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  #101  
Old 04-16-2017, 08:06 PM
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I like it. Is ol smokey stockish? Would be cool to get a comparison between a stock motor and one with a cam, ect. Or see how much gain an air filter adapter ,ect gives.
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  #102  
Old 04-16-2017, 08:07 PM
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That's what the idea was behind this dyno build.
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  #103  
Old 04-16-2017, 08:09 PM
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It's a blueprinted AKRA bottom end with a real good 64cc (edit: it's a 14 cc head. I've been working on my hot rods again and got my numbers mixed up) big valve head on it. I made pulls with it until the header broke off and it was very repeatable. When the header fell off it lost about 3/4 ft/lb of torque.
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  #104  
Old 04-16-2017, 09:12 PM
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I can't remember but was it an in/lb wrench or ft/lb? With the display showing triple digits my thought was either it's reading with a decimal on ft/lb or was all in in/lb.
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  #105  
Old 04-16-2017, 09:14 PM
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Ft/lb. it has a decimal. I could hold it steady at about 10.4 before the header fell off. I could close the valve fast and shock it higher because of the inertia, but I think 10.4 was my best steady number.
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  #106  
Old 04-16-2017, 09:16 PM
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Can't wait to see more comparisons.
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  #107  
Old 04-16-2017, 09:23 PM
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My neighbor just built a zero deck predator with .0205 quench area with a rtc-8 head milled to 16cc, BSP-2 cam, arc +.020 rod, arc flywheel, and a home bored carb at 32 degrees of timing on 100 low lead. I'd sure be interested to see what it makes, but I don't know if he'd be willing to run it on there or not. I was making pulls with mine a couple of weeks ago and he said "well, that's about as hard as you can be on an engine" so I doubt he'll be on board.
I'll get the header situation worked out and do some tests with timing adjustments and then move on to nitro (percentage of course) vs methanol.
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Last edited by Flyinhillbilly; 04-16-2017 at 09:24 PM. Reason: Hukt on foniks dint werk fer mee
  #108  
Old 04-16-2017, 09:28 PM
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Tell your neighbor to Buck up. Lol.
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  #109  
Old 07-08-2017, 04:18 AM
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Quote:
Originally Posted by mckutzy View Post
(thinking out loud......)
I guess with that guy... there isnt a need for a known length of bar to be used in the calculations... the torque applied, is what is applied.......
Attach a short ratchet extention to the input of the torque box.... Have a piece of pipe welded with a cheap matching socket to the output for the torque bar.....
Why wouldn't you need to know the length of the bar? A bar 4' long is going to read differently than a bar 1' long due to leverage. You can always say the load cell reads 20 lbs, but at an unknown length the reading is meaningless.
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  #110  
Old 07-08-2017, 07:04 AM
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Because there is no bar. That one measures the torque via twist and a load cell.
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  #111  
Old 07-08-2017, 10:27 AM
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I think he was referring to the other video posted, where the guys had a long bar and a load cell. What you've got probably is easier to use just for a quick check.
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Old 07-08-2017, 11:40 AM
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As I understand the bar need to be a certain length to determine the torque precisely.
An example..
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  #113  
Old 07-08-2017, 05:31 PM
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You could, in theory, do this with no load cell at all. With the right transducers and algorithms, you could derive all your numbers from the flow and pressure being created by the pump, with the known constants of pump displacement and fluid viscosity.
  #114  
Old 07-09-2017, 07:56 AM
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in theory... yes.

it's far from practical though, just the changes in viscosity alone will ruin the measurement.
And the temperature of the fluid WILL change (thanks to the pressure)
Of course one could generate a lookup table with viscosity at temperature,
but even that has to be an interpolated value at some point which again will be inaccurate.

But then another inaccuracy kicks in (the pulsing behaviour of the pump)
IDK about the number of veins in FHB's pump but chances are the pulses are significant enough to be picked up during measurement.
And we're back to interpolation ...

giant flywheels are a pain to run (from a security standpoint) but in the end, due to the inertia they provide (evening out pulsing and other side effects)
and the more massive they are, the more you can ignore even their bearings and whatnot.
In the end you do not only end up with the much 'simpler' setup, you also have the easiest possible math to calculate the torque provided.

But truth is.. nobody want's to have a giant weight spinning in his workshop, for sure not at the rpms we talk about here...
if it catches on your clothes you'll break some of your bones, your skull even..
if it breaks free of it's fixture it'll create some serious mayhem (and again breaks bones if you get too close)

Sooo fluid pressure measurements is the way to go for DIY... IMHO...
and a load cell does make sense to cancel out most of that guessing and interpolation,
measuring "real" physical torque the old fashioned way (torque bar length and force applied)

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  #115  
Old 07-09-2017, 01:24 PM
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I'm not arguing the fact that a load cell simplifies things drastically. Just saying it could be done.

You'd need transducers for pressure, flow, and fluid temperature at the orifice, then the viscosity temperature curves for the fluid, and engine RPM. And some pretty serious real-time calculation capability, which would pretty much mean making your own interface module and writing some rather extensive programming.
  #116  
Old 07-09-2017, 06:26 PM
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Quote:
Originally Posted by mckutzy View Post
As I understand the bar need to be a certain length to determine the torque precisely.
An example..
Well yes. 10 lbs of force applied at the end of a 12" bar would be 10 lb-ft, but 10 lbs of force applied at the end of a 24" bar would be 20 lb-ft. My point was just that if you don't know the length of the bar, then you can't calculate the torque. But with the gadget he's using, all of that is irrelevant.
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