Yeah 21.7psi...major typo.
The reason for this is you can then make ratios.
For example, 7 psi of boost can be thought of as (14.7+7)/(14.7)=~1.48 times the engine displacement.
Now times you engine size by that, for example 1275cc.
1275x1.48=1887cc. So 7psi of boost of a 1275cc is equivilant to a 1887cc.
My mistake on the incorrect (geez I was way off...???
) numbers for psi. I should have made reference to where all this was coming from. I was reading some information a friend of mine printed off the internet for deciding on pulley size, or supercharger size for desireable boost at desired rpm.
And 7psi of boost is just that, 7psi of boost. However, no boost is approxmately 14.7psi. So for the ratios to work, you need to consider the atmospheric pressure.
This makes other units of pressure more useful. 1 bar of boost, is approximately 1 atmosphere of boost which is approximately 14.7psi. So 1 bar is approximately double the engine size. a 998 with 14.7psi of boost is going to be almost a 2 litre! Awesome.
Of course in the real world it doesn't really work like that I don't think. But I've read a few books on turbocharging and supercharging and they speak about displacement of engines with boosted cars in this way.
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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T
