Run in stand/dyno build.

A dirty one just for you Ray.

^^^ Stainless?

Terry Keeley said:

A dirty one just for you Ray.

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Awesome, make one hell of a wig for me.

Steve White said:

^^^ Stainless?

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4140 HTSR, final trimming is between centers.

Terry Keeley said:

A dirty one just for you Ray.

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Nice assortment of tooling Terry

Final trimming between centers to 5", shud give a 10-15 sec. runup.

I have had a few trials and tribulations with my dyno. I was fighting an intermittant problem with the engine rpm being erratic. I switched the engine sensor and wheel sensor locations to see if the problem followed the sensor. It fixed the problem. That confused me, but I moved forward. I was now getting solid numbers so I cleaned up the wiring and remounted stuff that was moved in the diagnosis process. Next was to mount up a mod 30cc motor. I want to get before and after of converting it to a long rod. On water performance is better with the long rod engines in my twin, but I want to quantify it with dyno results. First run and my data is all over the place. RPM sensors are both acting up, weather data is wacky. I walked away for a bit to mull this over. During the run, I did note that the 30 shook more then the stocker that I had been running. Then the light bulb came on. when I switched the RPM sensors, I had to relocate the data recorder do to cable lengths. I had just set it on the table on a towel. When I put everything back together, I remounted it to the dyno cart. Vibration was affecting it. I took the screws out and layed it on the lower shelf and the data was clean. Lesson learned. Nothing mounted to the cart except the dyno!
During that run the over running clutch failed. The bicycle freewheel, while it has 3 engagment dogs, only engages one at a time. They are slightly offset to give more engagment points reducing back lash. When it failed it wedged the body and distorted the shaft adapter. I decided to do away with the clutch. Mike and Lohring ran thousands of tests with out one.
I am just getting it back together after the rework. I also made a dedicated spot in the shop for it to live. Boat building has gotten in the way, but I will be up and running tests later today.

Fantastic. We always had some issues with the rpm sensor. Are you using the magnetic pickup or one of the other sensors? I always felt that the magnetic pickup was at fault, but we did have the data logger on the dyno stand. I need to visit you sometime to bring you some more fun engines and the lambda meter. I'll get in touch next month.

Lohring Miller

Thanks for sharing your progress, including all the trials and tribulations, maybe it will help someone else that finds this thread down the road.

I really thought the bike freewheel would have worked, do you think the sprags got hammered to death? I had a hell of a time with this with the one way bearing releasing as the engine rpm cycled above and below the wheel rpm several times a second. Think a freewheel with more sprags would work?

Lohring, I am using the magnetic pickups.
Forgot that while doing the rework, I moved the clutch off the engine. This makes it much easier to change engines. I will snap an update pic. today.
Terry, they might. I would need to find out if they engage multiples at one time or are just finer ratchets.

I've always wondered why the forward drum and 34 element sprag out of a T-400 transmission wouldn't work for this application.. it would take some machine and fab work to support the shafts, but with a billet hub and 34 over running sprags all locking in, there's no way it would fail...the drum itself would basically become the inertia wheel..

Larger dynos use a PTO one way clutch. I'm not sure we really need one on our dynos as long as there's some type of fuse. We liked the square key and it mostly proved itself over a lot of runs.

Lohring Miller

That looks like the hot ticket....
I only mentioned the T400 drum and sprag because it has potential to kill two birds with one stone... overruning clutch as well as the inertia drum.. and they are proven to live in 3000+ hp applications..

Plus you could even use a band around the drum as a brake in an emergency to stop the drum from spinning..

It has been almost a year since I updated my progress. I have done a bit of testing and I think the dyno is in its final state. For some reason I was twisting and breaking square keys so I shortened the distance between the two collets and they seem to be living an acceptable time. Not going to be much of a fuse, but for now I am moving forward as is. My last Big step was fabricating a removable one way bearing that replaced the square key so that I could do a coast down test. It worked and I got the needed data. Here are some current photos.

Great to see you got the kinks worked out!

Would be great to see some plots if you get a chance...

I still don't understand why you had so much trouble with the key. As you can see from the picture, we used really long keys. The only difference I can see is that your dyno has the clutch and Lovejoy coupling position reversed compared to ours. I have no idea how that could matter.

My favorite thing about your dyno is the eddy current brake. Have you considered locking up the clutch so you can do friction coast down testing on the engine? It would be interesting to see if you could measure the friction loss in a new versus broken in engine. Just getting a picture of the friction losses under different conditions would be interesting. I've always thought ring friction was the biggest contributor. Testing with rings removed as well as similar tests would be interesting. Does a long rod reduce friction loss?

The thing I most regret about our testing is not measuring the exhaust gas temperature both at the exhaust port and in the pipe. The first indicates the correct mixture for peak torque through out the power band. That would be a good carb metering test. The pipe temperature is essential for pipe design.

Lohring Miller

After a little thought I finally figured out why you had key problems. Your flywheel is 6" in diameter compared to the 5.33" diameter of our flywheel. That means the moment of inertia and the torque to accelerate it is around 1.6 times larger. You probably need a larger coupling. You might try a 5/16" collet with a 5/16" hardened steel shaft in place of the key. Speedmaster makes a collet that should fit. Even a 1/4" shaft and collet might work. There should be enough play in the clutch assembly to make up for the rigid connection.

Lohring Miller

Lohring,
While I was at Mark shop, we ran a few times. He had a new key to start with. I think we did like 3 or 4 pulls. It seemed to twist about 1/4 to 1/3 turn for each pull. So it not a huge issue. He just has a bunch of keys laying around and changes after 10 pulls or so.
Mike

Mike, the testing that we did on your engine was very limited, testing pipes, it is a pain. I had to remove the engine and replace the key every 2 pipes or chance a failure. I hope to test a few more this weekend and maybe with the closer spacing, it will help.

Try round inserts with plain 1/4" rod. I bet it will work and allow quick engine changes.

Lohring Miller