March Tech Notes
A Supplement to The Engine Analysis Software
The Prop Duplicator
After a weekend visit with an engineer friend of mine, Brian Callahan,
we have a REALLY NEAT new testing tool. Brian told me that he spent a lot of
time, timing people through the turns at the Nationals. What was the significance of this?
He said that most people took about 2.2 to 3 seconds passing buoy 1 until they passed
buoy 3. There were a few people who were able to run less than 2 seconds. He said that
on the timed run that I had with my 67 Roadrunner, I ran 1.4 seconds. What was the significance of
this? He made a crude spreadsheet and showed me that with this data and a single timing of your
boat between buoy 3 and buoy 4 (straightaway) along with the turn time,
you could know a HUGE AMOUNT about the dynamics of your boat. If you add in how
well you drove on the turns (How close to the buoys), it was possible to calculate MANY things
about your course speeds, times, lateral acceleration in the turns ("G's"), and what time
was possible with PERFECT TURNS. WOW.........!!!!! What a neat tool for testing. You know
I can't keep anything to myself!!!
Well..... Here is the spreadsheet for doing this. If you have Excel click Here to Down load.
If you have different courses size you can input the radius of the turns and
the straightaway length suite your application. After you download, and unzip
the file, move the file LAP.XLS or LAP.WB2 to your directory for Quattro
Pro or Excel.
Enjoy this little program, and let me know if you beat my 1.4 sec. If you do, I will be VERY interested in
For those of you who have my Engine Analysis Software, some recent testing has determined that the current optimum "Trapped Compression Ratio" for .21 engines on 60% nitro(O'Donnell), with the water cooled plug head, should be 10.4:1. For the .67 engines, on 60% nitro, with water cooled glow plug head, should be
9.4:1. I ran a test this weekend on the .67 engine trying 10:1 and I lost power. This further convinced me that
9.4:1 was correct. If this doesn't mean anything to you, You NEED The Engine Analysis Software. In
addition to the program, there is an unbelievable amount of data on many peoples engines in the database.
NEXT MONTH I WILL START A SEVERAL PART TECH SERIES ON HOW TO BLUEPRINT AND SETUP AN ENGINE FROM SCRATCH USING AVAILABLE TOOLS, INCLUDING THE ENGINE ANALYSIS SOFTWARE & SPEEDMASTERS HEAD CLEARANCE GAUGE..........be sure to get The Engine Analysis Software and the tools you need the tech articles start so you will be able to understand and apply the information.
Until Next Time...........