[TR] zenith or su's ?

Wayne Lee wayne at motorcarriage.com
Wed Dec 2 13:49:17 MST 2009


Randall,
     I meant a Throttle Position Sensor or Rheostat onto the Piston Lift 
detector device I sent the link to.
It explains how he already had it set up:

 "The Idea was to use a stack of optical slot sensors with a vane that sits 
on the piston to drive LED's to display the position of the HIF piston at 
any point of drive. The parts cost under $30 and it worked."

As far as the A/F Meter accuracy It doesn't matter if its not like this: 
"The stoichiometric ratio is 14.7:1 when expressed as an air/fuel ratio, or 
1 when expressed as a lambda value.  A richer mixture will have a lower 
air/fuel ratio and lower lambda value. e.g. an air/fuel ratio of 12.5:1 
equals a lambda value of 0.85, and is a typical value for a naturally 
aspirated engine under full load."

All that matters is that it's somewhat static across the Rev Range and take 
Plug Readings to get a Jet adjustment. All this would do is take the Needle 
Profile out of the Tuning equation.

Wayne

--------------------------------------------------
From: "Randall" <tr3driver at ca.rr.com>
Sent: Wednesday, December 02, 2009 2:56 PM
To: "'Triumph List'" <Triumphs at autox.team.net>
Subject: Re: [TR] zenith or su's ?

>> They sell Air/Fuel mixture gauges that are cheap enough
>
> Unfortunately, the cheap ones don't tell you what you want to know.  They
> are only accurate right at Lambda = 1.0; which is neither best power nor
> best fuel economy.  "Wide band" sensors are available, but are 
> substantially
> more expensive.
>
>> If you could get a throttle position sensor or something like
>> a rheostat hooked up to a rig like this it would be very informative.
>
> But, throttle position doesn't directly translate to piston position.  You
> can infer piston position from throttle position & engine rpm (with maybe
> some correction for altitude/air density), but it varies with your
> particular setup and how are you going to calibrate it?
>
> These are exactly the same problems one faces when setting up a fuel
> injection system.  You need to know the actual airflow into the engine to
> know how much fuel it needs.
>
> -- Randall
>
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