Run in stand/dyno build.

[Mark Anderson]

The failure in the freewheel was the dog spring. It is just a piece of spring wire that goes around the outside of the dogs. Centrifical force threw it out of its groove. It got on top of the dogs and locked the assembely. Back to the drawing board. I made 6 runs after it froze up, so may just eliminate the over running clutch. Would prefer to keep it though.

 

[Terry Keeley]

Can you post some pix of it? We might be able to offer a fix.

I'd sure want it, if something locks up there's a lot of energy in that wheel that hasta go somewhere.

Are you getting rpm data from both the motor and the wheel? If so were you able to look at the plots to see if the freewheel was "keeping up"?

 

[Mark Anderson]

I will get a pic. I am logging data from the engine and flywheel. Because its a pawl clutch it does not slip once the engine clutch locks at about 10k. I want to try to lower the clutch lock up rpm a bit. I think there is some usefull data for accerating from the mill from 8k. The first couple runs the freewheel worked as expected. When I took it apart, everything looked great except that piece of wire.

 

[Mark Anderson]

The spring is .070 square. It is kept from rotating by a pin like a piston ring. My only thought is to epoxy it in a couple places

 

[Terry Keeley]

Epoxy might keep it in place, you mean to glue the ends down so it can only spread out a certain amount?

What about a laser spot weld on each end?

 

[Mark Anderson]

So I got some time this week to work on this project. I epoxied the spring in the freewheel in three spots around the circumference a long time ago, but lost 5 weeks to the Rona and never got to try it out. It is working great! I have made 20 pulls over the last couple of days. I also built a magnetic brake similar to Terry's. The EGT thermocouples came in so I mounted one in the exhaust flange. I am getting good data except the engine RPM sensor is wonky. At times it works perfectly at others, it reads double actual RPM. I am only using it to monitor the clutch slippage so not a big deal, but I am going to call Performance Trends and see if we can figure it out. Going to swap the two rpm sensors and see if the problem moves to the flywheel first. The cooling system is almost complete, and is working well. I have a 5 gallon bucket mounted under the bench with automotive antifreeze/water in it. The pump is much larger then needed so the plumbing has a bypass to relieve about 2/3 of the flow. The bypass water goes thru a transmission cooler with an electric fan on it before returning to the bucket. At the moment the fan is not hooked up. Over 10 pulls, the cylinder head temp is very consistent. The clutch was not fully locking up until 10500. I wanted to be able to test below that. From telemetry data from a sport hydro, we mill on plane at right around 8000. The clutch that I am using has no pivots or springs. It is one piece steel with two thin spots that flex to engauge. I took .005 off the arms and lowered the lock up to 8400. I want to drop it a bit more, but its not going to take much to get to the goal. Maybe just a swipe with a file at this point.
It' a cluttered mess at the moment. Need to do some wire managment.
This engine was a brand new stocker when this project started. It has been interesting to see it break in as testing has progressed. It has almost 40 15 second full throttle pulls on it along with warm up and shut down, and is still picking up power. I start the test when the head temp comes up and stabiliizes at 155. It has been in the mid 40s in the shop. Head temp at the end of a run is around 185. Most runs have shut off between 16 and 17k.

 

[LohringMiller]

Wow! You got a lot fancier than we did. I need to make a trip up to take a look. I also have a box full of engine parts for you to play with. There are several stroker cranks and two Quickdraws as well as lots of misc parts. I'm glad you're feeling better.

Lohring Miller

 

[Terry Keeley]

That's awsome! You got a functioning unit and can start testing all the stuff you've been dreaming about for years.

What kind of EGT's are you getting? How are the top end of the curves, is the s/w giving weird results like mine?

Would love to see some plots!

ps: Rona sux.

 

[Mike Hughes]

Mark,
You might be getting some transient voltage induced on your sensor wires to cause your wonky readings. Cant see how they are routed under table, but if they are bundle together, that might be the issue. A choke on those would help if that is the case.
Mike

 

[Mark Anderson]

Lohring, Thanks to you this project got off the ground and is now starting to show some results. Between you and Terry, the actual building of the contraption was fairly simple. Just a bit of debugging and learning the software away from some real testing.
Terry, my limited knowledge says the curves look good. Still just making a few runs and trying to evaluate what I am seeing. Tweeking little things on the Dyno. I have not changed anything on the engine over the last 20 pulls. Just trying to get familiar with things and make sure it repeats. Slowly learning the software. EGT is just a bit above 1000f. 1010-1022 at peak power, tapers off during over rev. I need to figure out how to post a plot.
Mike, What I think is going on, is the magnets in the flywheel are the culprit. The cables have good seperation. I am using a sensor on a magnet in the starter pulley that is on the flywheel side.
Some folks run Futaba telemetry sensors up against the case picking up the flywheel magnets. I tried that with my sensor and it didn't like it. Im going to switch the dyno and engine sensor plugs at the box and see if the problem follows the sensor or stays with the engine side. Need to give the neighbors till noon before I fire it up though.

 

[Terry Keeley]

Lohring, Thanks to you this project got off the ground and is now starting to show some results. Between you and Terry, the actual building of the contraption was fairly simple. Just a bit of debugging and learning the software away from some real testing.
Terry, my limited knowledge says the curves look good. Still just making a few runs and trying to evaluate what I am seeing. Tweeking little things on the Dyno. I have not changed anything on the engine over the last 20 pulls. Just trying to get familiar with things and make sure it repeats. Slowly learning the software. EGT is just a bit above 1000f. 1010-1022 at peak power, tapers off during over rev. I need to figure out how to post a plot.
Mike, What I think is going on, is the magnets in the flywheel are the culprit. The cables have good seperation. I am using a sensor on a magnet in the starter pulley that is on the flywheel side.
Some folks run Futaba telemetry sensors up against the case picking up the flywheel magnets. I tried that with my sensor and it didn't like it. Im going to switch the dyno and engine sensor plugs at the box and see if the problem follows the sensor or stays with the engine side. Need to give the neighbors till noon before I fire it up though.

I think my curves going wonky at the top end is because the wheel is accelerating so slowly the software doesn't know what to make of it, I'm gonna cut another 1/4" off the wheel and see if that helps. Wish someone mentioned that before, lol.

EGT is sure up there, have you messed with the high speed needle yet? I've heard it's not as critical as with nitro.

I just take a screen shot of the plot: Ways to Take Screenshots on Windows 10 and Windows 11

 

[Mark Anderson]

Do you mean the way that they drop off? Looks like its just not making power anymore. My curves look very similar, mine are just lower RPM. I would think that cutting the flywheel would effect the lower rpm more then the top end. Your tests take much longer then mine to run. Mine are 15-17 seconds on this stock Zen.

 

[Terry Keeley]

No, more like these:









Here's the same run before and after trimming:








It doesn't seem to matter if you start logging before/after you open and stop after/before you close the throttle if that makes sense. How are you doing it?

I think the slow acceleration (long run time) after the HP peak might be messing up the software.

 

[Mark Anderson]

I had a couple yesterday that did like the first on you show. I got stable readings from both RPM sensors now. The engine and dyno are locked up from 8K up, Didn't test below that.
There is an initial jump in power, then a valley, then it takes off again.
I turn the recorder on, hesitate open the throttle. turn the recorder off hesitate and shut the throttle. At least thats the plan. I seem to open the throttle and turn it on at the same time according to the graph.
I keep getting a dialog box saying that I have selected lap time instead of Hp from Time/accel. This happens randomly.

 

[Mark Anderson]

 

[Mark Anderson]

It just hit me that I have never seen a dyno graph that the HP and torque do not cross at some point. None of yours cross.

 

[Terry Keeley]

Very cool! If you play around with filtering (I use heavy) and RPM Increment (I use 250) under the Graph tab on the main screen you should be able to smooth it out a bit.

Also under Format on that screen, Data Multipliers if you check Preset by User then Assign Preset Multipliers for Calculated Channels you can put HP on the left axis and by assigning a CF of 0.01 to oz-in and 0.001 to the EGT and CHT it'll make it look more like this (if that's what you want, lol):



It looks like your torque and HP curves are crossing because your gas motors are making so much more torque down low that nitro?

Are you using any coast down correction?

 

[Mark Anderson]

No, I have not set up the coast down.
Makes sense on the torque. Its interesting that your curves have the same dip down low.
I have been working toward repeatable good data and mechanical reliability and have not looked into the software at all. Need to do some reading.

 

[Terry Keeley]

No, I have not set up the coast down.
Makes sense on the torque. Its interesting that your curves have the same dip down low.
I have been working toward repeatable good data and mechanical reliability and have not looked into the software at all. Need to do some reading.

Me either, I think there's more drag in our setups winding down than going forward with our one way bearings/clutches and I found it added (I think) too much correction.

Ya, they talk about that dip on another two stroke forum I'm on, it's common and there's a name for it but I can't remember it. Maybe Lohring will.

 

[Mike Bontoft]

We always used ft-lbs and one vertical scale so ours always crossed at 5252 rpm.