home made water brake

[DaveMcLain]

Back when I put the dyno setup together I bought the brake from Land and Sea along with the Dynomite computer, load valve and computer software. Dick at Land and Sea was very helpful and he gave me a lot of advice when putting things together. I don't have a whole lot of money so rather than buy I had to build whenever possible, he understood that and he sold me just what I needed. Their stuff isn't really cheap but I was able to put the dyno together and have it operational for about $8500 or so and then later I added some options as I could afford them, EGT probes, air flow turbine, automatic load valve etc.

Their stuff has really improved quite a bit since I bought mine 6 years ago, the little dyno computer which is very cool, is now more powerful with more channels, faster processing and even better servo controls.

[99-1134301289]

hello, I do not understand how the Land and sea water brake functions on a stuska the body turns on its axis and a lever transmits the engine torque on a load cell hydraulic or electronic I do not see a lever on the Land and sea how it functions.

[DaveMcLain]

The Land and Sea absorber has a torque arm bolted to it's front side you can see it sticking up next to the ignition coil in my installation. It's just a flat piece of aluminum, anodized red with a strain gauge. It sticks up and hits against a stop which resists the rotation of the absorber and when it does this it causes the torque arm to deflect and this is registered by the strain gauge. All in all, this system is quite simple and foolproof.

Without the torque arm the absorber could just rotate around with the engine rotation, turning along with the shaft.

Most people are amazed at how much load you can place on the engine with the dyno and the absorber isn't all that large either. The water really shoots out of the drain hose and that's fun too. I need to get some video of that one of these days when I'm running an engine, attaching the end of the hose to a weight is an absolute must. HOT water shoots out for probably 75ft or more when you hit it with an engine with some horsepower. You can change the drain rate of the absorber with an orifice that screws into the outlet in order to load engines with a smaller water supply. I don't do this, I run mine wide open since it's more responsive and the absorber runs cooler with more flow.

[gofaster]

Dave,
Thank-you for all the detailed photos aand text explanations! You are making the home built dyno look more possible/doable for me, now. But first I need to get the flowbench finished.
Thanks for taking the time to post it up.

[DaveMcLain]

I really think that a homebuilt dyno setup that's similar to mine, mostly home made with a few key components that were purchased is within the reach of a lot of folks, probably more than they realize.

Most people who have seen my dyno in action are quite amazed actually at how functional everything is, simple but quite effective. Smart shopping can go a long way, for instance I use a 21 inch flat screen CRT monitor on my dyno PC(the one that records the data) and it's great because the real time gauge readouts are very large and easily read from across the room. I bought the monitor as a re-ferb for $75 from Tiger Direct!

Go to the dyno pull video thread and you can see a pull on my dyno. It was a sort of rainy day, note the Ford pickup project in the background. We were running a 650 horsepower engine that day. Notice how at the end of the pull the cooling tower dumps hot water through the yellow hose and how the servo load valve picks up the engine and keeps it at the hold rpm till I start the test. Not the best video in the world, the guy shooting it was standing behind me, note my back etc, but the sound is very good, it's incredibly loud see how I'm wearing hearing protection at all times!

[99-1134301289]

hello, here what students one manufactured I think that it is the same principle which a Land and sea

[bruce]

After looking at that link, it would not be all that hard to machine up the parts for a water brake like that. The case appears to be just machined out of billet alum with no internal fins so that would not be hard to machine. The rotor could be setup on the rotary table and machined (I lack CNC so I have to do it manually) I'm sure for someone with CNC it would be a peice of cake! Any ideas on the placement of the water inlet/outlet holes?

[Mattz Larsson]

Does you have pictures of the inside of the water brake

[DaveMcLain]

I don't have any pictures of the inside of the water brake but the rotor looks just like the one in the drawing that's in the link above.

On the Land and Sea brake the water enters through a -16 fitting that goes in just above where the shaft comes through the rear bearing. Then there is a vent, about a -4 line clocked at about 2:00 if the inlet is at 12:00. The outlet is about a -8 and it's mounted on the bottom of the housing and angled in the direction of rotation. The housing is actually made from 4 pieces, two end plates with fins milled into them and two open sections one of which has the water outlet. It's all sandwiched together with about 12 little allen bolts around the outside with O rings sealing the sections.

[ddelzel]

[bruce]

Check the link CRE posted earlier in this thread, it shows a DIY water brake dyno inside and the "math" that goes along with the design. This design doesn't appear to have fins on the outer housing though.

Looking at the pics one can easily reverse engineer the machining part of it.

[Tony]

It seems a fairly simple design that could be sand cast in aluminium. That would eliminate a lot of milling, and a lot of waste material.

The various parts would still need to be turned on a late in order to seal and fit together properly. But the rotor fins could be just be a casting rather than individually milled from solid.

[gofaster]

Can anybody offer any insight into ballpark sizing of a unit like this as it relates to horsepower/torque capacity? I checked out Dave McClain's photo site, and the absorber looks tiny next to the monster motors he plays with! Great effort, Dave, I really enjoyed the drag strip and speedboat clips! (Boat racers are a brave breed)

I looked at Stuska's site, and their absorbers make huge capacity jumps as the sizes increase. I was seriously considering a used Stuska in the 200 h.p. capacity size, but I think that it would be too limiting as engines in my field are getting much more powerful. A few years back I would have thought 200 h.p. capacity would be plenty, but not any more.

I hope I didn't miss something in the archives, but basically I want to know how to figure what diameter would work for a given h.p. range.

[bruce]

If you look at the link posted by CRE earlier in this post you will find under "deliverables" there is a technical paper as a PDF file that shows the calculations for the impeller design.

I'll post the link:

If you enlarge the pics on that website link you can get a really good idea of how to reverse engineer what they built. Be sure to look at all the pics they posted. The thumbnails view as a larger file if you "view image"



Edited By bruce on 1163520121

[gofaster]

Larry,
Thanks for sending me in the right direction. Now I understand why the size changes bring such large capacity increases. It's all about volume, mass, and inertia of the rotors.

Thanks