Performance Tech News            
May 2010
These newsletters are intended to be informative and helpful.  If there is a topic you would like see covered, just drop me an email ( and I'll see what I can do to get it in a future issues.
News -  Free Performance Calculators

The Auto-Ware web site now has a section of calculators to address common automotive math problems.

There are the basic calculators for engine displacement, compression ratio, torque & HP, but also more advanced calculators for valve timing based on cam specs.

You can calculate HP based on 1/4 mile times or on straight "flat out" max speed.
There are calculators for coil springs, leaf springs and sway bar rates, and even cornering G force or center of gravity height.

To top it off, why pay for a gear program when you can use our free calculator to determine RPM and speed.  Click here to see these free calculators and more!
Tech Tips - It's About Time

All forms of racing have one thing one thing in common, it's all about time.  The funny part is how 3 people watching the same thing can get 3 different times.
Many decisions and conclusions are based on lap times, and while transponders are growing in use, the stopwatch is still our first tool of defense.  But, even this simple device requires some techniques.
When timing I always stand in the same spot, but pick your spot so people or safety vehicles, etc will not block your view.  Next, pick something on the opposite side of the racing surface to use as a start/stop point.  This point should be close to perpendicular to the flow of race traffic and may require that you stand in a different spot (pick wisely as this is your home for the rest of the weekend - don't change points).
When clocking your car do not look at the car, rather, focus on your timing object on the other side of the track and hit the button when the car breaks your line of sight.  This does take concentration to hit your car if in a group and you may need to glance to your car a few seconds before it reaches the line, but quickly look back to your object before the car reaches the line.  Now, just hit the button.  I find my thumb is more repeatable then my index finger, but you may be different.
The final tip is the age of your stopwatch.  I find that after one season of every week usage, the buttons get worn.  The thing will still start and stop, but I notice the buttons have a different feel and my times tend not to match the transponder.  However, with a new watch I'm nearly always within 0.03 seconds (or closer) of a transponder time.
Equation of the Month - Pinion angle vs Toe
All cars are very sensitive to rear wheel alignment.  You can make a car totally undriveable or fix a car that will not respond to other adjustments by making small changes at the "back."  On open wheel cars (IRL) I have use 0.0075" (or 0.015 shims when feeling brave) to make rear toe changes.  On NASCAR Cup cars I have changed the rear toe by 0.050 degrees and have the driver report a noticeable change in handling.
The trick to toe changes on a solid rear axle car is in the rear camber.  If you rotate the pinion 90 degrees then the camber is now toe.  So, use the following equation to relate pinion angle changes to rear toe angle changes.
sin(PA)*C = Toe change (angle) where PA is Pinion Angle (positive is up and negative is down), and C is Camber (use standard convention where the number is negative if the top of the wheel leans inboard).  A positive toe change angle from this equation is toe-in and a negative value is toe-out.
Basically, rear toe-out makes the car very free or oversteer and toe-in can make the car tight or understeer.  Go easy on this adjustment as a 0.1 degrees toe change typically produces a large change in the driver's eye size. 
I need your help!  Tell your racing buddies about these newsletters and get them sign up, too.  Have them go to and use the newsletter link to sign up.
Happy racing,
John Block
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