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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-762548@logan.com>
Subject: Re: [FlyRotary] injector life and reliability
Date: Mon, 28 Feb 2005 12:19:23 -0500
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Bernie,

Your injectors should be fine, the drivers won't hurt the injectors -
however, the injectors can hurt the drivers.  Because a saturation driver is
expecting more resistance (less current requirement) from a saturated type
injector of around 12-16 ohms.  If you stick a Peak and Hold (around 2.5
ohms) in a circuit designed for saturation injectors,  they (Peak and hold)
will draw considerably more current and may exceed the design limit of the
saturation  injector driver thereby damaging it. On the other hand, if the
designer "over-designed" the driver it may cause no damage at all.

If you put a saturation injectors in a circuit designed for Peak and Hold,
you will not damage the drivers because the saturation injector will never
exceed the current draw the P&H circuit was designed for - but, you may not
get very good injection especially at the lower rpms.

So if anything could have been damaged - it would have been the EC2, but
Tracy has done a good job of providing a bit of margin there as well.  I
don't doubt you had a bad injectors ( I have had several - they are just
getting old), but I doubt it was caused by the lack of resistors.

Tracy, of course, will correct any incorrect reference to his design work
{:>)

Ed A


----- Original Message -----
From: <jbker@juno.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, February 28, 2005 8:30 AM
Subject: [FlyRotary] injector life and reliability


>
> Here is a comment from the TWM site that Rusty suggested:
>  Most peak and hold drivers will drive both high and low resistance
injectors but, under no circumstances, should peak and hold injectors be
driven with saturated drivers.
>
> I mistakenly ran short time without 5 ohm ballaster resistor in line with
P&H injectors. Wonder if I killed their life? My used injectors that came
with Bruce's package were cleaned and flowed before mistaken running. One
died shortly and I replaced with a rebuilt auto store one. Now I believe
another was has an anomally. Yuk!
>
> Should I trade them all out before I fly?
>
> Makes me glad that I put the injector disable switches in and have 2 per
rotor.
>
> Bernie
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>