Hi,

For the servo, you should aim for max approx 0.5sec from min to max. This is if you want to run RPM sweeps. We use the valve from Land and Sea, and it probably takes 0.1-0.2 sec from min to max, it is super fast. 

Water brakes themselves are pretty slow to react because it takes time for them to empty or fill the chamber of water even if the valve reacts immediately. Therefore they can be tricky to stabilise in all situations (hard turbo boosts for example) when you do a RPM sweep. A good alternative is the Brake sweep, which starts off at a certain RPM, then slowly releases the brake or increases the brake. With this you can get nice sweeps, but it is not steady state capable. If you run this option the requirement on fast response of the valve is much less.

There are super nice servos out there with very high torque ratings but they get expensive. A setup with a stepper and a stepper controller is quite cheap, so you can check that out.

Hi,

Thanks for the reply. A Land And Sea valve will not work on this water brake, as it's an Froude water brake with two impellers that move closer together to generate more brake force.

I've been looking into stepper motors and I think that's the way to go. Have you got any recommendations for a stepper motor? 

That looks like a heenan & froude DPX series  maybe a dpx-3 ? , they use a sluce gate valve arrangment. The sluce valve isn't really a good design. Correct me if I'm wrong.

Indeed, it's a Heenan & Froude DPX series waterbrake. I don't know how the sluice valve design relates to other designs performance wise, but for what I'm aiming for it's sufficient. I'm only using the water brake to tune the programmable ECU and to break in the engine. At the moment I'm doing this by manually controlling the water brake and that goes surprissingly well. I would like to get some numbers though, and make tuning a 1 person job instead of the 2 persons we need now 🙂

@maikelvanuden

Hi, did you get an answer on a motor to drive your DPX3 sluice gate ? I have the same Dyno and would really appreciate any help with fitting a stepper motor - pictures of what you’ve done or any ideas would be gratefully received 

thanks

simon 

There is no reason why you can't totally remove the very old sluice gate of the dyno and fit a v_groove( slotted) global  ball valve arrangment of correct shape and size to control the load. Adapt a steppermotor to a v_groove global valve problem solved.

Water sluice gate valve ain't linear in operation , 1950's technology!

@mach_1

Thanks for response, so I assume that the valve will control the water input to the dyno and I just leave the exit valve open ? 
simon 

You need an adjustable output valve too, but this is a manual valve that you keep in one position after some trial and error. 

@admin

Does that need to be a special valve ? The current output valve is just a standard gate style which was standard fitment on the DPX dynos

if I am limiting the amount of water going into the dyno does that create some weird cavitation effects because it’s not full of water ? 
thanks for replies folks this is helpful 🙂 

No, any output valve will do :-).

Output valve position is set with a few things in mind:

• Small opening = faster filling (= faster torque ramp up), slower torque ramp down, possible water heat problems
• Large opening = opposite of above, plus lower possible max power (brake will never be full)

You need to experiment a bit.

That makes sense thanks, my water brake was upgraded by Heenan and Froude specialists in the 1990’s to run up to 7500 and 300hp - I am only using it for engines in the 70 to 130hp range so it won’t be overstretched 

simon 

As Admin suggested the the h&f dpx series engine dynos were made way back in the 1940s and 1950s era. You will be experimenting to get the right valving to work.

I had a dpx back 30 years ago, they were bitches to run .... the threads didn't turn nicely lol on the gate valve. 

Keep us all posted how you go about the conversion BW03734 ? I think i still have the factory manual for the dpx somewhere at work. But the sluice gate valve was one hideously ugly setup but i guess it worked  back on the 1940s'&'1950's.

Just thinking out allowed... leave the sluice gate full open and fit a v-groove global ball valve after it??? I'm going to dig out the factory manual and have a closer look.

@mach_1

thanks ! Appreciate the help