I am in the middle of my small engine/hydraulic pump dyno build myself, so I cannot say what works, but I can tell you what I am doing.

Here is the pump I am using...….. using the YourDyno calculator it is good for 67 hp.

https://www.surpluscenter.com/Hydraulics/Hydraulic-Pumps/Gear-Pumps/2-07-cu-in-Dynamic-GP-F25-34-P-C-Hydraulic-Pump-9-12242-B.axd

I had planned on the next size larger, but they are on backorder for at least 2 monthes…...it was good for 77 hp using the same calculator.

https://www.surpluscenter.com/Hydraulics/Hydraulic-Pumps/Gear-Pumps/2-38-cu-in-Dynamic-GP-F25-39-P-C-Hydraulic-Pump-9-12243-B.axd

Here is the 3/4" npt flow control valve I am going to run......

https://www.surpluscenter.com/Hydraulics/Hydraulic-Valves/Flow-Control-Valves/3-4-NPT-25-GPM-Prince-WFC-1200-Inline-Flow-Control-9-7960-12.axd

Jeff

I've done this using a 25cc pump I'm still having problems with controle.

When the valve is under pressure from the pump it gets very hard to turn. 

I used a 3/1 ratio stepper motor and was not even close to strong enough I've now got a 100/1 stepper to test and hope it does the job.

I would show pics of the build but I'm lost on how to post pics on here lol

Hi,

In-line flow control valves are not good to operate under pressure (with fine control). I am in the process of building a hydraulic dyno for up to 35 hp engines. I have selected a 38cc gear pump and 3/4" flow control valve. I selected a 3/4" flow control over the 1/2" because I know the 1/2" will be very tight under pressure to manually control. It should be manageable when testing the 7-8 hp engine as that should peak around 80bar pressure. It will be up around 200 bar for the 30hp engine, so I imagine hand adjustment of the flow valve shall be difficult. Because of this I have recently been looking into a proportional pressure relief valve & controller so pressure control can be done via the outputs on the yourdyno controller. 

I am several weeks away from finishing the build.......but I shall post some results once I get it going!

Hi, I have start yesteeday the test with my dyno with manual brake control. I use 70cc gear pump, and ndv 3/4 flow valve. I suggest you to use bigger valve as possible to avoid too high back pressure when valve is fully open and consistant oil resorvoir (30/40l could be ok).

In my setup it's quite simple control manually the brake, but next step is to use electronically controlled brake.

I suggest you to hold the engine with big rubber anti-vibration and prevent the backing of the motor plate with 2 end stop pads. 

I'm very intrested in this controle valve setup as I think the stepper motor way will work but not grate way to do it. 

Moog valve would be much better and should do the controle with ease keep me posted on how you get on.

Also I had trubble with the load cell vibrations kill them in no time all the engine's I'm running are 100cc 2 stroke so they vibrate alot and go to 20,000rpm 

I had a company make me a special wax sealed load cell as the other ones just broke after 10mins Somthing to think about with the pump on a torque arm with load cell.

Email me a.curtis@fugro.com and I'll send some pics of my build 

I killer vibration with engine plate with antischock, the works good. Post here the photo of your dyno. 

This was mock up 

Box full of tricks lol

Very nice setup, I see the transformer and the stepper driver, what are the other 2 devices in the box?

This is it all done 

One of them Is egt 0 to 5v converter as i needed 2 thermo temp sensors and the other one is a temp sensor to switch on the fan to cool the engine down

Very nice setup! At the moment what kind of hydraulic valve are you using?

What pid setup are you using? 

How do you control the fan? 

Posted by: Dynokart

One of them Is egt 0 to 5v converter as i needed 2 thermo temp sensors and the other one is a temp sensor to switch on the fan to cool the engine down

Very nice work, congratulations!!