Aluminum Fly Wheel... Dangerous?

[CMsoccer21]

Ok so i was reading through a thread earlier and some guy suggested the thread starter get an aluminum fly wheel and then some other guy says "aluminum fly wheel, are you trying to get this kid killed?" I thought that aluminum fly wheels were safer because stock fly wheels can explode at high rpm's do what is this guy talking about?

 

[Russ2251]

A stock engine with aluminum flywheel will not explode, even if original flywheel was cast iron or zinc.
Those of my engines that were not aluminum have been changed over to all aluminum, be they Tecumseh, Briggs & Stratton, Lawn-Boy, etc. I only had trouble once and was due to directly modifying original flywheel.
My understanding is that clones are not as tolerant of higher rpm's.

 

[iwanttogofast]

i am lucky and have always used stock flywheels on my briggs and i blew up 4 engines by just putting the stock briggs under to much stress. But i have never shattered a flywheel. One of my friends once told me to drill holes in the flywheel for weight reduction and i knew that was a bad idea and didn't take his advice.

 

[Russ2251]

...i have never shattered a flywheel.

Darn near impossible to do so.

One of my friends once told me to drill holes in the flywheel for weight reduction and i knew that was a bad idea and didn't take his advice.

Absolutely!!!

 

[Kenny_McCormic]

Its a bad idea to use any factory flywheel on a motor modified to spin faster than it did box stock minus the gov. There are different construction methods for flywheels, Billet(milled form a solid block) is extremely strong and will take 10,000rpms without a problem. Cast wheels(factory0 should never be taken past 5000 RPM.

 

[Russ2251]

Cast wheels(factory0 should never be taken past 5000 RPM.

Sources?

 

[Kenny_McCormic]

Personal belief.

 

[iwanttogofast]

if the limit on stock is 5000 rpms i consider myself blessed.

 

[Russ2251]

My only flywheel explosion was around 9-10k with no load on a weedeater.
I was shocked for a moment then broke out in laughter.
My bad for modifying it.

 

[iwanttogofast]

lol...i wish you had that on tape. I always have wanted to use nos in a briggs. 10 hp shot of nos would probably blow it up. but i would want to have a steel plate between me and the engine.

 

[jr dragster T]

Yeah most billet flywheels are rated at 12 grand. And Russ could you elaborate on this flywheel explosion? What kind of mods where done?

 

[iwanttogofast]

getting 12k rpms out of a briggs would be crazy. I have heard don't know if its true but i heard the world formulas go around 12k but i have always seen like 10k rpms on specs.

 

[Russ2251]

And Russ could you elaborate on this flywheel explosion? What kind of mods where done?

Look closely here:
Prop-Cycle
Not sure if you can tell from pics, but flywheel was machined to make way for prop and associated hardware.
I had 2 of them made up. One for a working model and one to experiment with. I made the mistake of running with nitro/methanol/castor oil with no load.
Fracture started at 'molded in' flywheel key and just split apart.
Sounded like a gun shot and was probably just as lethal.
Luckily, I was standing behind and not to the side of engine.
I never did find all of the coil laminations.

 

[Magice]

I dunno about flywheel explosions.. they seem more of a myth.

My stock 5hp briggs minus springs + carb turns 6.5k on my kart.. I've been ripping around for a few months now. maxed out rpm down hill many many times and haven't had any problem.. maybe a little bit of backfiring but that's ok.

I recently rebuild it and the only problem it seems was the piston was beat up pretty good.. looked like lack of oil.

 

[jr dragster T]

Look closely here:
Prop-Cycle
Not sure if you can tell from pics, but flywheel was machined to make way for prop and associated hardware.
I had 2 of them made up. One for a working model and one to experiment with. I made the mistake of running with nitro/methanol/castor oil with no load.
Fracture started at 'molded in' flywheel key and just split apart.
Sounded like a gun shot and was probably just as lethal.
Luckily, I was standing behind and not to the side of engine.
I never did find all of the coil laminations.

Leave the model rc fuel to my rc nitro truck.

 

[Russ2251]

I dunno about flywheel explosions.. they seem more of a myth.

Myth it is. If kids were being injured or killed, lawsuits would abound. They haven't, they don't, they won't.

Leave the model rc fuel to my rc nitro truck.

Not r/c fuel. I make my own stuff for 'special projects'.
Off the shelf model airplane fuel doesn't cut it.

 

[jr dragster T]

One question. Where did you get your hands on nitromethane? And they make rc truck fuel up to around 45% nitro. Plane fuel is NOT going to work anyways. Oil content is usualy too low.

 

[Kenny_McCormic]

Plane fuel has more oil in it.

 

[jr dragster T]

Realy? I was sure it was lower becasuse they have MUCH more airflow than a car engine would.

 

[Kenny_McCormic]

Really, the planes can run more oil because they need no throttle response.