My GY6 Engine Dyno - Built, not bought! (with full DIY CNC computer control)

[T@BD]

I think this is the best fitting forum section for this post, as this build project is in the spirit of methodically testing GY6 upgrades to verify what works (and what doesn't).

IN PROGRESS

I started building this dyno in 2012, before I knew anything about hydraulics, embedded electronics, or circuit board design. It's been a long project, and a deep learning experience. Although it's not done, this build is now at the point where competes with $20,000 turn-key small engine dynos at around 1/10th the price. Even with the low cost, it still beats them out on functionality and modern tech.

To be fair, there are already several GY6 shops with dynos that have tested GY6 engines. Most that I've seen have the DynoJet SD-12, or a similar inertia dyno (more on this below). Why don't they post much about their results? It's rare to see actual data from them. Search YouTube for "gy6 dyno", and you'll find only a couple interesting runs, but mostly incomplete teaser videos of GY6 scooters on a dyno apparently when they first setup the machine, but no numbers, charts, or other data published after they get familiar with the system. I believe it is because they're using the wrong type of dyno, and getting results that aren't relevant. This build is different, and I believe will help us get answers that others can't.

So what do I mean by that...? Well, most times when we think of a dyno, an inertia type comes to mind. You roll your vehicle up onto a machine (or mount your engine) in such a way that spins and accelerates a weighted drum as quickly as possible. As soon as you hit redline, the test is over. This only lasts between 20 to 30 seconds tops. That's good for measuring power if you only want to know how the engine runs in short bursts of acceleration at WOT on flat ground, but doesn't allow us to test engines the real way we all ride the 150's. There are all sorts of terrain scenarios to measure that an inertia dyno isn't capable of reproducing.

That's why I chose to create a hydraulic brake system over an inertia type. With a brake dyno, we can control and simulate all sorts of terrain and scenarios (even hill climbing) all in real time. We can test the engine and transmission's responses to varying loads, and even hold a steady RPM under high load for long duration to test for specific problems. This is awesome for reliability and longevity testing especially for developing new powerful big bore, stroker, and high-compression configurations.

If you'd asked me in 2012 how long it would take to build the dyno, I would have told you "2 months tops". That turned out to be somewhat true. The physical frame and hydraulics were all functional at that point, but capturing good data out of the machine (with no computing system for data acquisition) was difficult, near impossible.

"2 month" version of the dyno (no data acquisition system)



Rolling my own dyno computing system

A dyno is only as good as its data. Otherwise, it's just a fancy test stand. Dyno manufacturers wanted $3,000+ for a barebones data acquisition setup that I felt has very limited usefulness. Even with that price point, the technology is old and clunky. Given the awesome amount resources for learning about microchips and embedded engineering available these days (Arduino for example), developing a system myself for my exact needs was the obvious decision. This is what I ended up with (below).

On the left is the heart and brain of the system. Inside of the enclosure are all of the components to take readings from sensors, transmit data wirelessly to the operator's desktop for logging and graphing. I wanted to take this a step further and add stepper motors which will control our brake valve and engine throttle on the fly in real time. On the right are the stepper motors, driver, and power supply. This lays the groundwork for full CNC dyno control. And "one touch" automatic dyno runs executed according to pre-scripted testing routines, really helpful for Quality Control on our engine builds, and maybe even automated break-in runs for new engines before they ship. Install your new engine, and haul butt right away without worrying if you're breaking it in right. Everything you see here was less than $300, sourced from generic online parts stores. It's a way more robust system than the $3k yesteryear tech.

The green board itself was originally going to have a much more important role, but technology advances so fast that it's a bit outdated now and I'm just leaving it in for show. Back when I bought the green board, I didn't have a clue how to design electronic PCB's. I'm up to speed now with a lot of practice from developing NanoEFI boards over the last two years. At this point, the only thing of importance on the green circuit board is the $1.50 microchip it houses, and the built-in USB programmer module. The real intelligence and logic in this box is going to be on a completely custom circuit board that I'm designing from the ground up just for this project (more on that later).





This project is entirely funded by your orders.
YOU make this possible. Thanks for your support.

[T@BD]

The dyno chassis and hydraulics

Here's the first version of the dyno. It was a mess, but the hydraulics worked great. I could crank down on the brake and really make a GY6 engine cry.



The frame was an old rusted piece of junk I picked up at an estate auction for $35. I wasn't the only bidder, and I still wonder what in the world the other guy wanted it for.

I used an old Yerf Dog Spiderbox swingarm for the engine cradle. Free from one of our part outs.

The hydraulic tank is an old trashed water heater, cut down and resized for 10 gallons and a flat top welded with vent cap and strainer. Another freebie.

Several NPT bungs were welded into the tank for 2x in-tank oil heaters, temperature sensors, inlet and outlet, and a mechanical temperature gauge.

A heavy duty heat exchanger, honda radiator, and water cooling are being used to remove heat from the hydraulic system. It's critical to tightly regulate the hydraulic temperature, and this will likely end up being a challenge. I'm unsure if the small radiator will be able to eject 15+ HP of heat energy, which is around 40,000 BTU. If not, I made sure there is enough space in the frame to mount a second radiator (or up to 4) in modular fashion.















A little paint goes a long way. Rustoleum safety blue and yellow.



Finishing touches...

Personally, I prefer the look of build projects that are plainly stated and not too flashy over the top visually. Function and a factory look are king in my book. To finish off the appearance and help protect the surface, I pulled out a few new strips of Yerf Dog Spiderbox grip tape.

[T@BD]

More details on the data acquisition system

Main Processor: Microchip 64Mhz PIC18F45K22
Responsible for Automation and Data Acquisition



Co-processor: Particle WiFi Module (120Mhz ARM Cortex M3 processor)
Responsible for wireless communications between the main processor and the server:



Main board
This is the Mikroe PIC7 development kit. This board itself was originally going to have a much more important role, but technology advances so fast that it's a bit outdated now. Since the work mounting it is already done, I'm just leaving it in for show.

Back when I bought the green board, I didn't have a clue how to design electronic PCB's. I'm up to speed now with a lot of practice from developing NanoEFI boards over the last two years. At this point, the only thing of importance on the green circuit board is the $1.50 microchip it houses, and the built-in USB programmer module. The real intelligence and logic in this box is going to be on a completely custom circuit board that I'm designing from the ground up just for this project (more on that in a later update).



Serial Peripheral Interface: Getting the processors talking over the SPI protocol

Getting the processors communicating with each other required a bit of hookup wire to the correct pins, and a voltage level translator in the middle. The processors communicate over a protocol called SPI. SPI is a serial data protocol that allows the chips to share information at high speed, millions of bits per second. This is more than fast enough for the streaming sensor data and commands in real time.

Although I like the "DIY" look of the hookup wire, this will all be replaced with the custom board. The new board will snap into place on the green board, and will contain circuitry for all of the voltage translation circuits, as well as all Input/Output conditioning, filtering, and protection for the overall system.



SPI Signal Diagram
Here's a good diagram of what an SPI conversation "looks like" between processors. This the main processor transmits "S" and the co-processor transmits "F". This happens about 1 million times per second at speeds that I've tested so far.



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The enclosure











Making a wall mount

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After a quick trip to the plasma table...
The unit you see on the left is the hydraulic fluid heater control circuitry and solid state relays. I'll cover details about that side of the system in a later update.

[T@BD]

Feedback, opinions (and any criticism) are very welcome. The end goal with this project is to have a machine with a level of accuracy and repeatability that can produce relevant data for us all to chew on. If I'm missing something, let me know.

[neo71665]

Thats pretty cool.


Starting to understand why the nanoefi is taking ya so long

[OLDKID]

YIKES' !!! The term " FULLY IMMERSED " comes to mind .

[scjeep4.7HO]

That is very cool and obvious that you have put a lot of thought into this.

[EVILWS6]

Yes, very nice. Very nice indeed

[T@BD]

Thanks guys! Any ideas for testing topics you want to cover? I've got a list a mile long. Other than the power adders, I'm itching to do reliability/torture tests. Proper air filtration and oil types are the first topics I want to tackle. And a lot of eBay myth busting.

Since I'm using WiFi for transmitting data wirelessly, the dyno is actually connected directly to the internet. You could ping it right now if you knew the right IP address and port number. Live video/audio/panel webcasts are not only possible, but very high in the plan. Tune in from home and watch us grenade a GY6 with your testing idea.

But money makes all of this work. Warning, shameless plug: If you guys need some parts, go get some lightning deals to push this forward faster! Here ya go:

Buggy Depot Lightning Deals

Support vendors who support the sport!

Originally Posted by neo71665

Starting to understand why the nanoefi is taking ya so long

Tell me about it. There's always too much to get done!

[neo71665]

I'd like to know the truth, does a 1p57qmj actually produces more power (I understand it's only supposed to be 2 tops) than the normal gy6. I've heard hearsay it's supposed to but have never seen proof.

I know mine (basically stock) isn't having any problems turning over these half bald 24s when 22s are supposed to be the max.

[xlint89]

Impressive. Should be quite valuable when finished.

[ckau]

This is some good stuff , Travis. you can definitely de-bunk a lot of myths. rumors and false claims though the use of a dyno. I have a overly simplified version of your dyno where the motor capabilities are measured through the motor's ability to produce hydraulic pressure at specified rpms. I can create a graph illustrating the motor output throughout the rpm range and horsepower is found through a math formula on a calculator. A crude but effective way to illustrate the effects of motor modifications.
You stated It's critical to tightly regulate the hydraulic temperature. I was curious as to why?

[BEEFKING69]

This is so cool....Would be awesome for tuning carbs and efi if you had an afr meter hooked up also.

[T@BD]

Originally Posted by ckau

This is some good stuff , Travis. you can definitely de-bunk a lot of myths. rumors and false claims though the use of a dyno. I have a overly simplified version of your dyno where the motor capabilities are measured through the motor's ability to produce hydraulic pressure at specified rpms. I can create a graph illustrating the motor output throughout the rpm range and horsepower is found through a math formula on a calculator. A crude but effective way to illustrate the effects of motor modifications.
You stated It's critical to tightly regulate the hydraulic temperature. I was curious as to why?

Keeping the hydraulic temperature regulated tightly helps to reduce variation in readings. With viscosity of the fluid changing with temperature, power readings at 150° will be inconsistent from readings at 175° (even if all other variables remain the same). So temperature swings can be a big problem when testing from one engine to the next. Or even on the same run if it lasts for more than a minute or two. I'm planning on some extended torture testing, so we need to be able to balance heat in and heat out.

But accuracy aside, probably more important (safety related) is how fast the temperatures shoot through the roof when under full load. It's scary. Back before I had any cooling at all, I won't say that I ever looked up during a run and had a tank full of smoking oil. Nope, never happened.

There are some other design constraints. The pump's maximum temperature rating is 180F, so I'm considering that our max limit for the system. Right now I'm shooting for an operating range between 150° to 160°, with 155 nominal. This will probably change as I get closer to the point of needing to make a final decision on which fluid (ISO 32 or ISO 22) I'm going to run.

My current working theory is that it is best to keep the viscosity as light as possible to reduce drag in the system (which I believe will rob power at higher flow rates without being measured). The pump's manual specifies an acceptable kinematic viscosity range in centistokes from 200cSt (very thick) to 6cSt. Water is 1cSt for comparison.

So I'm going for a viscosity range of 10cST to 15cST (some margin for safety), and will code the processor to compensate the HP calculation for the small viscosity differences across the 10 degrees of temperature range. Would like to get that down to 5 degrees, but won't know until firing it up and seeing how well the cooling system works. And adding a second radiator if needed.

Thankfully, viscosity changes are (more or less) linear with temperature. I traced over the graph below to show what I'm expecting for our temperature vs viscosity over a 10 degree range.

[T@BD]

Originally Posted by BEEFKING69

This is so cool....Would be awesome for tuning carbs and efi if you had an afr meter hooked up also.

Going with the PLX AFR wideband sensor kit. I picked up a Gen 4 back in 2012 when they were new. I believe they're on Gen 6 now.





I think that it's great that they're designed to be used with external data loggers. The PLX generates a 0 to 5v analog signal that corresponds to the A/F ratio in that moment. So reading A/F from my processor is a simple deal without a lot of hardware headache. I plan to use a diode array to protect my processor's input pin against over voltage from the PLX, but that's about it.

Here's the note in the manual on the 0-5v output for use with data acquisition. Well worth the money.



And here's the chart showing output voltage versus A/F, and the formula for the processor. This will be part of the real-time data recorded and sent to the operator display.

[scjeep4.7HO]

The oil temp not being axactly the same isn't a huge deal as long as you have some info as to what the oil does with increase in temp and you can build a easy spreadsheet or model if your smarter than I am and it can adjust for the difference in oil temp.

I'm interested in the tuning portion of these since I have been running a boosted Jeep since about 2006 or so.

[BEEFKING69]

Nice....how much was that afr package?

[T@BD]

Originally Posted by scjeep4.7HO

The oil temp not being axactly the same isn't a huge deal as long as you have some info as to what the oil does with increase in temp and you can build a easy spreadsheet or model if your smarter than I am and it can adjust for the difference in oil temp.

Part of the fun of the dyno will be testing on topics that stir up conversation and debate. Keeping accuracy factors like oil temp as tightly regulated as possible will help to keep conversation focused on the parts and the merits of the test data (instead of points being made against the design of the machine itself). If I rely too much on corrections, I feel that the first thing a naysayer will do is point to the weatherman's forecast model. Like how it was supposed to snow here yesterday, but we didn't get a single flake.

I expect a bit of kickback from sellers who are offering exaggerated claims (outright lies IMO) to sell their parts. You see this on eBay and Amazon a lot. The lack of real testing by manufacturers makes it easy for sellers to get away with making up bogus claims. I don't want to give them any wiggle room when we all start calling them out.

Originally Posted by BEEFKING69

Nice....how much was that afr package?

Around $200 I believe, was a while back so the Gen4 might be priced lower now.

[Delois]

The hydraulic tank is an old trashed water heater, cut down and resized for 10 gallons and a flat top welded with vent cap and strainer. Another freebie.