Header Kit With Sidepipe

I always thought that a highboy roadster hot rod should have an external exhaust system. Having a small budget for the build of the 1929 Ford hot rod, I started looking around for options.

Patriot H8010 weld up header kit on the 1929 Ford roadster

Anything I would find at a swap meet would require hours and hours of modifications and really wouldn’t provide me with the look I wanted to achieve. The great thing now, is we have the internet, so searching for options was easy. Buying a new set of roadster or sprint style headers didn’t make a lot of sense as shipping to my location would be expensive considering the size of headers I wanted. Even several of the speed shops near me quoted insanely high prices. Now I was starting to worry a bit. Then I came across header weld-up kits. What a great idea! Now I started to price out some options. With the small package size shipping was a bit more reasonable. Then one Saturday on my way home from a car club meeting I came across a new hot rod shop only a few minutes from my place. I decided to go in a see what they could come up with. To my amazement, they could get the Patriot Exhaust sprint / roadster weld-up kit H8010 for my small block Chevy engine for cheaper than ordering them on-line. How was this possible?? Oh well, I made the order and paid a deposit. On a side note about this speed shop, they are no longer in business. I guess their pricing scheme was too low and they went out of business a short time later. A week later I picked the Patriot header kit up and started another building quest on the hot rod. What a jig saw puzzle! Below is a short high definition video on the process I had under taken to build this set of headers? I must say at times it was very frustrating. No instructions and none of the primary header pipes were labelled. Oh well, this is what hot rodding is all about.
In the end, due to a minor clearance issue with the tires, I decided to start over again with some different. To avoid clearance issues due to the huge inward offset of the Corvette rims on the C4 suspension, a set of Lakester headers made sense. This will be another story and build in the next post.

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Designing & Fabricating Exhaust Baffles for Hot Rod External Side Pipes

Friday, March 7th, 2014

Designing & Fabricating Exhaust Baffles for Hot Rod External Side Pipes
I thought it might be interesting to explain a bit about the exhaust system I decided on for the 1929 Ford roadster hot rod. The idea of having an external exhaust system on the hot rod appealed to me. What came to mind was to use roadster headers with external side pipes. With a bit of searching and price comparison, I decided on a set of Patriot roadster headers. Ordering a set of pre-made headers didn’t make sense as the shipping cost would be out of this world due to the size of the package. I opted for the weld up kit and ordered it for a fair price at a local hot rod shop. When I received the box, it was an amazing jigsaw puzzle. Figuring out where each pipe went took a bit of time. In the end, the headers looked great on the 29 Roadster, but I had one tiny problem. With the C4 Corvette suspension from the 1986 Corvette, stock Model A Ford wheel base, and the huge inward wheel offset, the inside of the tires where just touching the front exhaust tubes. One option to solve this problem would be to use one inch wheel spacers. Using wheel spacers would effect of dynamics and performance of the front suspension. This is something I didn’t want and coming this far with the build why not do it right? I started pricing Lakester headers and thought these would look good on my 29 Ford. Not wanting to inhale exhaust fumes, the idea of side pipes continued. This time it was a bit more of a challenge to achieve. With a lot of thought and making small models using plastic pipe I came up with a solution to incorporate the side pipes on the roadster. This will all be explained in another post. For now, lets start with something simple, designing and fabricating the exhaust baffles to fit into the 3.5” side pipes I am using on the hot rod.
Over the years I have designed and built many exhaust systems which included mufflers. Some were successful with reducing the exhaust noise level and some were not and needed a bit of massaging. This was all part of the learning experience. Having an electronics background, the theory of waveform addition and subtraction can be applied to an automotive exhaust system. Using the idea that the amplitude of a forward waveform can be reduced by an out of phase reverse waveform, I came up with an idea to apply to my exhaust system. For example if a forward waveform had a frequency of 500 hertz with an amplitude of 1 volt peak to peak and the reverse waveform had exactly the same frequency and an amplitude of 0.75 volts peak to peak but was 180 degrees out of phase, the resulting waveform would be only 0.25 volts peak to peak. Using this theory to the exhaust system, the exhaust coming from the engine would be the same as the forward waveform. If I can create a reverse path in the exhaust pipe, I will achieve a reduction in exhaust noise. There is software available to design exhaust system that I do not have. So I will attempt the trial and error route and a bit of common sense.

exhaust gas path & flow pattern
CAD drawing of an exhaust baffle

Below is a video illustrating the fabrication process I undertook for this project. In the end I did achieve my goal of a quiet exhaust maybe a bit too quiet while testing this in the shop at idle and medium rpms. I will ultimately know for sure, once the car is on the road and I can test this out at higher rpm levels and at various engine torque conditions.

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