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Originally Posted by XFi
GREAT WRITE UP! Thanks LostCause!  PM me with a name and address and I will send you out a sticker. |
Thank you for your generosity and I am glad you liked it. You are going above and beyond your ecomodder duties...
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Originally Posted by Frank Lee
LostCause has a good list- I have some questions:
How are the supercapacitors used?
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The best analogy I can come up with is another idea I decided not to post due to its impracticality: the inertia starter. An inertia starter uses a flywheel that serves as an energy storage system to provide a high impulse of energy over a short period of time. The battery or human turning the flywheel serves as a low impulse form of energy over a long period of time. Essentially, it utilizes each form of energy in its most efficient form. Batteries are great sources of energy storage, but they have high voltage sag due to high internal resistance. Supercapacitors, atleast in their current state, are poor storers of energy, but have extremely low internal resistance/voltage sag so they can dump their energy much more efficiently. Overall, the idea is to get by with a smaller battery (i.e. one not required to put out 500+ CCA), route the energy to the supercapacitors with a lighter cable, and place the supercapacitors closer to the starter where a short section of heavy, thick cable can be used to lower impedence. Lowering system weight is essential when you are trying to get by without a battery.
Awesome stuff...
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Is VW tranny fluid special?
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It is just an extremely low viscosity, non-synthetic transmission fluid that has passed industry protection levels. I forgot the exact scale that rates protection, but it ranked 4 out of 5. VW also makes a slightly thicker synthetic that has a lower viscosity when cold. It is costly, though. I'll find the link when I have more time.
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If there's a completely smooth belly pan, what good are side skirts? And vice-versa.
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There are three primary reasons I can think of: yaw angle, spillover (for lack of a better term), and downforce. When I have more time, I'll describe each in more detail and with greater accuracy.
Yaw angle refers to the apparent air velocity direction under the vehicle. I need to refresh on the exact mechanism, but essentially high pressure air at the front underside of the vehicle tries to escape out the sides rather than flowing continuously back. This air travels obliquely to the direction of vehicle travel (which entails a energy loss in itself) and in doing so hits the wheels. While the front wheels show the greatest effect, the rear wheels are also affected. The wheels, which visually appear to have a small aerodynamic cross section, are much more dirty due to this oblique airflow. Skirts physically block off this phenomenon by removing the "easier" route for air to follow. Skirts allow the air direction to stay closer to the direction of vehicle motion.
Spillover is very similar to yaw angle, but it just describes the mixing of two regions of different pressure. Like the tips of wings, where high pressure air tries to rise up to the lower pressure upper surface, differences in pressure between the bottom of the vehicle and sides cause the direction of airflow to be altered. The more you change the air surrounding an aerodynamic body, the more drag you create.
Lastly, as Lotus had done with their open wheel race cars, side skirts allow the creation of a venturi under the vehicle. While the venturi would create downforce to counteract the lift generated on vehicles, I am not 100% sure whether this counteraction would decrease cL. Lift, as measured by the lift coefficient, brings rise to induced drag. As unintuitive as it might seem, cars generate lift like airplane wings and create the same type of vortexes. I suppose at the very least it would allow corners to be taken at higher speeds, lowering the use of brakes...
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Cost/benefit of HID vs. regular lights? Can resistors be put in-line with headlamps to bring them down 10 watts? What's it save?
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It depends on how cheaply you can get OEM headlights. HID technology is old enough that they will probably start showing up in junkyards soon. I believe headlights currently cost $300-500 for a pair. As far as gas prices are concerned, it can either be thought of as a long term investment to hedge against rising energy costs or it can be added later when the technology is cheaper, parts are more available, and gas prices are high enough to lead to an immediate payback.
I suppose resistors could be used, but they are inefficient (they generate heat, which equals lost energy) and 10w incandescent light bulbs will not be very bright. 55w incandescents may pass for those in well lit areas, but the true benefit of HID is that they produce more light at 55w than an incandescent at 65w. Logically, you could feed HID less energy (say, 45w) and have the same amount of light as the original lamp. Additionaly, as far as I have seen, HID's even outperform LED's in Lumens/watt. No need to wait for or waste money on bleeding edge technology.
10-20w won't save much by itself, but if it allows you to run without an alternator you will reap huge savings (MetroMPG showed a 10%+ increase). 10-20w may not seem like a lot, but when running without an alternator, I'll take whatever I can get.
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How does double-clutching save money?
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Two ways: lower clutch/synchro wear and the ability to run a lower viscosity MTF.
The section should have really read Rev-matching/Double clutching, but the logic is that by matching transmission and engine speed you lower clutch and synchro wear. Double clutching is only used when decellerating, but downshifting is one of the areas of greatest clutch and synchro wear, I believe. Prolonging the life of a clutch may not be worth much, but it is not tough to do and every penny counts. Synchros, while long lived, are generally extremely expensive to replace (if you don't just replace the transmission itself).
The ability to run lower viscosity oil may be contentious, but the logic is that double clutching removes the reliance on synchros. The biggest complaint I've seen of running low-weight oil, especially with people who have worn transmissions, is grinding when going into gear. This grinding is generally caused by worn synchros failing to rev-match mating gears. Rev-matching/Double clutching, as done in the days of the Model T, is completely unreliant on synchros. In the end, it is a personal choice of choosing whether to risk damaging gears by not providing enough lubrication. When you have an old car whose transmission costs $100, the choice is easier. +1 for old cars...
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Originally Posted by metroschultz
I think he forgot to add the electric assist trolling motor for high traffic slow speed mobility.
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My logic is to install an injector kill switch, put the car into first, let out the clutch and hit the starter...instant electric car. Obviously this is taxing the starter and battery, but I figure going to the junkyard, finding a couple starters cheap, and learning to rebuild them negates any wear. I still need to sort out the battery issue, but Lead Acid batteries are so ancient I'm putting my money on newer types (NiMH, Li-ion, etc).
Buying starters and rebuilding them may be mildly expensive, but I figure it is a hobby that saves me money rather than pure economics...plus, I like to think it is a long-term investment that will pay off. The way gas prices are these days, it might not be that long term...
I hope that answered every question thoroughly. I wrote this quick so please excuse the poor grammar/spelling...
(Do I get a star for length?
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- LostCause
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