Home made engine dyno with Superflow brake

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turbobaldur
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Home made engine dyno with Superflow brake

Post by turbobaldur » Sat Mar 28, 2015 2:02 pm

Now that I'm currently unemployed and have lots of time on my hands I figured I'd post some pictures of the dyno I built for myself with the help of some friends a couple of years ago.
I picked up an ancient Superflow water brake on eBay late 2012 from a marine engine builder in New York. Then I started gathering some more parts I needed, such as load cell and speed sensor. Initially I was going to get my hands on a Superflow water servo but the wallet didn't allow that at the time so I built my own servo valve using a 1.5" ball valve and a stepper motor and some parts I had machined for me on a water jet.

For data acquisition and control I decided to use an ARM+FPGA based ECU I had designed earlier, just with firmware changes to run a dyno, the ECU had all the IO I needed, 24x 12 bit ADC channels, 2 programmable level speed inputs, 6 logic level inputs, 26 low side switch outputs, 8 logic level outputs, 100Mb ethernet, 2x CAN, 2x rs232. I desoldered some parts and repurposed 8 of the low side switch outputs for logic IO to interface with the water servo and future expansion boards. I also made EGT boards that take 8 thermocouples each and output the data over rs232 into the main control board. It interfaces over UDP/IP to a Windows application I wrote for tuning ECUs but made some extensions to for dyno operation.

The chassis is made of 6" U section and I opted to rigid mount the brake and use a U joint driveshaft instead of going the Superflow route of having a short splined shaft and requiring a bellhousing that bolts to the brake. Reason is I wanted to be able to test snowmobile and motorcycle engines as well.

For the first year the dyno was operational it was hired by a local company who were developing diesel additives and needed accurate fuel consumption tests. This was accomplished by putting the fuel tank on a scale which was interfaced with the dyno controller as we had no luck getting repeatable numbers with flow turbines due to foaming of the fuel returned from the engine back to the tank. They ran three engines during this time, first was an International 6.9, next was a Mercedes OM662 and the last an Isuzu 3.0 common rail. In none of those cases did we do any acceleration tests and hardly any application of full throttle except to figure out the parameters to use for the fuel economy tests. The fuel economy tests were done steady state with double control loops. Dyno controlled brake load to set constant RPM and engine throttle to set a constant power output.

Brake as it arrived, I believe it comes off a SF801 but to my surprise most parts sold by Superflow today for the current generation SF833 actually fit this one.
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Water outlet servo
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48V DC Power supply for servo
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Testing the drive code for the servo, as it's a stepper the code must take care to not accelerate or decelerate too hard or steps will be missed and accuracy is compromised.
https://www.youtube.com/watch?v=7BZTkccdjTo


Extra 1.2V feed because when I did the layout I failed to note that different variants of this Cyclone 3 in the same 144 pin package have different pin-outs.
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Fitting out the data/control box with 8 external logic inputs for frequency or duty cycle sensing (flow turbines, injector pulse width sensing, turbo speed sensing, etc), 16 external analog inputs for pressure sensors, wide band lambda and such and 16 K type thermocouples. I'm using XLR connectors for the sensors. 3 pin for the logic level sensors and 4 pins for the analog. The analogs get an extra 12V feed along with the 5V reference.
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Logic level input buffer expansion board on the right, instrumentation amplifier for the torque sensing load cell on the left
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Nearly finished control box
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First test with 6.9, august 2013
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Calibration, the eye at the end of the arm is at a 1000mm radius to the centreline of the brake. Local value for g is 9.82 and so hanging 30kg weights off it nets a reading of 294.6Nm.
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First petrol engine tested, an ancient Ford 302 with TBI and a turbo
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Live trace of one of the tests done on the 302, it didn't perform well, fell flat on its face and started to detonate at 4300RPM, probably overheating the plugs. But seeing as this is the only petrol engine that has been dyno tested in this country (I am the only one with an engine dyno) it is still holds a national record for measured horsepower.
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One of the early tests on the 6.9
https://www.youtube.com/watch?v=KIGKFZD8NBA


The Isuzu being tested
https://www.youtube.com/watch?v=yb15HcSz2ig


Acceleration test of the 302, aborted due to knocking at over 4000RPM
https://www.youtube.com/watch?v=TkJqy_fIfJY

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Re: Home made engine dyno with Superflow brake

Post by PackardV8 » Sat Mar 28, 2015 3:54 pm

Very nice work and congrats for being the first in Iceland with an engine dyno.
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Re: Home made engine dyno with Superflow brake

Post by mk e » Sun Mar 29, 2015 10:17 am

Very cool!
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Re: Home made engine dyno with Superflow brake

Post by RL » Tue Mar 31, 2015 2:38 am

Very cool, too.

Wish I had the money to just buy stuff, but I have to do the DIY instead.

I've been looking at your neighbours site across the pond for ideas. LOL

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Re: Home made engine dyno with Superflow brake

Post by Rizzle » Tue Mar 31, 2015 1:32 pm

Thanks for sharing, thats a cool project.
Are you really the only one in Iceland with an engine dyno?

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Re: Home made engine dyno with Superflow brake

Post by turbobaldur » Tue Mar 31, 2015 3:32 pm

Rizzle wrote:Thanks for sharing, thats a cool project.
Are you really the only one in Iceland with an engine dyno?
Yeah well this nation is very much in the horsepower dark ages, haha. Partly because hardly anyone lives here, population 320k, and partly because we're all poor as dirt.
There's two rolling roads in the country but one is located in a trade college and not available for public use (and doesn't see much use at all, it's just used for teaching, nothing else), the other is an old Bosch unit that has trouble coping with anything above 200 horsepower.
There is a dyno located in a different trade college but that is just an uncomputerised Froude brake that's been permanently attached to a single diesel engine for the past decades, not much use, just a teaching tool.

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Re: Home made engine dyno with Superflow brake

Post by 41apache » Tue Sep 01, 2015 8:05 pm

Hey you did a nice job with the dyno project. That dyno came from me on ebay. Still trying to finish my own dyno project.

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Re: Home made engine dyno with Superflow brake

Post by LarsPerformance » Sun Sep 06, 2015 9:24 pm

Looks Nice!

Im working on a Similar project. Same WaterBrake as yours.
With the original valve and Console.

I have been looking for a new Load Controller.
The one we have is build in to the Console (SF 800)
We have new DataLogger, that takes care om Meassurements, but we need a Load Control.

How did you buildt yours?
What can it do? Steaddy Stady, Ramping, Break In?

Is it only Controlled from PC?

Do you mind sharing some detales.

Regards
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Re: Home made engine dyno with Superflow brake

Post by turbobaldur » Mon Sep 07, 2015 3:42 pm

I built the load controller by fitting a nema23 stepper motor to a 1.5" ball valve, the valve is driven by a chinese stepper motor driver and a 48V power supply built from scraps.
The control signal for the step driver comes from an automotive ECU I designed several years back, which has a good amount of I/O and an FPGA to implement custom high speed peripherals.
The control box interfaces by ethernet with a PC which runs the user interface (also bespoke) and high level control (test operation). The low level control (the actual load control) is done on the control board in the microcontroller. The valve step signal comes from a custom peripheral in the FPGA that creates a variable frequency pulse train, the frequency of which takes into account the fact that the stepper motor cannot accelerate, decelerate or change direction instantly.

The load control can do steady state and it can also do ramping. There is also a throttle control and each control loop has configurable parameters, I can make the load valve control engine speed and I can also make it hold a torque target or a power target. Same applies to the throttle control, I can make the throttle control torque, power or speed. The usual configuration for an automated test is to make the load control target the speed and make the throttle target the power.

It is also possible to tie parameters to analog or frequency inputs on the control box so a knob or lever for manual operation of the electronic throttle or load valve could be added, as well as for adjusting the control loop targets. There are also two CAN bus circuits on the control board and while they're not currently utilised by the dyno software they could be utilised to record data from the engine's ECU into the dyno data for logging or control operation or to transmit dyno data to the engine's ECU for logging or self mapping on that side.

For dynamic operation, such as break-in or drive cycle tests, the interface software is scriptable and the scripts can modify the parameters of the controller on the fly. An example of what can be done in a script would be to increase throttle at a rate of 5% per second until engine speed is above target, wait until speed drops below target, apply full throttle, wait 2 seconds, start recording data and initiate ramp test at 100RPM/second.
Another example of a script is a warm up script, which could for example set static load and increase throttle input at 10% per second until engine speed reaches 3000RPM, then drop throttle back to zero instantly, wait for speed dropping below 1500, repeating until engine temperature reaches a set point or script is interrupted by user. Another option would be to set a static throttle opening and alternate between ramp-up and ramp-down on the speed target, there's no lack of possibilities.

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Re: Home made engine dyno with Superflow brake

Post by LarsPerformance » Wed Sep 09, 2015 2:23 pm

OK! Thanks.
Congrats with the first Dyno on Iceland.
Almost similar here in Norway, have to Drive for 5hours to find one. except for som Rolling Roads they Charge a Billion to Use.


And How strong is the Stepper, is it Fast enough.

I allready have the System for Collecting the Dyno Values.
http://www.dtec.net.au/

I bought this, mostly for the Software.
Its able to pick Values from meassurement to make its own plot.
And it also has a function to calculate Torque under the curve.
It looks fantastic for now, even we have not played with it a lot.
(We are waiting for them to implemet LoadControl into the Software.)

Only Cons is the lack of Inputs. only Load Cell + 4 analog + RPM

The Load Controller for Steaddy State im building is based on a PID speed controller made for a CNC Router controlling Spindle Speed up to 12000rpm.
Running on a ARDUINO UNO. (have to play with some values to get it stable i think)

Im planning a NEMA17 Stepper with som kind of reduction Gear on the Load Valve. I hope its strong enough.

For Warmup, Road Simulation, Sweep Ramping etc. Im just manipulate the Setpoint on the Steaddy state PID.

Throttle Controll is for today Running an NEMA17 Stepper directly controlled by a Potentiometer.
Unshure of what direction im going here at first.

I Clearly see that you are more familiare with Programming than me.


Ill Post something when im Closer to Finish.


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Re: Home made engine dyno with Superflow brake

Post by LarsPerformance » Thu Sep 10, 2015 5:39 am

And by the way!

Is it possible that you have the wiring for the original SuperFlow Load Valve.
Do you know if it is a Stepper, Servo or a DC motor with feedback

Im at work, and dont have the chance to meassure it.

LarsPerformance

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Re: Home made engine dyno with Superflow brake

Post by turbobaldur » Thu Sep 10, 2015 7:57 am

No I have not even seen a Superflow load valve up close and personal. From what I gather it's a DC motor servo with position feedback. I constructed my own load valve because my brake came without one. My valve is not perfect but it does the job. What could be done to improve it is to eliminate the backlash in the interface between the belt sprocket axle stub and the ball itself.
I have looked all over for a suitable industrial motorised flow control valve that is fast acting and they don't appear to exist outside of some very special (and expensive) applications. Most of the flow control valves you can buy off the shelf are very slow acting, like 30-60 seconds from fully closed to fully open. For dyno operation I'd say the slowest you could possibly make do is 2 seconds. Then there's all the valves that aren't designed to partially restrict flow or aren't designed for motor operation, they all include various amounts of backlash in the interface between the control knob and the valve mechanism.

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Re: Home made engine dyno with Superflow brake

Post by Kevin Johnson » Thu Sep 10, 2015 1:34 pm

https://www.youtube.com/watch?v=ZubCyWe075I


https://www.youtube.com/watch?v=T-h_7kUyOWI

The flow optimizing disk seems very desirable. https://assuredautomation.com/index.php I would contact them and ask if it is possible to easily increase the rate at which their valve opens and closes.

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Re: Home made engine dyno with Superflow brake

Post by LarsPerformance » Thu Oct 08, 2015 10:54 am

Ok!
Some update!

The Valve is working.

We use the stock motor on the Valve.
It is a 6-wire unipolar stepper
It is now wired as a Bipolar, on a new fleaBay driver.

There is a Preciscion Potentiometer on the Valve used for feedback.
Im running the Motor with Closed Loop. Eliminating any missed steps.

PID Steddy State next to come.



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Re: Home made engine dyno with Superflow brake

Post by turbobaldur » Thu Oct 15, 2015 10:28 am

LarsPerformance wrote:Ok!
Some update!

The Valve is working.

We use the stock motor on the Valve.
It is a 6-wire unipolar stepper
It is now wired as a Bipolar, on a new fleaBay driver.

There is a Preciscion Potentiometer on the Valve used for feedback.
Im running the Motor with Closed Loop. Eliminating any missed steps.

PID Steddy State next to come.



LarsPerformance
Well that's interesting to know. You still have to limit the acceleration although you don't have to be as careful about it. I've seen steppers run backwards when accelerated too hard. Please post pictures!

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