> There are two types of dynos one is an eddy
> current and I forget the name of
> the other
I beleive the other type is referred to as a "water
brake" dyno, which uses water pressure to load up the
rollers...
They're not used much anymore I don't think. Too
expensive and complex and heavy and failure-prone.
One of the big advantages of the new breed of eddy
current dynos is that it's far easier to test dynamic
outputs with them. That is, with the old water brake
dynos, the standard practice was to measure torque at
a static RPM - say 1500 RPM, then again at 2000 RPM,
then again at 2500, etc. Then you'd take those
figures and mathematically calculate the horsepower
(torque x RPM/5252) and chart the output. It all
seems well and good, except that's not how engines
operate in the real world. An engine can make awesome
static torque, but if it doesn't rev freely and/or
quickly, it feels doggy on the road. Unless you're
interested in towing a yacht with your MGB, static
torque figures are virtually meaningless.
So one of the big advantages to the
digitally-controlled eddy current units is that they
can test the engine as it rapidly accelerates from
say, 1500-6000 RPM. It's a dynamic test, with the
engine accelerating through the process. It gives
MUCH more useable, accurate results and helps you tune
the car for actual operating conditions.
=====
Paul Misencik
1971 MGB Vintage Race Project
Huntersville, NC USA
www.sopwithracing.com
Learn the truth at www.misleader.org
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