View Single Post
Speedy Squirrel Speedy Squirrel is offline
Rocket Scientist
Join Date: Jun 2008
Location: Detroit
Posts: 898
Originally Posted by RarlyL8 View Post
There is no need to use merge collectors with unequal headers like that, they don't need collectors at all. Step-up log design will work just as well and eliminate collectors altogether. If all you want to do is get the gas to the turbo just use a straight pipe and connect the cylinders to it.
Do not make a header by welding cylinder runners to a straight pipe. Lots of flow separation from at the edges of the junction. SAE paper 2000-01-0290 has a great sequence of Schlieren photos illustrating this. (Have you seen those pictures of model aircraft in supersonic wind tunnels? The ones that show the shock wave? That's a Schlieren image). After 120 years of internal combustion, that's the level of analysis exhaust pipes are subjected to, and this paper is 10 years old. You can imagine what goes on now, especially with variable valve timing thrown in. Smashing gnats with sledgehammers.
Old 01-13-2010, 07:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #90 (permalink)