Document flywheel explosions with pictures!

[jr dragster Tyler]

These are the pictures Oscar was talking about the lawnmower flywheel explosions. Now just imagine if that hit somone....Look what it did to a Iron supporting beam in his shop!

http://gardentractorpullingtips.com/flywheelbreakage/flybreak.htm

[freakboy]

He probaly had a steel key on flywheel so he hit something and without the govenor or a broken one it split appart.

[jr dragster Tyler]

This is tractor pulling here. Some of you guys here asked for documentation of a flywheel killing/severely injuring people. I got those pictues of 4 cycle and theres alot of people over there who agree and have seen flywheels explode on a STOCK engine with just the governer removed.

[newrider3]

He probaly had a steel key on flywheel so he hit something and without the govenor or a broken one it split appart.

If you had read the page, you would've noticed it wasn't a lawn mower in use, it was an ungoverned engine on a racing mower.

[Kaptain Krunch]

i have seen a few threads about this, but for the most part it was user error, like one guy lightening a stock flywheel.

[freakboy]

Ohhh well reading isnt my kinda thing do to and i just got back from a party..........so yeah.

[Affair_driven]

theres alot of people over there who agree and have seen flywheels explode on a STOCK engine with just the governer removed.Let's see that documentation!!!

[Raywelder]

Wow, Went through the wall even! and dented that beam. Thats amazing.

[freakboy]

Im not sure if this would also be a problem but the flywheel itself is one with built in blades would the drag on that make enough force to make it less stable or something like that then do this?

[theo]

I would like to see documents of a flywheel exploding on a new engine. You don't know the history of a old fly wheel, it could of been removed with a sludge hammer once.

theo

[Affair_driven]

I recently posed this question on another forum and here's the answers I got.
Post #1
I HAVE A SET OF 5 HP IND/PLUS I/C MOTORS ON MY KART . BEEN BUILDING THESE MOTORS FOR YRS AND CAN TELL YOU I TWIST MY TO 75OO RPM'S AND NEVER HAD ONE FLY APART. IT IS ALL IN THE BALANCE AND FLOW WORK DONE. YOU CAN USE A ALM 3HP WHEEL AS WELL AND WILL HAVE MORE RPM'S BUT YOU WILL LOOSE IN THE LONG RUN. AND HARD TO START. MAKE SURE THE ROTATING MASS IS BALANCE RIGHT REMOVE ALL CASTING MARKS FROM INTAKE AND EXT PORTS AS WELL AS ALL OTHE INTER PARTS. KICK THE TIMING UP 3 DEG. USE THE HIGH FLOW CARB OFF A BLOWER AND REMOVE CHOKE PLATE. THIS IS IN GENERAL . IF DONE CORRECT THESE B/S MOTORS WILL RUN GREAT AND ALL WITH STOCK PARTS. MY KART IS GOING 66 MPH WITH A 175 POUND DRIVER.AND MOST; IF NOT ALL THE JUNK YOU SEE IN THE KART SHOP TO HOT ROD THESE MOTORS IS B/S. AND IF YOU CUT DOWN THE HEAD ABOUT 15THS AND USE 105 OC GAS YOU WILL EVAN GO FASTER. CAN SEND YOU PIXS IF YOU LIKE TO SEE MY SETUP.
Post #2
ill say i mostly agree with the other poster, i used to run a I/C briggs 5hp on my old kart and it ran for hours at 7000 rpm no prob. i hear people get way more than that out of them too. putting a 3hp aluminum fly wheel is cool to cause you can make your adaptor plate for the coil very easy to adjust timing. i ran mine on methnol with a big ex pipe and adapted a big carb from a 10 hp tec engine and it worked alright. never had a flywheel problem. port out and polish the ports good and look at aggressive cams if you really want mad rpm. use GOOD oil. good luck. i can't tell you what rpm a stock cast iron wheel would fly apart at but id guess well above 10000rpm. just a guess.
They really did not answer my question, but post #2 came closest to reality.

[Kaptain Krunch]

What i would like to do (and might when we move into a new house) is start collecting free push mowers that people dont want, get them going good then take a day, set them up in a field with a string on the governor, and one by run run them till they blow and see just how many flywheels actually fly apart. I would have to carefully torque and inspect each flywheel, but even with an old wheel i dont think any of them will explode before the engine throws a rod or something like that.

[Affair_driven]

i dont think any of them will explode before the engine throws a rod or something like that.Quite correct.
Nobody has yet to prove otherwise.

[jr dragster Tyler]

I have a old Briggs 3 HP with removed governer and It will only rev to 3900-4000 RPM before the flow cannot keep up and I've never had a flywheel probelem. I'm making a new cam for this engine ATM:wai: This is Mike Clemments exact words.

If you take a stock Briggs cast iron flywheel and turn it up to 10,000 rpm, which many limiteds will do, the magnet is moving at 256 ft per second. And, do to inertia weight and centrifugal force, that magnet weighs in at 2808 pounds. Being hit by just the magnet is like standing out in the middle of the freeway and letting a small car hit you at 60mph. How many guys are up for trying that on ?

Don't be a dork. Use a billet flywheel. If you can't afford one, don't race till you can afford one. It's not just your life that is at stake.

[Affair_driven]

Don't be a dork.Takes one to know one!:thumbsup: :thumbsup:

[Kaptain Krunch]

Jr, dont get me wrong, i do believe a flywheel will explode if you can get it to spin constantly at 10k for a little while, but without lots of modifications you will not get it to 10k, and if your putting that kind of money to completely redo the engine, then you most likely will and can get a billet flywheel. What i was talking about was JUST removing the governor and nothing else, and doing that you would be lucky to get past 5k and at 5k with all stock engine you will most likely throw a rod or blow something else before the flywheel explodes.

[theo]

I agree if you are racing, but most guys here i believe are only using their engines in a yard or off road kart. I think, but could be wrong, but is it sustained high rpms that makes a flywheel come apart?

theo

[jr dragster Tyler]

Takes one to know one!:thumbsup: :thumbsup:

Lol. I suppose you guys are right, Briggs, Tecumseh, Kohler ETC all designed these engines incase of mechanical governer failure and worst case situation.

[oscaryu1]

They really did not answer my question, but post #2 came closest to reality.


There was a rumor that Briggs & Stratton tested the 5HP flywheels for like 7000RPM or so at factory...

But I did recieve an email from a good friend of mine saying at the track, when 5HP flywheels started to come apart, they switched to 3HP flywheels (less rotating mass - less chance of KABOOM), and it stopped most of the explozions.

If anything, at least switch to a CAST 3HP flywheel.

[jr dragster Tyler]

So is the Aluminum flywheel on my 3 HP a hazard when I get my new cam in there?

[pmat]

I really dont think this is worth argueing, weve seen the pictures of what can happen, and that it CAN happen. the best thing to do is just to get a 1-3 hp stronger engine and gear it differently, you will get the same power, without running the risk of serious damage to your engine and most importantly yourself.:sifone:

[jr dragster Tyler]

Ohh where not arguing. Just though it'd be neat to see what a cast flywheel could do if it blew up. You wana see real aruging? Go over to 4 cycle where I found these pictures, Tough business over there!

[sayre315]

well, that guy prolly had a huge cam, billet rod, high comp. head
and a carb around 42mm
but... no billet flywheel

and on the ones that were just no govner they were probebly running without any load or had a cracked/chipped flywheel

[oscaryu1]

well, that guy prolly had a huge cam, billet rod, high comp. head
and a carb around 42mm
but... no billet flywheel

and on the ones that were just no govner they were probebly running without any load or had a cracked/chipped flywheel

If they could afford all that stuff, they heck better be able to afford a flywheel :roflol:

And yes, an aluminum flywheel = bad.

[jr dragster Tyler]

Well before I made that cam it would only run 3900-4000 RPM no governer. Havent tested the engine with the new cam as I am waiting for the sidecover gasket from my friend.

[oscaryu1]

Meh. Wouldn't be too worried. My trashpicked mower has a faulty governor. No muffler, and the carburetor just dumps fuel in. Runs about 5000 every startup. Loud.

[jr dragster Tyler]

So it just shoots to 5000 RPM or so then goes back down? My lawnmower is a trash picked mower, I built a 2 stage header for it. Its pretty loud but not too loud.

[Kenny_McCormic]

Just remember like Tyler said that magnet flying off at 10k is making ~2800 FT/LBs of energy, that's the same as the average 12 gauge slug.

Factory loaded .44 magnum 240grain hollowpoint ammo only makes around 800 FT/LBs, hot as you can load em in a carbine they only make around 1800 FT/LBs.

[THE HUNTER]

If you take a stock Briggs cast iron flywheel and turn it up to 10,000 rpm, which many limiteds will do, the magnet is moving at 256 ft per second. And, do to inertia weight and centrifugal force, that magnet weighs in at 2808 pounds. Being hit by just the magnet is like standing out in the middle of the freeway and letting a small car hit you at 60mph.

it weighs 2808 lbs... while its spinning. once its off the flywheel, and flying in a straight line, it weighs w/e it would when its sitting still. its NOT like getting hit by a small car doing 60mph

but i deff wouldnt want to be in its way.



Just remember like Tyler said that magnet flying off at 10k is making ~2800 FT/LBs of energy, that's the same as the average 12 gauge slug.

thats not its energy, just how much it would weigh do to centripetal force (which occurs when something is turning)


it said its traveling at 256 fps (which btw, is 174.5 mph), knowing that, and how much the projectile weighs (while resting) you can figure out how much energy it has. i doubt its anywhere near 2800 ft/lbs.

how much does a stock magnet weigh?

[Kenny_McCormic]

My bad, 2800lbs of stress is almost nothing. Assuming a weight of 2 ounces, its making somewhere around a .22LR(about 130 ft/lbs with Winchester silver box). That will still put a hole in your face and scramble your brains, or due to the large size of the magnet, cave your skull in.

[THE HUNTER]

yeah, i figured you just misread it lol

but thats still nothing to mess around with.
if i was going to run an engine at such high rpm i would get a better flywheel. even if a stock one could take it, i wouldnt want to take that chance.
its kinda like pointing a gun at yourself (or others). sure, as long as no one pulls the trigger (by say damaging the flywheel) you probably wont get hurt.
but its still not a risk i would like to take.