Jim builds his second v-8

[stevehuckss396]

couldn't edit. This is what i meant

Yes I do. I just have that small radiator so it heats up real fast. I think if I did the same thing you do with the can I could get about the same time as you. 6 minutes is pretty darn good in my book.

 

[jpeter]

My hope was to be able to idle it forever. Not happening yet. Some builders at the shows have huge radiators, way to big for scale (heater cores maybe). Your Demon radiator looks really appropriately sized for scale. I thought mine was somewhat large but not too bad but I'm leaning towards making it bigger. I think thicker wouldn't too seriously hurt the scale looks . I'm also thinking I'd like to find a way to make really thin aluminum fins and lots of them like a commercial radiator, with aluminum tubes too. Chime in folks and tell me how to do it.

 

[Art K]

Hey guys
Correct me if I'm wrong but those things have virtually no cooling in the head where the heat is produced so 6-7 minutes is quite good.
Art

 

[jpeter]

Not so Art. My heads have a 5/32 water passage running lengthwise full length. Water enters the heads from the back of the block then exits through the intake manifold to the radiator.

 

[enfieldbullet]

the aluminum tubes radiator with thins can be done.

you can solder the thins on. would take some time, but then again everything in this hobby does.

perhaps beer cans for thins?

btw, nice engine! i love it.

 

[Swifty]

The scale radiator would look better with the engine, is it possible to have a larger radiator on the ground that can be plugged in for longer runs ?

Paul.

 

[Art K]

Hi,
Yes .156 is some coolant passage but without a multi part head with a pocket over the combustion chamber you don't have anything near the scale coolant surface area. Yea Yea I know lots of big words. Probably a year ago Jan. we were in Akron, PA visiting the in-laws and I went to Cabin Fever. A guy I got chatting with had built Ron's Offy. I asked him why I never heard them run more than a minute or two. He says see this radiator hose, yea, when I see bubbles in the hose its starting to overheat. Yes it has cooling but not enough, made perfect sense when he said it but hadn't occurred to me beforehand. You probably get 80% of your cooling from the block.
I don't know what you used for a temp. gauge but I like it, another thing I wouldn't have thought of. you knew the exact temp and how long it took to reach. My next engine will be water cooled so I will keep that in mind.
Art

 

[gbritnell]

Hi Jim,
As you are finding out these little engines make much more heat than you would think. The only way to cool them is to add more water and cooling surface. The only way to do that is to use an oversized radiator. As we have talked about many times there are just some things you can't scale down and one of them happens to be the cooling. When I designed my engines I wanted to have a somewhat scale radiator just like you but soon found that it won't happen. The only thing I could say would be to use the small rad in front of the engine and put a larger one in a base under the engine so it would be somewhat hidden. The next issue is getting enough air through whatever type of rad you use. The fans are also scaled so they don't move enough air. The only cure for this is to make an oversized fan and overdrive it so that it will move more air, and shroud the fan.

 

[smpstech]

http://www.xoxide.com/swiftech-mcr120-quiet-radiator.html

These are used in watercooled computer setups. They are a bit large (this one is 5" x 6.2" according to the website,) but would probably provide ample cooling to allow the engine to idle for quite a while. I'm not sure how the positioning of the barbs would effect you. They are both at the top, as is almost all computer water cooling radiators, so you may have a problem feeding the pump.

If you buy into the idea of electric fans, the radiator already has holes setup to mount a standard 120mm fan such as:

http://www.xoxide.com/yate-loon-highspeed-120.html

 

[stevehuckss396]

My hope was to be able to idle it forever. Not happening yet. Some builders at the shows have huge radiators, way to big for scale (heater cores maybe). Your Demon radiator looks really appropriately sized for scale. I thought mine was somewhat large but not too bad but I'm leaning towards making it bigger. I think thicker wouldn't too seriously hurt the scale looks . I'm also thinking I'd like to find a way to make really thin aluminum fins and lots of them like a commercial radiator, with aluminum tubes too. Chime in folks and tell me how to do it.

Well!!

If you build a box under your engine like mine you could plum your cooling thru the engine and a small radiator. Then have it go into the box where there are tons of tubes, fins, and fans. Model engine builder mag has an article about building small radiators using real radiators and cutting them up into desireable size pieces and fitting new tanks. I could fit 3 rows of radiator fin with computer fans between them if I wanted.

 

[johnny1320]

First I have to say I am very impressed with the work on this sight, as for cooling how about using a heat exchanger with dry ice or regular ice for that matter. It could be plumbed on the inlet side of the engine.

 

[jpeter]

You can see by the picture I've temporarily added the radiator. I used a small fan too to move air through the radiator. I ran it for 15 minutes with the temperature stable about 85 degrees C. I thought the idle was a little fast then so I slowed it down some and not long after started making steam. Idle is important to me so maybe I'll try increasing the pump speed some. A little bigger pulley on the crank should do it. Hey, 15 minutes is a great improvement from where I started. (6 min.) Progress comes for me at least in small steps.
I'm looking for opinions.

 

[Art K]

Hi Jim,
I'm glad to see that you got it to run for 15 minutes at a stable temp, maybe I was wrong about not having enough cooling area in the head. I had an uh hu moment of agreement when you said try speeding up the pump a bit. Excellent build. What are you using for a thermostat? that is a great idea.
Art

 

[metalmad]

Hi Jim
Inspirational Video on the V8
Looking at your coil the positve and negitve seem to be connected, is this a opitical illusion ?
Im afraid I dont know a lot about ignition systems and always have trouble remembering how I did it last time :fan:
Pete

 

[jpeter]

Regarding the thermostat question: I've got none. I've got a thermometer though. Its an old school glass Celsius job. The bulb will just slip down the fill hole in the radiator.
Regarding the ignition question: The wires are not joined, I used a piece of silicon zip cord from the electronics unit to the coil. You know how zip cord wires run parallel to each other. In the picture they looked joined but they just come together at the back of the coil. The hall effect sensor is in the distributor. Notice the radio-control aileron extension wire from the back of the engine to the ignition electronics. The board is hanging off the coil peeking out on the left side of the picture. The green wire is there just to hold the control wire away from the exhaust header.
BTW, for you using hall effect sensors I found an application sheet showing how to bullet proof hall effect sensors in ignition setups. It works. I've had sparks flying off everything and this ignition still works. I'm still using the first hall effect sensor I started with. I've got a basket full of dead hall sensors from previous ignition board setups.

 

[metalmad]

Hi Jim
I am thinking Hall effect at the moment but as you may have guessed dont know much about it :fan:
Would love a link to that aplication sheet
Thanks Pete

 

[jpeter]

Interested in hardening a hall effect sensor, check out the picture. It works.

 

[jpeter]

Bad day in Jim's shop. I'm not sure if it's totaled but close.
It got running really poorly so I ran a compression test and found the front 2 cylinders to have about 40psi while the back 2 came up to 75psi or so. Middle cylinders all tested somewhere in the middle. Curious to find the cause of the deviation I removed a head and found the front pistons to have 1/8 inch less stroke than 7 and 8. That's when I removed the pan to discover disaster. Something went bad wrong with the oil system.

I think I need a beer. Ouch!

Check out the crank throws. They all look about the same.

Rods all look like this.

 

[Lakc]

Looks like a little bit of work to do there, what were the rods made out of?

 

[stevehuckss396]

That sucks!