Speed graphs for Spitfire and Hurricane

[Buchon]

Originally Posted by camber

Hi Buchon,

I agree with you but with some terminology issues. The Brits are not using the term boost as something that is turned on and off. "Boost" is just manifold pressure with atmospheric pressure subtracted, so + 6 1/4 psi boost is 21 1/4 psi manifold pressure. I assume boost was used as a term as the supercharger is boosting manifold pressure above atmospheric. Maximum manifold pressure is set by the boost controller with a cutout that can be modified to give a higher manifold pressure (+12psi) on command.

So even with the economic weak mixture setting, there is still "boost" (+2 1/4 psi). The problem is as you say, that the boost setup is wrong. From the plots to me (thanks Klem et al.) it appears that post patch the boost will read +6 1/4 psi, but give performance approximately as for +2 1/4 psi with weak mixture.

camber

Ohh, I see thanks