Custom Exhaust, just want to see what people have done |
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Custom Exhaust, just want to see what people have done |
turnaround89 |
Nov 21 2008, 12:55 AM
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#1
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Senior Member Group: Members Posts: 671 Joined: 17-May 08 From: Rockford, Illinois Member No.: 9,067 Region Association: Upper MidWest |
I am wondering if it would be possible to fab up my own exhaust system for my 1.8L engine. I figure i might be able to save some money this way, instead of buying a brand new one from AA or whomever and i'll learn how to make an exhaust as well. Just wanted to see what other people have done and how they went about it. Pictures would be great. I plan on getting rid of the heat exchangers if that helps out at all!
Thanks in advance everybody!! |
jd74914 |
Nov 21 2008, 01:29 AM
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#2
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Its alive Group: Members Posts: 4,782 Joined: 16-February 04 From: CT Member No.: 1,659 Region Association: North East States |
Well, first off you will need to make some flanges to fit to the heat. The easier way to make those is by cutting the ends off of an old set of heat exchangers.
You also need to decide if you are going to run a 4-2-1 or 4-1 merge, and figure out which cylinders have opposite firing orders so you can join those cylinders for maximum scavaging. Pipe lengths and diameters are a function of the header design you choose, your cam, the size of your engine, a power band you are looking to use most. If you are interested in any of that stuff you can look online for papers/websites on helmholtz resonance and other exhaust tuning methods. Many utilize a pressure wave which bounces back and forth, and with correctly tuned pipes can be used to suck exhaust out of the engine (aka scavaging). The pipe diameter is a function of the velocity you want. There are also formulas to find that out. IIRC you are looking for a gas velocity of approximately 300ft/s. After that you'll want to look around for suppliers of mandrel bent tubing (I've had good luck with Bassani exhaust). Once you have all of the supplies and the theoretical lengths calculated the fun part starts . . . packaging it. You'll want to cut one piece at a time and tack weld them together as so you can break of pieces when they don't fit as desired. Packaging is the most challenging part, you just want to try and get the lengths as close to equal and to the calculated length as possible. Of the non-pros I think Biggy72 (?) here probably also knows some stuff since it looks like he has done some FSAE exhaust stuff like I have. I'm exhausted so I can write some more tomorrow, or if you want to PM me I try to help you out. The below is the start of the last set of headers I made. Attached thumbnail(s) |
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