My Cox .049 Marine inboard engine

Juan the flywheel mass should do just fine.

The Dumas flywheel weight was set up to do well with Reeds and
TD engines for the Dumas submerged prop.

Hello 1/2A nut
What is the difference of performance between surface and sumerged?

Juan

Depends on many factors. Boat type, weight etc. Surface drive offers less prop load
when on plane for more speed. Hand launch if you decide to max out the prop load
for top speed. Plenty of data online about it. Submerged props are good for slower
throttled speeds for vintage designs and duty type boats.

Juan, very good job!
Guys, maybe it's a stupid question but I don't know. So how does water circulate through the engine coolant pipe? What force makes it circulate there? The progress of navigation or what?...and if you start the engine and support the boat and don't throw it into the water, in that case, how does the water circulate?...thanks!

MauricioB wrote:Juan, very good job!
Guys, maybe it's a stupid question but I don't know. So how does water circulate through the engine coolant pipe? What force makes it circulate there? The progress of navigation or what?...and if you start the engine and support the boat and don't throw it into the water, in that case, how does the water circulate?...thanks!

Hi Mauricio, The system uses a water "pick-up" tube or orifice that is angled to "catch" the flow from either the forward momentum of the boat when mounted forward of the propeller.. or it can be a more pressurized-flow if the pick-up is mounted just aft the propeller. After water flows through the cooling-coil (around the cylinder head) the cooling-water is then routed through the side of the hull and expelled above the waterline. Water will NOT flow through the system until the boat is in the water.





The example below shows a special rudder with integral pick-up.. and also a pick-up tube aft the propeller.

Thanks for replying to Mauricio`s questions and the posted photos. I plan to place the water pick up on the propeller stream that way I think will get better cooling. Here are some pictures of the water jacket I made. The water channel is not as big as the jacket since I thought that making it that way it would also help with the cooling by having extra surface to radiate heat and also to hold the O rings that seal the jacket. On a next version I migh add some cooling fins.
                                                                                             Juan

Thank you very much Roddie...I understand then that once you start the engine, you must put the boat into the water almost immediately, that way it begins to cool...otherwise it can be harmful to the engine... is that so?

Hello Mauricio
                         I think that if you are running the engine at idle RPM you could have a little more time but if the engine is at full throttle the engine could get hurt due to the overheating and lack of cooling.
                       I made a new reed intake for my Cox.049 marine engine with the AP Hornet.061 carb that was given to me by 944 jim I had not placed on the engine until I polished the carburator yesterday. I made a turbo glow head with an old td high compression head, also placed the new heavy flywheel on the engine. I still need to make a few parts before I try to run it. here are some pics.
                                                                                    Juan

how does the water circulate?...thanks![/quote]

Hi Mauricio, The system uses a water "pick-up" tube or orifice that is angled to "catch" the flow from either the forward momentum of the boat when mounted forward of the propeller.. or it can be a more pressurized-flow if the pick-up is mounted just aft the propeller. After water flows through the cooling-coil (around the cylinder head) the cooling-water is then routed through the side of the hull and expelled above the waterline. Water will NOT flow through the system until the boat is in the water.





The example below shows a special rudder with integral pick-up.. and also a pick-up tube aft the propeller.

[/quote] For a slow boat model I tested a different way for installing the water intake but especially the way of outlet rather than letting the water out freely outside the water line I placed the outlet tube in front of the propeller place near the blades so as to create a suction effect and at the same time convey more water to the propellers and increase the flow constantly no need to always be at full throttle or even to be in motion. the boat can be static on site and still cool down Another possible beneficial effect for hidroplane models Providing more water to the boat's propeller when it is half above water As in the photo, the rudder with the water intake is ideal for a hydroplane. because taking the water behind the propeller when the propeller takes in air it can introduce air into the system and reduce the efficiency

I finally had time to set up a test of my Cox.049 Inboard Marine engine. I took some video of the engine running now I have to figure out how to upload it from my phone to you tube to share with you guys. I set up a water supply connected to the waterjacket to provide cooling as soon as the engine started to run I let the water flow. I ran it for about a minute. I haven`t leaned the mixture yet as it was my first run,it sounds healthy. Engine is based on a Blackwidow That I had. here are some pics.
                                                                                              Juan

 

Here is a link to the you tube video of my first run of the Cox.049 Inboard marine engine. I still need to do some fine tuning.
                                                                                     Juan



https://www.youtube.com/watch?v=lHIR4oUUleI

Nice!!!

Juan, you can use the YouTube tab here on CEF and insert the link to provide the video with your post as shown:


Jun 10, 2024

By: titoplane
Cox .049 Inboard Marine Engine first run
This is the first run of my modified Cox .049 for marine use.
The following parts were custom made head with turbo plug, aluminum water jacket to
provide cooling, rear reed intake with R/C carburetor, steel flywheel and motor mounts.
Still need to do fine tuning to get full potential.

Congratulations that is a truly exceptional piece of engineering.

I like the carb mount you made and the flywheel good job ! The run was sounding good and water flowing right on through too . Your on the way now .

Ohhh Juan.....I was missing all this!....how beautiful the engine turned out with the AP .061 carburetor!...congratulations!....

Hello all
               thanks for your kind comments I appreciate them. It has taken me a while to get the engine running and I had to learn about boat engines. I`m posting a video of the second test run. Yesterday I had a lot of vibration from the engine that I traced to a wobbly flywheel. I placed the flywheel on my late and by removing material I was able to have it run true. I placed the flywheel on mi high point balancer and when I was spinning it I noticed the wobble. Now I still have some vibration but that can`t be helped on a single cylinder engine unless you use a balance shaft. I will continue working on the engine. thanks again.
                                                                              Juan
Please use audio tach and let me know reading, my tach is reading above 28K.

Plenty of rpm, would not run it up too fast on the bench without an air prop to cool the crankcase.
Can install it in a boat and air flow will help the case also castor needs to be higher than
normal with boats. Are you going to build a boat for it next?

What is the total weight of the assembly?

The engine ran near 28k, as audiotached with my RPM Gauge Android phone app:

She was Screaming !! Bee careful with the no load as Brad said she will pop Shame you can't get that little bit of vibration out do you think it will bee ok with the rig/propeller hooked up ?

1/2A Nut wrote:Plenty of rpm, would not run it up too fast on the bench without an air prop to cool the crankcase.
Can install it in a boat and air flow will help the case also castor needs to be higher than
normal with boats. Are you going to build a boat for it next?

What is the total weight of the assembly?

Hello Brad
                     The weight is 3.9 ounces for the unit but I can lower it. Is just that for pleasing looks I made the cooling jacket that way and it weights .4 oz. The motor mounts can be reduced in weight, specially the front that weights .3 oz. The motor mounts are acting as a heatsink for the crankcase and after a run the engine doesn`t feel really hot. The Black Widow crankcase is great for this mod since it`s completely anodized which helps with  crankcase wear in the crank bearing area now that the engine is running a heavy flywheel at high RPM.
                    I took the engine apart to inspect it for wear and heat damage. The crankshaft bearing area has no play. I noticed a little bit of castor oil crud in the oiling groove on the bearing area and cleaned with a wooden tooth pick. I will be polishing the crankshaft to get a few extra R`s. The fuel I`m using is a mix of 30% VP nitro,20% Blendzall racing castor oil and 50% methanol that I mix, is this mix ok?
                    I will be building a boat, I bought the Dumas half pint die crunch kit. I`m going to make the universals for the driveshaft to the prop using a set of car dogbones,the Dumas parts that I received looked big for an .049. Thanks for the continuous advice given.added a photo.

                                                                                  Juan

balogh wrote:The engine ran near 28k, as audiotached with my RPM Gauge Android phone app:

Hello balogh
                       Thanks for your help. I don`t trust my audio tach because it has given me erroneous readings before.
                                                                                 Juan

getback wrote:She was Screaming !! Bee careful with the no load as Brad said she will pop  Shame you can't get that little bit of vibration out do you think it will bee ok with the rig/propeller hooked up ?

Hello getback
                          I beelive that I have done all I can on the vibration problem. From what I read single cylinder engines have an imbalance at 90 dregrees of the piston travel and it would take a balance shaft to smooth engine run.
                          I`m a newbee to radio control boats. I will need to learn as I go.

                                                                                      Juan

Hello Juan,

This Android phone app is proven to show the same results as the hand-held photocell based rpm gauges.