My Cars

My two personal vehicles/testbeds. Page updated frequently as I try out more modifications.

2013 Toyota Prius


Visualizing airflow on the cheap


1991 Toyota Hilux









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How Spoilers Work

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Buckle up, this one's long. After hanging around Ecomodder for years, I had a pretty messed up idea of the function of spoilers because of what I had read on that forum. You might too.   See, the prevailing theory there—based entirely on posts by one forum member who is widely seen as an aerodynamic “guru”—is that spoilers “reach out” to an ideal “template” profile . By so doing, the theory goes on, a “locked vortex” is captured and the airflow above the spoiler follows the “ideal” template line as the air just ahead of the spoiler recirculates. So, simply position a spoiler and extend it until it touches a template profile overlaid on a side-view image of your car and, voil à ! Lower drag—because the spoiler isolates negative pressure in front, higher pressure in the wake behind it, and the outer flow follows the “template” shape. Someone might want to tell this person that the "perfect match" RS spoiler was, according to Burst himself , supposed to be 15 to 20 mm long
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A Practical Guide to Aerodynamic Modification

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Updated August 15, 2023 Tuft testing shows the streamlines on a car as the yarn aligns itself with airflow while you drive. Gas prices have recently reached their highest level in nearly a decade. You may find yourself looking at your car, wondering if it’s possible to use less fuel on your long commute and keep some money in your pocket. You may have heard of people who modify their cars to get better fuel economy. You might have even seen cars like the Aerocivic, a weird-looking contraption that was reported on in mainstream media articles during the gas price spike of 2008-09. Would doing something like that work on your car? Can you modify the aerodynamics of your car at home? The good news is, you can! The better news is, you don’t have to (and shouldn’t) make your car look like the Aerocivic. Air drag has an influence on the fuel economy of cars, and that influence is greater the faster you typically drive. You can also do a lot more with airflow than just reduce drag. Many peo
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Tuft Testing: A How-To Manual

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Updated September 13, 2023 Tuft testing is an incredibly powerful technique for visualizing airflow. Tuft testing is one of the easiest, cheapest, and most enlightening methods for measuring airflow over your car. Tuft testing is so effective because the behavior of the tufts tells you something about both the characteristics of the boundary layer and the velocity at any spot on your car. Background and Theory To see why tufts are such a great way to test, we first have to look at the paths that air can take over a car and the various ways we have available to visualize them. Aerodynamicists typically use three different illustrations of airflow: pathlines, streaklines, and streamlines (there are more, but we won't get into those here). If we divide the air into tiny “parcels” of constant volume (the technical term is Lagrangian parcels ), the path that a single parcel follows as it moves around and over the car forms a pathline , a record of its movement over a certain elapsed
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