Using Vertical-Shaft Engines

[EagleTalons]

Why would you even pay for a lightened flywheel then..?

 

[freakboy]

Its the craaaacccckkkkkkk.

 

[frederic]

So the question is: is a lawn mower engine have a heavy enough fly wheel without a blade to maintain through the power stroke/ stabilize drive shafts? Where is the payoff of a lighter flywheel more torque off the line?

The payoff is above the 4k-5k mark and above.

With less rotating mass, the engine can change it's speed quicker - up or down - from idle all the way to redline where ever that is determined to be. Kinetic energy doesn't get started at any particular RPM. Even at 1 RPM the flywheel is storing some energy. The higher the RPM the more energy can be stored. The more flywheel mass the more energy can be stored. The larger diameter the flywheel, the more energy can be stored. And the slower it will accelerate and decelerate.

How much you notice the difference depends on the power to weight ratio of the vehicle, it's gearing, and so on.

For example. Let us say a mower flywheel weighs 5 lbs, and the engine internals weigh 15 lbs, totalling 20 lbs.

If we shave off 1 lb off the flywheel, we now have 19 lbs, so 1/20, or a 5% difference.

If we're smart and remove that weight from the outside edge of the flywheel, the gain is actually higher than 5% because weight towards the hub is less useful in a flywheel role than weight at the outside diameter. About 6-1/2% increase in acceleration/deceleration capability of the engine.

That means your engine can go from 1000 RPM to 4000 RPM 6.5% faster in this example.

But your kart won't accelerate 6.5% faster.

With a 15 tooth sprocket on the engine and a 60 tooth sprocket on the axle, that's a 4:1 ratio so the live axle would have capability to accelerate and decelerate 1.625% faster than with the original flywheel on the engine, using the same made up example above.

With a tiny engine that's not much of a difference.

On a full size vehicle that produces 500 HP and has a 1:1 5th gear, that is a noticable difference. In auto racing that noticable difference might be a factor in winning and losing. This is why road racing cars (off-road rally cars, road course track cars, etc) often have short-stroke engines with button clutches. Less rotating mass far from the crankshaft centerline allows these engines to accelerate and decelerate quickly, which gives the driver more control of the car because he/she can shift through many gears keeping the RPMs up in the engine's peak HP range no matter what the speed.

 

[Rotore]

If you guys wouldnt mind using a vertical on a go kart is as simple as mount it, rotate the carb and add some extra oil.

Some of you might say bull but this is on for engines that use splash lub. Since the connecting rod on the crank move in a rotary motion at little extra oil for the connecting rod cap to splash in will actually create a fine mist as anderkart mentioned to me before. So it's not as hard to have a vertical on a kart just add some extra oil.

 

[DustinWolfe]

hey kaptain... can you post another link to the peerless 820? the link seems to be broken.

 

[DustinWolfe]

after writing that i thought... why dont i just look it up lol.

 

[Thedude]

using a vertical engine doesn't seem hard. just do this

http://www.youtube.com/watch?v=2mYDqKUqU1g

 

[Doc Sprocket]

Interesting vid. Two quick points- 1) He tosses the camshaft onto the floor with a resounding smack. Ugh. 2) The hammering of the gas tank is somewhere I wouldn't go, either. Extend the intake manifold instead.

That said, this was a proof of concept and he obviously doesn't care about this engine...

He didn't seem to have any trouble pull-starting it either, a topic that has come up with regards to vertical engine conversion (flywheel). Could that be because the compression is weak on that engine, or is it that the flywheel is heftier that some other verticals?

 

[Russ2251]

He didn't seem to have any trouble pull-starting it either, a topic that has come up with regards to vertical engine conversion (flywheel). Could that be because the compression is weak on that engine, or is it that the flywheel is heftier that some other verticals?

A combination of the above...OR...he is smart enough to know that he has to yank with some fortitude.

 

[sideways]

I didn't watch the vid (56k internet) but If he does what I did then yeah, it's easy. You could do it in an afternoon.

1. Take engine off mower
2. Remove boss from shaft
3. Take side cover off (assumeing engine is clean, if not clean it)
4. Remove oil slinger (it'l probably fall out when you take the side cover off)
5. Unbolt con rod big end
6. Make experimental dippers from tin
7. Make final dipper from plate steel
8. Torque big end bolts
9. Block old dipstick hole (the dip stick will leak if you leave it as is)
10. Get new/make/risk using old side cover gasket
11. Torque side cover bolts
12. Extend inlet manifold (I used a peice of poly pipe and a spare Briggs inlet)
13. Make supporting bracket for carb/tank
14. Make motor mount
15. Bolt engine to mount
16. Fill with oil to correct level (have fun doing that, easier said than done)
17. Try and start it!

When stating it, pull it as fast as you can, if you don't then it will bite you and not start.

Thanks

Hayden

 

[Thedude]

Hey sideways did yours work? i cant find your thread

 

[Russ2251]

All well and good...
Let's see it mount/work on a kart.
Anyone?
Anyone at all?

 

[sideways]

Hey sideways did yours work? i cant find your thread

Yeah, it ran fine, keeps on breaking pull starters though. The thread was "Briggs vertical to horizontal conversion" I think.

All well and good...
Let's see it mount/work on a kart.
Anyone?
Anyone at all?

Russ, I'l put it on my "scrap kart V2", we'll see how it goes then. It should be fine.

Thanks

Hayden

 

[Thedude]

keeps on breaking pull starters

couldn't you rope start it?

 

[Thedude]

also after you get driving the momentum of the kart will take the engine through its compression stroke

 

[Doc Sprocket]

also after you get driving the momentum of the kart will take the engine through its compression stroke

Once it's running, it will be fine. Don't need the kart's momentum.

 

[Russ2251]

Only thing I have done regarding lighter flywheels is to raise idle speed slightly higher than what might be considered normal and/or richen the low speed mix. The latter is not possible on an emissions carb.

 

[sideways]

couldn't you rope start it?

No, it's got a side starter, there's nothing to wrap a rope around. I'm making a kick starter for it anyway.

It runs fine once you start it, it didn't like idling but it didn't with the blades on either, the carby needed a new diaphragm, among other things.

Thanks

Hayden

 

[redsox985]

How about a vertical from a pressure washer? Those probably have heavier flywheels right? Or am I missing something else in the pressure washer that acts like a flywheel?

 

[sideways]

How about a vertical from a pressure washer? Those probably have heavier flywheels right? Or am I missing something else in the pressure washer that acts like a flywheel?

You could, but then you've still got the tapered shaft issue. Tapered shaft is easy enough to get around though, especially if you don't want a cent clutch or TC.

I'm pretty sure you can fit the flywheel from a normal Briggs anyway.

I don't find the flywheel thing an issue (apart from the mashed pull starters of course), you kart will accelerate slightly faster with a lighter flywheel anyway. If my pull starter was better designed and stronger it wouldn't be an issue.

Thanks

Hayden