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.12/.15 engine

Old 03-15-2006, 07:19 PM
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Tim Wiltse-RCU
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Default .12/.15 engine

Well guys I think I want to dig my boat designs back out. I really like this new "class" of .12/.15 sized boats. What are some of the engines that are being used in these boats? I will be running them in an outrigger. I see that there is a number of the .12's on eBay.

Thanks for the help,
Tim
Old 03-15-2006, 08:31 PM
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Ron Olson
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Default RE: .12/.15 engine

Right now the O.S.'s seem to be the hot ones. I'm still waiting for CMD Racing to come out with the new A/A .12. Think of it as a small MAC engine. I see that there is some work going on with a new tuned pipe, they're calling it a square wave pipe. It's a little hard to explain right now.
If you want to make it IMPBA legal, stay with the .12's unless you have no plans of racing it.
When shopping for a .12-.18 for a boat, try to find one with the long threaded shaft, no short cut ones like for Associated vehicles or SG shafts otherwise you'll run into hardware problems. A rotary carb is easier to set up than a slide carb.
The class, "A", hasn't been used yet at any race that I know of. The Hydro Masters meet in September is considering it and has had a lot of interest so far so it looks like it will be a go.
If you need some help along the way, I've had quite a bit of experience playing with the .12's the past few years and having a blast making mine scoot, both monos and 'riggers.
Old 03-15-2006, 09:47 PM
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Default RE: .12/.15 engine

Tim, listen to Ron's advice about staying within the IMPBA classes, you NEED to join some of our races when you're ready. It's a great group of guys. However, as Ron said, the .12 class doesn't have much activity yet. We have a couple guys with .21 size riggers, but no .12s.
Old 03-16-2006, 08:57 PM
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Tim Wiltse-RCU
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Default RE: .12/.15 engine

Ron, Chuck,

Thanks for the info guys. Looks like I'll go with a .12 sized boat now then. I was looking at the NovaRossi .12 RE and the HPI Nitro Star .12R for engines. I can make up a flywheel on my lathe and am drawing up some ideas for the rearend hardware that I would like to make on my milling machine.
I think before I get to far into a .12 size rigger I am going to build up a 1/2a sized rigger to run one of my Sniper DR .049's in. Something about 12" long 8"wide. Balsa over foam sponsons and balsa tub. Only hard thing will be digging up a small enough prop for it...hummm that might be hard to find[:@]

LAter,
Tim
Old 03-16-2006, 09:08 PM
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Default RE: .12/.15 engine

how do i upll the piston out of a .15 for a rebuild.
Old 03-16-2006, 09:11 PM
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Default RE: .12/.15 engine

ORIGINAL: Tim Wiltse-RCU

I think before I get to far into a .12 size rigger I am going to build up a 1/2a sized rigger to run one of my Sniper DR .049's in. Something about 12" long 8"wide. Balsa over foam sponsons and balsa tub. Only hard thing will be digging up a small enough prop for it...hummm that might be hard to find[:@]
WOW! I am very interested in the 049 idea! I don't believe finding a prop would be hard as you could use the smaller props for electrics. Please keep me up to date on the rigger ideas Tim.

EDIT: I take the head off first and the back plate. Then use 2 or 3 snap ties and insert them through the exhaust when the piston is below the exhaust port. Then I rotate the crank to push the cylinder sleeve out. Once the sleeve is out I find positioning the piston at TDC and sliding the connecting rod off the crank to be the easiest. Then pull the piston out the top.

Ryan
Old 03-16-2006, 09:28 PM
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Default RE: .12/.15 engine

We were thinking of downsizing the Hammerhead .12 just for the heck of it for 1/2-A power. There are props that can be used as Dumas and Octura both make them that small, X-427 and X-430.
www.microhydros.com has a lot of plans for boats this small.
Old 03-16-2006, 09:33 PM
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Default RE: .12/.15 engine

What speeds would be possible from such a small boat? Also how stable would it be at these speeds? 1/2A power has a cheap running cost compared to the larger engines. It would be great to have one of these in the fleet.

Thanks, Ryan
Old 03-16-2006, 09:41 PM
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Default RE: .12/.15 engine

what side does the pistons side with the raise in it go?
Old 03-16-2006, 09:43 PM
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Default RE: .12/.15 engine

I wouldn't expect it to be a speed demon but maybe fast enough to be fun. Stability shouldn't be a problem except for water conditions as you'd need pretty much an almost glasslike surface to run a lt of them.
The Dumas Short Stuff and Lil Rascal were both built for .049's to .10's originally.
My .12 boats only have 4 oz. tanks and I have a blast plus a lot of run time with them.
Old 03-16-2006, 09:52 PM
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Default RE: .12/.15 engine

Dumas Short Stuff, that sounds familiar. I believe it is a deep vee but I could be wrong. I have a .15 size engine with a 4oz tank and I achieve about 15-20 minutes of fun. What size fuel cell would the 049 use? Somewhere around 2oz - 75cc?

Ryan
Old 03-16-2006, 10:23 PM
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Tim Wiltse-RCU
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Default RE: .12/.15 engine

Well it's been 15 years since I last made a hydro to run a .049. It was a Dumas Atlas Van Lines with a straight shaft. Big heavy standard size servo(only rudder) and a standard i.e. sized rx battery. With todays modern radios and gear and construction methods a guy could make a boat that would really move(for its size).
A good tank size is 1oz for a .049/.061 engine. The Norvel line of engines are around $50.00 and are very powerful. I know it's more or less apples to oranges but a Norvel .049/.061 can turn 23,000 rpm without breaking a sweet. I made a rear disk valve conversion for the old Cox reed valve engines and it will turn 23,000 also. Here is a picture of my engine conversion I make( and anodized) as well as my 1/2a sized carbon fiber tuned pipe I made.

LAter,Tim
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Old 03-16-2006, 11:22 PM
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Default RE: .12/.15 engine

They both look amazing! How would you set these engines up to fit standard running gear for a boat? Do they have a standard 5mm crank like the .15 or are they much smaller?

Ryan

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