Dear Reader
I’d like to announce a new resource on my web site
http://www.leylandaustralia.com.au. This resource performs vehicle performance calculations using the methods described in detail in my book The BMC Engineering Companion. Now, any of you who have purchased this book will know that it is heavy going on the mathematics. To make things more accessible, I’ve programmed the equations for vehicle performance into an App and all you have to do is to enter your input data, press a button and some interesting results are displayed.
I have set up two sample analyses for YDO5 Morris Mini 1100, and a YDO26 Leyland P76 V8 4 speed manual. It is interesting to compare the gear and performance characteristics for both cars. You can see this yourself if you select each on using the drop down list of “profiles” and performing the calculations by pressing the button, or you can just see from the pictures below.
For your car, if you are interested in these types of calculations, there is a facility to upload the required input information and perform the calculations. There is a document link on the App which gives details of what is required.
Why would you want to do this? Because using these calculations, you can predict changes to your vehicle’s performance as a result of making changes to your vehicle (such as changing the wheels from steel to alloy, reducing the frontal area, altering the torque curve) without expensive dyno tuning and road testing. Of course a practical measurement is very desirable, but a calculation such as this goes a long way to optimising things before you go on to the track or dyno.
I’ve compared the results of the calculations for the two cars mentioned above with those from Wheels road tests of the period. Given the many variables involved, the agreement between the calculations and Wheels’ figures is pretty good.
Once you are familiar with these graphs, there is a lot to learn about how gear ratios are chosen the way they are.
On a historical note, these types of analyses were taught to us young hopeful engineering students in the mid 1970s by Ray Habgood who by day was Manager of Vehicle Engineering at Moorebank, and by night, was a part time TAFE teacher at Ultimo. Habgood is still around, although now retired of course.
So readers, I hope you enjoy this new facility and that this adds to your appreciation of your BMC vehicle.
Sincerely,
Tony Cripps
