> LEAKDOWN TESTER PLANS
>
> Here it is as it appeared in the September, 1990, RIGHT LINE.
> All rights for reproduction remain with Steve Soar.
>
> -------------------------------
<Major snippage>
>
> Caveat: Professional leakdown testers read out in "%" leakage,
> converted from psi. There must be a calibration factor used based
on
> the amount of pressure drop for a given orifice size but I have
been
> unable to determine what the math for this might be. Any Fluids
> types listening out there?
I'm certainly not a "fluid-type" but I DID disect a "real" leakdown
tester ("Auto Test Inc., Bellville, Wisc") and discovered that the
leak percent guage is simply a regular gauge reading psi pressure
with an extra dial face "surround" calibrated in inverse
relationship to the psi gauge readings. For instance, this gauge
happened to read to a maximum of 60# psi and that pressure was "leak"
calibrated as 0 % leak, 54# psi was 10% "leak", 30# psi was 50%
"leak" , 0# psi was 100% leak and so on.
In experimenting with this tester, I also discovered that the 60#
inlet pressure and gauge calibration may be clever in spite of the
"simple math" appeal of the 100 pound gauge and calibration . . .
It'll be hard to control rotation of the engine at much over 60 psi.
I would also invite prospective builders to consider using a simple
1/4" npt pipe tee from the hardware store rather than all that
drilling and tapping of a block of aluminum. The #60 drill size
orifice can be placed in the solder, braze or epoxy-plugged inlet
coupler to gain the same effect.
Cheers,
Tony
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