Making a Supercharger for 4HP-100cc-2 Stroke Engine: Got Ideas?

[asnipit]

I took an engine out of a snow blower (a 100cc-4hp-2 stroke) and was planning on hooking a turbine/fan assembly from a leaf blower, up to the carburetor. I plan on taking a 200/300 watt electric motor with a speed controller (HOOKED UP TO TWO 12VOLT 12Ah RECHARGEABLE SCOOTER BATTERIES) and connecting it with a 60 tooth pulley attached to the electric motor and a 12 tooth pulley to the turbine/fan so the ratio would make it spin fairly fast.

I would mount the snow blower engine on the end of an electric scooter and mount the supercharger on the side then run some sort of tube/pipe to the carburetor to the turbine. The electric motor would also be mounted to the side of the scooter and would connect to the turbine/fan pulley with a belt. The batteries would be under and inside the scooter. *The supercharger would most likely be used to add acceleration upon take off opposed to using it at the engines max power for top speed.

Do you think it will work?
Any thoughts or suggestions?

 

[Danger]

Welcome to PF, Asnipit.
I have some serious doubts about this, but I'm not an expert.
First of all, determine what the cfm capacity of the blower is. It might not deliver much more than the engine breathes normally. Remember that gearing the fan up from the motor won't result in a corresponding increase of airflow because the drag on the system will force the motor to work harder. If it turns out that you can get some significant boost, check with the engine manufacturer to make sure that the parts can take the stress. It's unlikely that a snow-throw engine has things like a thick-top piston, strong con rod, or premium bearings that a blown engine requires.

 

[asnipit]

Welcome to PF, Asnipit.
I have some serious doubts about this, but I'm not an expert.
First of all, determine what the cfm capacity of the blower is. It might not deliver much more than the engine breathes normally. Remember that gearing the fan up from the motor won't result in a corresponding increase of airflow because the drag on the system will force the motor to work harder. If it turns out that you can get some significant boost, check with the engine manufacturer to make sure that the parts can take the stress. It's unlikely that a snow-throw engine has things like a thick-top piston, strong con rod, or premium bearings that a blown engine requires.

I agree...Since the engine was used for a snow blower, it doesn't have an aftermarket following and I am sure its not meant to handle extra air into the engine. What specific modifications do you think i would have to do in order for the engine to be able to hanlde a supercharger?

 

[pantaz]

What specific modifications do you think i would have to do in order for the engine to be able to hanlde a supercharger?

A supercharger or turbocharger adds power by increasing the combustion chamber pressure. Therefore, any components directly influenced by that pressure need to be looked at -- head bolts, piston, connecting rod, rod journal, crankshaft, main journals. After that, just follow the flow of power transmission.

It's impossible to offer specific modifications without knowledge of the engine you are using.

 

[Danger]

My most serious recommendation in this instance, for the sake of both simplicity and economics, is to simply get yourself a bigger engine to start with. It'll save a lot of hassle.

 

[asnipit]

My most serious recommendation in this instance, for the sake of both simplicity and economics, is to simply get yourself a bigger engine to start with. It'll save a lot of hassle.

I thought about it but I am trying to use what i already have, to save money. I got the snow blower engine for free. I would like to first see if i can make modifications to the engine so it can be supercharged and save some money before i go out and buy a new engine. Its a fairly big engine (100cc 4hp) compared to most gopeds/gas scooters which have between a 25cc and 49cc engine.

 

[Averagesupernova]

I say try it if you want to. Sure you could blow it up, but it might be fun trying right? It was free right? It might be a waste of time and effort and maybe a few pennies in driving the blower but if you have considered all of the downsides and still have the desire to do so then I say do it.

 

[Danger]

I certainly agree with ASN that experimenting with stuff like this is the best way to learn as long as you're willing to risk failure. I've blown up a lot of **** in the past, and gained knowledge every time.
Another thing to look into is your local laws concerning such vehicles. Powered scooters are illegal where I live.

 

[Ranger Mike]

Whoa there pardner!
you may be at risk of seriously messing up the engine..here is why
some two strokes use a reed valve that premits entrance of the fuel/oil mixture. it is a thin steel plate that opens when engine vacuum sucks on the intake cycle...it closes as the piston compresses, thus sealing off the intake..the reed is designed to operate with normally aspriated engines..turbo/supercharge would pressureize the reed to open position
there are other design two cycles so research and fundamental knowledge of operation is a must before modifying

old go kart guys amped up the H.P. with lots of trick porting and other modifications..more compression etc..you may be able to modify the 4 hp to 8 or ten...
option 2 - run it on alcohol
3. NITRO? its been done before...

 

[asnipit]

3. NITRO? its been done before...

I probably wouldn't use a nitros kit (although its not totally out of the picture) because it would be a temporary speed boost, expensive, and would be hard to find a place to refill. I've thought about it and it would be pretty sweet to do but the nos would not last that long opposed to the electric supercharger hooked up to 2 12volt 12ah scooter batteries. Using the electric supercharger i would be able to stop/turn off, increase, and decrease the speed of the turbine because its hooked up to a speed controller.

 

[Ranger Mike]

Not nitrous...nitro
As in same stuff top fuel dragsters run
We ran it in a go cart
Instant hp
But about $100 a gallon these days

 

[asnipit]

So since superchargers don't work much on 2 stroke engines because the exhaust ports are open at the same time as the intake ports are, is it possible to build pressure in the cylinder using a supercharger?

 

[Ranger Mike]

Yes
If no reed valves
Are used
If the mill is timed via port exposure
U may be ok
We amped up the 2 stroke by
Cutting wider ports
Go for it...
If some is good
And more is better
Then too much is just enough- stroker mcgurk 1947

 

[Danger]

Aye aye on that, Mike. Horsepower is like sex, money, and firepower; more is better and too much is just right.

 

[jslade]

You need an expansion chamber exhaust. It is truly magnificent invention. It consists of a convergant and divergent cone. The divergant cone causes a negative pressure on the exhaust sucking fuel/air mixture into the header. The convergant cone causes a positive pressure whith crams the fuel rich exhaust back into the chamber under presure. The length of the chamber is such that the returning wave is syncranized to arrive at exhaust port just before the exhaust ports are closed. It is a super charger with no moving parts, INGENIOUS. Expansion chambers are standered on mondern high performance two stokes. I had the equations for building one once, I found them on the web. It was just simple math and easily measurable dimentions from your engine.

jslade

 

[ray b]

you need a compressor not a fan to supercharge
a leaf blower will not work to compress air
it is just a fan

twostrokes and add on superchargers doNOT go well

 

[asnipit]

you need a compressor not a fan to supercharge
a leaf blower will not work to compress air
it is just a fan

twostrokes and add on superchargers doNOT go well

I still think i could get pressure using a leaf blower fan assembly. If the air is being pushed into the tube/pipe that would be connected from the leaf blower to the carberator, then i think the air would be forced into the intake. The fan would be spinnning at high rpm's so i think it would compress the air enough to make a speed boost but i don't know that for a fact because i haven't tried it yet, and i haven't had much time to work on it.

Heres a pitcture of the leaf blower fan and cover to show exactly what I am using...

 

[Danger]

If you're planning to blow through the carb rather than suck through it, you have to rebuild the carb first. They're not made to take an overpressure from the outside. You'll have to build some sort of 'hat' to place over it.

 

[Averagesupernova]

A 2 stroke first draws the fuel/air charge into the crankcase through reed valves. The reed valves are to allow the fuel/air charge to enter the crankcase but to keep it from being pushed out as the piston pushes downward. When the piston uncovers the exhaust port the exhaust leaves the combustion chamber, however, some is left. A bit farther down on the stroke the piston uncovers the intake port which allows the compressed fuel/air charge into the combustion chamber from the crankcase. The crankcase compressed the fuel/air charge so it readily flows into the combustion chamber. Upon entering it helps expel any remaining exhaust.
-
Ok. I know the above is basic stuff that everyone on here already knew, but the point was to illustrate that if we have a blower pushing fuel/air charge into the crankcase while the intake and exhaust port are uncovered, there is nothing to stop the fuel/air charge from blowing right through the whole engine. I fail to see how anything can be gained unless some serious re-engineering of the exhaust system can be done to prevent what I described from happening.

 

[jslade]

Does no one see the beauty of the expansion chamber exuast?

 

[wolram]

An engine that comes to mind
http://www.paut-motor.com/source/B2Page_En/B2PageEn.htm

 

[Danger]

That's an intriguing little bugger, but I've had a bit too much beer to follow it right now. Will read it later.

 

[Ranger Mike]

too much beer?
what?
never!
quit trying to re-invet the wheel and go big cubes...and fergit the huffer...if some is good, and more is better, than too much is just enuff...Stroker Mcgurk..1947