Can you give more details about the water brake dyno you have make/model and what exactly do you hope to accomplish with you engine dyno setup???

I'm sure there are people on here who can answer specific questions you have??

I got a waterbrake dyno if there was anything you wanted to know about my setup id be happy to share.
https://www.youtube.com/watch?v=jOUd8EBPkBQ

Is there anyway you can call me?

Posted by: Mach_1

Can you give more details about the water brake dyno you have make/model and what exactly do you hope to accomplish with you engine dyno setup???

I'm sure there are people on here who can answer specific questions you have??

 

It's a patraco mark 3 water brake Dyno for motorcycles and ATVs up to 200hp...the Dyno was originally designed to run off a garden hose..the previous owner switched it to a self contained unit with a pump...the problem is anything over about 20hp it blows through the brake...brake will hold a function correctly on lower hp motors..my main question is how fast does a water gotta spin to function right? And how is the water brake supposed to be plumbed? Will it ever work as a self contained unit?

Hi, 

My experience with water brakes (hands on with our a land and sea unit capable of about 1000hp, plus discussions with a number of people). 

1. Brake force is given by the fill level and the RPM (i.e. not by the valve opening directly).
2. Brake force is very dependent on RPM. At low RPM the brake force is low, and then it increases very rapidly with RPM until it kind of flattens out. 
3. Water brakes generally can take very high RPMs (10,000 and more is not uncommon)
4. You control the input valve. The output valve is either a fixed valve (most common) or a valve that goes opposite from the input valve (= faster response)
5. Water brakes need something like 20-40 PSI dynamic pressure (i.e. pressure with valve fully open!). More HP means you need more dynamic pressure. We have a 3kW (!) pump on our brake. I have heard people use even higher. This may be over doing it(?) but it is important that the brake is not starved for water when you open the valve
6. Static pressure should not be too high, so you need a pressure regulator
7. We used an accumulator tank in addition to the pump, but found it did not make a big difference
8. You control the input valve, which gives the fill rate, but brake is dependent on the fill level. The brake force is also very non-linear. This means that the control is more complex than an eddy brake. 
9. A water brake PID regulator needs a Kd > 0 (due to be above) to be stable in most conditions. This parameter is typically 0 in eddy brakes.
10. It is possible to make a self contained unit. 

To test what your brake is good for, just close the output valve or just leave a trickle, have the inlet valve fully open so the fill level is 100% and floor it (not for long or it will heat up!). If your brake cannot hold the engine RPM, then the only thing you can try is maybe gearing it up. If it holds, then you can start working on the plumbing, valve, pump, etc. 

Posted by: admin

Hi, 

My experience with water brakes (hands on with our a land and sea unit capable of about 1000hp, plus discussions with a number of people). 

1. Brake force is given by the fill level and the RPM (i.e. not by the valve opening directly).
2. Brake force is very dependent on RPM. At low RPM the brake force is low, and then it increases very rapidly with RPM until it kind of flattens out. 
3. Water brakes generally can take very high RPMs (10,000 and more is not uncommon)
4. You control the input valve. The output valve is either a fixed valve (most common) or a valve that goes opposite from the input valve (= faster response)
5. Water brakes need something like 20-40 PSI dynamic pressure (i.e. pressure with valve fully open!). More HP means you need more dynamic pressure. We have a 3kW (!) pump on our brake. I have heard people use even higher. This may be over doing it(?) but it is important that the brake is not starved for water when you open the valve
6. Static pressure should not be too high, so you need a pressure regulator
7. We used an accumulator tank in addition to the pump, but found it did not make a big difference
8. You control the input valve, which gives the fill rate, but brake is dependent on the fill level. The brake force is also very non-linear. This means that the control is more complex than an eddy brake. 
9. A water brake PID regulator needs a Kd > 0 (due to be above) to be stable in most conditions. This parameter is typically 0 in eddy brakes.
10. It is possible to make a self contained unit. 

To test what your brake is good for, just close the output valve or just leave a trickle, have the inlet valve fully open so the fill level is 100% and floor it (not for long or it will heat up!). If your brake cannot hold the engine RPM, then the only thing you can try is maybe gearing it up. If it holds, then you can start working on the plumbing, valve, pump, etc. 

Going off the brake rpm on Dyno software it's only turning about 800rpm at the rollers...the brake is a direct drive off the roller..i could very easily add a jack shaft and gear in higher if that's the issue..so the brake doesn't need a gravity drain?...is there anyway I can call you??

One I use doesnt really work until 2000rpm being hooked up to the crank which makes diesel engines quite hard to dyno since thats where there power is coming on. Will hold a 1000HP engine at 9000rpm easy but struggles with a 1000hp engine thats only turning to 5000rpm.

Runs 40-50psi from a 2kw water pump thats pulling from a big water tank outside the workshop that works to cool it.
Flow/load is controlled by a manual ball valve since its running on a old stuska system.
Then dyno drains out to a 40L tank thats below the brake before a 2nd small pump takes it back to the main tank.

Its mainly my bosses project so he knows the thing instead and out since I stick to the rolling road dyno.
I could posiably get him willing to talk to you over the phone but would have to work out a good time that works with both our timezones.

Little bit of a update...I am running small single cylinder Motors...I was trying to make the pulls in 4th..I just tried again in 5th and then in 6th..the water brake  is definitely alot more effective in 6th than in 4th..could it be that I'm just not spinning the water brake fast enough??? The wheel speed on these bikes are only about 50mph in 6th gear at 11k rpm

Sounds indeed like you need to gear your pump up. This is very effective on water brakes! 800RPM is way too low for most water brakes. 

Find me on facebook at Jostein Fonneland and we can have a chat on Messenger, evening time CET is best.

Posted by: admin

Sounds indeed like you need to gear your pump up. This is very effective on water brakes! 800RPM is way too low for most water brakes. 

Find me on facebook at Jostein Fonneland and we can have a chat on Messenger, evening time CET is best.

I sent you a friend request on Facebook..