THE BEAST!

[Terry Keeley]

Your setup is a very compact unit.  The dyno you pictured looks like Dave Marles' dyno.  People I've talked to have twisted 1/4" cable connectors, broken belts and destroyed Octura pin couplings.  Prop loads are much kinder than the dyno flywheel.  Try that style of one way clutch and see how it does.  Single cylinder engines pound the couplings.  I was very cautious with over engineering our dyno, especially the flywheel.  The Lovejoy coupling also wasn't needed.  We destroyed a softer rubber element before we switched to the hardest one.  The key into Aeromarine square collets also had a limited life.  The keys and square collets are cheap, though.

Lohring Miller

Yup, that's one of Dave's older units, here's his latest (hope he doesn't mind me sharing!).

I plane to build mine on a larger base (24" x 12" of 3/4" MIC 6 gauge plate) so I can clamp it to a fold up table to run outside, at lease when I use it as a run-in stand with the Byron fan unit attached instead of the inertia wheel. 

Wow, we sure jacked Dave's thread didn't we!  :lol:

 

[dwilfong]

Yup, that's one of Dave's older units, here's his latest (hope he doesn't mind me sharing!).

I plane to build mine on a larger base (24" x 12" of 3/4" MIC 6 gauge plate) so I can clamp it to a fold up table to run outside, at lease when I use it as a run-in stand with the Byron fan unit attached instead of the inertia wheel. 

Wow, we sure jacked Dave's thread didn't we!  :lol:

View attachment 98725

No problem. some times the best stuff just happens spontaneously.

What ever happen to the Dyno with the disk drive magnets for a brake?

Still think the torque cradle with a brake would be the best set up. 

Could load and unload the eng gust like it was on the boat going around the track.

 

[Ken Retallick]

Terry, any Pics i had would be long gone unfortunately.

 

[tnrcboatracer]

Cool.  I'm gonna use a one-way bearing plus one of Dave Marles steel shoed clutches:
http://www.prestwich.ndirect.co.uk/gasengineaccesories.htm
https://www.vxb.com/CSK15PP-One-way-p/kit10968.htm
That's a serious stand you have it on!

Terry, is 13.5 Nm torque capacity enough? The GMN FP427Z sprag clutch has 94 Nm torque capacity.

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[LohringMiller]

I built the disk dyno.  See below.  After playing with it a while I decided it worked better as an inertial dyno.  We ran in engines on our inertial dyno.  The short full throttle bursts seemed to work well on gas engines, especially for ring seating.  It was great for carb settings as well.  The whole idea of an inertial dyno is that it mimics the acceleration down the straight.  Below is a graph of break in  after an afternoon of testing on a new engine. 

I still like the direct drive unless you plan to test a series of different engines.  My next dyno will have two different diameter flywheels.  I think that will make a more reliable unit.  I'm interested to hear how your one way clutch holds up.  I've been thinking about using a 78 mm clutch assembly, but the standard 54 mm clutch seemed to be adequate.  We did break the plate that holds the shoes and made a billet one. 

 

[Terry Keeley]

Terry, is 13.5 Nm torque capacity enough? The GMN FP427Z sprag clutch has 94 Nm torque capacity.

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Probably would work but I don't see any keyways in it so not sure it that's what I need:  https://www.gmnbt.com/product-view.htm?type=sc&product=55

Was thinking of going with this:  https://www.vxb.com/CSK15PP-One-way-p/kit10968.htm 

The one way bering will be "after" the main clutch so power will get transmitted through it gradually until about 15K rpm or so then WOT for a 10-15 sec. pull. 

The main shaft will be 15 mm Thompson shafting and I plan to use WIB 6202 bearings through out with these drip oilers:  https://www.ebay.com/itm/Mulitple-OD-BSP-Brass-Sight-Gravity-Drip-Feed-Oiler-Lubricator-Hit-Miss-Engine/322652241011?var=511670253318

Wonder where the WIB's are coming from?  

 

[tnrcboatracer]

I prefer taco oil mist lube, but that is a little more expensive.

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[tnrcboatracer]

 
Probably would work but I don't see any keyways in it so not sure it that's what I need:  https://www.gmnbt.com/product-view.htm?type=sc&product=55
Was thinking of going with this:  https://www.vxb.com/CSK15PP-One-way-p/kit10968.htm 
The one way bering will be "after" the main clutch so power will get transmitted through it gradually until about 15K rpm or so then WOT for a 10-15 sec. pull. 
The main shaft will be 15 mm Thompson shafting and I plan to use WIB 6202 bearings through out with these drip oilers:  https://www.ebay.com/itm/Mulitple-OD-BSP-Brass-Sight-Gravity-Drip-Feed-Oiler-Lubricator-Hit-Miss-Engine/322652241011?var=511670253318
Wonder where the WIB's are coming from?  

 
Probably would work but I don't see any keyways in it so not sure it that's what I need:  https://www.gmnbt.com/product-view.htm?type=sc&product=55
Was thinking of going with this:  https://www.vxb.com/CSK15PP-One-way-p/kit10968.htm 
The one way bering will

The FN 437 M has a keyway, 15mm shaft, and is rated at 176 Nm. https://www.gmnbt.com/sc-fn-437-m-complete-freewheel-clutch.htm

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[Terry Keeley]

The FN 437 M has a keyway, 15mm shaft, and is rated at 176 Nm. https://www.gmnbt.com/sc-fn-437-m-complete-freewheel-clutch.htm

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Musta looked at the wrong part, that might work too!

 

[LohringMiller]

Our bearings were grease lubricated and were only replaced once.  Considering we ran to 20,000 rpm frequently and 25,000 rpm occasionally that's pretty good service over 10 years.  You will be running way over the maximum rpm for the clutch.  That's another reason to prefer a positive type clutch.  Does Dave's second dyno even use a one way clutch?  The belt will make a great fuse if it holds up to normal running.

Lohring Miller

 

[tnrcboatracer]

Our bearings were grease lubricated and were only replaced once.  Considering we ran to 20,000 rpm frequently and 25,000 rpm occasionally that's pretty good service over 10 years.  You will be running way over the maximum rpm for the clutch.  That's another reason to prefer a positive type clutch.  Does Dave's second dyno even use a one way clutch?  The belt will make a great fuse if it holds up to normal running.
Lohring Miller

GMN also has models that are sealed with grease or oil lube.

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[Terry Keeley]

Our bearings were grease lubricated and were only replaced once.  Considering we ran to 20,000 rpm frequently and 25,000 rpm occasionally that's pretty good service over 10 years.  You will be running way over the maximum rpm for the clutch.  That's another reason to prefer a positive type clutch.  Does Dave's second dyno even use a one way clutch?  The belt will make a great fuse if it holds up to normal running.

Lohring Miller

I was thinking the oil drip lube would have the least amount of friction (hopefully) making the power numbers more accurate, plus I'll be running closer to 30K and beyond if I test 21's and 45's.  This will (of course) require a smaller wheel but I want that capability down the road.

I'm hoping the one-way bearing will hold up, seems to be doing fine on my buddies dyno.  I really, really like the idea that if the motor seizes suddenly the wheel can keep motoring, especially since I probably won't have as solid a table as yours.  Also I wouldn't be real happy closing the throttle suddenly therefore shutting off lube to the engine and still have the wheel drag it along at 25K+ until the main clutch disengages at around 15K.  That right there could cause a catastophe! 

Not sure if Dave is running a one-way or not, I'll ask him...    

 

[tnrcboatracer]

I think that oil mist lube is lowest friction, but drip is a close 2nd. Just make sure that bearing doesn't fill with oil. Need to have a way to shut off oil when not turning

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[Terry Keeley]

Terry, is 13.5 Nm torque capacity enough? The GMN FP427Z sprag clutch has 94 Nm torque capacity.

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Lohring can confirm this but our biggest motors might make 25-30 inch-pounds of torque, 13.5 Nm is about 120 in-pounds so that's not an issue.

 

[tnrcboatracer]

 
Lohring can confirm this but our biggest motors might make 25-30 inch-pounds of torque, 13.5 Nm is about 120 in-pounds so that's not an issue.

Hreat. I had no idea hoe much torque a 67 produced.

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[Terry Keeley]

I think that oil mist lube is lowest friction, but drip is a close 2nd. Just make sure that bearing doesn't fill with oil. Need to have a way to shut off oil when not turning

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 Gonna use this type:  http://www.lubriteindustries.com/downloads/drip-feed-oilers.pdf

They have a needle valve to adjust the flow plus a sight glass and shut off.  Was thinking I'd drill a small hole in the pillow block that holds the bearing with an outlet right at the back of the bearing in the ball area then attach these to the top.  Probably leave the shield on the outside and remove the inner. 

 

[DaveMarles]

I have not used a one way bearing on either of these dynos. At first I would blip the throttle when the flywheel was slowing down after a run, but in practice the flywheel disengaged pretty quickly. If there is a brake on the flywheel then it can be slowed very quickly. One of those things where it is possible to overthink what in practice is quite simple. On the first  dyno in the previous pics (roughly based on info Lohring kindly provided) I used 2 couplings with a square shaft between the motor and the clutch but the square material twisted pretty quickly and I changed to having the clutch directly on the engine. The downside being the time taken changing motors over but in practice I mostly used one crankcase with different cylinders. I did hundreds of runs without a problem.  On the belt drive dyno I have a coupling between the motor and cluch so that I can easily swap between motors and also use it for 91 nitro engines. 

 

[Terry Keeley]

Here's Dave's dyno after he modded it:

 

[LohringMiller]

What Dave said.    Your picture is close to what I'm considering for my new dyno.  Thanks.  Watch the flywheel diameter if you plan to test nitro engines.  We melted the piston on all (3) 11 cc nitro engines we tested. 

The first inertial dyno for model engines was designed and built by Marty Davis and Brian Callahan.  John Ackerman built the dyno.[SIZE=10pt]  [/SIZE]I found an article on it at https://web.archive.org/web/20030205134346/http://rcboat.com:80/dyno.htm   and https://web.archive.org/web/20030209190150/http://www.rcboat.com:80/dynotech.htm It has calculations and mentions that they used a 3.75 inch diameter by .75 inch thick flywheel for .45 cubic inch engines.

 

[John Beardslee]

Marty’s dyno needs new bearings but other than that I think it’s in tack. We talked about rebuilding it a few years ago when I started back racing boats but we haven’t gotten serious about it since.