I will never break in an engine in a boat again!

[eekern]

I will never break in an engine at the pond again....biggest time saver ever!

 

[DeanJohnson]

That's an awesome setup! What engine is that? Looks like the DD case, but with rear exhaust.

 

[eekern]

.21dd.....

 

[Blackout]

Nice pipe too!

 

[Samuel Hagan JR]

I guess the propeller is to help carry a load?

 

[DeanJohnson]

Duh, now I see. You can't run a straight header with a plane prop!

 

[eekern]

yeah, to load the engine. I was a little worried about the prop going nuclear at the rpm it was turning but it held up just fine Probably double the rpm what they spin with a plane engine.

 

[user 6667]

Eric, what did you use for the prop adapter?

 

[Tim leyde]

Great ideas. **** looks like I'm going to have to bring nothing less than my "A" game next season. I'll have a suprize for ya!

 

[Duck899]

That's a nice set up but I gave up on that idea back in the 70's. Its much different when your fitting a new engine to an airplane and you want to make sure the engine will make the maiden flight successful. I find that just installing an engine in a boat, running it on the rich side for a few tanks is the way to go. In a boat it just stops on the water, an airplane, well, that can spell disaster.

 

[eekern]

I picked up some 1/4-20 threaded rod at the hardware store, cut it to length of about 3 inches, and turned about an inch of it down smooth to 3/16ths on my taige lathe. This slid into the octura collet. I then threaded on two nuts tight to the collet, a prop washer, the prop, another prop washer, lock washer and another nut. This made for a super rigid shaft that didn't wobble and gave me a bit of clearance for starting with the belt.

I was able to heat cycle the engine at least a dozen times in only a couple hours with half a gallon of fuel....it was very cool seeing and hearing up close as the engine started to perform the more time it had on it and as I leaned the mixture. When it was finally lean enough to really hit the pipe.....holy cow......the wind blew my starter right of the bench!

 

[Ray Sametz]

How did you control the throttle?

 

[eekern]

I controlled it manually using a 2-56 rod with a clevis on the end.....Ear plugs are a must! I've thought about taking it to the next level and rigging up a servo so I could be further away from the action but decided to spend that time on more productive boat building

 

[ALLAN YUEN]

How much of percent nitro will you start to run break in and how long will run ?

 

[moparbarn]

i've watched jim allen do this also, eric. he uses a prop MUCH larger than needed, way too much load in stock form. he trims the tips down to get the load right. this ends up drastically reducing tip speed, wind, noise & DANGER. he uses only carbon fiber props for bench running at our high rpms.

 

[El Zorro]

Back in the '70's and early '80's I did a lot of engine work on controline, Free Flight and racing engines and I had a test stand that I made onto a piece of pipe that I could drive into the ground. I didn't live far from the airport so I would go over there when I needed to run an engine. I tested a LOT of head inserts with different combustion chambers and learned a lot in the process. When I started running boats in 1985 all of a sudden I had a tuned pipe and a throttle to deal with. Many of the boat engines of that period had an equivalent airplane engine. At that time I was running Picco .45's in D mono and Picco .21's in B mono. I simply exchanged the flywheel for a drive washer for the propeller and propped the engine for the RPM that I wanted to run in the boat. To run the .45 I had to turn the case 180 degrees so that the exhaust came out behind the prop. To operate the throttle I used a piece of wire with an "S" bend to attach it in the throttle arm and rubber banded it to the base of the engine mount. I could set the throttle anywhere I wanted it to be.

Your set-up to mount the propeller would be MUCH safer if you got rid of the collet, flywheel, etc. and got a regular airplane drive washer, washer and a nut ( I'm sure Glenn could find one for you ). I would also get rid of the wooden prop. Anything over 20,000 RPM you could shed a blade, and you don't want to be around when a blade comes apart! Get a good composite prop like the ones that APC make. I don't know what these engines should RPM at, so again, ask Glenn and then you will know how to prop the engine. My guess would be an 8X3 or an 8X4.

I will agree with you that this is a great way to break in an engine. You have to be careful around the prop, because it will hurt you if you're not.

Dick Tyndall

 

[eekern]

I used the same fuel that I run on race day, Torco 66%. I like to use the heat cycle method because you actually get the engine up to operating temps for a couple minutes, 200-220 then shut it down and let it cool at BDC. Your still running extremely rich but not so rich the engine cant get any rpm and make any heat. I also vary the rpm constantly. I like the heat cycle method better that the "run it so rich on the bench you have to run it wide open to keep it running at constant rpm" method. The engine never gets up to temp and the stress on the internals with that method has to be extreme.

 

[Matt Mordja]

Eric I am glad that worked out for you without incident, Hudy makes a bench with a guard, mabee a bit safer.

 

[eekern]

I bought some parts trying to do the whole airplane spinner thing but they didn't fit right on the engine. I had just gotten my lathe so I decided to just fab something using what was readily available. I was actually running a 9x6 prop and I think I could really go bigger or more pitch with the DD...thanks for the tip on the carbon props

 

[eekern]

Looked at the hudy, only comes with attachment for an SG shaft