Kartorbust
Inmate #627
Car alternators use about 2-3hp or so.
I decided I wanted a dyno
- Thread starter Flyinhillbilly
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bob58o
SuckSqueezeBangBlow
Sure so 12V at 100 amps is 1200W or 1.6 HP. 50% efficiency gets up to about 3HP.
6500 Watts is close to 9HP. Might work?
Kartorbust
Inmate #627
Generac 6500w generator uses a 389cc engine. A similar sized Predator generator uses a 420cc...either way they use twice the power of a 6.5, so it may work. But I thought generators used a tapered shaft?
it's worse than that..
a generator might serve as a working load.. but only if power is actually drawn from it.
otherwise it's more or less dead weight without much 'load' to the engine at all..
then, how accurately can you measure the power that's drawn and the efficiency of the generator to produce it and thus the power the engine has to provide?
That's a much much bigger can of worms than measuring just the torque and time IMHO.
you could in theory short the generator of course to basically create the "ultimate" powerdraw.. but that'd abuse the generators internals (coils heating up affecting internal resistance and efficiency) and all premade assumptions are practically out the window before the engine even revved to it's peak power.
So that isn't as great of an idea either, especially since efficiency (the most important part of all following calculation) is dependend on load and speed and thus will vary for each and every different data point.
just sayin'
'sid
a generator might serve as a working load.. but only if power is actually drawn from it.
otherwise it's more or less dead weight without much 'load' to the engine at all..
then, how accurately can you measure the power that's drawn and the efficiency of the generator to produce it and thus the power the engine has to provide?
That's a much much bigger can of worms than measuring just the torque and time IMHO.
you could in theory short the generator of course to basically create the "ultimate" powerdraw.. but that'd abuse the generators internals (coils heating up affecting internal resistance and efficiency) and all premade assumptions are practically out the window before the engine even revved to it's peak power.
So that isn't as great of an idea either, especially since efficiency (the most important part of all following calculation) is dependend on load and speed and thus will vary for each and every different data point.
just sayin'
'sid
Kartorbust
Inmate #627
So basically, it wouldn't offer a steady controlled baseline since it would vary too much and cannot be measured easily?
even with a very steady load on the generator it's efficiency would vary as the engine rev's up or the generators temperature increases...
by how much I can't tell... depends on the quality
I'd say too much, yes;
but without testing I cannot tell for sure of course.
The thing that makes me want to toss the generator idea out the window is,
in order to calibrate it properly (should be done per load and engine seperately)
you will need to measure the engine's power out first in order to properly assign an efficiency ratio to any given speed/watt/temp of the generator.
And since that's what you want to find out... where's the point in adding the generator afterwards?
'sid
by how much I can't tell... depends on the quality
I'd say too much, yes;
but without testing I cannot tell for sure of course.
The thing that makes me want to toss the generator idea out the window is,
in order to calibrate it properly (should be done per load and engine seperately)
you will need to measure the engine's power out first in order to properly assign an efficiency ratio to any given speed/watt/temp of the generator.
And since that's what you want to find out... where's the point in adding the generator afterwards?
'sid
Flyinhillbilly
The great cornholio
I read that an AC motor can provide a controlled load by applying DC current to the motor.
mckutzy
Well-known member
Depending on the motor.....it'll most likely catch on fire.
A true AC motor would only heat up.. to eventually catch fire (or just melt down)
a Universal motor would act just like a DC motor ...
Without knowing the generators efficiency ratio at that time you will not be able to determine the engines power out.
To know the efficiency ratio you will need to know the engine's power out first.
And since that's what you're after with a dyno.. I don't really see the point.
Frankly as much as I love all the electronic stuff, I think this is a task for a heavy flywheel and a tach with timer.
since in the end all you want to know is the acceleration of a mass (which gives you the Force applied) and the rotational speed to derive the Power from that force..
it's quick, it's easy
and all you want to / need to take care of efficiency wise is a good set of bearings to lower your error level below 5%
(opposed to ~20% for any mechnical/electrical conversion)
just saying.. just saying...
(personally I like the oil pump brake better than an electric contraption for this task)
'sid
a Universal motor would act just like a DC motor ...
Without knowing the generators efficiency ratio at that time you will not be able to determine the engines power out.
To know the efficiency ratio you will need to know the engine's power out first.
And since that's what you're after with a dyno.. I don't really see the point.
Frankly as much as I love all the electronic stuff, I think this is a task for a heavy flywheel and a tach with timer.
since in the end all you want to know is the acceleration of a mass (which gives you the Force applied) and the rotational speed to derive the Power from that force..
it's quick, it's easy
and all you want to / need to take care of efficiency wise is a good set of bearings to lower your error level below 5%
(opposed to ~20% for any mechnical/electrical conversion)
just saying.. just saying...
(personally I like the oil pump brake better than an electric contraption for this task)
'sid
Flyinhillbilly
The great cornholio
That's exactly why I went with the oil pump. I should be able to hold it at a steady rpm at wot for as long as I like.
mckutzy
Well-known member
So any news on the HB dyno... Any new work to show off for us.
Flyinhillbilly
The great cornholio
Not lately. I'll get back on it after Christmas.
Kartorbust
Inmate #627
We're getting restless on this whole thing to either put it to rest or to know for sure.
outcrydrummer
KART ART
Ok It's practically 2017 now........
$&*! or get off the pot haha
$&*! or get off the pot haha
supermanotorious
Winchmaster 5000
you see this site?
http://www.dynomitedynamometer.com/dyno-dynamometer-article.htm
---------- Post added at 09:16 PM ---------- Previous post was at 09:15 PM ----------
I need a dyno, or at least one I can rent in the form of taking my engine there and paying a fee, I need it bad
http://www.dynomitedynamometer.com/dyno-dynamometer-article.htm
---------- Post added at 09:16 PM ---------- Previous post was at 09:15 PM ----------
I need a dyno, or at least one I can rent in the form of taking my engine there and paying a fee, I need it bad
Flyinhillbilly
The great cornholio
I have a lot going on right now with the situation regarding my daughter and grandson. This will have to wait. I look at it everyday and think about it, but my family comes first. When it gets done, it gets done.
supermanotorious
Winchmaster 5000
yeah man, family first, good luck
Flyinhillbilly
The great cornholio
I picked up the metal for the main frame today. I'm hoping to get my trans put in my black truck within the next couple of days and then it will be back on the dyno at maximum effort since our local kart dirt track opens in two weeks and I need the dyno to tune my engine.
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mckutzy
Well-known member
Thats pretty cool looking... cant wait to see this thing work.....
Do you have a stock Rotaderp to use as a base line tester?..
Do you have a stock Rotaderp to use as a base line tester?..
Flyinhillbilly
The great cornholio
Not anymore, lol. I don't really care how accurate it is as long as it'll give me numbers that I can compare to tell which adjustments make gains.
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