Track Tac

Prototype Hydraulic Dyno

Me and my brother have one, works best for us to have one operate and the other write down numbers as we take reading every 500 rpm to compare. If I am by myself I try to video it and look back at the numbers when I am done. It can be all computerized if you want to spend the money.
 
Thanks for the reply. Do you happen to know the GPM rating on the pump? I guess what I'm asking is what formula do you use to find HP OR torque
 
We run a clutch on ours. Makes it easier to start the motor and then allow it to cool a bit prior to shut down. It has no adverse effect on the results. We always heat the oil to 120 deg F before a dyno pull. Oil temp has a huge effect on results
 
Bmoll10x said:
We run a clutch on ours. Makes it easier to start the motor and then allow it to cool a bit prior to shut down. It has no adverse effect on the results. We always heat the oil to 120 deg F before a dyno pull. Oil temp has a huge effect on results
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temperature has no effect. this might start a big argument but temperature has very little effect on the power needed to turn a positive displacement pump at a certain speed and pressure.
 
I have self built hydraulic dyno designed from the Prototype. I run up to my target rpm, look at the pressure, Let off the throttle, write it down, then on to the next check point. The oil temp does make a difference. I test between 90 to 120 degrees.
 
Well 40 years in the pump biz and 10 years on this dyno tells me viscosity makes a tremendous difference and the viscosity of oil varies with temperature. If you truly subscribe to consistency in your pulls always start from the same parameters or be able to adjust for the differences and that includes atmospheric conditions as well.
 
i imagine your pump has a lot of blow by then. Thinner fluid blows by the gears (assuming this is a gear pump) easier. i have only dealt with pumps at work with very minimal if any at all. we physically measure flow after the pump though.

if you are noticing differences in output based on temperature than any calculations based on the pump being a PD pump and its flow is linear with rpm are invalid. to truely get power you would need to measure flow. OR you could put the pump on a bearing support and do a reaction are with a load cell. that would be accurate.
 
I know I sound ignorant but I think I'm missing the point.. on my dyno I have a tach, flow meter and a pressure gauge. Do you use the the GPM at the flow meter or do I need to know the GPM on the pump? I'm probably just overthinking it. Someone walk me through this step by step.. it'll make me feel better. Thanks guys for your help!
 
Yes you use the flow meter that reads gpm. You start a Dyno pull by turning on the toggle switch for the tank heater warm the oil to 100? then turn off the heater. Start engine with the load valve full open. Bring rpm up a little then start to close load valve until your full throttle. Adjust load valve to bring rpm down to your start point I use 3000 rpm. Write down your rpm psi gpm then open valve a little till your at next rpm point and repeat. You can use the formula above to do calculations. If you don't need actual HP numbers most people just look at rpm and psi a engine that makes more psi makes more power.
 
One thing I generally do because I have had trouble in the winter and times getting the oil temp up is have a motor to use as a constant. If I am going to make several runs I take a motor I know and run it first as a base line and some times run it last too and make sure the base line is consistent. I use a direct drive which is an old clutch welded up. I also have a spreadsheet I put the numbers into that helps graph the curve and stuff.
 
The flow meter on our Prototype is such poor quality we dont use it. Instead we calculate flow on a spread sheet based on rpm. We then video all of our dyno runs on a cell phone so we can record pressure/ RPM/ Cylinder head temp but flipping through frame by frame I found a nice web site that shows how to measure your gear pump so you can plug those values into a formula. We record data in 100 rpm increments but you can break in down anyway that suits your needs. Try: unwinhydraulic.co.uk (not a link just a site address)
 
Bmoll10x said:
The flow meter on our Prototype is such poor quality we dont use it. Instead we calculate flow on a spread sheet based on rpm. We then video all of our dyno runs on a cell phone so we can record pressure/ RPM/ Cylinder head temp but flipping through frame by frame I found a nice web site that shows how to measure your gear pump so you can plug those values into a formula. We record data in 100 rpm increments but you can break in down anyway that suits your needs. Try: unwinhydraulic.co.uk (not a link just a site address)
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the way you are doing it then 100% temperature matters. i didn't realize you didn't have a flow meter. that was my mistake.
 
use A loading scale and do away with the gauge and meter(pump is mounted to swivel with A 1ft arm to push or pull on the scale)? I'm going to try this out and see how it works for small weedeater (comer) engines. Just want to test carbs and such with it.Ive seen A few do it on here.
 
duke said:
One thing I generally do because I have had trouble in the winter and times getting the oil temp up is have a motor to use as a constant. If I am going to make several runs I take a motor I know and run it first as a base line and some times run it last too and make sure the base line is consistent. I use a direct drive which is an old clutch welded up. I also have a spreadsheet I put the numbers into that helps graph the curve and stuff.
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I know this is a very old thread, but is there any way you'd be willing to share that spreadsheet? I just got one of these dynos and would really like to be able to graph my output. Thank you.
 
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