First the plug only fires once every 720 degrees thats right every two
revolutions, and on normal 87 octane unleaded gas upon start up the engine
is firing at 6 to 10 degrees BTDC, most gas engines pull the maximum
advance between 2200 to 2800 RPM at about 35 degrees BTDC, The whole idea
is to get as much advance as possible without detonation (pre ignition).
NASCAR engines run about 60 degrees timing hard set, on 100 octane gas
without additives.
90 degrees total timing would suggest that the hydrogen mixture is about
130 octane but burns slower than gasoline. Thus they're able to get that
much timing without pinging.
The Engine in Mercedes are aluminum block with cast iron cylinders or
sleeves. The 4.1 litre Cadillac V8 is basically the same style aluminum
block cast iron sleeves.
Thats all for now.
Terry Martin
catfish@alltel.net
P.S. Sorry to all thoses on the list that actually know about internal
combustion engines. I'm just trying to get the facts straight to the ones
less knowlegdable.