2 questions
 

Hey O.S.
#1
I recently made a truggy from a T-maxx and the HCR mutnat maxx kit.... I had to make a new center diff brace and Upper chassis so I could put a larger Spur gear on it....I'm now in the realm of super low gearing and finding out alot of engines made for off road don't rev as high as I'd like them to....yes I have changed the CB and tried 12/13/14t the 12 just seems to work the best but I need more RPMs...I'm using a VZ-b (not the V-spec) right now and was looking at On-Road .21 mills....are there ANY reasons why I shouldn't do this?? I'm mostly concerned w/ Bearings, I was told alot of On road mills use ceramic bearings.......

#2
I have 2 RG mills I modded but they don't seem to like the higher RPM range it has now and eats Conrod bushings....any suggestions on another Conrod that fits the RG......as it is now I check the one engine every 2-3 tanks to be sure it's not eating the lil bushing.....actually they are spinning in the conrod and blocking the lil hole on the bottom...I'm sure w/ enough time they would grenade like that if I don't catch em

RE: 2 questions
 

Our O.S. car rep suggests a .28-.30-size engine. His thoughts are that an on-road car engine will not be effective. It won't have any low-end torque, which is what you need for your type of truck.

Here are the new O.S. enignes that will be more likely to suit what you want to do:

OSMG2075 13960 .30 VG(P)
OSMG2076 13980 .30 VG(P) SR SAVAGE (accepts roto-start)
OSMG2077 13970 .30 VG(P)-X (has recoil starter)

RE: 2 questions
 

well my issue isn't low end torque, it's high end RPMs......right now it's got a 62t spur gear and 12t CB that puts me around 5:2 priamry ratio...I'm also using 1/8 scale diffs putting me even lower for my final ratio than stock T-maxx gears.....when I ran my fantom .27 in it it was a monster....I had all th elow end torque adn loads of top from RPMs....well that engine is definately a throw away.....QC on them Sucks and I want something w/ buttloads of RPM.....it was a great combination of torque and speed.....as it sits now w/ the older mill it almost snatches the front off the ground.....and this thing is long (wheelbase) and runs a buggy drivetrain.....is torque the only reason you're swaying me from that route???
I am looking at the O.S. .30 for my basher MT though...looks like a sweet mill......

and any help on the RG conrod replacement would be appreciated as well
Thanks
Eric

RE: 2 questions
 

Bearings are usually eaten by the way many R/C car modelers run their engines. The fuels used have too little oil, and the engines are leaned to within an inch of their lives, trying to get every bit of RPM out of the engine.

If the bushing in the rod is spinning, then there's not enough lubrication getting to the lower end. Either the fuel doesn't have enough oil, or the engine's being run too lean. Gearing can be a factor if the engine's turning extremely high RPM. Run to hard or too fast, and engines don't last too long.

If low-end torque isn't a concern, then go with the on-road engine. The sacrifice some low-end torque ability because they're ported for high-end RPM.

For fuels, O.S. states that oil content of NO LESS than 18% be used. We'd also suggest going with a fuel that has castor. That gives a LOT of protection to the engine. There's a flip side to that, though. Fuels that help preserve engine life also don't clear as well when going from low to full throttle. Racers hate that, and so use low-oil fuels to get cleaner throttle action.

The thing to remember is that the people whose engines don't last too long either totally don't know what they are doing, or are pushing them very hard. That's why you see a lot of broken engines in racers' hands....they push and push and push.

RE: 2 questions
 

I absolutely agree w/ the tuning and oil issue....currently I use Maxy's 25% and add castor oil to it...yeah it does load up when it idles but it runs cool.....The Conrod issue is definately from modding the engine...I ported/polished the fuel intake on the crank and polish the journal and the whole crank (mostly just for fun), also polished th esleeve ports....didn't mod them just polish.....this increased the upper RPMs on the mill and I don't think that conrod handles it very well...I love the engine stock and modded but it really east the conrods in the port modded one I have......I noticed when I got it I ran 30% and was doing the same thing...someone recommended the 25% fuel and I had no more conrod issues.....now tha tI modded one the conrod issues ar eexactly what I had happening w/ the 30% fuel...the brass bushing spins and then the oil hole won't line up anymore...I know this was a very poular engine to mod a few years ago but nobody can tell me if another conrod has th esame dimensions......

Gearing can be a factor if the engine's turning extremely high RPM. Run to hard or too fast, and engines don't last too long.

are you reffering to gearing too high of a gear and it working the engine too hard or too low of a gear and it revs too easy.....right now I'm not too concerned w/ the overall life as long as I can get at least 10 gallons of usable service from it.....that Fantom gave me less than 1 gallon and it's done...looks brand new and has no compression even cold...I can turn it over w/ my pinky....I get over 10 gallons from my RGs and that's considered a low end mill......

RE: 2 questions
 

"Lugging" an engine can cause rod problems, and the rod usually ovals out and eventually has the lower-end break because the sides have been stretched too much.

Over-revving causes the rod to tend to seize to the crank because oil just can't get in fast enough to keep it lubed. They can also have a catastrophic break on the sides due to the high loads imposed when the rod changes direction from up to down.

RE: 2 questions
 

I just noticed your signature...are you the guy I'd talk to for Futaba warrantee issues too???

RE: 2 questions
 

Do that in the Futaba Support forum, or call the support phone number. You'll get one of our able technicians. Krysta handles most of the Futaba Support questions.

RE: 2 questions
 

thanks.....