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Re: determining correct ignition timing

To: Malcolm Cox <malcox@napanet.net>
Subject: Re: determining correct ignition timing
From: Brian Evans <brian@uunet.ca>
Date: Wed, 9 Sep 1998 08:21:15 -0400
In my experience, since we often must use unleaded race gas here in Canada,
I don't like unleaded gas.  It will definitely change the way your engine
runs, usually for the worse, it makes your eyes water, if exposed to
sunlight it will precipitate out solids in a very short period of time, and
according to urban legend, it doesn't actually meet the legal definition of
gas!  I treat it as a hazardous substance, and use it as little as possible.
I've never seen uleaded gas of high (110 plus) octane outside of Canada.

The engine dyno (as opposed to chassis dyno) at BVR Cars is a Superflow with
mass flow sensors for air and gas flow, and calculates air fuel ratios based
on actual input to the engine.  If you dyno and set up your engine for the
brand of unleaded that you'll use, then you'll probably be ok.  We've seen
engines burn pistons when changing from normal race gas to unleaded without
re-calibration of fuel and timing.

brian



At 01:31 AM 9/9/98 -0400, you wrote:
>"A good quality Air / fuel mixture meter will also help determine the
>best air fuel ratio and timing."
>
>That raises a good point, the (chassis) dyno shop I am about to try,
>won't hook up his O2 sensor, since I use 110 octane leaded gas and his
>O2 sensor costs $900 to replace and leaded gas "poisons" the catalytic
>action of the sensor metals.  Its possible that I could use less than
>110 octane, though at 12:1 compression, it seems unwise to experiment.
>
>Seems logical to should switch valve seats for unleaded gas next time I
>get a major cyclinder job overhaul, then I can use an O2 sensor and dial
>my mixture in on the dyno.  
>
>Anyone care to comment on octane availability of unleaded gas at track,
>or any other unleaded snags I dont know about.
>


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