Originally Posted by
Evol-Eagle-96
that's not entirely ruling out the idea that the flow could pick up velocity again in the straights. But seeing as how there is nothing to provide additional inertia behind the slowed gas flow aside from the same slowed gas flow, I cant imagine this being the case.
you're thinking about this in terms of one constant flow. In an exhaust, it isn't constant, it is pulses, and you have to remember that it isn't just one pipe, it is part of a set, and there is something that will speed it back up, the vacuum created by the pulse of exhaust just before it. in one runner, no, it just slows down, but as soon as you hit the collector, the pulse in front, "pulls" the pulse behind it, which in tern, "pushes" the pulse in front of it. Pretty much the most important part of the entire exhaust system, as far as making power goes, is the collector.
Originally Posted by
Evol-Eagle-96
Another thing to consider in this equation is that forcing super heated gasses downward is also sure to slow it's flow...knowing the downward slopes of the header design would also be helpful in determining flow capability...along with the approximate EGT throughout your powerband...AND the ambient temperature of the area you are running the car in (to determine total thermal resistance)in other words...there are A LOT of variables.
are you trying to imply that the super heated exhaust is going to want to rise because hot shit rises?
It is hot enough that, that isn't going to apply. I mean, yeah it would in an open air environment, but that isn't going to make any difference at all in this situation. The gas is so hot and moving so fast, that it doesn't really care which direction it is going, as long as nothing is in its way.
I see where you are going with the whole ambient temp thing, and again, that doesn't really matter. A good header is a good header in 50* or 120* Yes, the flow will be different, however, not a variable that you have to consider when designing.
Originally Posted by
Evol-Eagle-96
Ultimately, the best design to evacuate exhaust gasses would probably be to have straight pipes angled squarely away from the engine at a 40 to 45 degrees upward angle...but I doubt seriously you want your car to look like the dragula car from the rob zombie video lol.
Something like this lol.
actually, that is a really crappy way to design a header. There is no collector, so you are loosing that scavenging effect. and you actually have more air pressure to push through because of the dramatic drop in temp.
You want at least some pipe beyond the collector to let the exhaust continue to move out of the way while it cools down. What about F1 cars you say? They have a collector to take advantage of that. and because they rev out so far, they have a lot more exhaust flowing out of that pipe, and they dump their exhaust into the vacuum of air just behind their car. The "rules" change a little bit when you're doing over 10,000 RPMs when you slow down.