|
I too, have always wondered if they work.
Let's take a more scientific approach to understand the dynamics that could be why there are claims that it works, and if you've seen the info-mercials, know that the device is a fixed metal object placed in the air inlet flow path on the car's intake manifold.
First claim: By increasing the air velocity at the intake, the car's performance and air/fuel mixture will be better. Well in theory, I agree the performance will be improved, otherwise we wouldn't be using turbo's or superchargers. There is a weak arguemnt that the increase in velocity may improve the efficiency, depending on whether the intake path is conductance limited, or is flowing at rates which are impeded by friction and/or resistance in the flow path.
Second claim: The redirection of air flow into a vortex improves the fuel efficiency. This, in theory, can be supported looking at the flow dynamics for a flow path through a conventional cylindrical tube model. The velocity of air traveling through a cylindrical tube is fastest at the inside cylinder walls and slowest in the center of the cylinder cross-section. It is at the tube walls where the air velocity is subject to frictional loss the most and re-directing the air flow from against the walls toward the center of the tube will actually increase the air flow. The vortex device, in theory, does this.
The big question really is whether or not the increased airflow in the center of the tube can improve the A/F mixture and combustion efficiency. I can see that if the vortex device is placed in close proximity to the point in the intake manifold or above the carburettor where the fuel is delivered into the center of the air flow , this may make a significant improvement. It seems to me that the biggest benefit from one of these devices would be in a carburetted or port injected engine where the device can be place where it can direct flow to the fuel delivery jet or injector.
In contrast, I cannot see much benefit where the overall air flow is in a conductance limited flow regime, or when the flow is substantial enough amount that the vortex device itself adds to the firictional resistance of the overall air flow, such as in a high performance engine where flows are always large. It may be quite good for large bore intake's or low performance engines which never see huge A/F mixture flows, like trucks, mom's minivan or dad's station car.
In our Volvos which have electronic fuel injection, and may also have a turbocharger, the conditions to see improvements may never be realized. The injectiors are so far away from the throttle bodies where the vortex device is placed that by the time the flow is modified and re-directed into the intake plenum, the flow reaching the injectors is going to be close to, or the same as if the device was never there. I could see that an improvement may be possible if one of these devices were to be placed into each intake runner, just prior to the point where the injector squirts the fuel. On a turbocharged engine, I would think it pointless to use.
--
'89 245 sportwagon, destroyed by hit & run driver, RIP. '04 V70 2.5 T Sportwagon, 12k mi and '91 245 5-speed, 209k mi, replaced the '89
|
