[KA67_72]

I'm starting this thread to continue the discussion from the "Engine Test Stand" thread we were hijacking.

I put water in the brake today. It's was leaking everywhere. Venting it helped most of it. I think a little Teflon and some hose clamps will fix the majority of the rest but it looks like the shaft seals are going to leak some. Completely full, it seems to be stalling my na SBC at around 2000rpm. Megatune kept locking up. I put 6 inlets and outlets for both sides. It has a double sided rotor and two stators. My intent for all the fittings is to be able to experiment with computer controlled load with multiple valves and to possibly recirculate the water through a cooling system. I think the way I have the hoses routed from one fitting to the other right now may be reducing the load by allowing to act more like a pump than a brake.


Watayahknow,
To answer your questions: I tried working on other people's stuff but wanted to work on my own and it's easier and more profitable to just get up and go to my day job. My intent was to make money to by tools to build and eventually sell my own parts. I just decided to go ahead and buy the tools. I've spent the past couple of years trying to learn how to maintain and operate the 5 axis machining center I stuffed in my garage. The Quad Turbo runs but I have some oil return issues with the lower turbos to sort out. My plan is to finish it when I have parts to show off.


Kevin

[KA67_72]

I need about a 20ft throttle cable. Do you guys have any suggestions as to where I can get it by the foot? I was thinking marine stuff would work great but be pricey.

Thanks,
Kevin

[KA67_72]

I have a 26' Teleflex on the way. $16 new on ebay. I did some more testing yesterday and couldn't get the water back out of it. It turns out I was completely wrong about how and where pressure would be generated in the brake. Today I added a couple ports on either side of the rotor perpendicular to the shaft on the bottom. It comes out now and was able to get the motor to rev past 1700 rpm. I'm trying to combine the data from the OPTO and Megasquirt because I don't have the RPM part working on the OPTO, but I do have torque readings. This pull was part throttle from 2000-4000 rpm. It has a carb with Megasquirt running timing right now. I think the dips are where it needs more timing.

Kevin

[dtracy]

Kevin,

Try the local bicycle shop as they sell brake cable and housing by the foot. I have used if for throttle cable and it works very well.

Dave.

[KA67_72]

Dave,
Bike cable was my original plan, I've used it on a car as well, but I was able to find a 26' long marine throttle cable really cheap on ebay.

Thanks,
Kevin

[gow589]

Kevin did you build that from plans?

[KA67_72]

Gow,
I started from scratch. I drew the brake in cad and had it laser cut. The rest I did on the fly. This brake is my first attempt. I already have some ideas for the next gen. I will most likely mill the next rotor from solid steel and cast the stators from aluminum. My intent is to make them easily stackable as my power requirements go up. The next one will probably be smaller but it seems the volume (about 2 gal) of this one may let me run it with less water flow. We'll see how much steam it makes when I try doing some steady state testing under boost.

Right now I'm working on electronics. I'll reiterate some of our previous PM to bring others up to speed. I'm planning on building a microprocessor based card to do all my I/O with a single GUI, but while I'm learning, I have a kluge of stuff. I'm using a Megasquirt-II to datalog from the engine. I have an Opto 22 ether I/O to collect torque, RPM, and MAP. I'm planning on using a DATAQ di-148u to collect 8 egt's. The Opto and Dataq can easily be combined in Excel.

I've spent the past few days trying to sort out collecting RPM. I have a LM2907N ( http://www.ti.com/lit/ds/symlink/lm2907-n.pdf ) using the minimum component tach circuit. I've tried it with an inductive clamp and a VR sensor pointed at different rotating things. Both were erratic. Now I have a trigger on the back of the brake and am getting a steady signal I just need to calibrate it. I'm about to just stick a dc motor on the back and read voltage off of it. If anyone has any simple ideas to convert RPM to 0-10vdc let me know.

Kevin

[gow589]

You might need a de-bounce circuit.

I think I told you but I used the PAK VII chip to measure pulses. It worked well for RPM. I was actually able to read PWM from radio controlled airplane receivers using it.

With the PAK-VII (and other time chips can do this as well) I was also using this to measure timing measuring the difference in time from the crank trigger to the spark relative to RPM.

The problem I had is it worked briefly on the actual engine because I don't have the spark induction isolated enough. It was locking up my USB interface. What I needed was an opto-isolater....at least that was the next thing I was going to try.
So from that I would look at de-bounce and ops-isolators.

[gow589]

http://www.awce.com/pak7.htm

[KA67_72]

I hadn't seen that chip before. I'll have to read up on it.

[gow589]

I guess my question with that for you would be can your software communicate with something such as this instead of reading an analog input? This would communicate with serial communication which would basically ask the chip what was the last high or low duration on pin 0-7 (8 channels in total).

If not you could use say an Arduino to do the communication with the chip and sort out the details then return with an analog output value it could read.

Infact if you google "aurduino rpm" you'll come up with MANY ways to read rpm which may be easier then the PAK VII. With the arduino you could pick up a several inputs your program could not process and output them digitally or analog.

[KA67_72]

I got the RPM working and my throttle cable showed up. Here's a short clip.

http://www.youtube.com/watch?v=uNIpUZEDa-c

Kevin

[mercmad63]

I notice you have no way to adjust the load ,did i miss something in the pics?
Also, you need gland seals on your shaft to cope with the pressure .
. Froude dynos use a valve that opens or closes to adjust the water which is fed in one side and it gets pushed out the exit port .The exit is close to the inlet . Froude invented the dyno to test Ship engines up to 110,000 Hp in 1877.

Here is one in Finland which is being used to test a 27 liter Rolls Meteor engine. This is the land based version of the merlin V12 and were commonly found in Centurion tanks.
Meteor on Antique Froude dyno.

[gow589]

I saw this which looked real interesting for the money:

http://www.aemelectronics.com/dyno-s...pro-series-75/

[Wags]

Originally Posted by KA67_72

I'm starting this thread to continue the discussion from the "Engine Test Stand" thread we were hijacking. Kevin

I would be interested in building one, where did the discussion start?

Wags