Really nice work, I am eager to see it in action!

Welcome to the forum Andrew, very nice work and subscribe to this thread with interest. Keep the updates coming! What part of Australia are you located at?

After reading your posted blog , what did you model you stator/rotor vanes on ?

The rotor/stator design isn't anything particular, the concept in all of them is the same so I went for something easy to build for a relatively small cost.

There is not much solid data for home built water brakes so if this is a success there will be some actual measurements and design notes to build off.

The brake will work, the question is weather it is responsive,how much water it needs etc. I have a full machine shop so I am lucky to be able to try things and build them to a commercial quality, however the design requires no special machines and could be copied in the home shop with minimal help from a machine shop. Hence the Blog, I really hope it helps people thinking of doing a build.

Ok , cropped ends on the rotors isn't good idea.  Unless you are planning to turn the grey motor 10,000rpm plus ? You will have buggeral sensitivity down in the rpm range, if any! 

I read a few of your other blogs. I see your in Victoria. 

What waterbrake stators/rotors have you actually  seen?

Superflow 801,901 example is a better shape with cups , cropped ends is good for VERY high speed application  heaps of slippage.

My mobile phone did something silly  , meant to say

heaps of slippage around 5500 -6000 rpm before even the dyno can load up.

Mach_1 Interesting stuff, but there are too many variables to say "cropped" ends are not a good idea, like water control, vent size and location, water inlet and outlet ports, diameter etc. There is no way of knowing (even with CAD and fluid dynamics software) how the complete system will perform until it is actually tested in real time. I have the capability to build any design I can dream up, throw a billet of alloy in the VMC and carve it out but I chose to fabricate because it is cost effective and it is more in the reach of your average DIY builder.  No, it wont be the best and most efficient brake but that is not what I am trying to build. If you have some good solid data of a complete DIY system (measurements pictures etc) please share. Yes my dyno may have inherent problems or even be totally unusable, but I will find out and table it save others the same mistakes.

Cheers

Maybe you misunderstood when i ment slippage ( dyno efficency ).

Let's  say hypothetically your hotted_up holden 6 cylinder grey motor 138 cu,in produces 200ftlb of torque at 4000 rpm  and 300bhp@5700rpm. A cropped end rotor the water brake dyno will not hold it! You will not be able to apply a load. It won't even hold a BBC 454 that produces 500bhp@6700rpm.

A heenan&froude GB4EH water brake engine dynonameter  has a cropped rotor and is rated at 1000+Bhp@12000rpm.... if your holden 6 cylinder grey motor was coupled up to this engine dyno. The dyno wouldn't be able to load that 300Bhp@6500 rpm at all.

I can assure you of this. I have a h&f GB4 ( which has special shaped cup rotor ) and a h&f G490EH ( which has a cropped rotor).

Do you know how the water travels around inside the water brake?

Heres a picture of a superflow 901 water brake stator housing.  Superflow has been around since 1970's, H&F have been around since 1880's so i guess you know who superflow copied. But have a closer look how the cup vanes are shaped. 

Regardless you have time and access to machinery. The R&D has already been done by others. I'm just putting my 2cents in. Not meaning to pick on your ability or railroad your thread.

I understand what you are saying and it may be valid in your experience but the issue may be specific to your dyno setup. Early Superflows did have the open rotor design and are very capable of good results on small engines. In essence the fluid flow in the two designs are almost identical with the cupped design being more efficient.  There is a good paper titled "Design development of Dynomometer water absorber" by Karlis Banis.  Yes all the R&D has been done BUT until someone writes a definitive paper on building a DIY water brake we don't have access to any useful data. Measuring a commercial unit is fine but in reality most people don't have access to the equipment to build a copy of one, or the power and water required to run one. So if you or anybody has a set of drawings and some data to show the capabilities of  there DIY water brake please post it. I appreciate your input tho

Ok Andrew , will watch your thread with interest.

Which Superflow  water brake absorber engine dynamometer has cropped rotor(s)?

Several guys on this forum http://forum.savarturbo.se have experiment with " Homemade Water Brake Engine Dyno " unfortunately it's in Swedish language and google website translater is you best friend. It was many many! Years since i searched on that website so sorry can't give you a direct link to the exact post(s).

But keep the updates coming. Will be interesting.

Yes i have read Karlis Banis's paper before. Just a thought , since Karlis Banis study involve 21 dynos and varying  many parameters to see what design changes influences affected the water brakes operation shoot him a email. His listed his email address on the paper k.banis@yahii.com . Outline what you are trying to accomplish  and what engine(s) you plan to test FTLB@RPM and Bhp@RPM.

Maybe Karlis will asist and share some valuable information?

Would be nice to get him on this forum!

Thanks for sharing Andrew, some great work and information there. I'm embarking on a similar voyage and have produced the drawings in CAD for casting and machining a brake. I was given a Clayton chassis dyno in near new condition but the brakes aren't rated very high so I'm going to replace that.

Cheers
Jay

My Froude FO209 have croped rotors

I am not happy with that under 2500rpm max was 150N/m