"Gord Beaman" wrote in message
...
(Hildegrin) wrote:

Higher octane allows you to use higher boost pressures. It doesn't
create more boost, it just allows you to "overboost" the engine at
lower alts. Thus at rated alt and above, increased octane had no real
effect (it may have reduced power by a tiny amount, because the fuel
has a lower calorifc value, I think).


Yes, this is exactly right...some think that the higher the
Octane Rating the more "powerful" the fuel when actually high
Octane fuel is less 'powerful' that low Octane fuel. You get the
extra power because you can increase the Manifold Air Pressure
(boost) without causing DETONATION. This is the whole reason
behind high octane useage. Heavy detonation will trash an engine
in short order so you must prevent it.

Lead tetra ethyl is not short of energy, Gord.

Water injection also results in higher engine power in a slightly
different manner.

No. Water injection only prevents the connecting rod bearings from being
destroyed by detonation. Much the same as an EGR valve on automobile
engines injecting exast gas into the manifold.