I spent a lunch hour trying to find a study comparing HP and torque for a V-type engine with single exhaust vs dual. My interest would be for a non-race car with 350 CID or less.
A single 3" diameter pipe is very close in cross-sectional flow area to dual 2 1/4" pipes. The advantages to a single pipe would be weight, the dual system is more than 50% heavier; space, obviously the dual takes more room under the car; surface area, although the flow area is very close the dual system has more surface area which means more drag. Lastly, less material and less labor to produce and install should mean less cost.
When I bought my wagon the first thing I did was replace the small single exhaust with a custom fabbed 3" system. I had them come off the manifolds with pipes that matched the manifold opening diameter and joined those two pipes with a Flowmaster "Y" pipe connected to a performance cat with 3" inlet/outlet, a 3" pipe to the largest stock-type muffler with 3" I/O. If memory serves I think the only muffler they could find had a 2 1/2" outlet. The tail pipe ended in a turndown even with the bumper.
It sounded fantastic, not too loud at highway cruising speed and very cool idling around town. At the time I had a 30 mile, mostly highway commute and it made a small improvement in gas mileage which means it was probably more efficient. However, I always wondered how horsepower and torque were affected. If anyone is aware of a comparison or has conducted a comparison I would love to see it.
A single 3" diameter pipe is very close in cross-sectional flow area to dual 2 1/4" pipes. The advantages to a single pipe would be weight, the dual system is more than 50% heavier; space, obviously the dual takes more room under the car; surface area, although the flow area is very close the dual system has more surface area which means more drag. Lastly, less material and less labor to produce and install should mean less cost.
When I bought my wagon the first thing I did was replace the small single exhaust with a custom fabbed 3" system. I had them come off the manifolds with pipes that matched the manifold opening diameter and joined those two pipes with a Flowmaster "Y" pipe connected to a performance cat with 3" inlet/outlet, a 3" pipe to the largest stock-type muffler with 3" I/O. If memory serves I think the only muffler they could find had a 2 1/2" outlet. The tail pipe ended in a turndown even with the bumper.
It sounded fantastic, not too loud at highway cruising speed and very cool idling around town. At the time I had a 30 mile, mostly highway commute and it made a small improvement in gas mileage which means it was probably more efficient. However, I always wondered how horsepower and torque were affected. If anyone is aware of a comparison or has conducted a comparison I would love to see it.
