Building a Water Brake

[Tony]

Quite a few ways for the hobbyist to go about casting a dyno rotor and stator combination A very good resource is the Backyard Metal Casting site:



And the associated Forum :



One way is to just fabricate a wooden pattern, and hand it to a professional foundry, and tell them how many you want. Not cheap though for a one off. But if quite a few people here get together and make this a Forum project, that could be an excellent solution !!!

Or you can build yourself a furnace and melt some scrap aluminium, and do it all yourself, practically for nothing. Without looking it up, aluminium melts at roughly 660 degrees Celsius, readily achievable in a fairly simple to construct home LPG gas furnace.

If you only want one rotor, you can very easily use the lost foam process. Foam is very easy to shape, and you can glue small pieces together like the rotor fins. Bury the whole thing in ordinary fine sand, and pour in the molten aluminium. It may take several tries to get one perfect rotor, but heck, it costs nothing and it is fun.

Many people are doing this type of aluminium casting at home, and getting excellent results. There is a wealth of knowledge and experience on that Forum.

I started doing this myself with the intention of eventually casting myself a water brake.
But right out of the blue, suddenly had the opportunity to purchase a whole chassis dyno complete with Telma eddy current absorber at a very friendly price.
So I never did build a water brake. Still have a small test furnace though.

[Dave W]

I could see it being cheaper but the time to make a mold get all the right stuff and hope it comes out right is worth the extra expense for me to just mill the aluminum. It will cost me about 400.00 bucks to have the brake with the shaft complete including the arm. I am debating to go with plastic bearings over the ball bearings. I have to call the company and find out a little more info on this set up then I'M going shopping.


Dave

[106-1194218389]

Dave,
If it was me I would mill my stuff out of billet. Especially taking into consideration you may want to dyno something in the 9000 + RPM range. I do not think I would trust something I cast myself to do that - I can't remember for sure but when we put new bearings in the Stuska brake it seemed like they cost a fair amount as the had carbon seals. Now it has been a long time but I will try to find out for sure, but our brake was spun to 9000 rpm at times as it was hooked straight up to the crank. I stood in the dyno room a few times not far from the engine twisted that high and it sure can make the old sphincter tighten up.

John

[Tony]

I bet it did !!

If I was going to cast something up myself, I would probably prefer to use bronze not aluminium. It is far stronger, and it will not corrode, or erode away from cavitation. I would probably melt down an old marine propeller.

I have rather mixed feelings about the suitability of aluminium, from several aspects. But the commercial water brakes seem to get away with it.

Yes, I would not trust an aluminium flywheel at 9,000 rpm. Or a cast aluminium dyno rotor for that matter. My application was to be a roller dyno peaking out at maybe 4,000 rpm.

[Dave W]

Its definatly possible in the future this dyno will see a 8-900 hp small or big block and somewhere down the line 9000 rpm might not be out of the question.

I looked at all different seals. If i go with a metal bearing the seals will be carbon-ceramic. If i go with Plastic bearing the seal will most likely be a lip seal.

The mounting to the engine will be a drive shaft type.

Dave

[Dave W]

The material will be 6061 Aluminum.

[bruce]

Have a look at this info on the Depac Dyno website:

There is also some talk on seals for the Stuska water brake:



Edited By bruce on 1224419765

[Dave W]

The seals they are talking about in depac are the carbon ceramic which is used in water pumps.

The drive shaft thing with that lord coupling is my intention but as always things change. I just don't want to do like my flow bench I want to build it once and have fun.

Dave

[86rocco1]

This is somewhat off topic but looking at simplicity of a Stuska water brake assembly, one can't help but wonder why they need to cost so much. True, the rotating assembly needs to be stout and well balanced with high quality bearings and seals but even so, they still seem really over-priced.

There are probably a lot of people that would like an engine dyno but consider it out of reach, if Stuska (et al) cut their price in half and changed their marketing focus to target those people, the increased sales might well offset the decreased per unit profit margin and increase their bottom line.

[bruce]

Humm, sounds like this forum and what we did with the cost of flowbenches ???

[86rocco1]

[Dave W]

I said the same thing . All the money is in the software and the data equipment. The little attachments that the dyno company's sells you are about double the price. Here is one for ya Land and Sea bearing kit for the 13" water brake around 160.00. Now just by looking at the picture they look like abec 1 single row ball bearing good to 10K, 25 bux and a simple lip seal just say 15 bux 80.00 your cost.

Your forum is killing the industry Bruce. Just kidding
I will be the guinea pig for this one since the this forum saved me mega bucks and time on the flow bench. I want to have this project done by the end of Jan. 09.

Dave

[86rocco1]

Only 7 minutes and you've already got your first sale, these things sell themselves! :laugh:

[Dave W]

[86rocco1]

But you can still build a perfectly functional water brake dyno without any electronics whatsoever. My friend's Stuska dyno is 100% mechanical, even the tachometer. If I think of it, I'll snap a few pictures the next time I'm over at his shop.