25 cc Horizontal Engine

[Roger B]

Thank you both. I made a similar but smaller radiator for my vertical engine:

http://www.modelenginemaker.com/index.php/topic,2093.90.html

For this version I milled a 6mm slot in the top of the top header to connect to the angled section. The smaller one just had a 6mm hole which makes it hard to get the air out of the system.

I soldered the plugs in the end of the headers with my 75W electric soldering iron, but I think I will have to use the blowlamp for the final assembly. There are two aluminium strips which are slightly wider than the headers bolted to the sides to keep everything square and in place.

I now have to decide if I think that the fins will stay in place during soldering or if I need to make some aluminium spacers to keep them square 

[Roger B]

I decided to make some spacers. I had a length of 20 x 5 mm aluminium which I cut down the middle and then could saw off two blocks at a time. The soldering was done using a Camping Gaz blowlamp. It wasn't easy to control the heat so I ended up with quite a few blobs. When the main body had hardened but not cooled right down I held it on end in a vice and soldered the top header tank on. I hope to solder the inlet, outlet and filler with an electric iron.

Lots of cleaning up to do 

I know that the forum likes pictures, this thread now has over 500   

[Dave Otto]

Nice work on the radiator Roger.

Dave

[Rustkolector]

Roger,
Regarding your cooling options, the easiest option would still be an evaporative cooling system with gravity flow to a larger hopper type tank and let the water boil in the water jacket. You would need generously sized coolant pipes. It can be a very effective cooling system. If you go with the radiator and pump I highly suggest a good water pump design such as the gear pump design by Jerry Howell. It is a positive displacement pump easily constructed for any flow needed. Gear stock blanks are available from gear manufacturers like Berg so you don't have to cut your own gears. I have used .500" O.D. 10 tooth gears with good success. The pump is easily constructed using a .500" end mill for the gear pocket. Flow is varied by the depth of the gears used and RPM. Since you aren't building a hydraulic pressure pump, the gear side clearances are not as critical as you might think.

If you are going for higher wattage on your engine generator you are also going to need a fan on your radiator. I like your load bank. 
Jeff

[Roger B]

Thank you both for your interest.

I have decided to make a gear pump. I have some plastic gears which together with a brass body and stainless steel shafts should work ok. The radiator is planned for use with a 60mm square computer type fan. As I am intending to generate electricity I might as well use some of it 

[Roger B]

Last bits of the radiator build. The filler hole is difficult to keep on centre as the cutting edges on the drill are not equally supported.

The new generator has a 1/4" shaft that is a little to big for the existing pulley. I have ordered a slightly larger one (20T instead of 12T) which will also reduce the generator speed. All my English drills are in England, but I have found a short length of 1/4" silver steel I can use to make a simple reamer.

[Jo]

That radiator looks very impressive Roger 

Jo

[Kim]

That is a FINE looking radiator you made there Roger. Thanks for sharing the process.  You did an excellent job on it!
Kim

[b.lindsey]

Nicely done Roger. The radiator came out great. Any thought to powering a muffin fan with the dyno to cool the radiator? I am not sure what voltage they require though.

Bill

[Roger B]

Thank you all for your kind comments 

If a muffin fan is the square black type used for cooling electronic equipment my plan is to use one on the radiator. 12V types are common, I think that 5V are also available. I will have to see what I get out of the new generator.

I have attached my 'electronic back of an envelope' design for the radiator in case anyone is interested. It is made from the brass sections typically found in model/hobby shops.

[Ian S C]

I run a Muffin fan on the radiator of one of my hot air engines, I think it's a 6V one, there is quite a range of Wattage and voltage in these little fans, so if you have a choice you get a chance to match it to your motor.  The tubes used in my radiator came from the core of a car heater radiator, I think the round tubes would be easier to put together without leaks than the flat tubes that I used.
Ian S C

[Roger B]

A bit more playing. I made a mounting plate for the new generator and opened the pulley out to 1/4" with a homemade reamer.

I started looking at the details of the water pump. It looks easiest to drive it with another 40T gear from the camshaft gear. This will also be a better place to mount the fuel pump if I ever get to trying out my fuel injection system. I have some 12T module 1 gears. A 2mm drill just about fits the tooth space giving a rough area of 3 mm². The gears are 9 mm wide so the volume of a tooth is about 27 mm³.  If 2/3 of the teeth are available for pumping (depends on the size of the ports) 16 teeth worth of water will be pumped per revolution = 430 mm³ per rev. If the engine runs at 3000 rpm the pump speed will be 1500 rpm so without losses the flow will be 1.5 (converting from mm³ to cm³) x 430 = 645 cc per minute. This seems a little high but I expect there will be significant losses so it should work.

I am not sure whether to use brass or aluminium for the body  . I have more suitable pieces of aluminium available and with plastic gears and stainless steel shafts it should be ok. I will however have to glue or screw in the pipe connections.

I tried out the new generator. Turning the engine at 450 rpm with the cordless drill gave an output of 1.2V so 2500 rpm should give around 6.5V. As I final play I connect the 6V accumulator directly to the motor and with a little help at the start it would turn it over quite well. With 12V it would certainly start the engine!

<a href="https://www.youtube.com/watch?v=07Q_f5J7Cyw" target="_blank">http://www.youtube.com/watch?v=07Q_f5J7Cyw</a>

[Roger B]

Had a good run tonight with the new generator. 6V 6A = 36W at an engine speed of 3500 rpm. This was the maximum burden, 1 ohm, that my load bank can supply as I was planning on 12V operation. I may try and bore the 12T pulley out to 1/4" to get the generator speed and voltage up a bit but first I will change the camshaft to the wider overlap version. I must admit that after my experience with the vertical engine I think I may be going in the wrong direction  There is always more to learn    At least I know the engine will be capable of supplying it's own ignition and cooling fan plus a bit 

<a href="https://www.youtube.com/watch?v=7is0tIKkJx4" target="_blank">http://www.youtube.com/watch?v=7is0tIKkJx4</a>

[Roger B]

I fitted the new camshaft this evening and had a trial run. After advancing the ignition timing a little more it would achieve 4000 rpm under load which took it up to 6.8V 6.8A = 46W. There seemed to be little, if any, detrimental effects. It will still idle around 1200-1300 rpm and starts without problems (although only with the drill). All in all a success 

[fumopuc]

Hi Roger, your R&D work seems to go into the right direction.