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View Full Version : Found a good overview on exhaust system design



temperacerguy
09-19-2011, 08:16 PM
The article is on basic/intermediate level exhaust system design, thought you guys would be interested:

Out the Exhaust Part 1 (http://autospeed.com/cms/article.html?&A=1466)

Out the Exhaust Part 2 (http://autospeed.com/cms/title_Out-the-Exhaust-Part-Two/A_1474/article.html)

Out the Exhaust Part 3 (http://autospeed.com/cms/A_1484/article.html)

It's from Australia, so everything is metric, so get out your calculators Americans,

I disagree on his line about aftermarket cats. I have seen properly sized Random Tech cats flow just as well as a straight pipe (as shown by dyno graphs), I have also seen aftermarket cats that were just like throwing a brick in the exhaust system.

I do agree on his comments about exhaust manifolds on turbo cars. While it is unpopular with many shops who sell "bling" tubular manifolds, or performance shops who build their own turbo kits, I believe that a cast manifold, or a turbo header made of thick cast pipes (weld els) is superior over a tubular "header type" manifold for durability and heat retention. For my project, I will be milling the CT26 flange off of my factory 3S manifold, welding on a stainless flange, port matching the manifold to the head, then sending it off to extrude hone to polish the runners.

I also feel that while he touched on thermal insulation, that there is far more to be discussed. Heat management is what I believe will be the future of automotive engineering. we lose so much energy through heat that it's crazy. If we captured back 50% of that heat lost, cars would need smaller engines, producing more power, and better gas mileage... but that's a discussion for another time.

I also believe that 95% of the companies that use a thin liquid or low temperature "powder coat" type insulation with little ceramics in the matrix are just worthless.

I personally have used many of these companies, both large and small, The ones that offer a 1-2 day turnaround time are worthless as it's basically a quick liquid sprayed on paint with little ceramic, and while Jet Hot's thermal barrier is great for appearance and corrosion protection, it does little for thermal insulation. I now use (and will only use) swain technology. Their White lightning insulation is not pretty, but it is an amazing thermal barrier! It's expensive, and turn-around is not the fastest, but it's worth it. As for the appearance. the pearl-like coating is a perfect base for standard automotive high temperature paint. I will be using swain's white lightning barrier on my manifold, turbine, downpipe, and engine under pipe to the cat. I will then be painting it with some silver/titanium/grey colored high temp exhaust paint.