"Tyre pressures should always be at the maximum end of the manufacturer’s recommendations however, I do not recommend some of the extremely high pressures that people chasing fuel economy sometimes run. (I’ve seen suggestion of pressures of 50 psi – the ride will be terrible, the handling suspect, and I wonder if the insurance company would even cover you if you had a1n accident.)"
I will assume you are referring here to the car manufacturer's recommendations and not the tyre manufacturer's maximum recommended pressure as printed on the sidewall.
Reducing Fuel Flow
have you heard of the "electronic diverter" by george wiseman of eagle research? this is a device that modifies the signal from the ecu to the fuel injectors, it allows one to reduce the amount of fuel injected into the cylindrers . i have the schematic diagram , let me know if you are interested, i can forward them to you . this sounds like a great idea if it works.
Reducing the amount of fuel that goes to the cylinders is very easy. The hard part is doing it when a car is in closed loop operation...
First of all - Great publication. Ive been reading for many year and love all the stuff you guys do.
Now, why i am emailing you: Truck batteries. In this months article titles junkyard dawg where you went to the truck wrecker you mentioned the batteries. I worked for a certain large mobile battery service for a while and truck batteries new are readily available and not as expensive as some people would think.
The batteries we are looking at are mostly part of the n50 and n70 family (see the exide range). Your typical family car battery starts at about $149 and these start at about $179. They are quite good for the heavy duty/car audio thing and you can always run them in paralel like any other battery. Alot of the small trucks just use regular albeit premium batteries which you could fit into most regular road cars. They are also common place in 4wd's. Large truck and boat batteries are also worth investigating and are up to about 70cm long. They are quite expensive though.
So just a headsup truck batteries are a common deal i fitted a few to regular road cars one in particular was a honda prelude 4th gen with an n50 battery. He had a big car audio install in it and was using one previously and it all worked well. Fit right in aswell. This certain battery supplier/emergency service will let you fit a larger battery. Last i knew they would give you options over the phone and this certain prelude job was sent through to the pda with that battery listed. So id say if your in the market for a new battery to do a little research first. They arent all that expensive and you dont have to settle for a second hand job.
IF your looking for a second hand battery all of them are dated and to help you out - heres how :) The supplier probably doesnt want the world to know this but who cares?
Its an alfa-numerical code. 1 Letter, 2 numbers so as an example lets use G05. The G is the month the battery was produced: G being the seventh letter of the alphabet its a july battery because july is the seventh month. The 05 simply represents 2005. It is burnt into the batterys casing usually on one of the sides and usually on the top lip. Sometimes they are on the top. All batteries i know of have a date stamped into them. This code is specific for exide batteries but alot of batteries are just rebadged exide anyway.
You dont want to buy a battery that is over 2 years old. Its quite common for them to die in the 2-3 year bracket especially on trucks. The oldest lasting battery ive seen was on a hilux and the battery was 14 years old - The hilux was completely optionless though and id say the battery was a freak so dont go expecting 14 year old batteries from the wreckers to work. If there is a fair bit of black sludge under the batterys caps then stay away. Generally the less black sludge the better the battery.
In your article "Tyres, Grip and All That ..."
"Classical friction theory must be modified for tires because of their structural flexibility and the stretch of the tread rubber. Instead of depending solely on the coefficient of friction at the tire-road interface (which is determined by the nature of the road surface and the tread rubber compound), maximum stopping ability also depends on the resistance of the tread to tearing under the forces that occur during braking." 
"Further, the size of the contact area is very
important in car tires because the traction is dynamic rather than static; that
is, it changes as the tire rolls along. The maximum coefficient of friction can
occur anywhere in the contact area, so that the greater the area, the greater
the likelihood of maximum traction. Thus, under identical load and on the same
dry surface, the wider tire has a greater contact area and develops higher
traction, resulting in greater stopping ability."
Need for Noisy Hybrids?
You may have read "Electric cars 'silent killers'
(Mark Hinchlifffe, August 23, 2008, http://www.news.com.au/couriermail/story/0,23739,24224490-953,00.html)
and wondered how this nonsense came to be. I started following this effort since
April 2007 in a blind
advocacy mailing list because I wanted to find
'the dead bodies.' But my interest increased after a bill was introduced to the
USA Congress, HR 5734, April 2008. That bill, "Pedestrian Safety Enhancement Act
of 2008", mandates noise levels from hybrid electrics. We call it the "Bell the
Hybrid Act," as it would ban all hybrids and electric cars that didn't make
Workshop Construction and Drills
Great series on construction of your shed/workshop [starts at Building a Home Workshop, Part 1]. I was really interested by your DIY drill - can you provide more detail on that? I've destroyed plenty of cordless drills (mostly the gearbox or battery life) in various projects and would love to revamp them...
A drill with a defective gearbox is a hard fix, but if the batteries are worn out, just wire an external battery to the original battery terminals, using a long cable. I used two 12V sealed lead acid (SLA) batteries in series.