4wheelinrevo

Ok im getting a new engine for my TC31

please vote which one Would be the best for the thundercat 31, and why you think it would be the best choice. im running a pretty decient size prop, the Octura M447 (sharpened and balanced perfectly)

thanks for your help

oldlugs

Since the engine's going in a 31" cat, go with the OS .46 marine... That boat will scoot, even on 30% fuel. I would have chosen the OS VZ-M .21, but only for a smaller, lighter hull than your cat has. The M447 prop should work OK as a starting point with the .46 (which is also a popular, legal engine size for organized racing). Be sure to get a good, quiet pipe for the .46 as well...

piper_chuck

My Feedback: (12)

There's also an OPS .45. Aeromarine sells them for $255 including the pipe.

oldlugs

That OPS is a good choice.

Another .45 that's probably still available and under $300 is the ol' Rossi: [link=http://hyperprod.bizhosting.com/7_5_inboard.html]ROSSI 45[/link] When I was down there about a year ago, the .45s were in stock. Also have a look at the K&Bs; the .40 should be an ideal sport engine for a 31" cat: [link=https://shop.mecoa.com/shopdisplayproducts.asp?id=26#]MECOA K&B RETAIL PRICES[/link], and the "new style" 7.5 (.45) goes pretty well, from what I've heard (but I think I'd still have the OPS, Rossi or OS... probably in that order)

Duane

4wheelinrevo

one think that i really dont like about some of those engines is the belt start, just dont like belt start, dont wuit know why but i just dont.

Ron Olson

My Feedback: (1)

What you'll have to watch out for on a lot of your choices is that you may be getting a slide carb or one that is SG shaft equipped which will make it a nightmare to blot on the flex cable coupler.

f16man

REAL MEN HAVE BELTS LOL. BELT STARTING IS THE EASIEST ON THE BOATS STRINGERS AND YOUR FINGERS. IVE HAD TO MANY ISSUES WITH PULL STARTS AND THE LIKE, NOTHING TO GO WRONG WITH THE BELT!!

Ron Olson

My Feedback: (1)

I've only broken one belt in my years of boating. They're a lot easier to change that having to pull the enigine and repair a pull-starter. When they start to show signs of wear, I replace them.

4wheelinrevo

when i look at the shaft that is on the dynamite .32 it looks pretty much the same as some of my other truck engines, except it is a little shorter, i can easily cut it down to make it fit, the only spot i would run into problems is if for some reason the threading or if the shaft is thicker then the dynamite .32 is, but i doubt that.

as far as a slide card versus a rotory is concerned i can easily fadricate a little bracket to to mount the throttle linkage on, if i do decide to get eh O.S. .30 i have a carb that im looking at for it that will fit nice and is 1mm wider for the same inlet and dead on for the outlet (part that goes into the crankcase) and it is rotory, so i do plan on gtting that

misshydro

Theres good and bad with both starts systems.pull starters can were out and cause hull damage by hard pull starts. Electric ones hulling a big battery and other junk. Now on SG cranks?I'd cut off the shaft by the thread.You proubly fin a flywheel to fit it.I'd fab my.21 fly wheel and works.On a hydro I might like it better because when I shorten the shaft and flywheel it moves the motor back about 1/4 to 1/2 backwards.That good.thats less weight on the front end on hydros.Cab is a different issue,Now My local hobby shop guy told me that the side carbs are better and quicker responce then the rottery carb,but some boat you cant get them to fit/to wide for some motor compartments. But on the starters I'm going to try electric and see if the hooplas are right.For motor the guys who sells them on ebay told me the STS.30 has more power then the OS VS motor.But the OS.21 turbo motor is fast.I'll get the video that lastrestort but in his Miss Elum boat and man she's fast!!

misshydro

here the video of lastresort4X4 OS .21 vz turbo motor!![link]http://www.youtube.com/watch?v=xMeRQQwiMrU[/link]

oldlugs

Ron, I'm going to make up a few short flywheels & cones for those SG cranks... Appearance, OD & belt groove position like the Nova & CMB flywheels, but the collet mounting face in closer to the threads. When used with a piloted flex coupler, they'll grab plenty of threads. Andy Brown sold me a similar flywheel to convert my MAC OB powerhead to inboard, by also switching to the MAC buggy crank (with a trimmed SG shaft). I'm just waiting on some 7mm chucking reamers before I start cutting... Little lathes are fun.

Duane

4wheelinrevo

thats one fast boat, but i wonder how it would do on a TC31, which is a bigger boat.

still leaning towards the O.S. .30

looks like the results show this so far

sts 1 vote
o.s. .21 2 votes
o.s. .46 3 vots.

none for the o.s. .30

4wheelinrevo

also if i get a motor with a SG crank do i have to use the gold belt starter collet? as long as im using a non belt start?

the reason i ask is because i can just cut the crank downa bit, screw in a little back plate on the crank and then screw the drive shaft coupler on it tight.

misshydro

Like I was told you can cut off that smooth part off.I did that to my thundertiger.21 car motor that I'm planning to put in one of my boats.For a hydro it should work great,because by shorting the crank it allow you to move the motor back 1/2" that great.It take the weight back more to midship and less weight on the front nose/front of the hydro. also I have a vegas coupler that I'd redrilled and taped to fit it.Most .21-.32 have a 1/4 by 28 thread.[8D]

gooycheese

You have to run a flywheel or some sorta weight if ya didnt want a flywheel, it helps keep the engine turning.

4wheelinrevo

i know that one!!!

i just wanted to know (since imn new to boats) if that was essential to the connection tot he drive shaft, i should have been more clear.

it looks like its close betweent he O.S .46 and the O.S. .21VZ

the VAZ is a nice motor, just wondering if anyone has used it on a boat the size of the TC31 thou.

either way im sure any of the above motors will perform better then the dynamite .32

wave waker

i got OS .30 for my 1/8 monster truck though, lots of power dependable, easy starting..

but i vote for OS .46

misshydro

Heres my thundertiger.21 car motor.As you can see I'd cut off the crank and had mod a flywheel to fit it.But with the thundertigers,the car motors have mostly the same parts as the boat motor.just the crank and carb and head.The blocks are the same so the boat carb will fit.But I'll try to use the car cab if possible.

4wheelinrevo

i went to the LHS tonight and looked at a few different motors, they have a rossi 53 marine there and an O.S .21 rg, looked nice, but not the power i need/want

also looked at this speedwerks engine, its only a .26, but this is the same engine the guy at the hobby shop runs, i got to see it this weekend during the sunday LHS bash at the forest preserve, the engine does have alot of low end torque, and good top end, its rated at 2.74 hp and 34,000rpms, from what i saw and heard its not that far off. plus its only $130,

the axial .32 looks good, but for that price i can get the O.S. .30

misshydro

There a guy on here who can mod out a.26 sportwerks.He said it will have 4hp and 42.000rpms.He'd done one.When I get my hand on one I'll be send it to him.his name on here is BBmods.But money is realy tight and I try to make do in what I got. That why I'll use the tiger motor,2.4hp top rpms at 38.000.I'd payed 10 dollars for three of them and that a deal.

Hydro Guy

MISSHYDRO YOUR FLYWHEEL IS TO SMALL FOR THAT ENGINE IT WIL BE ALMOST IMPOSIBLE TO GET IT TO IDLE.

misshydro

On my other.21 I'd have had much proublem with idle issue.Plus it's steal and the others are brass,so steal is heavyer then brass and it should compsate for the weight.Cars have the alum flywheel with clutch,So I'm thinking it should be very close in the counter weight in the flywheel.[8D]

4wheelinrevo

ok im going today to grab the speedworks .26.

does anyone have any reason why i just not try this motor out?


i figure worse comes to worse i can always use it for my truck if i have to

oldlugs

My 7mm reamers came on the big brown truck yesterday, so I finished up a flywheel and cone to fit on an SG crank:



You can probably get a buddy with a lathe to trim down a production NovaRossi, CMB, Picco, etc. flywheel so that it'll work on a car/buggy engine. I'm playing with a new mini lathe, so cut this flywheel & cone completely from bar stock. I've got a few car & buggy .21s to convert, and wanted to make some simple parts myself. With so many choices for good car & buggy engines (as compared to marine), it should be fun playing with some Frankenstein combos...

Duane