SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: hotrod56cars on February 01, 2008, 10:19:44 AM
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I stumbled on this...
MSD - RPM pills/Ohms
3000 - 1930
3200 - 2084
3200 - 2086
6000 - 4590
6100 - 4700
6300 - 4910
6400 - 5010
6400 - 5020
6500 - 5130
6700 - 5350
6800 - 5460
6900 - 5570
7000 - 5690
7400 - 6150
Now you can make your own.
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What, you don't like spending $50 on a $.01 resistor?
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What, you don't like spending $50 on a $.01 resistor?
You could have said... What, you don't like spending $50? :D
Anyway, it didn't suggest the wattage of resistor required. Go big, it'll be cheap.
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What, you don't like spending $50 on a $.01 resistor?
I dont get it ???
2sav
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The MSD pills are resistors. Resistors in quanitity are about 10 to the penny. MSD charges ~$50 for a set of pills, which are pretty 1/4 watt resistors.
For the power requirement, that is easy enough -
E=IR
or in this case use a little algabra -
E/R=I
so
12Volts/1930 OHMS = .0062 Amps
Amps * Volts = Watts
.0062 * 12 V = .074 Watts
So in theory, an 1/8th Watt resistor could work (.125W) - but you usually (at least) double for guardbanding.
Keep in mind the 1930 ohm resistor would draw the most current - the higher RPM pills would draw even less.
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I doubt that you'll find that exact value (1930) in a resistor. You can go 1.8K or 2K and keep in mind there is a +/- 5% shift possible.
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The MSD pills are resistors. Resistors in quanitity are about 10 to the penny. MSD charges ~$50 for a set of pills, which are pretty 1/4 watt resistors.
For the power requirement, that is easy enough -
E=IR
or in this case use a little algabra -
E/R=I
so
12Volts/1930 OHMS = .0062 Amps
Amps * Volts = Watts
.0062 * 12 V = .074 Watts
So in theory, an 1/8th Watt resistor could work (.125W) - but you usually (at least) double for guardbanding.
Keep in mind the 1930 ohm resistor would draw the most current - the higher RPM pills would draw even less.
Got it ;)
Thanks 2sav
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Now that we know the resistance ranges, it wouldn't be had to make an adjustable pill, like the one MSD offers.
.....wow just typed in a google search to find a pic of the pill MSD offers and acidently found a how to on making one, enjoy http://www.corral.net/tech/powerplant/arm/
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I doubt that you'll find that exact value (1930) in a resistor. You can go 1.8K or 2K and keep in mind there is a +/- 5% shift possible.
Good point. You can get a 1% resistor, but those that aren't EE's or Physicist don't realize - everything in electronics is an approximate. 1930 ohms is the calculated value, not nessasarly the exact one. Close enough is a way of life.
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Good point. You can get a 1% resistor, but those that aren't EE's or Physicist don't realize - everything in electronics is an approximate. 1930 ohms is the calculated value, not nessasarly the exact one. Close enough is a way of life.
I figure a 2K 1/4 watt would do the job nicely. Better to be a little high than low and burn out something.
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only if you want the rev limiter to come on at 3K...otherwise you need a larger value...
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so....you could just wire in a variable resister and mark your favorite limts on the dial.
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only if you want the rev limiter to come on at 3K...otherwise you need a larger value...
I was just using the 2K as an example. Meaning I was rounding up from the 1930 ohm. Hell you can buy these resistors from Jameco . Com for around a penny a piece. Problem is you have to buy 100 at a time. Group buy??? LOL :D :D
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I was just using the 2K as an example. Meaning I was rounding up from the 1930 ohm. Hell you can buy these resistors from Jameco . Com for around a penny a piece. Problem is you have to buy 100 at a time. Group buy??? LOL :D :D
How many of us would it take to come up w/ a buck?
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How many of us would it take to come up w/ a buck?
Hmmm, From what I've read maybe 30 or 40 of us. LMAO!!! :D :D :D :D