The Stovebolt Site Forums The Shop Area Engine Shop 65 chevy exhaust back pressure question

Is it necessary when running a dual exhaust to connect the exhaust pipes with an H pipe or an X pipe for back pressure?
What happens if You don't?

No. I've run them for 60 years without any. Some of the performance guys will chime in with a good explanation but I think it just provides a slight HP increase & does not sound as good as separate duals.

Ditto, Not necessary.......

The crossover pipes just help equalize the exhaust. Not so much back pressure, more of a exhaust back up or traffic jam. If one muffler is full, the exhaust can get out though the the other side by way of a crossover. Since the exhaust is really just a bunch of pulses or burst of hot exhaust gases, the X-pipe type crossovers can actually pull exhaust from one side to the other due to high and low pressures of a exhaust pulses.

Normal driving won't have much effect on the crossovers other then noise, they tend to take out some of the harshness. Nascar really started the crossover use, the high rpm engines really like them.

Joe

An inline 6-cylinder does not need a crossover pipe, because the firing order separates the exhaust pulses from the front to the rear manifold outlet between each cylinder. A 1-5-3-6-2-4 firing order puts 1, 3, and 2 out of the front flange, and 5,6, and 4 from the rear. here's no way two pulses can stack up behind each other and restrict the flow. A Chevy V-8 is different, with two consecutive exhaust pulses, 5 and 7, coming down one pipe on the driver's side right behind each other. The crossover allows both pipes to share these pulses, and back pressure is reduced. The only way to avoid that is to use tuned-length pipes for each cylinder, and have at least the volume of one cylinder contained in each pipe before they dump into the collector. I did that on a 440 Dodge tractor pull engine, and ended up with primary header tubes over 8 feet long. Another way is to route consecutive exhaust pulses to the right and left exhaust pipes respectively, but that makes the underhood or under-frame area look like a snake pit. Smokey Yunick did that with some dyno research engines back in the late 1960's, and got some impressive HP and torque figures, but the plumbing was very impractical for street use.
Jerry

Thanks for the Information Guy's.That makes it easier for Me too finish My exhaust. Since I will be using my truck for a daily driver and won't be burning the rubber off the tires on Saturday night's I won't be needing to mess with the extra pipes.
Thanks..
Ron