Q&A Forum
Hello guys, looking to see if anyone has made a hydraulic pump based dyno for motorcycles on here. Primarily looking for a chassis setup with a small roller(s) that a single person can operate. 8hp-60hp if possible. Also looking for any input on parts and setup if someone has not built this exact type of unit.
I researched and designed an inertial dyno for use with DataMite so I got familiar with inertial dyno properties so I will admit I am new to this hydraulic brake dyno setup. But I think it would be better for me based on cost, simplicity and size.
With my understanding of how it works, I will need a PWM adjustable setup to operate the flow valve and the "run" will start by taking the engine to top rpm and closing flow valve until the engine is slowed down to low RPMs.
Is there any way to do a reverse run where your pull is from low RPM to high, reducing the time at redline? Possibly set the flow valve to offer a set resistance and do a traditional pull? Or is it possible to set an RPM value to trigger the PWM curve to close the flow valve the second the engine hits redline?
Thanks for any help guys, I plan on documenting and posting this build as it goes this year.
Hi,
My first dyno was the dyno you see in the pictures here: https://yourdyno.com/hydraulic-brake-example/
It worked well up to about 90 hp.
You can control it manually or via a stepper motor. Several guys on the forum has made brakes using a hydraulic pump.
Yes, you can run from low to high RPM or high to low RPM. You can use any brake mode with automatic start and stop. For a gear pump the Brake sweep is quite good.
Cheers!
Define " small rollers " ? What diameter ?
Why not a small eddy brake retarder ? more precise and quicker load control & speeds.
Hi,
My first dyno was the dyno you see in the pictures here: https://yourdyno.com/hydraulic-brake-example/
It worked well up to about 90 hp.
You can control it manually or via a stepper motor. Several guys on the forum has made brakes using a hydraulic pump.
Yes, you can run from low to high RPM or high to low RPM. You can use any brake mode with automatic start and stop. For a gear pump the Brake sweep is quite good.
Cheers!
Thanks for the quick reply and info. Could you give any guidance on a good pump for this setup? Also, could you outline how the low to high RPM pull works with relation to the stepper motor controlled flow valve and also load on the engine? Its hard to envision this when compared to the videos I have watched where the engine is taken to redline and is loaded down to almost dying. How does this work going in reverse? Will one stepper motor curve work with 8hp to 60hp? Or will multiple ones be needed for appropriate load for HP? Thanks again for your help,
Mach_1 -
I plan on running small rollers like you see on motorcycle starter setups. With adjustable gap to accommodate 12" and 17" wheels. Linked with a chain and a chain going to the pump.
I know eddy brakes are based on electromagnetic resistance. I will have to research them. I literally put all my research time into inertial roller dynos and designed one in solidworks, etc. Having to start over now after discovering a better option. Can you tell me what the pros and cons would be for the Eddy dyno? It might be a better option for me. Thanks for any input!
Looked at the Eddy brakes, very few places to buy from and even the cheapest ones were budget busters.
I think the hydraulic pump is still the best option for my requirements.
Did you ever pull this off? I just about did the first run on a small hydraulic dyno I made from mostly scrap. total money spent without the yourdyno is about 350 euros including 50l of dextron oil.
the size of the pump is made by what is the max pressure you reckon is safe for it to run or the max rpm before it will cavitate. the operating range of the pump can be chosen based on gearing and can be changed to suit.
The pump I used is by typing the gear dimensions into an online calculator about 37cc/rev. with a 6hp honda GX160 geared at 4:1 I see about 40 to 50 bar max pressure which is about 45 Nm at the pump shaft. so lets say we maximum want to run 200 bar the pump would take roughly 170 Nm which is about 3500 rpm if you want to brake 80hp. just about doable id say, a slightly bigger pump would not hurt.
here is a video of the thing in action https://www.youtube.com/watch?v=8q7y87FZGr4