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engine prop size

Old 09-02-2006, 02:25 PM
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mrfixitwhite
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Default engine prop size

can any one help!
i just got a 3.5cc engine-about a .21 im guessing! dont know the make yet,its not arrived!!(ebay)lol
i was wondering what sort of prop size will run on this size engine
i know its a bit of a guess but i really dont have a starting size so any ideal size will do
its to go on a scratch built 'PANTHER' inboard-plans off of the net which i have scaled down to 1/8 size
the full size takes a 280hp v8! so i figured a little nitro would probaly push it!
h**p://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ih=009&item=190022661569&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1
thats the link for the engine off of ebay if that will help any!
ive NO idea how it will run yet! no muffler with it either!! any ideas there as well!

Thanks
Graham
Old 09-02-2006, 04:56 PM
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misshydro
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Default RE: engine prop size

Hi,Which motor did you win on ebay?I was keeping my eye on some of the .21s.Do you win it this week? On the .21 your boat need to be smaller then 1/8.you need a 1/10 scale.The 1/8 scale is to big and to much for the .21 motor.Your boat need to be 29-36 inc long. Thats what all the boats that I see that has.21 in them.The shock wave has a .32 motor in it.That the same block size, but bigger cc.I'm running a ABC h-4.I was told that would be a good prop to start with.Here's other props octura x440,x442 prather 215,220.All of these props are hydro's.That's what I got. I don't know what prop to use on the deep v's.But I'm sure the other guy's will tell you and help you out with.
Old 09-02-2006, 05:07 PM
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mrfixitwhite
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Default RE: engine prop size

if you take the ** out of the link and put the tt in!
that will give you the engine
the model im scaling down is a 15' speed boat so scaled to 1/8- 15' to inches then multiply by for 25.5mm and then divide by 8!
that was my reckoning! and it works out about 21"
so should push it about ok! i hope!
Old 09-02-2006, 08:02 PM
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misshydro
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Default RE: engine prop size

Hi,The motor looks like a old k&B /valco motor. Your scale if you doing 21" that would be 1/12 scale.I have a Miss Budwiser hydro,it's 27" long by 14"wide.That 1/12 scale. Trust me and look around ebay at boats and you'll see them. The lower the number of your scale,the bigger your boat will be.All the boats that I'd seen on Ebay with.21 in it are 27-36"long.Plus I have a 30"long hydro too with .21 in it and it looks like it belongs in it.The 21" long might be a little small for your .21 motor.The motor looks very old,I hope it run for you.[8D]
Old 09-03-2006, 06:00 AM
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Default RE: engine prop size

it actually works out at 22 1/2" long at 1/8 scale
and when i say scaled i mean only size wise not performance wise-the faster the better!!
the original 15ft boat has a 11-12" prop with 14 pitch! with 280HP behind it! so i really hope to get a similar power ratio to get mine moving some!
scaled down thats ABOUT a 38mm prop.
i just wondered if the engine will spin something like that?
Old 09-03-2006, 06:55 PM
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misshydro
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Default RE: engine prop size

Hi,Look at these boats on ebay their in scales and you'll see for your self that 1/8 is to big for your .21 motor.Here the ebay idam# 1/12 scale Miss bud like hydro#110028144978,the 1/8 bud hydro like 230023732275,Here your scale 1/10 that your .21 would go in to#140025305587 #16002584611 that the shock wave 36. If you want to do a 1/8 scale boat,you need a zenah motor its like a weed wacker motor. The higher the scale number,the smaller your boat will be=like 1/12,1/14.1/16 and so on. The lower the scale numbers the bigger your boat will be=1/12 1/10 1/8 1/6 1/4 and so on.Anything over 38 inc is to big for your .21.And anything under 27 inc is to small for it to.I see alot of boat with .21 between 28 inc to 38inc. I wouldnt BS you about the scale size,you can look and see what I'm talking about. I'd hope that this helps.[8D]
Old 09-03-2006, 07:42 PM
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Default RE: engine prop size

To me taht sort of looks like an old Picco or Rossi, but I coudl be wrong. I dont believe it is a KB tho, when you get ti, there shoudl be some sort of inscribing on it saying who it is made by.
Old 09-04-2006, 01:53 AM
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mrfixitwhite
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Default RE: engine prop size

the motor should arrive today hopefully! maybe tomorrow!
as regards the scale MH- mine is 1/8 at 22/1/2" long
you will get all different sizes depending on what size boat your scaling down!
you say that 1/12 is smaller than 1/8 but if you scaled down an aircraft carrier even say 1/32 would be massive!
maybe the hydros are longer than 15' to start with
i am gonna wait for the engine to arrive to have a measure first ! but if it fits in the engine bay then its going in lol!
i know it doesnt look much but if it goes thats a good start for me-my first nitro boat!
gotta sort out a muffler for it though! got no idea what to use[sm=confused_smile.gif]
Old 09-04-2006, 04:50 PM
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Default RE: engine prop size

Hi,Model ships and planes are scaled different then boats and cars.Boats and cars/trucks are scaled the same way. The bigger the scale number the smaller your boat will be, like 1/12 1/14 and so on.The smaller the scale number the bigger your boat will be,like 1/12 1/10 1/8 1/4 and so on.[8D]

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