the trigger pulse repetition maximum of about 250ms is a build in
feature in the MSD unit. M&W does not have it, that is why it works.
It certainly has nothing to do with battery voltage.
Richard Sohn
I don't understand what you mean about this. "pulse repetition
maximum of about 250ms"
Did you mean 2.50 ms??
If you did I don't think that is right because the rotary racers are
turning up to 11,500 before shifting with MSD. systems. Lynn Hanover
raced his rotary for years at 9300 RPM
133.3 revs per minute. 2.22 revs per second at 8000 RPM. There are a
thousand ms in each second. That is one rev in 2,222. ms. That is a
long time in a micro computer.
Check my arithmetic.
This is with a 3:1 gear box. Most aircraft people won't turn the
engine that fast.
The MSD 6 is a real old design. Great improvements in switching
transistors have been made in the last few years so it is now
possible to build a system with better specs. Better even than the
M&W. Check out the Mallory CD.
Here is a 3 rotor on the RB dyno with six MSD's
For years it was the standard ignition for rotaries.
Paul Lamar
That arithmetic would get you an F-. 8K rpm is 133 rps or 1 rev in
7.5mS
On Sunday, August 20, 2017 3:55 PM, paul lamar
<
rotaryeng@earthlink.net wrote:
Robert LeClercq
Paul,
Yes I see where I made the mistake. 8000 per minute is 133.rev per
second and then divide that into 1000. = 7.51 ms
Thanks Robert.
Paul Lamar
Ok, I hope this is a little clearer.
On the MSD the first trigger pulse never fires, it is always firing from
the second pulse on. If the second pulse does not occur less than 250ms
after the first pulse, that pulse is considered the first one and does
not fire. Does that make it clear?
Btw I am running a MSD on my test stand with a car battery and a 4ft
piece of 4awg wire. And the engine is turning over some what faster because
of some more loose interiors.
Richard Sohn
"loose interiors." you mean leaking seals?
Paul Lamar
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