Aircooled VW South Africa

Cool little tool, I wonder how accurate it is.

http://www.partsemporium.co.uk/rpm&speedcalculator.htm

If you want to calculate for a split bus, don't forget to take your reduction gearbox ratios into account. This calc doesn't.

I entered the data as per the workshop manual for my 59 30hp bus and it comes up with +- the same answer.