I should add that I am open to other suggestions to control the valve. (such as a servo)

Jeff

How about one of these?

1712oz-in Closed Loop Stepper Motor NEMA34 12NM Hybrid Servo Driver 2HSS86H Kit

https://www.ebay.com/itm/1712oz-in-Closed-Loop-Stepper-Motor-NEMA34-12NM-Hybrid-Servo-Driver-2HSS86H-Kits/121787201520?epid=2176446433&hash=item1c5b1537f0:g:Hz8AAOSw165c56FS

Why closed loop feed back ? It is a big torque steppermotor nema34 unit.

Yourdyno has no provisions for position feedback? As far as I'm  aware!

What is your plan of attack ? Direct couple drive to a stepper motor ? Or some form of reduction gearing ?

I am asking because I do not know the answer.

I can direct couple or belt drive as needed. Belt drive would allow for corrections in ratio if needed.

I do have a Nema 34 stepper from another project that I will try first since it is not being used. ( I forgot I had it till after I posted )(Old Age Sucks)

The driver I have is a DM2282 and can be set to 200 pulse per rev. , so should work O.K.

Jeff

Find a members hydraulic pump engine dyno build his name is " eric91 " he did a nice job on his dyno build and document it well on this form.

Er0ic91 would possibly provide you some good advice.

Hope eric91 reads your post and can provide a link to his.  

Read theses threads if you haven't already, you will get some helpful information. If not just keep asking the question.

Support for Stepper motors released  

https://yourdyno.com/community/questions-and-answers-questions-and-answers/support-for-stepper-motors-released/

https://yourdyno.com/community/questions-and-answers-questions-and-answers/nema-34-stepper-motor/

QUOTE eric91, "Hi, in my hydraulic dyno I use nema 23hs45-4204s, with high torque (stepper dimensions is 56mm*56mm*112mm), you can buy it in stepperonline web market, it is very cheap and work very well with brake sweep brake control mode. 

I use st-m5045 microstep driver set full current. I suggest you to dont use smaller driver. "

Hi Man, I have built dyno for kart engine with hydraulic gear pump.

I suggest you to use bigger displacement pump, you can work with lower pressure. I usually test 125kz engine and I have 70cc gear pump with vrb 1" Flow valve controlled by nema 23 stepper engine.

The required torque of stepper motor depends by the transmission ratio between stepper and valve. In my setup I have a reduced ratio, so the valve is quite slow but is good for sweep test.

Finally I suggest you to use big oil reservoir (about 30/40lt) and at least one oil filter in return or intake line (to avoid cavitation I prefer in return line, after Flow valve). 

Mach

Thank you for the info !!

Jeff

Eric

What king of horsepower are you making and at what RPM ?

I will be testing 15-25 hp mostly at 9000 max.

Using 12 gallon (45 liter) reservoir.

I have two flow control valves available.  A 3/4" and a 1". The 3/4" has 5 turns open to close. The 1" has 8 turns open to close. I assume only about 3 turns are actually used?

Jeff

I suggest you to use 1" valve. Bigger the valve, less the power absorbed when it is fully open. I test engine like tm kz10c, 40hp at 13800 rpm. What kind of engine are you using? I hope no 4 stroke 😂

Yeah, 4-stroke garden tiller engines...... Based off of the Honda GX200.

The 1" valve has a Gilmer belt toothed sprocket on it already.

I will set it up as 1-1, but build it so I can change ratio if needed.

Happy Racing!!

Jeff

Here you can see my Flow valve control assembly (the stepper motor is not the actual i'm using). The Flow valve under pressure is quite strenght to close, so I suggest you to demoltiplicate the transmission ratio. 

Attached is a photo of my 1" valve. ( it is 139mm long, 50mm square)

So you are turning your valve slower?

Jeff

If you do not use pid control, it is not necessary have very fast valve. 

I have tried a lot to work with pid control system but I found that is not good for this type of dyno. Sweep brake works good with hydraulic dyno and not require very fast valve control.