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How can I modify a .18 to a .21

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How can I modify a .18 to a .21

Old 10-15-2003, 11:45 AM
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Default How can I modify a .18 to a .21

I have a kyosho Heatwave discotinued model that Towerhobbies still supplies all parts for now this boat is almost 30" long and comes with a .18 watercooled engine
I want to up-grade to a .21 size nitro engine has any one ever done this in this boat,
I have two engines of choice I have a new ofna p4 and a Hpi 21bb I was thinking of a O.S. rg series engine cause they are light and the power band will not harm the drivetrain (the boat is direct drive) well my major problem is space it has a small tank probably 75cc mounted right behind were the engine sits I have placed the p4 in place and sits nice with out the pull start once the pull start goes in the gas tank its in the way...
I really wanna get this project rolling this is my second boat and I love it its a catamaran style with ladder hull and a octura stell prop and kyosho alum. turn fins
right now I am running a modified associated .12 and it moes but I know I can do better boat is very stable and handles well in turns and out of turns.

Can anyone help ???
Old 10-31-2003, 09:56 PM
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Default RE: How can I modify a .18 to a .21

i dont think you can. if you mean like boar it out i wouldnt b/c your gunna have to buy a new piston and its not worth screwing it up.
Old 11-20-2003, 03:02 AM
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Default RE: How can I modify a .18 to a .21

The engine itself cannot be changed to a larger displacement, unless you have expert machining skills.
If all you want to do is install a larger motor, that's pretty easy and won't require an engineering degree.
I know the boat you are talking about, I just recently retired mine after running over too much flotsom.
If you want the easiest route, go with a Hot Bodies .18 car engine. The bolt pattern for the mounts are close. I believe the crankshaft is the same size so you can use the stock universal for the prop shaft. And this motor has about 2 times the power. It is air cooled though, so it would be best to run it w/o the deck cover.
Check out the car motors on the Tower Hobbies site. Find the HB 18 and check out the specs.
The Kyosho 18 GPM is a pretty good motor, but does not have the advantage of the race orientated porting that the more modern race engines have. It was intended as a sport motor.
Actually, a lot of .15 size motors have more power that the Kyo 18.
Old 01-30-2006, 01:01 AM
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Default RE: How can I modify a .18 to a .21

I have a Heatwave Nitro boat. Although it's old and no longer made I've only run it once in fresh water since I bought it years ago. I now want to get back into racing it. I am in the process of re-spraying it and I want to know what would be the ideal Tuned pipe to put on this engine? Would I get any power gain from having a tuned pipe rather than the standard exhaust that comes with the .18 engine?

I also know that replacing the standard plastic prop will help with speed gains as well. What would be the ideal one to buy?

I know this thread is years old but I thought it might be relivant since it's abotu the same boat.

Old 01-30-2006, 04:18 AM
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Default RE: How can I modify a .18 to a .21

if you do go with a car engine just water cool it its dead easy just make a cooling coil with brass tubing i just did my 61 size plane engine take a look !!,the cable ties are temporary till i solder it .[img][/img]to bend the tubing just tape up one end and fill with sand or water then tape other end up and bend it arround the head as tight as you can one end will be input one out easy !!job done and it works well .
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