Quote:
Originally Posted by -tWv-
The longer tubes in theory should allow the gas to exit at a higher velocity and promote scavenging even though there are some bends in there. Good scavenging normally helps with power delivery in the mid/high rev range since the gas can escape faster and is being sucked down the tube by the previous exhaust pulse. The stock headers don’t really have any sort of collector or design to promote good flow. Obviously they work just fine, but probably could be improved.
Now I’m not saying that these cheapy headers were designed with a lot of thought in mind so they may not be the most effective, but at least that’s the idea with longer tubes and a central collector.
A helpful video to understand exhaust velocity/scavenging: https://youtu.be/jjPeP_Nn2B4 |
I agree with your philosophical points above, but in my opinion the benefits which you note above are pretty much moot for a car which will be driven primarily on the street. For a track car which lives at high rpm's, definitely, but for normal stop and go / freeway driving I genuinely doubt that you'll see any differences.
What you did not mention: Where the stock early tube manifolds shine are in their flow advantage over the stock 3-in-1 cat manifolds.
Wanting to replace my cat manifolds, I did not even consider aftermarket headers since I've wasted far too many hours of my life already struggling to make various aftermarket headers fit a variety of engines. Sometimes you get lucky and they fit well; other times you curse and swear and beat them up with a hammer. So, I found a pair of these early tube manifolds, Jet-Hot coated them, and used them:
These early manifolds have individual runner I.D.'s which perfectly match up to the head exhaust ports, so I fell that the gas flow potential is not compromised too much by their lack of a collector - again, for a street driven car. I consider these manifolds to be 'poor man headers', but for me their key advantage is that you know that they will 100% fit perfectly. Plus, they are more compact width-wise than are most splayed tube headers, which should serve to keep heat away from such things as power steering hoses and the valve cover area.
By the way - It's probably too late for you considering your broken bolt trauma, but I would have recommended that you replace the old broken bolts with studs and nuts. Your car's future owner would have thanked you:
