also i was looking around tower and found this motor, would this make a good first motor to have, its cheap so i wont be out to much if it goes, thanks

http://www2.towerhobbies.com/cgi-bin...?&I=LXMPG9&P=7

I think for a 31 inch boat it to big
http://www.horizonhobby.com/Products...ProdID=DYN6450 dynamite engine
http://www.impba.net/ lots of info here

alright , i like the os and the dynamite the best for cost due to my first nitro boat build. and thanks for hte info. i am still learning thanks clay

alright if you were in my shoes, what ( just one) motor would you choose, remember im new in nitro marine and i like speed

[link=http://www.impba.net]IMPBA[/link] is the org that CMBC belongs to..

alright if you were in my shoes, what ( just one) motor would you choose, remember im new in nitro marine and i like speed

I would pick the OS, OS is just a good motor if taken care of it will last you a long time, preformance is good and parts are easy to get

I think that you are in IMPBA country so look at www.impba.net . The rulebook is a downloadable .pdf. you can download the parts that you want to look at.

alright i am doing that as we speak thanks

I have just purchased an OS .32 for my 31" Pranther V-hull and it is very quick!. Motor was so easy to break- in and tune. I looked at the 0S .21 but have been told that even though it has higher rpms the .32 has more torque and can swing a far bigger prop.
This is not my first boat and I have used other models of motors such as K & B and ASP. OS are not the cheapest but their quality has been proven and they are easy to setup and hold a tune.
But I guess everyone has different opinions, I find that when looking at a specific model of engine before purchasing it helps to talk to people who have actually owned that particular one.

dude thanks for the info i was trying to chose from 3 motor and thta one was looking great the other two are
http://www2.towerhobbies.com/cgi-bin...?&I=LXKKP0&P=0

and

http://www2.towerhobbies.com/cgi-bin...?&I=LXBY94&P=0

what do you thikn or just stick with the os .21. hopw to hear from you thanks clay

In my opinion (which may mean nothing!) and based on what I have been told at my local club, a .46 is too gruntly for this size hull.
A .32 is the recommended maximum size, considering this size hull is for a .21 anyway.
As for your 2nd option of the .21 looks like its a real goer, though seems a heck a lot of money if you do not intend racing the boat!
If I were you I would do some searching for any feedback on the .21 which is obviously OS's latest and greatest!

I ended up going with the .32 as I wanted the pullstart and had heard a lot of good feedback on t as well as seeing it in action in the same size hull. No doubt everyone has different opinions, thats where ther eis nothing better than to see the setup you are after in action.
By the way the Dynamite .32 where others have suggested in this thread...if I were you I would stay away as it is only a cheap sport motor designed for cheap RTR kits. I use to have one and had majors issues in trying to get it to hold a tune, so ditched it for my currect OS.

Good luck with your decision...I know what its like when you want to buy NOW cause you can't wait to hit that water!! I would be interested to know what sort of speed you get out of your .21!!!!!!!!!

The IMPBA rulebook I have shows the following:
"B 0.130 thru 0.219"

If you're running by the rules, a .32 would end up having to race in D, probably against MACs, CMBs, and possibly some Piccos or even .45 OS engines thrown in there.

The .45 is too much for the hull, and the VX-M is really pricey for someone starting out. Consider starting with this one (you'll also need a tuned pipe):
http://www2.towerhobbies.com/cgi-bin...?&I=LXALL8&P=7
and learn to tune the hull and engine to get the most out of both of them. This engine will allow you to run in B mono, if you're planning to race, and will be a good match size-wise, with your hull. A .32 would be ok for fun running, but if you compare the numbers, the .32s don't really have any power advantage over the better .21s.

we did do the math on the .32 dynamite engine in my tc31 and could have run it in the .21 cat class but the hull was bigger and the .32 isnt as good as a .21 so I didnt race it..Im telling ya thats why we had 2 other people on the figuring It just fell into it by a nats n#+ in that class but hay 2 people with calculators that did not care if i raced or not could be wrong.

Sounds like they didn't care.

has any one used the O.S. .21 VZ-M Marine engine, just looking for sume specs, or rating on it thanks clay