Re: [6pack] TR5 and TR250

[Mark J Bradakis <mark@bradakis.com>]

Ashford Little wrote:
> Hmm, which brings up another question to the uninformed (me). How did 
> the PI system meter fuel? Or why was it the higher altitudes caused 
> issues? Obviously the air gets thinner, and it didn't compensate, so 
> what did the PI lack that the carbs had to compensate for altitude?
It was simple mechanical injection - the same dose of fuel regardless of 
barometric
pressure.  So as the air got thinner, with less and less oxygen, the air 
fuel ratio gets
screwed up.

The constant depression type carbs like SUs and Strombergs would not 
raise the
pistons as much in thinner air, which limited the amount of fuel getting 
mixed in,
so they dealt with altitude changes more readily than simple PI.

mjb.

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