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PostPosted: Sat Nov 26, 2011 2:35 pm 
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Yesterday, I had an opportunity to participate in my very first engine dyno run. While not for my Locost, it was still educational. A friend had just rebuilt his Formula Vee engine and we went to another's house where there he had a vintage analog water-brake dyno in his garage. It took us several hours to set up the engine on the stand. Then we had some ignition problems to sort thru. We finally got the engine running for the first time after the rebuild. We did get a chance to warm up the engin and do a couple of data points to learn the system before having to shut down due to time constraints. They will have to go back and complete the full dyno runs on another day.

I won't go into just how it works as some of you may already know this. For me it was an education. However, if you want to know more, I'll try to explain the setup and how it works. It is a real basic, easily understood system.

All in all a very educational and intereseting day. Just though I'd share.

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PostPosted: Sun Nov 27, 2011 12:59 pm 
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Sure, tell us more. Dynos are essentially very simple devices. You put power into something like a water pump and then measure how hard the pump is trying to twist in it's mounting. You could use just a freight scale or nowadays the type of electronic strain gauge used in electronic scales that you see everywhere.

Engine stand dynos are ideal for doing real engine tuning work. Those guys couldn't care less what your car looks like. Ownong your own setup means you can be as honest with yourself as you want. :)

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PostPosted: Sun Nov 27, 2011 1:04 pm 
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rx7locost wrote:
... we went to another's house where there he had a vintage analog water-brake dyno in his garage...

Wonder how that plays with the neighbors.

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PostPosted: Sun Nov 27, 2011 5:49 pm 
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The dyno he has is a water brake dyno. It has an impeller with vanes that is directly coupled to the crankshaft via a modified driveshaft. The dyno housing also has vanes. The water/antifreeze acts as a viscous coupling between the two, the amount of water in the dyno cell (brake) controls the amount of torque loaded. The brake is pivoted about its center and has an arm which is attached to a hydraulic cylinder mounted to the frame. From the cylinder, a hydraulic line goes to the pressure gauge on the console. It is calibrated such that you multiply that reading x RPM /1000 to get HP. There is a tachometer on the driven shaft to monitor engine RPM. Think of it as a bucket with a hole in the bottom. The bucket drains at some consistent rate of flow. Then take a hose and try to fill the bucket. The more water you let in, the more water is in the bucket (the water brake). Slow down the flow and the water in the bucket lowers. This is how the dyno applies more or less drag on the engine.

Since he uses the dyno mainly for his Formula Vee, the engine stand is simply a stripped out transaxle housing with an input shaft attached to a short driveshaft connected to the brake. Mount the engine under test to the housing, attach all the fuel, throttle, cooling fans and various engine sensors and away you go. That takes about 2 hours setup time.

Rather than using a waste water system, He uses a closed loop system. A 55 gallon drum is filled with water/antifreeze mix. Then, there is an electric pump to pump the water from the drum into the brake, controlled via a flow control valve on the console. More flow, the more the brake fills and the more torque applied. The drain water from the brake falls into a container that has a sump pump which pumps the water back into the 55 gallon drum. The engine’s energy has to go somewhere. In this setup, it heats up the water. There is a temp gauge to monitor the drain water. If it gets above 140deg, it is too high and may boil. If it does boil, the engine’s RPM takes off since the test is done at full throttle. Not a good thing to have happen especially if you are taking measurements at, say, 6,000 RPM.

The control console has a RPM gauge, torque meter, water flow indicator, drain water temperature gauge, oil pressure gauge, Cylinder head temperature gauge, and a few other gauges which we did not use. It has a throttle lever and the flow control lever for the water brake. Keeping an eye on all of the gauges while trying to hold full throttle and control the load of the brake, read and write down readings at once is a bit daunting.

To perform a dyno run, it is simply warm up the engine, and then open the throttle while applying more and more torque till you have the throttle fully open and the engine loaded to 3000RPM. Try to hold that RPM using the flow control. When you have a stable RPM, take a reading and record. Then back off the flow and try to hold 4000 RPM…. Repeat as required; all the time checking the drain water temp and the oil pressure and head temperature and; and; and so you don’t accidentally blow the new engine.

As for the neighbors complaining, well, he is about 100 ft back from the highway. Next to him is a funeral home. Nobody was being waked at the time. And across the highway is a nursing home. In over 30 years there he has never had any complaints. I guess it wouldn’t be welcomed in a “normal” subdivision.

It was certainly a good education for me.

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Check out my rotary build log: click here


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PostPosted: Sun Nov 27, 2011 9:17 pm 
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We are Slotus!
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Quote:
Next to him is a funeral home. Nobody was being waked at the time.


Well, thank goodness for that!!! :shock:

:cheers:
JDK

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PostPosted: Sun Nov 27, 2011 11:05 pm 
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Possible Zombie movie???? Must eat COOLANT!!

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PostPosted: Sun Nov 27, 2011 11:15 pm 
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We are Slotus!
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Locost Pictures presents, a Slotus Production, in Living Techno-Black and White.... (Drum Roll...)

The Creature From the Water Dyno!


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creatureblacklagoon.jpg
creatureblacklagoon.jpg [ 53.73 KiB | Viewed 1081 times ]

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Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom
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PostPosted: Mon Nov 28, 2011 3:34 am 
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Location: Edmonton, Alberta
rx7locost wrote:
The dyno he has is a water brake dyno. It has an impeller with vanes that is directly coupled to the crankshaft via a modified driveshaft. The dyno housing also has vanes. The water/antifreeze acts as a viscous coupling between the two, the amount of water in the dyno cell (brake) controls the amount of torque loaded. The brake is pivoted about its center and has an arm which is attached to a hydraulic cylinder mounted to the frame. From the cylinder, a hydraulic line goes to the pressure gauge on the console. It is calibrated such that you multiply that reading x RPM /1000 to get HP. There is a tachometer on the driven shaft to monitor engine RPM. Think of it as a bucket with a hole in the bottom. The bucket drains at some consistent rate of flow. Then take a hose and try to fill the bucket. The more water you let in, the more water is in the bucket (the water brake). Slow down the flow and the water in the bucket lowers. This is how the dyno applies more or less drag on the engine.

Since he uses the dyno mainly for his Formula Vee, the engine stand is simply a stripped out transaxle housing with an input shaft attached to a short driveshaft connected to the brake. Mount the engine under test to the housing, attach all the fuel, throttle, cooling fans and various engine sensors and away you go. That takes about 2 hours setup time.

Rather than using a waste water system, He uses a closed loop system. A 55 gallon drum is filled with water/antifreeze mix. Then, there is an electric pump to pump the water from the drum into the brake, controlled via a flow control valve on the console. More flow, the more the brake fills and the more torque applied. The drain water from the brake falls into a container that has a sump pump which pumps the water back into the 55 gallon drum. The engine’s energy has to go somewhere. In this setup, it heats up the water. There is a temp gauge to monitor the drain water. If it gets above 140deg, it is too high and may boil. If it does boil, the engine’s RPM takes off since the test is done at full throttle. Not a good thing to have happen especially if you are taking measurements at, say, 6,000 RPM.

The control console has a RPM gauge, torque meter, water flow indicator, drain water temperature gauge, oil pressure gauge, Cylinder head temperature gauge, and a few other gauges which we did not use. It has a throttle lever and the flow control lever for the water brake. Keeping an eye on all of the gauges while trying to hold full throttle and control the load of the brake, read and write down readings at once is a bit daunting.

To perform a dyno run, it is simply warm up the engine, and then open the throttle while applying more and more torque till you have the throttle fully open and the engine loaded to 3000RPM. Try to hold that RPM using the flow control. When you have a stable RPM, take a reading and record. Then back off the flow and try to hold 4000 RPM…. Repeat as required; all the time checking the drain water temp and the oil pressure and head temperature and; and; and so you don’t accidentally blow the new engine.

As for the neighbors complaining, well, he is about 100 ft back from the highway. Next to him is a funeral home. Nobody was being waked at the time. And across the highway is a nursing home. In over 30 years there he has never had any complaints. I guess it wouldn’t be welcomed in a “normal” subdivision.

It was certainly a good education for me.


How long does he usually get before the water heats up? I've been looking into making an engine dyno with a stuska brake or a large torque convertor, but I've got to stay with a closed system as well, and my math was pointing towards gigantic tanks (500 gallons and up). Is it just because Formula Vee engines are fairly low HP, or is there a lot of downtime for water to cool while tuning?


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PostPosted: Mon Nov 28, 2011 9:52 am 
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I can't say for sure. We measured about 7 degrees rise in the barrel after about 20 minutes running. very little of that was at full power. I think the coolant barrel was ~ 1/2 full. A well sorted Formula Vee engine runs only about 55 HP from what I'm told. The water brakes are rated for TQ/HP. This one will only handle a max of 220 HP or thereabouts. Nothing says you can't run the return water thru a radiator or two to cool it off before going back to the barrel.

Gonzo, just where do you get these ideas? Your shrink must be on his 4th notebook (or 4th bottle!) by now! :cheers:

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Check out my rotary build log: click here


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PostPosted: Mon Nov 28, 2011 10:24 am 
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We are Slotus!
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Location: Tallahassee, FL (The Center of the Known Universe)
Quote:
Gonzo, just where do you get these ideas?


TWWTFM asks me the same kind of question, fairly often. I showed her your response, and she said that the problem was I didn't have a shrink, and therefore the rest of you have to suffer... She was kidding... I think...
"You were kidding, weren't you, Baby?" (Llllllooooonnnnnnggggg silence....)

Chuck, I apologize for stealing your thread. Can't help myself sometimes.
:cheers:
JDK

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Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom


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