Go-Power dyno help

[husky101]

Hey, I am part of the NC A&T FSAE team. We are reviving it after a 5 year break. We have an old Go-Power dyno. I can't even find the model of it. I have never tinkered with a dyno before this one. It has a tall aluminum water tower, a fairly large control panel and then the actual engine brake itself sitting on a stand. The manual has more then likely been lost since its last use around 5 years ago. Any help would be greatly appreciated in finding or buying the manual for this thing. My searches have turned up absolutely nothing. This dyno was made back when Go-Power was located in Palo Alto, Calif.
Thank you in advance

[husky101]

Hey, I am part of the NC A&T FSAE team. We are reviving it after a 5 year break. We have an old Go-Power dyno. I can't even find the model of it. I have never tinkered with a dyno before this one. It has a tall aluminum water tower, a fairly large control panel and then the actual engine brake itself sitting on a stand. The manual has more then likely been lost since its last use around 5 years ago. Any help would be greatly appreciated in finding or buying the manual for this thing. My searches have turned up absolutely nothing. This dyno was made back when Go-Power was located in Palo Alto, Calif.
Thank you in advance

[Poe]

What would you like to know? I used a Go-Power when I was on the FSAE team at NC State...

have any pictures of the brake so I can see how similar it is to the one I used?

[husky101]

hey, actually one of our team members has a good friend at NC State and we are trying to contact him, see if they can find the manual. Basically i need to know how all of the water hoses hook up to the entire system. I will try to talk to our advisor, he usually keeps the cameras and alot of the electronics in his office.

[drivetrainUW-Platt]

Go Power is still around. Do a google search. I have a dyno from the 60's I am trying to revive.

[husky101]

Sorry i must not have been specific enough. I know they are around, we actually contacted them because our sight glass broke on the water tower. We asked if they carried any parts for them and they said no and they couldn't even find the manual for it. We milled our own sight glass out of solid plastic but its miss and hit on the actually setting up of all the hoses and such.

[Poe]

If you can get some pictures, I can probably help you figure out what goes where...

[husky101]

hey, my buddy took some pictures, he currently has a friend on the SAE team, got some serial numbers and he's gonna try and copy the proper manual and send it to us. i'll post back on here if it doesn't work out though.

[Poe]

We didn't have a whole lot as far as manual and hookups were concerned, so if that doesn't get you what you need to know, don't be afraid to ask...I'll see what I can do.

[Ian M]

I am attempting to tackle the same issue this year with a Go-Power water-brake, but with more issues than just where the hoses go.
I believe this water-brake came from Purdue in the early 90's and has sat in one of our closets until I found it last year. Anyway, last year I got it hooked up to the motor, using universal shafts mounted to a modified sprocket, in order to put a load on the engine. The only problem is, there isn't any of the force measuring equipment still with it, and like husky101, I don't know how it was intended to be set up. I have been researching load cells and believe I could use one from 'Transducer Techniques' that measures 0 to 200 lbs. with an amplifier connected to output 0-5V with which I could hook this directly to my Motec M4's Aux. Voltage input and calibrate my own torque table by hanging weights off the end of the pump housing with a known moment arm.

Poe, if you or anyone could send pictures of your team's Go-Power water brake it would be much appreciated. Send pics to im11@evansville.edu
I will try to post a picture on here of ours, it sounds like Mike Duwe and I may have the same brake from the 60's...no exaggeration.

P.S. What size pump are you feeding the brake with?
P.S.S. How does the load cell typical mount between the pump housing and the support stand? There are threaded places on the support stand, but they are too big for most load cells and there isn't enough room for the housing of most load cells. I think I have figured out an easy way to mount it, but I was just wondering what you guys have done.

[Ian M]

Could anyone tell me an approximate flow rate for their water brake feed pumps?
Also, should the supply hose be at the top/middle of the water brake and the drain hose be at the bottom?
My thinking is that this hose orientation should work unless the pump doesn't produce enough pressure to pull the engine down, then maybe the return hose could be moved to the top of the water brake so more water is trapped which would yield more resistance on the engine.

Does this thinking make any sense, or would the inlet pressure be so high that the brake's pump is going to be full when the inlet valve is opened, so the position of the return hose isn't going to matter, anyway.

Do you guys use load cells to read torque from your water brakes?

Thanks.

[The Gus]

We also have a Go-Power water brake. It is very old and large for our motor (power wise). All the electronics are controlled through a custom LabView program. The electronics were completely overhauled during the 2006 FSAE season and we now have a very reliable and safe dyno.

Regarding the water connections - the inlet and outlet are both on the bottom (I don't think there is a connection elsewhere), and the outlet diameter is reduced (plastic insert with small hole, around 3/8" diameter). The orifice is necessary due to the slow brake speeds we run (because we connect the brake to the gearbox output, which slows the brake speed significantly). At lower crankshaft speeds it can still become difficult to hold a load on the engine. Generally we use a higher gear when we want to hold lower crankshaft speeds. FWIW, we typically run the motor in 3rd gear.

For the water source, we use a typical building water line for the supply - not even artificially pressurized. It is an open loop system and the exit water goes down the drain. We have an electric water valve to control flow rate (i.e./ load) which is controlled by the operator through the LabView program.

A load cell is used to measure torque. Our's is a 500lbs 'S' type cell. For your reference, our lever arm is 0.1150m (spec from brake manual). When sizing your load cell, be mindful of the gear ratios you'll be running. A 500lbs cell sounds high, but with our lever arm and gearing we use a good portion of the available range.

I hope some of this was helpful. How are you planning to control the electronics?

Best of luck.

George

[Poe]

I don't have any pictures of the current setup, but I did find some of the pictures I took a couple years ago. Hopefully they will still help out some. I've hosted the pictures on my university webspace, which I do not know when it will cease to exist since I've graduated almost a year ago now, so if you want to save the pictures, do so as soon as possible.

Here is a picture of the water hookups. Our brake has a single inlet (in middle) and two outlets. It is a two rotor brake, yours may be different.
http://www4.ncsu.edu/~ewpoe/DynoPics008.jpg

Here is our control console, manual throttle on left and manual load (water valve) on right. The torque meter in the middle is hydraulic, but we have since added a strain gauge and amp display to view torque (it also is connected to and logged in our ECU). The strain gauge would not fit where the original hydraulic load cells were mounted, so we fabricated a beam to extend the mounting points away from the brake.
http://www4.ncsu.edu/~ewpoe/DynoPics009.jpg

Here's a side picture of the brake:
http://www4.ncsu.edu/~ewpoe/DynoPics002.jpg

As far as circulation pump sizing is concerned, we did the standard calculations using the system head curve and pump head curve. The brake we have requires at least 35 psi inlet pressure and if I remember correctly, around 7-10 gallons per minute per 100 horsepower. Since these are run through the transmission reduction, horsepower at the brake is not going to be the same as crankshaft horsepower due to the rpm difference, so keep that in mind when calculating required flow rate. Also, it's much better to have too much pump than not enough. We ran the brake off of the tap water supply for several years before moving to a new shop, but the pump route seems a little less wasteful.

You'll also want a pressure regulator to regulate the pump supply water. However, you must pay attention to the type of regulator you purchase. You want one that will regulate inlet pressure by bleeding off excess as opposed to a regulator that regulates pressure on the outlet of the regulator. That way you maintain setpoint pressure from pump to water brake control valve and your pump is not constantly trying to pump against shutoff head. Also remember to check NPSH for the pump inlet as well.

The outlet of the brake does not like back pressure. Some restriction or even a valve may be desirable to achieve good transient control, but if the outlet of our brake was forced to pump uphill or against any pressure, it took much longer to unload once the control valve was closed than if the outlet was allowed to gravity drain.

I'm sure I've forgotten a lot of what was asked above, but that should be enough to get you started on figuring out pump size and the rest of the brake setup without spoon feeding all of what my teammates and I have learned over the years.

[Ian M]

Thanks a million guys!!! All of the info. was extremely helpful.
Gus, you saved me from pulling a bonehead and getting a load cell that was too small. I am also going through the gearbox, but I haven't gotten too far into things yet and didn't think about the extra force due to the gearbox. I did account for the moment arm, which mine will be around 4". I was going to use labview to log the data for rpm and the load cell, but it will be easier to read the load cell with the Motec's Aux. Voltage and set up a calibration table because then I can overlay throttle position, lamda, rpm, and torque.
I was planning on getting a load cell similar to the S type load cell that you have and hook it to an amplifier to get to 0-5V. I plan on mounting it similar to where Poe's hydralic piston is mounted, but below the brake housing because it won't fit between the brake housing the pump.
I will be using a manual throttle and water valve identical to Poe's.

Poe, Thanks for the pump sizing numbers. Sounds like Gus just hooked up to a big enough supply line and restricted the exit flow, which probably isn't a bad idea either. I have access to a hot tub pump that was used on a past project and a large water tank, so I basically just want to make sure that it is big enough and like you said figure out a good way to regulate it.
As Gus said, I think my brake is way too big for our engine, but I have this year and next to line everything out. I would like to get it going this year, but it sounds like there is a little more to it than I had originally thought.
This should probably be obvious to me, but is your manual water valve on the outlet hose or the inlet hose after the pump?
On a separate note, I need to find this hot tub pump that we supposedly have and see if it is regulated or not.
Basically, I need to get to figure out what I have to work with and whip out my fluids book and get to work. I wish I had all of the specs. for this old school brake because I wonder if the specs for mine are the same as the specs for yours. I may post the serial # if I get a chance to see if either yours or Gus's is close to the same.
Nice control panel! I will post a pic. of mine sometime, you will laugh.
Do you just copy and paste into this thread?

[Poe]

The hot tub pump will be borderline at best. The senior design class which began the dyno test cell project got one of those for free and was a waste of time because they hadn't done any calculations on it and was grossly undersized, plus the regulator they chose was normally open, which bypassed pump outlet straight back to the outlet line from the brake back to the holding tank.

The manual control valve is on the inlet line between the pump and the brake. You may also want to add a valve on the outlet in addition to the main control valve to give the ability to adjust response to suit your particular engine/brake combination. The main control needs to be upstream of the brake, not on the outlet. You don't want supply pressure constantly in the brake.

I hosted the pictures on my university file space and linked to them in the image tags (the little picture button above the reply to message box). If you want copies, save them now, as I don't know when they are going to turn off my user account. You'll have to host them somewhere, either your university filespace if you have that ability or something to the nature of webshots or another online photo storage website.

[The Gus]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> The outlet of the brake does not like back pressure. Some restriction or even a valve may be desirable to achieve good transient control, but if the outlet of our brake was forced to pump uphill or against any pressure, it took much longer to unload once the control valve was closed than if the outlet was allowed to gravity drain. </div></BLOCKQUOTE>

I think we have similar control issues caused by the orifice in the outlet of the brake. It has a slow response to operator changes when unloading the engine (reducing input flow rate). The system is good/quick when applying a load onto the engine. The orifice is probably not the best approach, but we need it due to the lower flow rate and inlet pressure we use due to not having a pump. In general, it works well and I'm happy with it. I think a pressurized inlet would be a better approach, but this still works well for us. We've used it like this since the team obtained the brake, about 8 years now.

Ian, I bet you'll be fine without any pump/pressure system if you restrict the outlet of the brake. The drawback is a slower responding system when unloading. It's not ideal but it would get you running and testing very soon. Make sure your outlet is a good gravity drain and doesn't need to go uphill.
I think feeding the load cell into your ECU is a good idea - especially to get the system setup so you can test quickly. Our LabView electronics were a lot of work, and not necessarily any better than using an input on your Motec.

[Ian M]

Thanks guys! It's good to see that there are still guys willing to help out on the forum as opposed to all of the "why don't you just figure it out yourself remarks" that seem to be flooding the forums lately.
Sounds like I will find this pump that we have, run some fluids calcs. with the info. that I know and try to 'best guess' the values that I don't, and put a control valve on the exit line to give a little bit of adjustment in case the pump doesn't quite have enough power to produce enough resistance in the brake.
I believe the only parts I would need to make this happen would be another control valve for the exit hose and probably a regulator.
Gus, how big of a line are you running into the brake?
The only line I could tap into here at school would be a garden hose (which I did last year). I built an engine stand and a "driveshaft" to hook the engine to the brake last year. I hooked it up to a garden hose after rebuilding the water brake itself (split the case, cleaned it out, resealed it), and ran the engine with the garden hose on. I think I only got the engine to 2nd gear, but the brake wouldn't supply enough resistance to pull down the engine (plus it leaked a little). Anyway, about the time I got this set up it was time to put the engine in the car and I ended up tuning on a neighboring school's Mustang chassis dyno. Due to the fact that it isn't my school's dyno, I can't get quite enough time on it to really fine tune the ignition timing and I am mainly only tuning at 100% throttle and interpolating the other values.
Truthfully, I am going to be a little nervous about spinning the brake in 3rd or 4th gear. I probably better build a "safety guard" around my driveshaft because that could get ugly!

Thanks again.

[Poe]

You need a control valve on the inlet, whether you use tap supply or a pump to supply the inlet water. Just to clarify, the pump we use is with a recirculating system with a holding tank. When we were at our old shop we used the tap water supply without any pump. Once the holding tank is full, the only tap water consumed is to the cooling tower.

You should be okay with a 3/4" tap water line, but our pump and closed loop system uses 1-3/4" or 2" lines attaching to the pump and about a 1" flex line from the pressure regulator to the control valve. I believe that there is a 3/4" reducer at the brake inlet fitting as well.

We ran the brake on a garden hose on the sidewalk behind the shop during the 2006 season, and had acceptable results. The faucet would flow 15GPM (assumed tap pressure of ~70psi.), which was borderline for full load at low rpm and high torque of our turbocharged setup. Especially turbocharged, we had to run 3rd gear, or 4th on the garden hose.

[Ian M]

yeah, I know I need a control valve on the inlet for sure now to unload the brake, but I am now planning on also putting one on the exit side whether using a pump or a garden hose inlet in order to restrict the flow leaving the brake.
Sounds like I should probably get the load cell mounted and set up and maybe just hook up to a garden hose for this year and then see about running a closed loop system with the pump if time permits this year. If not, finish it up next year.
Probably the reason I couldn't get enough load on the engine last year running on a garden hose was because #1. I didn't run in a high enough gear. and #2. The hoses running in and out of the brake are 1" hoses with no restriction on the outlet side and a control valve on the inlet side. Basically, I wasn't restricting the flow out enough to build up enough pressure to fully load the engine.

So instead of running a closed loop cooling system with a fan blowing on the radiator, you hooked a garden hose to your cooling system? Is that what you were referring to with the "cooling tower".

Thanks for the help again. I'll go from here and see what happens.

[Poe]

Yeah the cooling tower takes the place of the radiator. There's a temperature controlled valve on the inlet line, so that as the water temperature in the tower rises, it allows in progressively increasing amounts of water to cool the temperature. There's a pre-load adjustment on the valve spring to regulate the opening temperature. Last year we had this hooked to a sink, so that before we began testing/tuning, we could fill the tower with hot tap water (~115F), which sped up the process of getting the engine to operating temperature and allowed us to generate the main fuel table before having to deal with cold start compensations. An electric water pump that we used in the car a few years ago is used for cooling system circulation on the dyno, so that allows the pre-warm and fast cool down if there is a need to take something apart. It is not as long of a wait to cool off the engine before working on it.

You could do the same thing with an electronically controlled valve as opposed to the mechanical temperature sensing valve used on our ancient cooling tower. The only down side to this setup is corrosion in the engine cooling system. Frequent use lessens this issue, though.

[The Gus]

Our brake has 1.5" water lines connected to it.

Our cooling tower is not as elaborate as Poe's. It does not have any adjustment to regulate temperature. We use (another) water line for the "cold" side of the heat exchanger, and this water is used to cool the engine's hot water. The two liquids do not mix. The stock thermostat in the engine is used to maintain constant engine temperature, while the other side of the cooling tower is open loop and sends even more clean freshwater down the drain. The tower can absorb so much energy that if we do not use the engine thermostat the engine will never reach operating temperature (peak around 30-35 deg C). It cools the engine well and the only cooling issues we have are the occasional leak.

Our brake is connected at the transmission output via two CV's and the world's shortest driveshaft - exactly the same setup as we use on the car (it is leftover parts from previous vehicles). We also have a guard covering the aforementioned spinning shaft just as you suggested above.

If you want to see any pictures send me a PM with your email.

[Oloff_Kilter]

Gentlemen, lots of good information here, thanks for sharing.

I also have an early Go-Power Systems dyno. Serial # 4067 out of Palo Alto. I have no information or manual for it and have been trying to plumb it. If I may ask a few questions?

I will be using the dyno to test engines from 40 to 100 max HP. Most likely in the 40 to 80 HP range.

Mine has one inlet on the side of the brake and two outlet hoses at the bottom. Should I take it that the outlet hoses can go back to the holding tank unrestricted or would be better to have a valve added to fine tune the unloading process?

On the inlet side, the water comes from the pump or garden hose to the torque valve on the panel and then to the brake. Is that correct? I plan on using a plastic 55 gal drum as a supply source with a pump and regulator.

My brake uses hydraulic load sensors like Poe's. Can you uses standard hydraulic fluid such as I.S.O. 68 tractor oil? What is the best way to fill the system and should you bleed it? If so, how?

Thank you very much for sharing your experience.

[Poe]

We never used a valve or any restriction on the outlet of our brake, but it may just take some experimenting to find out what works best for your setup. When we began using the recirculating system, we just ran from the outlet back to the holding tank. The inlet line should be configured just as you said.

As far as the hydraulic fluid is concerned, I don't really know what it is. I want to say that the Go-Power guy told me it was something made by Dow-Corning, but it's been a while and my memory may be way off. You'll definitely want to bleed the system, but I have never done it and I'm not exactly sure how. I just know that after several hook up and disconnect cycles, the gauge's upper limit kept dropping until we rigged the s-bridge load cell. See what you can scare up about Go-Power on Google. I know that they still exist in some form or another, and they might be able to give you a better idea of what fluid to use and how to bleed the system. If not, I'm sure you can figure out a way to get it done.

[Oloff_Kilter]

Thank you very much Poe.

I found the FSAE.com site through Google. It has been the most informative site so far. Go-Power Systems is still in business but they are reluctant to deal with the older brakes made in Palo Alto.

Seeing as how we are only running engines under 80HP, do you think a Jaccuzi pump pushing 35 PSI at 7-10 GPM will work? I plan on adding a regulator as you suggested.

I'm sure I will have more questions.

You have been a great help. Thank you again.

[Poe]

The engine makes about 80 crankshaft horsepower, but the brake power will be different. The brake will be turning slower than crankshaft rpm and the torque will be multiplied, so be sure to account for that when sizing the pump. 7-10 GPM seems like it would be right on the edge of what would work. If you can get more flow and more pressure, you will likely be better off. You can always regulate the pressure lower - you can't add more if you don't have enough to start with.