For my due buggy engine swap, I decided to use a VW Jetta engine because of the price of the engine I found. I bought the engine, and found out there are not a lot of aftermarket parts out there for this engine. The engine is from a front wheel drive car, so the exhaust and header wrap under the motor and straight out the back. Since I was mounting this engine on a VW bus 091 transaxle, I would need to build a new header for the engine to fit within my rails.
I studied the current header, and a lot of websites. There are plenty of websites that will calculated the optimal length of exhaust tubing in a header from various parameters of the engine, cam, rpm, and exhaust size. Using one of these calculators, I determined the length of my tubes should be approximately 26 inches and 1.5 inches. I believe my RPM was calculated around 2000 RPM so that I would have more low end torque.
Hooker sells pre-bent header tubing in 45 degree angles and 180 degree angles. I currently had a collector from another exhaust that would work for this project. I decided to cut the header mount from the original engine exhaust an use it to make my new header. Using MS Excel and Solidworks, I was able to make a design for my header to fit inside the area I had available. First in Solidworks, I drew each piece of tubing as it would be when it arrived in the mail. I also drew the header mount and collector in Solidworks. I arranged the pieces of the header so that I there was no interference, and shortened the length of each piece until I ended up with all the tubes the same length. Below is a picture of the intended design from Solidworks.
I marked all the pieces with tape, and cut them with an angle grinder. Next I purchased an exhaust spreader from harbor freight to stretch the exhaust pipe and create slip joints. This did not work. I will explain in a separate post. Next I carried the pieces to a exhaust shop, but some of the pieces were to short to create a slip joint. I decided I would just weld the pipe together using angle two pieces of angle iron to keep the exhaust sections straight. My welding is not the best as you can see from the images, but it works and I have had no problems so far. I modified the original design slightly because there was some interference with the exhaust and the motor. I used some high temp exhaust paint to paint the exhaust. Below are some images of the finished product on the buggy. I also decided to use a smaller muffler from a air cooled vw instead of the big muffler shown in the picture. The smaller muffler sounded a lot better than I thought it would have, and was lighter.
As you can tell my welding is not the best, but it is not built for show. If you have any questions, fill free to comment or contact me for more info.
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