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Author Topic: DEPAC Dyno Systems, anyone used there stuff?  (Read 7673 times)
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Jon
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« on: April 06, 2013, 06:24:54 AM »

Hi

I am looking to get my old Go-Power 512 water brake dyno going.
I want to upgrade it to electronic load control while I'm at it.

This looks like it will do most of what I need; ADL-Lite
They recommend doing a couple of mods to the Go-Power dynos to make them easier to control at the bottom of this page; Mods

If anyone has used their stuff or knows if it is good or bad would be great.

Thanks
jon
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fordboy628
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« Reply #1 on: April 06, 2013, 12:27:23 PM »

Jon,

After over 40 years on & off in the business, this is my current professional opinion.    Keep in mind that other professionals from the industry, may disagree with what I value.
There are at least a couple of guys on the LSR site who also have a LOT of dyno experience.    Perhaps they might offer their opinions as well. . . . . .

Most of the dyno work I have done has utilized SuperFlow (mostly 901 & some 902) equiptment.    It is nice because everything is integrated into a system.    What is important with any dyno is: day to day repeatability and accuracy.    Without these, your development becomes meaningless.    Accuracy to a standard allows you to compare any information you generate to other "properly calibrated" absorbers.     There are people within the industry whose opinion is: that each absorber is a unique and individual unit that cannot be "accurately" compared to other units.    When data collection was primitive, and somewhat subjective, this tended to be true.    Now that data collection is computerized & more uniform, this tends to be less so.     But, after having had 3 indentical cells & absorbers to utilize, I am also familiar with having 2 units agree and the other slightly higher or lower.    This is why I value repeatability.    I want to be able to reproduce the data that was generated on a particular pull +/- .3%     I want to be able to "close the loop" in testing.     If you do not know what I mean by "close the loop", buy and read "Dyno Testing & Tuning" by Harold Bettes & Bill Hancock.

Early in my career I used whatever dyno facility was available for the application I was working on.    I used some Heenan & Froude absorbers and some Go-Power absorbers.   All were manual data accumulation.    Eventually, some were converted, more or less successfully.     You need to make some hard choices about what features are important to the information/engineering you are going to gather.     It may be more cost effective to replace your Go-Power with a good used SuperFlow, rather than trying to upgrade 1 system at a time or all 5 systems at once.    Only you can make that kind of decision based on the cost of upgrading.    I am currently working with an individual who has been upgrading his Go-Power, system by system over the past 2 years.    His choices have all been economically driven, and still are.    It has been a huge nightmare for him, and he still doesn't have the dyno he wants and needs.    He builds engines professionally, and his product and output are suffering because of the constant changes to the dyno setup. . . . . .

When you are upgrading from whatever. . .    You need to consider 5 issues:

1/  Load control
     Going from manual to computerized/electronic.    This may/probably will require modifications to the absorbers water inlet/outlet and/or the water supply/pressure pump.
     This can get expensive.

2/  Torque measurement
     Going from very old "dead weight scales" or old hydraulic transducers to electronic strain gages.    Strain gages would be the most repeatable, but need to be properly
     mounted and connected for "accuracy & repeatability".   Some older absorbers may not adapt easily to current gages.

3/  Data accumulation
     Going from "hand collected" to "computer collected".     This is a matter of sensors & software.    Shielding electronic components/sensors from ignition interference may
     be an issue.    In my opinion, more "data" (more collection channels) is always better.    There is nothing more frustrating to analysis than to be missing vital input. . . . .

4/  Data processing/manipulation
     Going from what is "collected" into "useful information."    This is a matter of how the software calculates & produces information after the pull or run.    Again, my opinion
     is that, "more" is always better.    Of course, if you do not use it, more info has little "value".     A software system which allows you to upload to a desktop or laptop for
     further analysis is a useful feature, in my opinion.    Converting printouts, by hand, into spreadsheets/graphs/etc, is a giant pain in the A$$.   And, if this is a business,
     your time is money. . . . .

5/  Environment, ie, the dyno room/cell
     Do not discount the value of controling the environment in which the engine(s) will be tested.    In my opinion, this is absolutely necessary to have repeatability.   This can
     get expensive to provide ducts, blowers, tanks, pumps, etc, etc, etc. . . . .

If you are going to be serious about development, more info and better quality is always the way to go.    If you just want to qualify or quantify numbers, a simpler system may serve your needs.
 cheers
Fordboy
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Jon
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« Reply #2 on: April 06, 2013, 01:24:51 PM »

Thanks Fordboy

It's point 1 that I'm specifically looking at addressing here, without getting that bit right the rest is a little wasted IMHO.
I want something that can hold steady state pretty well and do slow ramps and steps.
I'm not a fan of inertia dynos although they are by their simplicity very repeatable mechanically.
I will be doing upgrades to the water control system at the same time as per the second link in my original post.

I'll upgrade to a strain gauge which should help improve mechanical measuring accuracy and repeatability. Just need to work out the math to allow me to fit a strain gauge in the original mounting point to keep the unit compact. It's an older unit that bolts directly to the bell housing and I'd like to keep it that way with a remote control console and portable pump that can be connected to a small tank like a minibulk.

As far as data capture and logging will start off with a simple load cell, rpm MAP and MAT connected to a Wideband O2 with onboard logging and a laptop "dash" to make sure the repeatability is achievable.
A lot can be learnt from those simple inputs, later I will hook up the data logging system I bought for my bike to add exhaust thermocouples. Data is good if your going to use it to make a decision, if not it's just a bunch of numbers.

The price of decent electronics these days makes getting a decent measuring and data capture/analysis system pretty achievable if you can get the load control accurate and more importantly repeatable.

I have read the book you mentioned, I've let someone borrow it and can't remember who it was, it has a yellow cover, it wasn't James that borrowed it though.

Point 5 is going to be the hardest for me to address, I think my Dyno cell will often be really big with a blue roof, it has good ventilation but it gets wet when it rains.

Have you use the DEPAC gear at all?
I don't intend on throwing megabucks at this but they do claim to be able to produce good load control within my budget.

Thanks
jon
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« Reply #3 on: April 07, 2013, 08:51:13 AM »

Jon,

I have had the occasion to use 2 Depac equipted systems.

In the early '90's I consulted on a Depac equipted Go-Power for low bhp, low rpm 4 cyl engines.   (F/Ford & S/2000)   It was an early (?) version with a hydraulic torque gage.   It had repeatability problems from the hydraulic sytem, and the owner occasionally used it for V-8 testing.    It accumulated data fine, but there were accuracy & repeatability issues the owner could not afford to solve.    Using my Superflow 901 as a baseline for accuracy & repeatability, his system could not match up.    Eventually the repeatability boiled down to the hysteresis in the hydraulic torque sensor.    The repeatability got better (+/- 1%) but was not as good as the SuperFlow (+/- .5%)   The absorber was older & well used, and probably needed to be rebuilt.    The SuperFlow used for comparison was less than 5 years old @ the time.

Recently, I have been consulting on another Go-power/Depac sytem.    The Depac system is newer and accumulates more data.   The owner is in the process of updating the torque sensor from hydraulic to electronic, which will solve most of his problems, similar to those above.    But again, the absorber is older and well used, and probably needs to be rebuilt/refurbished for better repeatability.

I am also aware of a very sophisticated set-up of Depac equipted dynos/cells used for engine development for a professional race series.    I have never had access to the facility, but know the guys who run it.   Their engines are very successful, and they are very happy with their set-up.

What it boils down to is this:    Your dyno is just another tool, albeit a sophisticated & sensitive tool, but ultimately no different than a trick torque wrench.    It needs to be accurately calibrated, used carefully, and it needs periodic maintenance.    But it is just a tool, none the less. . . . . . .
 cheers
Fordboy

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« Reply #4 on: April 07, 2013, 01:57:06 PM »

Thanks Fordboy

No horror stories on their load control is good.

I've got one of their ADL-LITE systems coming.

The absorber I have is old but done very little work, it was used at a small technical college in a remote mining town.
When it was closed down the teacher bought it and it sat under his bench for years.
The stator and rotor still have the casting marks in them and show no signs of cavitation, it will get new bearings and seals as part of the tidy up.
I was originally going to go a hydraulic pressure transducer but now going to fit a temperature compensated S type strain gauge. Your info confirms that is the right way to go.

Thanks for your help.
jon
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Jon
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« Reply #5 on: April 08, 2013, 02:35:23 PM »

Interesting email conversation with David from DEPAC.
One of the things he pointed out to me was the base measurement design of the Go-Power unit I have.
The measurement is taken from two small rams, one either side of the trunnion bearing, they tee into a common line which goes the gauge on the original console.
This arrangement balances the forces across the trunnion bearing, going to a single load cell will get rid of this balance and work the bearing much harder.

This along with the other advice he has given me makes a lot of sense, I will be refurbishing the rams and measuring load with a high spec pressure transducer.

Cheers
jon
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Bob Drury
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« Reply #6 on: April 08, 2013, 04:20:37 PM »

  Fordboy and Jon, 
    I thank you both for having a great, entertaining and informative discussion about Dynamometer's on our site.
   Although I only read as a novice, I eagerly absorb (or at least try too) the information that you both provide to us mortals who while understanding the concept of "Dyno's" don't really know much about how they work or how they can register information different from other "Dyno's".
   What I have enjoyed most about this discussion is the lack of animosities, ego's, and chest pumping that normally occurs on this and other "race oriented" sites in regards to the technical side of racing (which means a lot to those of us who live in the sticks when it comes to the latest tech info).
   Everything that has been asked on this post has been answered with clear, consice information, and for that I salute you both.............
                                                      Bob (who while he may still be stupid, still tries to learn).........
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Bob Drury
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« Reply #7 on: April 08, 2013, 08:49:58 PM »

   Bob,
   Me X1. When we stop learnin' we ain't livin'.
   Doug  cheers cheers cheers
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« Reply #8 on: April 09, 2013, 10:58:42 AM »

Jon,
Having worked in hydraulics for 30 years I can only advise that if you want a system that is accurate (+or- .1%) and repeatable don't use hydraulics. The potential for hysteresis and non repeatability at the accuracy level you may want is almost a given where as a straight forward strain gauge will provide great accuracy and is easily calibrated via electronics. Not being knowledgeable of the details of your dyno, I can't comment on the exact application of a strain gauge to your set up but I would think that you would be ahead to strengthen any areas that are compromised by going with a strain gauge rather than using the hydraulics.

That being said, if you are still going with hydraulics I have some very nice and unused pressure transducers that I can include in the box with your air valves. Let me know the pressure range.

Rex
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Jon
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« Reply #9 on: April 09, 2013, 02:04:41 PM »

Thanks guys
Bob & Buickguy: I'm constantly humbled by the knowledge and help available on this forum, it is very cool.

Rex:
I'll give the hydraulics a crack as I have all the parts other than a transducer, it will need a service before using.

If I was trying to measure position I would be very worried about the hydraulic system, pressure not quite so much (probably because I'm naive) but would really appreciate you knowledge and input.
Ram is probably the wrong description, the hydraulic pots have bellows diaphragm, they have a single acting linkage to the absorber (push only).
There will be some stiction on the plunger seals and the roll action of the bellows.

If the results aren't what I'd like then I will change it, I'd really like to keep it compact so that its easily transportable, I sketched up a balance beam arrangement to take force from both sides of the absorber and feed into both ends of a strain gauge, do-able but complicated.

One of the bits I'm missing is a calibration arm, I have one coming from Go-Power, any accuracy and repeatability issues should be highlighted quickly at lower forces.

I have a transducer coming from DEPAC for the Dyno, I would be interested in some transducers for my datalogging gear though thanks if you have some available, I'll email you.

I'll post up a pic of the trunnion and pressure ram area of the absorber unit shortly.


Thanks
jon
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« Reply #10 on: April 09, 2013, 02:33:01 PM »

Please excuse the state of this, it's not as bad as it looks, honest......
When I bought it I checked the condition of the rotors and stators through the ports, gave it a very liberal dose of silicone spray, a couple of shots of grease and put it under my build table so as not to get distracted. The red stain is genuine Weipa/Cape York dust (most of the way up the pointy bit on the top right corner of Aus), its still an Aussie adventure to do a "Trip up The Cape".

Trunnion and hydraulic pots.

The whole absorber is supported on this bearing, there isn't a support at the back, the hydraulic pots being diagonally opposites balance the load in the bearing.


I will be giving the unit a birthday and upgrading to automatic load control and a very simple data logging interface over the next month, if people are interested I will put pics etc up here.
I don't need the Dyno now as I'll run the motor standard until I have me and the bike sorted some, it's got a higher calling for a while though.

Cheers
jon
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« Reply #11 on: April 09, 2013, 03:45:03 PM »

A couple of pages from the Operation Manual:



There are no seals on the piston stem, it runs in two Oilite bushings.

Cheers
jon
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