What is best motor for 1/12 miss llamar hydro
 

Want to upgrade the .15 dynamite to the fastest engine. No class racing, just back yard grudge racing.

pick a 21. example; o.s. 21 rzm.

A .21 is too much work to drop in. Any good .12 - .18 engine will almost drop right in. The Dynamite .15 is only considered to be a Sport motor.

thats vert true Ron, actually i didn,t think of the nova rossi 15 very quick little engine . i did have one of these in my nitro days just for a saw class .

Thank you! What will best prop for me and which fuel should I get.

It's got a pull-starter and side exhaust, 2 pluses for a RTR boat. Contact Glenn Quarles but probably not this weekend as his wife is shooting for a SAW record in Sport .12 hydro. Martin Truex Jr. is rolling into town to help them out plus probably aiming for a few more himself. You might get a better price than the one listed.
You might have to get a bigger prop as that should have a lot more power and RPM. I don't know what prop for sure as if it has the 1/8" shaft you're limited to the biggest 35mm as anything bigger you'd have to convert over to a 3/16" drive.
These little engines love the nitro. I've run 65% in my little ones but I'm a little crazy, 40-50% would be good.

yes if you are going for a more powerfull engine you will need a larger or higher pitched prop so in turn you really should consider changing the shaft size from the current 1/8 th inch to a 3/16 inch diameter. i wouldnt trust the 1/8 th shaft .

A guy at my club races his 28cc rigger with 1/8th piano wire :rolleyes:
No issues after many runs.

why would he set up a gas hydro with a 1/8th inch shaft ? there is no advantage of doing this even if its set up for saw, a well set up rigger requires a very minimul bend in the stuffing tube / shaft to reduce any drag in the line. also swinging a high pitched 70 odd mm prop would put an awesom amount of strain on a tiny 1/8th rod. i run riggers with the normal 1/4 in flex type shafts with powerplants producing up to 8 h.p. at 22,000 rpms , these are the new cc racing 29.5 zenoahs plus i wouldn,t like to lose a prop at the price there worth [ cocr props ] just because i was silly enough to fit a shaft more suited for a .10 cc glow engine. i am sure guys like andy brown and john finch would think the same. just my thoughts.

The day I saw it was in shock too lol but it works. The advantage is less line drag set in
bearings / more torque to the prop. He has the rigger set up for oval racing the wire drive
weighs less on the piston allowing an edge for faster acceleration once out of the turns.
Ran stable in the chop and wide open was getting 57 mph best pass per my radar.
Average passes 55 / 56. Most folks at the local club setup to turn fast with no lag consistency.

The 1/8" "wire' drive is one of the best if not THE BEST drive system out there - last I heard there was about 35 boats running it - including inline twins

It's the most advanced and proven more rpm and less friction.. I have not heard or ANYONE breaking a Byers wire drive yet including FE boats. I;m sure if you actually talk to Mr. Finch he will tell you that as well.


It's well know on couple of 'other sites' that it's the pinnacle of drive systems. I'd never even consider a 3/16" drive on any gas boat - 1/4" is the standard - but the 1/8" Byers wire drive is the best.. Below is info about the drive

I'm posting this to provide some technical information and not as a for sale post although one of those will come soon enough.

Here's some basic info about the system:

• The shaft is precision ground (0.0002") and polished and is made of a VERY high strength corrosion resistant steel
• The stub shaft is precision ground (0.0002") and is made of heat treated stainless steel. The drive dog flat is pre-cut.
• The collet insert is made of heat treated stainless steel, has very thin slots to maximize surface contact with the shaft. It fits the Zipp "Super" style collet. The collet will support 10 lb-ft of torque.
• The stuffing tube is hard anodized 7075 aluminum and has machined composite sleeve bearings periodically spaced inside. The stuffing tube material has almost twice the yield strength of K and S brass tubing while being only 1/3 the weight. The tube diameter is 9/32" instead of 5/16" for less drag.
• The struts are equipped two ways: 1) with 3, Japanese made, 440c stainless ball bearings (two rear, one front) or 2) with Teflon bronze sleeve bearings. The struts are modified Speed Master parts and have an oil injection port.

A few benefits:

• MUCH less friction than a cable. Shaft surface speed is cut in half and contact area is greatly reduced
• Saves about 1/4 lb on most boats
• 400-600 more RPM on top and 3-4 MPH....determined by back to back testing.
• Better acceleration out of mill
• Basically, a lot more of the power your engine is already making gets to the prop.

A few drawbacks:

• The system requires a single, large radius stuffing tube bend. Most riggers, hydros, monos and thunderboats can be retrofitted, but will require the stuffing box and engine mounting to be reworked. The system is not recommended for cats or other boats that require a small radius bend in the stuffing tube. Careful engine alignment is required.

https://youtu.be/mfdUGwr1ihI

well i do suppose after reading this it is understandable that the 1/8 th shaft running on good bearings aswell is not such a bad idea as i thought. my main concern was the high torque of a gas engine / high pitched prop could easily break this size wire.

Yes and no more oil cup needed, I have been using wire drives on Nitro boats with no issues thus far.

I have bought 3 times from Jeff Wohlt reasonable prices and very straight drive lines.
.062 /1.6mm, .078 / 2mm , .098 (2.5mm) is what he carries so .05 thru 60 size engines.

http://www.rcraceboat.com/

do you still have a slight bend in the solid wire shaft like we do with the flex wire shafts ?

Set up to keep striaght, however as you tweak the final strut depth it may end with a slight bit.

That wire drive may be the "best available" according to some but, that said, I doubt I would ever consider it for a scale build. When you're dealing with a boat that weighs in at 12+ pounds and being powered by an 11cc nitro motor, I wouldn't feel comfortable with a 1/8th drive

yes that was my original concern as most of the gas powered sport hydros etc weigh from 11 pound to 20 pound and as i mentioned with an engined developing approx 8 horsepower at 20 plus rpms swinging a high pitched 67 to 72 mm prop is a big ask for such a small shaft.
yes for smaller craft like electrics and glow power up to 11 cc might be ok. why doesn,t all r/c craft use this type of shaft ?

The gas rigger was set for oval races 28cc for a heavy scale hydro 3.5 mm would be plenty
and give you a power edge over the other boats.

actually this shaft set up would be much more benificial for SAW, not sure if it would stand up to the harsh oval racing. also if the shaft is dead straight there are not many boats that like a negative prop angle. True ?

Just something you would have to see or do for yourself like magic to some and form and function to others.

Next time that rigger is out running I will take a vid / start up on the bench to water action.
All the vintage scale hydro's running with the prop under the hull have quite a bit of down thrust.

Slow down gentlemen! We're getting way off-course here, we're discussing a little nitro boat, not a big gas one.

No arguments on that, Ron. I just don't trust things that are made undersized, be it in a sport 20 like my redesigned Dumas Pak or a gas scale like the 78 Madison I'm building now. Even with a 30+% weight reduction from a stock kit built, the sport 20 still weighs in at 5.3 lbs, too much for a wire drive in my opinion

Not true. Most run a flex cable drive rather than a solid shaft, just for the ability to adjust the thrust angle and depth of the strut. I haven't seen a newly built scale boat with anything else in years. As far as the older boats, most don't have that much down angle unless they were set up following directions in a kit that specified it as a starting point. Dumas boats were notorious for that.

yes the vintage hydros did use straight drive shafts as well as the naviga course power boats. one of my first r/c powerboats was a Precedent brand Sea Queen semi scale bay cruiser which was designed with a straight shaft [ 3/16 th ]