Hi,
My car is an 83 Mercedes 300D turbodiesel (3.0L 5-cyl turbo). I needed to replace the flex tube and down pipe coming off of the turbo, which is about
2ft long, and then attaches to the rest of the exhaust by a flange.To make a long story short, the entire system is 2.25" diameter pipe. When I installed the new downpipe, it was about 1.5 inches too short. To make up for this I bought an 'adapter' from autozone that is about 3" long, and goes from 2 1/8" to 2 1/4" diameter. I slid the 2 1/8 end into the one side of the pipe, so the area where the pipe enlarged would create a tight mating area. I used an OEM exhaust seal ring to ensure the two sides would mateup tightly and not leak exhaust under my car. I tightened the flanges and all is well.
My question is, Would a 2 inch long length of pipe that is 1/8th inch smaller than the rest of the system cause any sort of noticable restriction or backpressure, that I should be worried about it or get the area welded with a larger diameter pipe so that there is no restriction?
As I understand it, a diesel is just a big pump, and the only way to make more power is to burn more fuel. Gas engines have to worry about restrictions because any way to allow more air in and out will allow more fuel (because the ratio needs to be pretty exact, unlike a diesel), and thus more power. Since diesels have such an excess of air, and the fuel isnt changed by the amount of air going in, does it matter as much or at all?
Thanks very much for your help.
JMH